Planetary Playtime

SKY Live

Starting out three years ago I inevitably began my astrophotography with the Solar System, the planets and other related bodies are after all closest to Earth but, as it turns out, are far from easy to image.  At the time using a Skywatcher 150PLS and ZWO120MC webcam, I achieved some reasonable images of Saturn, Jupiter, Mars, the Moon and later the Sun but with plenty of upside potential for improvement! Shortly thereafter having acquired my current set-up, I realised that my interest lay in DSO targets and, except for the lunar eclipse in 2015 and the odd white-light image of the Sun, have mostly ignored the Solar System, until now.  Currently no less than 7 planets are present throughout the night at the moment, the largest of which provide good viewing and imaging opportunities – planetary sky above for 11th June 2017 at 11 p.m. taken from TheSkyLive.com

From April to July there are limited DSO opportunities for my scope and camera and the only choice is to look elsewhere; the absence of astronomical darkness also doesn’t help.  This year the problem has been particularly frustrating as I’m itching to get to grips with my new ZWO 1600MM-Cool camera, which after a few hurried shots early in the year proved very exciting.  And so I’ve recently been playing around, returning to old subjects and unfamiliar equipment – first imaging the comet C/2015 V2 (Johnson) and again trying my hand again at some of the planets.

Unlike the DSLR and ZWO 1600MM-Cool CMOS camera, I the ZWO 120MC video based webcam is more suitable for the planets, which poses a whole new set of issues and the use of completely different capture and process software, in my case Firecapture for imaging and Registax for processing. Both are excellent free programmes but after three years required some re-learning.

Firecapture helps a lot when experimenting to find the best gain, gamma and exposure settings for each planet but there are still other difficult tasks to overcome, in particular planetary rotation, size, seeing conditions and my personal nemesis – focus – which after numerous attempts I have still failed to master. The truth is that even with the gas giant Jupiter, the planet appears quite small with the 81mm aperture of my Williams Optics refractor and detail is difficult to make out in order to focus when also blurred by atmospheric turbulence.  Notwithstanding, the belts and even the Great Red Spot are evident in the resulting images taken between 14th and 25th June, albeit a little fuzzy!

Webcam image data capture even over a couple of minutes is prodigious and requires significant processing capacity to handle.  I have found the aptly named Castrator software useful in this regard to cut the final AVI image down to the actual size of the planetary object, thus removing substantial areas of superfluous black sky.  Registax is equally powerful for video processing and stacking, in particular the intriguingly named Wavelets, which magically help restore detail and sharpness.

Saturn

In the case of Saturn, which at the moment is quite bright and well orientated, the problem is also size and especially seeing, in my case not helped by a 35 minute imaging window as the planet transits between two trees at the end of my garden; at least the large copper beech on the left blocked out the Moon at the same time! At this location Saturn is less than 15o above the southerly horizon and as a result seeing conditions are at best poor and usually bad.  However, I manged some blurred images that clearly show Saturn’s rings and even a little colour.  I’m now looking forwards to seeing more of the final Cassini mission images before the satellite crashes into the plant in September.

These are obviously not my best images and I already feel the need try again next year, hopefully with a more appropriate telescope (Santa has already been informed). Notwithstanding, my return to the Solar System has been fun and, in between imaging I’ve also taken time to carry out observational astronomy – something I rarely do nowadays being otherwise consumed by astroimaging paraphernalia.  DSO astrophotography is likely to remain my main interest in the future and I can’t wait to revisit old favourites later in the year with the new ZWO 1600MM-Cool camera.  In the meantime, I have renewed respect for the planetary astrophotographer’s, I’ll be back another time.

 

Playing poker with the heavens

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It’s that time of the year when Earth ploughs its way through the tail of comet Swift-Tuttle, resulting in a the Perseids meteor shower. The name is derived from the location of the radiant point within the constellation of Perseus and Greek mythology’s reference to the sons of Perseus.  Such are the orbital paths that Earth’s encounter with the comet occurs around 11th to 13th of August each year and can provide an enjoyable spectacle as the meteor particles rain down through atmosphere.

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Travelling at some 37 miles-a-second, the sand-grain size particles literally burn up in the blink of an eye, with the energy created producing a bright path of the light path that very briefly shoots across the night sky, sometimes green or red coloured.  Some 16-miles in size, from time-to-time the comet itself actually passes nearby to Earth during its orbit around the Sun, last time being in 1992 and the next in 2126.

Perseid ZHR 2016

Whilst the timing of our annual encounter can be predicted with good accuracy, a sight of each individual meteoroid particle is entirely down to chance.  Over a period of two or three days the frequency (Zenithal Hourly Rate or ZHR) may vary from a few tens to a few hundred, depending on which section of the comet’s tail Earth is passing through. Of course, observation requires a clear sky – something that’s been notably absent here at Fairvale Observatory for some time now.  Notwithstanding, this year there were three consecutive clear, dark, warm nights, which occurred shortly after a new Moon that provided excellent Perseid observing opportunities.

Viewing is a matter of lying back in a suitable garden chair looking up towards the radiant position, which starts in the north east then moves to the south during the night and just waiting.  This year peak Perseids were on the evening of 11th/12th August between about 11pm and 1am, during which time we probably saw between 20 to 40 hits an hour; the previous and subsequent evenings were also quite good, though with slightly less hits.  Such is the randomness of each meteoroid hit that in practice Perseid trails occurred all over the sky and were easy to miss if outside the peripheral vision.  However, overall it was a very good and enjoyable show but probably  not as good as that from the ISS.

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At first this looks great but look again, it’s an aircraft trace – living next to Gatwick airport doesn’t help. The giveaway is in the next shot which shows the track continuing i.e. too long and too far for a meteoroid.

At the same time using the Canon DSLR and an ultra-wide lens, I also attempted to image the Perseid shower.  On the first night using Vixen Polarie tracking, set towards the radiant position and on the second night pointing east, without tracking.  Control was via an intervalometer, with camera settings at ISO 800, 20 or 14 second exposures, and 5-second shot intervals.  Even with such a high incidence of meteoroid hits, obtaining a photograph was still very difficult; mostly the strikes occurred outside the field-of-vision or sometimes in the 5-second pause.  In total I shot over 300 images but obtained just two Perseid hits and more than a few plane tracks!  Even with good preparation and clear skies it really is a case of chance but I was nonetheless pleased to have my share of luck this time and look forwards to another opportunity this time next year, weather permitting.

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Gotcha – the real thing: ISO 800 @ 20 seconds with tracking.

 

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Only just! This time the Perseid is just sneaking out of view at the bottom of the frame: ISO 800 @ 14 seconds, without tracking.

Transit

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Unfortunately not my image: Mercury starting its transit across the Sun today, photo by NASA.

The transit of Mercury across the face of the Sun takes place about thirteen times each century and today was one of those occasions; the next is on 11th November 2019.  With months of bad weather I’ve been unable to undertake very little astronomy for some time but albeit late, spring actually arrived last week and I took the opportunity to shake-down my equipment and experiment with settings for solar imaging in the hope of capturing Mercury’s transit.  Using a Baader solar filter and both the William Optics GT 81 and Skywatcher 150PL, I have successfully imaged the Sun before.   Of course, inevitably I aspire to a dedicated Lunt or Coronado solar telescope one day in order to image details of the chromosphere and prominences, which are not visible using a white-light solar filter.

