What Comes Around Goes Around


It’s nearly 4-years since I started astronomy, like so many inspired after observing Saturn through a telescope.  Not just any telescope but the 13” Astrographic Refractor at the Observatory Science Centre in Herstmonceaux.  Built in 1890 specifically to make use of the then new technique of astrophotography, the telescope was first employed as part of the worldwide Carte Du Ciel project to map the entire night sky by photography and subsequently for a crucial test of Einstein’s then new theory of General Relativity.  Soon thereafter I was to view the aforesaid planet once again with my first, newly purchased Skywatcher 150PL Newtonian telescope.  Inevitably something of a lesser view than that at Herstmonceaux it was nonetheless just as exciting, if not more so.  I was hooked!

I then attempted afocal imaging using a compact camera held up to the telescope eyepiece but with poor results, except in one respect.  By clamping the camera onto the front of the eyepiece and achieving longer exposures, nebulosity otherwise unseen with the naked eye was revealed in the resulting image, in this case Orion’s Nebula.  As crude as the image was, for me the penny had dropped and I’ve been pursuing images of the hidden beauty of the night sky ever since.

rosette map


Like mariners, through astronomy I have by now become accustomed to the seasonal procession of the night sky wonders throughout the year, none more so than the Rosette Nebula.  About 100 light-years across and 5,000 light-years from Earth, the Rosette Nebula is surely one of the annual highlights for most astrophotographers?  Located just east of Orion, the Rosette is at its best between December and February, so that I was first able to image this beautiful object myself at the end of 2014.

As a very large HII region the Rosette Nebula emits light mainly at narrowband wavelengths, which produces wonderful but mainly red colours when imaged with a modded DSLR camera.  As my astrophotography and equipment have since developed, it has become a pleasure and challenge to image objects as they return each year such as the Rosette, thereby also charting my own improvements or otherwise from year-to-year.  Its size makes the Rosette an especially attractive target for smaller telescopes such my own with an 81mm aperture, which nicely fills much of the sensor of an APS-C camera.

Despite having purchased a new ZWO1600MM-Cool mono camera at the end of 2016, by the time I was ready to use it at the end of the following March, the Rosette Nebula had almost disappeared over the western horizon for another year.  Notwithstanding, in the limited time remaining I managed to capture a few Ha-OIII-SII subs, thus marking first light for the camera, which ironically resulted in one of my favourite images for 2017.  Using narrowband for the first time it was immediately possible to see the potential of the new camera when imaging this type of object.

Returning from an extended overseas trip at the end of January this year, 10-months had passed since my last encounter with the Rosette Nebula last March and I found myself with the first real opportunity to image the nebula properly with the ZWO1600MM-Cool camera.  Since last year I’d acquired more knowledge and experience with the camera, plus this time the Rosette was now in the south eastern quadrant and provided significantly more imaging time than before.

After a break of nearly two months I needed to sort out the equipment, refocus the camera and start a new alignment model in EQASCOM.  For the first time I also decided to use longer exposure times of 300 seconds, which altogether produced a good Ha+OIII Bi-Colour image (top of page – awarded BAA Picture of the Week 4th March 2018); whilst much longer exposures are used with conventional CCD sensors, such is the sensitivity of the CMOS mono sensor in the ZWO camera that 5-minute exposures provide exceptionally good quality data.  Overall the impact of longer exposure, good focus, tracking and much longer total integration time had a noticeably positive impact on noise and overall image quality, though there’s still room for improvement – there always is!

To some extent, even after a year I’m still in the experimental phase with this camera.  For most of 2017 I used a high gain setting of 300 but this time I chose the Unity gain setting of 139 and for interest also imaged at a shorter exposure of 180 seconds.  Comparison between the two settings for Ha images – Unity gain at 300 and 180 seconds – shows that for such a nebulous type of feature as the Rosette, Unity gain works very well at the longer 300 second exposure (first image below) but not 180 seconds (second image below), which is too short to collect sufficient data.

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Notwithstanding, in the past I have found shorter exposures at Unity or less have generally been more suitable for brighter objects such as star clusters or galaxies like Andromeda.  An alternative SHO Hubble Palette image below of the Rosette Nebula at Unity gain and 300 second exposure also compares more favourably with the same image taken last year using less subs, higher gain and shorter exposure time.

Untitled-2 Crop2 (Large)When the object is right, such as the Rosette Nebula, narrowband imaging using the ZWO camera produces exceptional results.  This is evident in these recent images where it’s now possible to clearly see structural elements of the nebula, as well as the star fields located within.  Frankly I am very excited by these new images and can’t wait for next year to come around again!

Postscript: Research at Leeds University just published suggests that the Rosette Nebula is a disc but I believe my eyes and this image and many others which says otherwise!