Sun spot activity is limited at the moment but the Baader filter and WO GT81 do a reasonable job, although I find achieving focus of the Sun quite difficult.  Using the DSLR I experimented with the field flattener and an alternative basic 1/ 1.25” nosepiece, which produced a preferable result of a slightly larger and sharper image.  I also tried the ZWO ASI 120MC webcam but as I don’t use this very often struggled to get the settings right for any sort of image – I’ll experiment more with that over the summer. I also put EQMOD-ASCOM and the newly acquired gamepad control through their paces which both worked well, so I was ready for the transit – weather permitting.

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Last week’s test image of the Sun, with sun spot top left: WO GT81 + 1.25″ nosepiece | 1 / 2,500 sec @ ISO 100

After days of sunshine, albeit with high cloud that has continued to prohibit astrophotography at night, I was nonetheless hopeful of seeing at least some of the transit today.  Notwithstanding, Sods law arrived in the form of a belt of cloud over south east England last night!  Not to be defeated I watched the sky and cloud forecasts which suggested a glimpse of the transit might still be possible.

In hopeful anticipation I set up the equipment just before contact at 12.12 pm BST and shortly afterwards obtained a good view of Mercury as it started its transit across the face of the Sun. For the next three hours I managed glimpses of the planet as it continued its journey.  It is very, very small but forms a distinct, sharp black dot against the background of the Sun when compared to the more diffuse, grey nature of the sunspots.  It was an exciting experience and despite the drawbacks – cloud has now completely covered the sky for the rest of the transit – it was very enjoyable; so what’s the problem?

Despite all my preparation for imaging everything that could go wrong did and I was unable to obtain even a single photograph:

  • On setting up the camera and starting to focus the EQMOD-ASCOM tracking stopped and Carte du Ciel froze. Despite re-starting the set-up numerous times the tracking would not work!
  • Finally after resorting to the Synscan handset for tracking control, for some completely inexplicable reason I could not get any sort of image on the camera, that otherwise was working OK!

As I have learned many times before, the art of astronomy is patience and persistence but I am very disappointed not to have imaged Mercury during its transit today.  Ironically once the cloud put an end to further activity, I tested the EQMOD-ASCOM tracking once again and it worked fine.  Perplexed does not describe my feelings – oh well, 3-years to prepare for the next transit!

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How I felt after today’s imaging!!! The transit view was still very good and I’m grateful for the breaks in the cloud.

 

180 Degrees

Viewing from Fairvale Observatory is far from ideal but I have no choice and need to make the most of it:

(i) Without going down the garden (which is not practical and would then totally obscure the southerly view) my house blocks the entire northern sky, critically including Polaris;

(ii) We have very high +/-12ft hedges surrounding the garden;

(iii) Directly east is a large house that completely obscures the horizon;

(iv) South east and south are very large trees;

(v) To the west is a wooded hill, thus blocking the horizon in that direction, and

(vi) Some 7-miles to the south is Gatwick Airport which produces significant light pollution, as well as aircraft that regularly fly through my images as well as others from Heathrow, also not far away.

It’s a miracle I am able to undertake any astrophotography and I long for the day I live somewhere with better conditions.

In the meantime I have to make do with the 180o I have available.  For the record and with great skies and good weather, this week I compiled a photo mosaic of the aforesaid view – which illustrates some of the aforementioned problems and is in itself an interesting picture. The scene is stitched together from six DSLR shots that encompass most of the east to west panorama but in order to achieve this, the resulting photograph becomes severely distorted.

The principal view is directly south, with the Meridian pretty much straight ahead.  Low angle viewing and imaging is almost completely impossible but depending on the timing and some crafty shooting, the mid-angle objects can be accessed as they pass between the trees. The best imaging is therefore mostly restricted to a 20o range between about 65o and 85o and within +/- 20o of the Meridian; high angle east and west views are feasible but seeing in these directions is impacted by the greater atmospheric distance through which the light has to travel.

For now this is my night time playground: it is challenging and can be frustrating but with clear skies, preparation and patience it’s good fun and much can still be achieved.

Night sky panorama from Fairvale Observatory + obstacles: the tree on the left is very large +200 year-old copper beech, the coniferous trees  due south are closer to the property boundary - thus increasing their impact   on seeing.  The red line on the left approximately marks the East and the central red line is the Meridian.

180 degree night sky panorama from Fairvale Observatory + obstacles: the tree on the left is a very large +200 year-old copper beech, the coniferous trees due south are closer to the property boundary – thus increasing their impact on seeing. The red line on the left approximately marks the East and the central red line is the Meridian.

Equivalent Cartes du Ceil planetarium view at the same time.

Equivalent Cartes du Ceil planetarium view at the same time.

Canon Koppernigk’s Conjunction

This time of the year is something of a fallow period for astronomers: short nights combined by with the complete absence of astronomical darkness and fewer DSOs.  I have personally found this year more difficult than usual as since April 25th, following an operation to replace my left knee, I have been physically unable to set-up Fairvale Observatory and undertake astronomy of any sort.  Notwithstanding, once over the initial few weeks of pain, I have tried to use the extra time afforded me usefully.

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I have been reading Arthur Koestler’s excellent book The Sleepwalkers, which charts the history of man’s understanding of the universe and astronomy.  Speaking of fallow periods, in the book I’m just past the very long period of inactivity and general superstition regarding the cosmos that occurred during the Middle Ages, which followed the more enlightened thinking of the Greeks, particularly Pythagoras; taking account of the Greek’s progress in understanding the Universe, our astronomical knowledge might have been 1,500 years more advanced today were it not for this prolonged medieval hiatus!  Fortunately Copernicus (his better known Latin name) finally initiated what has become today’s heliocentric model of the Solar System, although his seminal work On the Revolutions of the Heavenly Spheres was only published just a few hours before his death after a delay of 30-years, such was his reluctance to put forwards such thoughts at that time.

Next, I have just completed the 6-week AstroTech MOOC course organised by Edinburgh University, which covered the scientific logic behind astronomical discoveries and the technology that lies behind them.  This was my third astronomy MOOC and provided some interesting insight into telescope and imaging technology, as well as filling time during my recovery.

Finally, as my (limited) mobility has slowly started to improve, the night sky has recently provided a fascinating show of its own that did not require the observatory’s paraphernalia and, furthermore, beautifully demonstrated the principles originally outlined by Copernicus in 1543.

During the latter part of June Venus and Jupiter moved inexorably towards very close conjunction by the end of the month.  Reaching just under ¾ of a degree separation on 30th June and 1st July this is a rare event, which with a clear sky could be easily viewed with the naked eye.  Better still, I set out to photograph the two planet’s journey during the preceding 12 days, thus illustrating Copernicus’ revolutions around the sun of these two heavenly spheres.  Whilst any school child will today understand this process, it is a frightening thought that belief in such a mechanism could once have led to the death penalty!

Obscured from view at Fairvale Observatory as Venus was just 17 ½o above the western horizon, I had to travel to a nearby location which provided a clearer westerly viewpoint of both planets at their low attitude.  In order to obtain a series of comparable images and thus show the real spatial changes occurring up to conjunction, all pictures were taken from exactly the same location.  With my Canon EOS 700D fixed on a photographic tripod I shot a series of images over a 50 minute period using either the 18mm or 55mm telephoto settings, playing with ISO and speed settings as darkness progressed; this was roughly the time the two planets took to disappear below the Earth’s horizon after achieving Civil Darkness.

The resulting photographs show Jupiter apparently advancing on Venus before at conjunction ‘passing’ close by on the aforementioned days.  Whilst Jupiter is the third brightest object in the night sky (after the Moon & Venus) and nearly 12 times the size of Venus or 1,400 times by volume, the planet looks very small by comparison to Venus.  This of course is the effect of perspective, with Jupiter currently some 565 million miles distance from Earth, whereas Venus is only 48 million miles; furthermore although at -1.8 the apparent magnitude (brightness) of Jupiter is high, at -4.4 Venus is much brighter.

18th June 2015: Jupiter left, Venus right - trees on the horizon provide a reference scale as the planets move towards each other during the month in subsequent photographs

18th June 2015: Jupiter left, Venus right – trees on the horizon provide a reference scale as the planets move towards each other during the month in subsequent photographs.

25th June 2015 + 7-days

25th June 2015 + 7-days

30th June 2015 + 5 days.  Nothing - dark thunder clouds completely obscure the western sky during conjunction!!!

30th June 2015 + 5 days. Nothing – dark thunder clouds completely obscure the western sky during conjunction!!!

1st July 2015. Bingo = conjunction; though one day later Jupiter has now moved to the right of Venus.

1st July 2015. Bingo = conjunction; though one day later Jupiter has now moved to the right of Venus.

1st July 2015. Close-up of the conjunction using 55mm telephoto setting and ISO 400 - Venus now left & Jupiter right.

1st July 2015. Conjunction close-up using 55mm telephoto setting and ISO 400 – Venus now left & Jupiter right.

Unfortunately I am expecting it will be at least another month before I have recovered sufficiently to consider setting-up Fairvale Observatory again, by which time Astronomical Darkness will thankfully be slowly returning.  In the meantime I’m looking forwards to the next section of The Sleepwalkers which covers Kepler and Galileo and hopefully exciting developments from the New Horizon Pluto fly-by and more from the Rosetta Mission and the re-awakening of its Philea lander.  Given clear skies there should also still be plenty to see without the observatory: The Perseids, Saturn and of course at the centre of our Solar System as determined by Copernicus, the Sun, which will be at aphelion on 6th July – though you wouldn’t think so judging by the high temperatures currently prevailing in the UK and Europe!

 

Alternative Eclipse

With astronomy preparation is everything and so with the prospect of a solar eclipse here today I have been getting ready during the past week.  I looked at and imaged the Sun using my Skywatcher 150PL and a bespoke solar filter last year.  Whilst I was pleased with the results, such is the field-of-view of the 150PL that the resulting image only covers sections of the Sun and a full picture needs to be created using a mosaic; the upside of this is high magnification and therefore better detail of the Sun’s surface.  With the prospect of an eclipse I wanted to try and image the entire spectacle this time and therefore constructed a new solar filter to fit my William Optics GT81 refractor telescope, which has a wider field-of-view and all together better optics that would comfortably image the entire Sun.

Using Baader AstroSolar ND 5.00 safety film and some cardboard, I constructed a tube which fits exactly over the end of the telescope, with the film across the front but not stretched.  By restricting wavelengths the film removes about 99% of the Sun’s light and allows safe viewing but is very difficult to work with and must be treated carefully to ensure it is not damaged; birds can be attracted to the film’s silver finish and may peck holes in it when fitted, it is therefore important to be aware of such threats and, in my case, I also constructed a cardboard slip to cover the filter when the telescope is left unattended during use.  It is also very important to either block off or remove the guidescope and / or finder from the telescope, which without a filter could otherwise also focus on the Sun and either burn out or even worse, cause personal injury.

Home-made solar filter on the William Optics GT81.  When used I blocked-off the red dot finder and removed the finder scope in order to attach another home-made Sun finder.

Home-made solar filter on the William Optics GT81. When used I blocked-off the red dot finder and removed the finder scope in order to attach another home-made Sun finder.

The Players: having constructed the filter and with a clear sky on Wednesday I therefore tried it out and furthermore experimented with exposure settings, with good results.  Earlier in the month I had captured an excellent image of the quarter Moon too.  So I was ready to go, right?  Wrong!

The Moon @ First Quarter  | WO GT81 & Canon 700D + FF| 1/100th sec @ ISO 100 | 24th February 2015

The Moon @ First Quarter | WO GT81 & Canon 700D + FF| 1/100th sec @ ISO 100 | 24th February 2015

GT81 + Canon 700D & Baader ND 5.00 Solar Filter 1/500th sec @ ISO 100 | 18th March 2015

GT81 + Canon 700D & Baader ND 5.00 Solar Filter
1/500th sec @ ISO 100 | 18th March 2015

The Sun 1/20th Sec @ ISO 100 | 18th March 2015

The Sun
1/250th Sec @ ISO 100 | 18th March 2015

Despite my best planning it was cloudy here at Fairvale Observatory this morning, something that has been proving a major obstacle to any astronomy all this month.  Notwithstanding, I have instead experienced an ‘alternative eclipse’.

First, I recorded the change in light during the eclipse.  Though ‘only’ an 85% eclipse here the deterioration in light was very noticeable as well as other features: it got colder and the birds became quieter.

20th March 2015 Eclipse - the sky just after contact at 9.50 a.m.

20th March 2015 Eclipse – the sky at 9.50 a.m. sky just after contact.

Contact + 15 minutes

Contact + 15 minutes

At maximum 85% eclipse.

At maximum 85% eclipse, 9.30 a.m.

Next I ‘looked’ at the progress of the eclipse using Google Sky, which seemed to be very accurate.  It was fascinating to note that four other planets were lined up alongside the Sun at the same time, though of course would not be visible in the daytime sky even if it had been clear.

Eclipse as 'seen' by Google Sky

Eclipse as ‘seen’ by Google Sky

Google Sky screenshot.

Google Sky screenshot.

In between my own real time experience, I watched the BBC coverage of the event which provided some excellent images from the UK and especially from the air off the Faroe Islands where totality occurred.

Uk eclipse courtesy if the BBC.

UK eclipse courtesy if the BBC.

Eclipse totality at 28,000 ft from the Faroe Islands.

Eclipse totality at 28,000 ft from the Faroe Islands.

Baily's beads in hydrogen-alpha image. Faroe Islands March 2015.

Baily’s beads hydrogen-alpha image.   Faroe Islands March 2015.

Diamond Ring hydrogen-alpha image. Faroe Islands March 2015

Diamond Ring hydrogen-alpha image.
Faroe Islands March 2015

An eclipse is astronomy in action and inevitably I’m disappointed not to see and image the actual eclipse here but my alternative eclipse was still interesting and good fun. I was lucky to witness a total eclipse in France in August 1999 so that’s a 50% success rate so far.  The next partial eclipse in the UK will be on 12th August 2026 so I have time to prepare but, of course, will be unable to do anything about the weather again.  Fingers crossed then I suppose!

Another perspective.  Eclipse 2006, taken form the ISS the Moon's shadow passing over Turkey.

Another perspective. Eclipse 2006, taken from the ISS the Moon’s shadow passes over Turkey at 2,000 kph.

Lovejoy Part-2

I first became acquainted with C/2014 Q2 Comet Lovejoy just before Christmas and have since been keen to obtain my own image of the object from Fairvale Observatory; at the time I was fortunate to obtain a photograph of the comet from a fellow astronomer in La Palma.  Despite the comet reaching its best positon on January 7th, some 44 million miles from Earth and with the apparent magnitude (brightness) improving throughout January to less than +4.0, unfortunately nature and life prohibited me from attempting this task: Christmas, New Year, travel, bad weather, full Moon etc.  A couple of clear skies did present a good visual sighting through binoculars but no image.

Last week, on Thursday evening, I eventually got my first opportunity but due to very strong winds (hence the clear sky) was unable to even set-up the equipment.  The following evening a cold but clear sky again occurred and this time I took my chance.

Photographing and processing a comet is not straightforward.  Since my last post, Comet Lovejoy has tracked west (to the right) of the Orion constellation and at the time of imaging was located just above the western end of Taurus, before it passes west of Pleiades on 19th January.  The first problem is therefore obvious – it’s travelling very fast, about 82,000 mph.  Fortunately Livecometdata.com provides real time information on the comet’s journey, which is both impressive (how does it do this?) and very useful.  Inputting the real time RA and DEC location data into the SynScan handset, the mount slewed straight to the comet, which was just off-centre of the field of view.  And thus I had my first, proper live view of a comet – fantastic! Now for the tricky part: how to get an image?

I had already posed this question on Stargazers Lounge and had a number of useful suggestions. Of course, whilst the mount tracks the celestial sphere, the comet is making its own way through the sky, which is not the same path as the stars seen from Earth; I believe it is possible to track the actual comet but that’s too difficult for me. Therefore, it is necessary to err towards lots of shorter exposures to avoid blurring; the longer the exposure the more likely it is the comet’s tail can also be captured in the image but it is a fine line between achieving this and blurring.  In the end I took two sets of images at 20 seconds and 60 seconds – probably too cautious but I was happy with the result and will be better prepared for my next comet, whenever that is.

Then came the next obstacle – stacking and processing.  I had not thought about this before but in the world of stacking, the software is unable to distinguish the comet from stars.  As a result it is necessary to identify the comet in each light frame by manually tagging it; at this point I regretted taking x40 exposures! Deep Sky Stacker will then stack using one of three procedures which basically prioritises either the comet or the stars or a combination of both – I chose the latter.  As usual post processing in Photoshop is then used to improve the final image.

C/2014 Q2 Comet Lovejoy WO GT81 + Canon 550D (modded) & FF | 40 x 20secs @ ISO1,600 + darks | 16th January 2014

C/2014 Q2 Comet Lovejoy
WO GT81 + Canon 550D (modded) & FF | 40 x 20secs @ ISO1,600 + darks | Fairvale Observatory 16th January 2015

Whilst I am very excited to have successfully photographed Comet Lovejoy, I was less than impressed by the stacked image and actually prefer the original.  Processing comet images takes the dark art of processing to a new level and I feel I’ve only reached the learning foothills so far.

Lovejoy will be in the sky for some weeks to come as it tracks across Andromeda and Perseus during February and into Cassiopeia in March.  Whilst the best may be almost past, I certainly hope to follow its progress and, subject to conditions, might even attempt to image it once again before it continues its 8,000 year orbit into deep space.  However, for now I’ve got my comet and am well satisfied – I will spend the intervening winter days practicing my comet stacking.

Comet Lovejoy WO GT81 + Canon 550D & FF | 15 x 60 secs @ ISO1,600 + darks| 16th January 2015

Comet Lovejoy
WO GT81 + Canon 550D (modded) & FF | 15 x 60 secs @ ISO1,600 + darks| Fairvale Observatory 16th January 2015

Reflections – 2014

2014 has been my first full year of astronomy and I thought it would be useful (for me) to recap, thereby hopefully providing some encouragement and momentum for 2015. It’s been a good year which I have enjoyed but it only gets a little easier, slowly, and I can see many challenges ahead.

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JANUARY TO MARCH

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At the start of the year I was still getting to grips with my original basic equipment, purchased in 2013 as an introduction to astronomy to see if I liked it: EQ3-2 mount, Skywatcher 150PL telescope and two basic Plössl eyepieces and Barlow.  Though good, the shortcomings of the equipment quickly became apparent even for modest viewing tasks, so I soon made some important additions.  In no particular order these were: RA and DEC motor drives, a Telrad finder and two better quality, wide-angle eyepieces.  All of these items made a noticeable improvement to my astronomy and eventually my growing interest in astrophotography.

As a result, at the start of the New Year I decided to purchase a Canon 700D DSLR camera, which has since opened up a whole new world, literally.  I have considerable SLR experience and had been using a compact digital camera for some years but the need to understand and use the technology embodied in a DSLR for astrophotography is, as they say, a whole new ball game.

At this stage, my approach to astronomy was to try and learn the basics first by using basic equipment, thereby understanding the nuts and bolts of astronomy before moving on to more technical processes and software driven equipment. Moreover, I hoped such an approach would provide a good, long-term foundation of knowledge to undertake more ambitious tasks one day; walk before you run.

Although a member of the Flamsteed Society, its location at Greenwich does not lend itself to regular, on-the-ground astronomy from which I might otherwise learn first-hand from other members. Unfortunately more local clubs are also absent, so the learning curve has been steep and mostly personal and hands-on, though I must recognise the extensive and generally excellent help gleaned from the internet and various astronomy blogs, noteworthy of which has been Stargazers Lounge.  I have often been disappointed by some of the retailers who, in my experience don’t relate well to customers and / or provide clear, helpful guidance or adequate aftersales support.  My interpretation is that they consist of persons who have probably started astronomy shops as an extension of what was previously a hobby and often lack the commercial and personal skills required for such a business. Thankfully there are exceptions and it is they who I shall return to with my business in the future, whenever possible.

  Date Object* Feature  / Name
Feb Jupiter Afocal Images
Moon DSLR mosaic
Greta Orion Nebula Afocal Images

*Record of photographic images taken in 2014

APRIL TO JUNE

By now I knew I wanted to pursue astronomy as a hobby and, in order to fast track my learning process and experience the subject at a higher level, I undertook a one week astronomy course at the private Tacande observatory in La Palma. The equipment there was outstanding and so was the night sky and guidance provided by the owner, Joan Genebriera.  Afterwards I was hooked and my aspirations were sky high, literally.

Virgo Group

Virgo Group – Galaxy Supercluster| Canon 350D from Tacande Observatory, La Palma

Returning from La Palma brought me back down to Earth, however, undeterred I felt it was time to try my hand at webcam planetary imaging. On the face of it easy but, as usual, looks can be deceiving. Online advice indicated that it was possible to adapt and rig-up an old webcam for such purposes but my attempts to do so using a spare Logitech webcam only ended in misery.  I therefore decided to bite-the-bullet and purchase a more suitable, off-the shelf one. The Holy Grail for entering webcam imaging is apparently the Philips Toucam but alas it is no longer made and finding one second-hand is very difficult.  I therefore soon realised that it would be necessary to purchase a new webcam and, furthermore, it made sense to get one which was specifically made for astrophotography, the theory being it would work out-the-box.  As a result I purchased the ZWO ASI 034 MC colour webcam but, despite my best efforts was unable to get a picture and decided to visit the retailer in person, determined to find out if it was me or the camera; as it turned out it was neither.

The first problem turned out to be the camera software SharpCap, which despite assurances, would not work with the camera.  Next, for reasons I still don’t understand, the alternative FireCapture software would also not work until a more up-to-date version was downloaded.  Notwithstanding, it also became evident that the camera would not work through a USB 3.0 port – though at the time this was not specified anywhere in the accompanying literature.  Finally, with the camera plugged in to the USB 2.0 port and the up-to-date version of FireCapture, it worked!  Getting to this point took me countless hours at home, a long trip to the retailer (who was very helpful) and then still some 2-hours to get it working.  So much for working out-the box!  This again seems to be a feature of astronomy.

From this and other experiences with equipment, software and manufacturers I have concluded that the world of astronomy is fraught with unnecessary problems often arising from just inadequate advice (see previous comment). It is assumed, by others: manufacturers, retailers or more technically minded astronomers, that the user will possess similar skills to make things work but, as many /most of us are newcomers this is, to say the least, an unhelpful assumption.  I have therefore learned that the internet is your friend.  Through the use of various online sites and blogs, other astronomers have given their very helpful and often not inconsiderable time and advice, for which I am eternally grateful.

Whilst this was all happening at the retailer, I took the time to review the camera I had purchased more closely and at the last moment decided to exchange it for the inevitably more expensive ZWO ASI 120 MC version, which unlike the 034 MC version can be used for autoguiding – I hoped futureproofing the purchase, time will tell.  It is interesting to note that the current version of this camera (a) comes with different software and (b) has been upgraded to work with USB 3.0 – well why wouldn’t it in the first place, as most computers now use this specification?  This suggests to me: did they really think about the camera’s design and operation properly at the beginning?  However, following this breakthrough using the webcam for imaging was still to provide its own problems, which I am still grappling with.

SW 150PL x2 Barlow & ZWO ASI 120 MC

SW 150PL x2 Barlow & ZWO ASI 120 MC

Using the ZWO ASI 120 MC I first started imaging Saturn, with some success. However, using the EQ3-2 mount to find, focus and image was very difficult, especially when I tackled Mars. In this case the size of the planet makes all the aforementioned issues even more difficult but, after lots of attempts I managed to get an image – altogether with plenty of room for improvement but satisfying nonetheless. I subsequently discarded the webcam in favour of the DSLR, with which I am more comfortable and due to the lack of suitable, mostly planetary objects through the summer period.  With the return of Jupiter in recent weeks and the prospect of using the ZWO webcam for autoguiding, I have returned to using it again but given the time that has since elapsed, I need to relearn its use all over again!

At this point I had concluded that I wanted to pursue astronomy and astrophotography.  I was also drawn inexorably towards astroimaging DSO objects; they provide numerous, albeit more difficult targets at all times of the year and I have found their combination of otherworldly beauty and science fascinating – I am now on a slippery slope that I feel will last for years!  The implications of this conclusion and based on what I had learned over the preceding year about my basic equipment had only one consequence, I needed better equipment.  There are astronomers who will say this hobby can be done cheaply, frankly I don’t believe it.  Even buying second hand and generally making-do, the need for another piece of equipment never seems to stop – ask my wife.

Resigned to this course of action and the inevitable extensive analysis of what equipment was best suited, I reached a conclusion of what equipment I needed surprisingly quickly, though still prevaricating over innumerable makes and models available.  In the end I purchased an AZ-EQ6 GT mount and William Optics GT81 FPL3 triplet achromatic refractor.  I could have shaved £400 to £500 off the cost by purchasing other very good but cheaper makes and models but the WO is a beautifully tactile piece of obviously very well made equipment, which is a pleasure to own and use.  I had originally intended to purchase an HEQ5 mount but on taking the long view (no pun intended) and considering the superior and critical payload capacity decided to move up to the EQ6, which then became the AZ-EQ6 GT for its superior belt driven mechanism and even better payload.

Date Object* Feature / Name
April M104 Sombrero Galaxy
M1 Crab Nebula
M3 Globular Cluster
M84 Lenticular Galaxy
M95 & M96 Group Spiral Galaxy
Virgo Group Supercluster of Galaxies
NGC 4435/38 The Eyes (Nonet) Galaxies
May The Moon
Mars
Saturn

JULY TO DECEMBER

The absence of good astronomical darkness approaching the Summer Solstice at the end of June and onwards until later in August, makes imaging difficult at this time of the year.  Furthermore, the summer skies are generally less interesting and altogether provide limited opportunities.  As a result the one object remaining, that hopefully dominates the sky at this time of the year, is the Sun.  It was therefore time to start solar astronomy.

Given the obvious dangers I approached the task carefully, getting a made-to-measure Baader Astro Solar filter for use with the Skywatcher 150PL.  Rightly or wrongly, at this initial stage I decided to use the 150PL as I figured the larger, open design of the Newtonian reflector would help cooling.  The result was fascinating, with sun spots and general surface granulation clearly visible. However, the set-up has two drawbacks: (i) the resulting FOV is small and requires six or more images to cover the whole of the Sun, and (ii) such a filter only produces a view of white light, not allowing the more spectacular features evident at a other wavelengths, such as prominences, to be viewed.  For this a considerably more expensive solar telescope or highly specialized filters are required – such is the fascination of our local star I can see the time I will want to pursue this branch of astronomy further.

Sun Mosaic SW 150PL + Baader Astro Solar Filter + Barlow x2 | Canon 700D DSLR

Sun Mosaic
SW 150PL + Baader Astro Solar Filter + Barlow x2 | Canon 700D DSLR

Having since used the new equipment for nearly six months now I have no regrets – you get what you pay for.  However, as usual there have been problems to overcome.  The mount is very solid and was a real pleasure to use but from the outset I have faced one big problem – polar alignment.  With no view of Polaris or any of the northern sky, as my house is in the way, combined with restricted views to the south, east and west due to adjacent housing and trees, the only options were drift alignment or the polar alignment routine that I latterly discovered in the SynScan handset. For the moment the SynScan method has become my preferred technique but it can still be problematical, as it is quite fiddly and often the stars chosen by SynScan are not always visible e.g. it is not uncommon that at times all the alignment stars provided by Synscan are located in the northern sky and cannot be seen because of the aforementioned problems.  However, I am getting better and with diligence and patience can now get to within 30” or less of true polar alignment, which has allowed exposures of up to 180 seconds.  I have tried drift alignment a few times but have difficulty finding suitable stars on the horizon, as I basically don’t have an horizon! Going forwards I am considering the use of Alignmaster software, which looks very useful for this purpose, though the lack of a northerly view might still be a problem.  In addition, I hope the ultimate goal of autoguiding should further enhance tracking accuracy even without perfect polar alignment – we shall see.

The second problem initially encountered was achieving an image when using the William Optics field flattener / focal reducer.  Try as I may, I could not get an image with the William Optics GT81 + field flattener + camera combination and after a few evenings trying became desperate.  How could it be so difficult?  All this money for top-end equipment and not even a lousy image, let alone a good picture. With the help and encouragement from members of Stargazers Lounge, I had another go.  This time I was more diligent with the set-up and at first using a very bright, easy to see star, was at last able to achieve a camera image and good focus using a Bahtinov mask.  In a nutshell, the problem was that the point of focus is very, very critical, just a fraction of a millimetre out and the image disappears.  Now I know this it’s quite easy but nobody points this out, least of all the manufacturer or retailer, who provided little to no instructions – I am learning this is also something common in the world of astronomy, which I find quite unacceptable.

So, after some weeks of trials and tribulations, the new equipment is mostly working very well and I have been able to successfully image a wide variety of objects.  There’s plenty of room for improvement but I have obtained some enjoyable and often quite exciting photographs.  Now for the next challenge, which has just started: computer control and autoguiding.

NGC 6960 AKA The Witch's Broom Canon 700D | 20x90 sec + darks.bias/ flats @ ISO 800

NGC 6960 AKA The Witch’s Broom
Canon 700D | 20×90 sec + darks.bias/ flats @ ISO 800

With DSLR or CCD / webcam imaging, processing is at least equally important as the original image capture.  In the later part of the year I have therefore also started to tackle this dark art.  Whilst compilation software such as Deep Sky Stacker and Registax requires some understanding to set-up, it is with post-processing that the final image can be made or lost.  As a result I am using the extra time indoors to try and master the various techniques, with mixed success.

I should also note that during this period my elder daughter, Alison, persuaded and then helped me set-up this website.  It has proved a useful discipline for organising my thoughts and images.  I am very grateful for her help and have surprisingly enjoyed recording my astronomy endeavours. Although intended as a personal record, I note from the underlying website provider that it has been read far-and-wide across the world – 36 countries this year – which is also gratifying.  I would love to hear from anybody via the WTSM site: questions, what are you doing, comments & feedback etc?

Date Object* Feature / Name
July M57 Ring Nebula
M13 Globular Cluster
M15 Globular Cluster
Aug M27 Dumbbell Nebula
M31 Andromeda Galaxy
M11 Wild Duck Cluster
ISS International Space Station
NGC 6888 Crescent Nebula
The Sun
Sept NGC 7000 North America Nebula
NGC 6960 Western Veil Nebula & Witch’s Broom
NGC 7380 Wizzard Nebula
M31 Andromenda Galaxy
IC 1396 Elephant’s Trunk Nebula
M2 Globular Cluster
Oct M45 Pleiades Open Star Cluster
Uranus
M33 The Pinwheel Galaxy
NGC 6992 Eastern Veil Nebula
NGC 6995 Bat Nebula
M42 & M43 Great Orion Nebula
NGC 7320 Stephen’s Quintet (Galaxies)
NGC 7331 Deer Lick Group (Galaxies)
NGC 7814 Spiral Galaxy
Nov NGC 1909 Witch Head Nebula
IC 434 Horsehead Nebula
NGC 2024 Flame Nebula
NGC 1973/75/77 Running Man Nebula
Dec M1 Crab Nebula
ISS International Space Station
NGC 2264 Christmas Tree Cluster & Cone Nebula etc.
NGC 2261 Hubble’s Variable Nebula
NGC 19818 Open Star Cluster
NGC 2244 Rosette Nebula
M35 Open Star Cluster
M78 Reflection Nebula

??????????????

Goals for 2015 are:

  • Transfer the mount to EQMOD computer control – I have already linked the equipment indoors, together with Cartes du Ciel, but have yet to use it outside live.
  • Upgrade camera control software – again I am already trialling Astrophotography Tool (APT) indoors, which looks good and provides lots of flexibility, though in some ways I still like the EOS Utility software, which uses more simple and therefore reliable control choices.
  • For astrophotography this is the Holy Grail and, if successful, should enable significantly longer exposures and thus better detail and sharper images to be achieved.  At the time of upgrading my equipment in the summer I also purchased a William Optics 50 mm guidescope – all I need to do is get it working! This will require two further pieces of software: (i) Push Here Dummy or PHD, which is responsible for controlling the interaction between the guidecope and the mount, and (ii) Astro Tortilla, which undertakes a process called ‘plate solving’, whereby using actual pictures taken at the time of set-up, it then recognises the section of the sky it (the telescope) is looking at, identifies the object in the field of view and using this information ensures that the telescope (and thus camera) are pointing exactly towards the chosen object by iteratively interacting with the other guiding software.  As a fan of the KISS principle, I must admit to being somewhat intimidated by all this but am assured by others that it is not so bad to use  (famous last words) and once up and running, will have a major impact.  We shall see!

Even at this stage, I can already see the need for additional equipment.  With numerous Ha-emitting nebulae a modified DSLR camera is beginning to seem essential and probably a more powerful computer for image processing.  I am sure this list will grow as the year progresses.

All-in-all, I am pleased with my progress during the past year, with a noticeable improvement since acquiring the new equipment.  There have been more highs than lows and, I suppose, that’s a result in itself.  It is very exciting when you first see Saturn, Jupiter or Mars and then image them but I have discovered that my metier and main enjoyment comes from DSOs, in particular nebulae.  I find their very nature beguiling; beautiful to view, challenging but very rewarding to image and scientifically fascinating.  I am therefore sure that in 2015 they will remain my main targets but, notwithstanding, there are many other objects worthy of attention, including in the UK a partial eclipse of the Sun in March.

Watch this space! 

Orions Sword. Top to bottom: NGC 1981 Open Star Cluster, NGC 1973/75/77 Nebulae, M42 & M43 Great Orion Nebula & the binary star Hatsya. WO GT81, Canon 700D + FF | 30 x 120 secs + darks/bias/flats @ ISO 800

My picture of the year: Orions Sword. Top to bottom: NGC 1981 Open Star Cluster, NGC 1973/75/77 Nebulae, M42 & M43 Great Orion Nebula & the binary star Hatsya.
WO GT81, Canon 700D + FF | 30 x 120 secs + darks/bias/flats @ ISO 800

 

The absence of light

“Light thinks it travels faster than anything but it is wrong. No matter how fast it travels, it finds that darkness has got there first, and is waiting for it.”  Terry Pratchet, Reaper Man.

dnb_land_ocean_ice.2012.3600x1800

It may seem something of a contradiction that as astronomers we seek very dark places and skies in order to see light, light that may have travelled millions of light years to get here – light travels 6 trillion miles in one year.  For human beings the perception of darkness differs with the mere absence of light, due to the effect of afterimages that are produced by the unstimulated (by light) part of the eye. Typically our eyes will take between 20 and 30 minutes to fully adjust to darkness, at which time the eye becomes between ten thousand and a million times more sensitive than in daylight.

Objectively the Bortle Dark-Sky Scale describes nine levels of darkness and thereby quantifies the astronomical observability of celestial objects and impact of light pollution http://en.wikipedia.org/wiki/Bortle .  With digital photography the colour of a point is described on the camera’s sensor by three RGB (red, green, blue) values, each ranging from 0 to 255.  Thus when each pixel is fully illuminated each colour component measures 255 or for an RGB image 255,255,255.  Conversely when all values are zero or 00,00,00, it appears black.  However, the night sky is not black but measures somewhere between 10 and 30 when imaged.

Night sky image (Eastern Veil) with dark point set at  0,0,0

Night sky image (Eastern Veil) with dark point set at 0,0,0

Dark sky image (Eastern Veil) with dark point set at 20,20,20.  This approximates best to the natural darkness of the night sky.

Dark sky image (Eastern Veil) with dark point set at 20,20,20. This approximates best to the natural darkness of the night sky.

There are even four subdivisions to describe approaching darkness at night:

Civil Twilight: begins at sunset and ends when the sun is 6o below the horizon or more practically, it can be described as the period after sunset during which terrestrial objects can still be clearly distinguished. Normally the end of civil twilight is usually 20 to 30 minutes after actual sunset.

Nautical Twilight: describes the period when the sun is between 6o and 12o below the horizon, during this time it is now possible to take reliable star sightings at sea.  It may more commonly be described as nightfall but it is still not strictly dark yet.

Astronomical Twilight: defined as the period when the sun is now between 12o and 18o below the horizon.  To the casual observer this may be considered dark but it’s not, only when Deep Sky Objects such as nebulae and galaxies can be viewed is it fully dark.

Therefore, only after this sequence is completed, which takes almost two hours after sunset here at Fairvale Observatory at this time of the year, does true astronomical night or darkness occur. The excellent FLO Clear Outside weather forecast website, which is linked on the front page of this website, shows the current timings for each of these periods every day along the top horizontal bar, just below the hourly sub-division headings.

Obviously this has a major bearing for astronomers and perhaps more so for astrophotography.  So sensitive is the camera’s sensor that when using long exposures the cumulative light recorded, even in a dark-sky environment, may result in a bright image that will need to be corrected during processing. Notwithstanding, the holy grail for astronomers is a dark, clear sky and the biggest enemy (other than bad weather and cloudy skies) is light pollution, which is spreading inexorably across the globe.

At the beginning of this post is a NASA picture of the Earth at night, produced as a composite of image data from the Suomi National Polar-orbiting Partnership (NPP) satellite, taken in April and October 2012 over a period of 312 orbits.  NPP passes over any given point on Earth’s surface twice every day,  flying 824 kilometres (512 miles) above the surface in a polar orbit, circling the planet about 14 times a day http://earthobservatory.nasa.gov/Features/IntotheBlack/ .  Away from the cities much of the other light from wildfires, fishing boats, gas flares or mining operation is also visible.  Whilst undeniably a beautiful picture, for astronomers it highlights one of the major obstacles we are up against, light, or more accurately light present here on Earth.  The night sky before the invention of the commercial light bulb by Tomas Edison in 1878 must have been a wonderful sight; I doubt that Messier (1730-1817) would have successfully catalogued all his 110 objects as easily with today’s skies.

The dark side of the world: city lights of Europe, Africa, Middle East & Central Asia

The dark side of the world, with light just over the western horizon.

Fairvale Observatory Part-1: Initial Equipment Set-up

The so called ‘observatory’ is unfortunately the back patio of my house – Fairvale is the house name.  In itself OK but with the house completely blocking the view to the north and houses, hedges and some large trees blocking much of the horizon looking east, south and west, it’s a wonder I get to see anything in the sky.  Furthermore, we are located just outside the M25 London orbital motorway, with Gatwick airport to the south about 8 miles away – hardly perfect light conditions.  However, for the moment it’s what I have to work with and I thought I’d start a series on the background of my equipment, how it has evolved and what I’ve learned from using it.  In Part-1 I’ll review my starter set-up purchased second hand just over a year ago.

The view East

The view East

The view south, note light pollution form Gatwick

The view south, note light pollution from Gatwick airport

As described in the section About Me, after years of prevaricating about which scope to buy, I was finally stung into action in April 2013 by my first ever view of Saturn and a feeling by now that there were too many answers to the question, which scope? So best just get on with it. My philosophy for the first year was to experience astronomy and, if possible imaging, in order to: (i) see if I enjoyed it (ii) learn the basics with basic equipment and (ii) learn from my mistakes for a small financial outlay before spending the big bucks, if indeed that was to be my next move (as it was – see Part-2 later). In the end I went for a Skywatcher 150PL with an EQ3-2 mount, which all things considered turned out well and has certainly whetted my appetite for bigger and better stuff (the retailers will be pleased to know).

Skywatcher 150PL (pre-motor drives) & Eq3-2 Mount

Skywatcher 150PL (pre-motor drives) & EQ3-2 Mount

It is clear that there has been something of a revolution in amateur astronomy in recent years, mainly I suspect (like so many other aspects of western life) through the development and manufacture of affordable high-spec equipment in the Far East, mainly China. This equipment is generally well made and now incorporates many technical features that an amateur astronomer could have only dreamt about 10-years ago; technology itself seems to have developed at an almost exponential rate, particularly in the field of astrophotography and related computing and processing, no doubt partly led by Hubble’s success and subsequent spin-off developments.

The OTA (optical telescope assembly) – Skywatcher 150PL

You get a lot of bangs for your bucks with a Newtonian refractor, making them a great starter telescope. In this case the OTA is just over a metre long, with a focal length of 1,200mm and an aperture of 150mm, which is a pretty decent size to start with – it certainly looks impressive! The ‘speed’ of the scope or f-number is calculated by dividing the focal length by the aperture, which in this case gives a number of f8.  Anything smaller i.e. higher than about 4 or 5 is considered to be a ‘fast’ scope (the terminology derives from photography but is not directly comparable) and anything over about 10 is ‘slow’ – as a rule of thumb, each being generally better suited (fast or slow) to either DSO or planetary astronomy respectively.  Therefore in my case this scope errs towards planetary work best, hence the suffix PL.  The physical size of the 150PL is something of an encumbrance at times but, as already indicated, the Newtonian is difficult to beat on price as a starter scope with a decent size aperture, which results in better light capture.

The OTA has no lenses but two mirrors to bounce the light up and down the OTA and into the eyepiece for viewing or photography, which is conveniently located on the side http://en.wikipedia.org/wiki/Newtonian_telescope.  From time-to-time it is good practice to make sure these mirrors are correctly aligned through a process of collimation, ensuring thereby the light path is perfectly set from the centre of each mirror to the centre of the eyepiece.  I am ashamed to say I have yet done this once, which is no doubt the source of some of my subsequent alignment and imaging problems! Oh well.

I should say that the scope also comes with a 30mm finderscope, which I have found to be of limited use, in particular since getting the wide angle eyepiece (see below) and a Telrad.  In the absence of GoTo facilities and even when you know and can clearly see the astronomical target feature in the night sky, it is still difficult to line up the OTA for viewing.  Strapping a Telrad to the OTA has virtually solved this problem. The Telrad is essentially a form of red dot finder, whereby a small red circle is projected onto a piece of 45o inclined glass through which you look and can therefore see the desired target feature. By then manually moving the OTA and thus moving the red circle until it coincides with the target, the scope is lined-up perfectly every time.

The wonderful Telrad RDF

The wonderful Telrad RDF

Telrad + homemade dew shield, using 3mm compressed foam

Telrad + homemade dew shield, using 3mm compressed foam

The Telrad loctes and screws quickly onto a base (available at different heights) fixed by cable ties alongside the finderscope.

The Telrad locates and screws quickly onto a base (available at different heights) fixed by cable ties alongside the finderscope.

Focus, Eyepieces & Filters    

One of the major problems throughout my introduction to astronomy has been focussing which, in the case of the 150PL, has been compounded by the low quality of the focus mechanism. In this case the 1.25” focus tube and fitting is a simple rack and pinion, which unfortunately has little finesse. As I have found to my frustration, achieving focus for astrophotography can be down to a fraction of a millimetre.  Due to the coarse nature of the 150PL focus mechanism, such tolerances are difficult to achieve and good focus is more by luck than design with this mechanism.

More so than the OTA, the importance of good eyepieces cannot be overestimated. The 150PL came with two basic Plössl x25mm & x10mm 1.25” eyepieces and a x2 Barlow. I subsequently added to these with a  x6mm and Ultra Wide Angle (UWA) x32mm lens, which though nowhere near top-of-the range, are noticeably superior to the originals and are now used most of the time in preference to the original eyepieces. They are also both Plössl construction but with better glass and the x32mm has an 82o wide angle field of view, which is a major advantage when first visually locating a feature in the sky before changing to the x6mm or adding the Barlow.  Furthermore, both the ‘new’ eyepieces have a larger eye relief, which for those like me wearing glasses makes observing much more comfortable; the eye relief is the distance the eye has to be beyond the eyepiece lens to achieve focus – a larger / wider distance means the eye can be further away from the lens. I expect to improve this collection of eyepieces further at some time – thinking about a better quality Barlow, a Powermate and perhaps a reticle – we shall see.

Eyepieces tucked up in their storage box with filters, laser pen and lens cleaner.  When working in the dark, literally, it pays ton know where things are.

Eyepieces tucked up in their storage box with filters, laser pen and lens cleaner. When working in the dark, literally, it pays to know where things are.

I was soon introduced to the need for filters when viewing a full moon, which was blindingly white.  As a result I purchased a Moon filter, in this case a Baader 0.9 ND filter, which claims a light reduction factor of 8 (whatever that means) and certainly has made viewing the Moon much more comfortable. Subsequently I indulged in a narrowband UHC filter, which claims to enhance viewing of nebulae by limiting the wavelength to the 400nm to 700nm range (peaking at 500nm), which might typically be associated with the light radiated from a nebula. I have only used this with the Orion Nebula and it did, to a degree, reduce the overall luminosity and produced a sharper, bluish view of the nebula’s stars – you could therefore say, the jury is out on whether this is worthwhile or not, it certainly is not cheap; maybe it’s effectiveness will be more obvious when used under a deent dark sky?  An Oxygen-III is an alternative, similar filter, which some claim is superior to the UHC? Most recently I purchased a Light Pollution Filter, which aims to counteract the light wavelengths emitted by streetlights and similar sources, though as yet I have yet to prove the real benefit of this.

The Mount – Skywatcher EQ3-2

Probably the greatest surprise in my first year of astronomy has been to learn how important the mount is – it is probably the most important item when imaging.  The Skywatcher EQ3-2 is a light mount, which becomes evident when you strap the large 150PL Newtonian on, especially if there’s a breeze.  I deliberately avoided the GoTo mounts (those programmed to move automatically to set features) from the start, in my quest to learn from the bottom up; some might say the hard way, I believe the best way to eventually learn and then later use technical skills is from first principles. As a result following targets whilst viewing (tracking) is not easy to do well manually using the right ascension (RA) and declination (DEC) control knobs and is almost impossible when imaging. Fortunately it is possible to buy a separate ‘strap on’ units that linked to a control box will at least track fairly well – at this stage anyhow. I therefore added both these motor drives with good results, though mostly only used the RA motor, choosing to ‘fine tune’ the less volatile DEC changes manually.

EQ3-2 mount with DEC motor drive fitted; note clutch to disengage and move manually if required

EQ3-2 mount with DEC motor drive fitted; note clutch to disengage and move manually if required

The OTA is fixed onto the mount by a standard Skywatcher dovetale bar, which fits into a matching slot on head of the mount   and is then clamped by screws.

The OTA is fixed onto the mount by a standard Skywatcher dovetale bar, which fits into a matching slot on head of the mount (see previous picture)and is then clamped by screws.

Around the other side is the RA motor drive, which has no clutch.

Around the other side is the RA motor drive, which has no clutch.

The RA & DEC motor drives are controlled by this handset (battery power unit not shown) which can be set at different tracking speed and for the north or south hemispheres, depending on where you are located.

The RA & DEC motor drives are controlled by this handset (battery power unit not shown) which can be set at different tracking speed and for the north or south hemispheres, depending on where you are located.

I have to say that the mount is noticeably ‘built to price’, which is particularly evident with the lower clamps necessary to lock the parts of each leg together when they are used to adjust the height.  The clamps are made of plastic with brass ferrules inserted, through which the clamp screw can lock against the internal / adjustable leg section. The instructions do note this should not be overtightened but to achieve a good, secure lock it needs to be firm and this inevitably led to the plastic failing.  The problem was easily and cheaply solved using three large jubilee clamps.  Notwithstanding, why not just make it properly in the first place?

The weak plastic leg clamps have all been supplemented by jubilee clips.

The weak plastic leg clamps have all been supplemented by jubilee clips.

Comments

The mount and scope sit directly on the patio (which I recently relayed to improve stability) and, as the house completely obscures northern views and thus Polaris, which would otherwise be used to align the scope, is aligned using black lines that have been previously marked, pointing due north for the same purpose.  This is far from perfect and I am hoping that with the next Synscan based mount, which incorporates star alignment, combined with drift alignment and eventually the use of a guidescope and various computer guidance and planetarium software, I will one day achieve a tracking accuracy that will enable better viewing and much longer camera exposures and thus better images.  It’s a way off but remains my goal for the next six months.

The biggest bugbear is that all this has to be carried out and back into the house, as well as aligned each time – thus my long time goal is a covered observatory but I’ll need a new house / garden before I can do that, which might take some time!

Overall I have been pleased with this equipment, although it needed some tweaking to get the best out of it.  Operationally, use of the mount and OTA has benefited significantly by the addition of: (i) RA & DEC motor drives, (ii) better quality eyepieces and (iii) the Telrad finder, altogether making it a pleasure to use.  So much so that contrary to my initial intentions, I now intend to keep the OTA for solar work and the mount as a portable set-up, matched with my new, more portable 80mm APO refractor scope, of which more in Part-2.