Object Rosette Nebula     NGC 2244 + 2237, 2238, 2239 & 2246   
Constellation Monoceros
Distance 5,000 light-years
Size Approx. 100 light-years or 1.3o
Apparent Magnitude +9.0
Scope  William Optics GT81 + Focal Reducer FL 382mm  f4.72
Mount SW AZ-EQ6 GT + EQASCOM computer control
Guiding William Optics 50mm guide scope
  + Starlight Xpress Lodestar X2 guide camera & PHD2 control
Camera ZWO1600MM-Cool (mono)   CMOS sensor
  FOV 2.65o x 2.0o    Resolution 2.05”/pix   Max. image size 4,656 x 3,520 pix   
EFW ZWOx8 + ZWO LRGB & Ha OIII SII 7nm filters 
Capture & Processing Astro Photography Tool,  Deep Sky Stacker & Photoshop CS2
Exposures 12 x 300 sec Ha, 6 x 300 sec  OIII & SII  (Total time: 120 minutes)
  @ 139 Gain  21 Offset @ -20oC  
Calibration 5 x 300 sec Darks  20 x 1/4000 sec Bias  10 x Flats Ha, OIII & SII @ ADU 25,000  
Location & Darkness Fairvale Observatory – Redhill – Surrey – UK        Typically Bortle 5
Date & Time 9th February 2018 @ 22.00h



Reflections – 2017

Following some important developments, I think it’s fair to say that the past year has hopefully marked an appreciable turning point for my astrophotography.  Reflections is a summary of my astronomy last year, in particular astrophotography, as well as some thoughts about how I hope to progress in the 2018.

I’m again pleased that there is continuing interest in Watch This space (Man) – A personal discovery of the Universe through astronomy and astrophotography.  This is a personal journey and I’m glad to see there is also regular activity in many of the older blogs, which altogether illustrate what I expect many others have experienced during their own personal journeys? For those starting out or with related interests, I hope they will find these pieces interesting, instructive and perhaps even inspiring; it’s not an easy hobby but when it works – it usually does with patience, perseverance and help from the wider community –  the experience is  very rewarding, often exciting and mostly fun.

I’m aware that many of my blogs can sometimes be on the long side, that’s because I want to thoroughly document and discuss the matters rather than superficially comment on them.  However, I am mindful that from time-to-time there are issues that can best be covered in a more concise manner or just events that speak for themselves and can therefore be brief, for which purpose I have now introduced the AstroBites section.  Unfortunately, despite the best of intentions, I’ve so far only used this item occasionally but hopefully will rectify the situation next year.

I’m always tinkering with the website, so even if you’re a regular visitor take a look around from time-to-time.  There is a photo gallery but for a simpler view of some of my better images I’ve recently added a FLICKR album, which is accessible from the Gallery menu.  The sharp eyed may also note that in response to new imaging techniques, I have changed the image and technical details summary for each picture; I find this information invaluable when looking at other astrophotographer’s images, as it can be very helpful when starting out in general or when using similar equipment or imaging the same object for the first time.

Once again the site attracted much interest from all corners of the world, which are summarised in the map below.  Please do get in touch if you have and relevant thoughts, queries or just to say – hello – contact details are in the ABOUT section of the main menu.

WTSM Heat Map

Reflections Crop


After overcoming some major technical problems that almost brought my nascent hobby to a premature end in 2016, I felt I needed to consider what would be the best way forwards thereafter.  My initial inclination was a larger telescope in order to get at those faint fuzzies but most of all I just wanted better quality images.  In the past this would inevitably result in acquiring a CCD mono camera and all that means in terms of very exacting technical issues and very long exposures, neither of which I was prepared to take on, or at least only to a degree – life’s too short and the UK weather too cloudy!

However, during the latter part of 2016 something of a game changer was emerging in the world of astrophotography and after following developments online for a few months, I was persuaded that the new ZWO1600MM-Cool mono camera could also give me what I wanted, without many of the issues of a conventional CCD camera.  As a result I purchased the aforesaid camera and matching x8 EFW just before Christmas in 2016  and eagerly awaited clear skies in the New Year.  Unfortunately it wasn’t that simple – now there’s a surprise!

The crucial benefits of the new CMOS based ZWO camera are three-fold: (i) very low read noise and high sensitivity achieved with, (ii) relatively short exposures – sometimes as little as 30 to 60 seconds, (iii) larger field-of-view compared to a CCD. Wow!  Unfortunately there was still much to sort out, notably the image train, image capture and processing, all of which differ considerably from a DSLR camera.  Notwithstanding, eventually first light (see image below) was achieved in March and it was immediately obvious that this was going to fulfil my astrophotography dreams and more for now – hopefully!

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Rosette Nebula in Ha | William Optics GT81 + ZWO ASI 1600MM-Cool & 0.80 focal reducer guided | 15 x 180 secs + darks & bias calibration Gain 300, Offset 10 | 21st March 2017

Using mostly narrowband filters – more on that later – I was initially able to obtain some exciting and very promising images of classic HII-region objects just before they disappeared over the western horizon; thereafter followed weeks of frustration whilst I waited for other suitable objects to appear – timing is everything.  The ZWO1600 camera is very good for most deep sky objects, nebulae, galaxies and globular clusters but with the William Optics GT81 the combination is best suited to larger targets.  As a result by late winter and early spring, when smaller objects such as galaxies dominate the night sky, it became necessary to find something else to do for the next few months.

Aurora Borealis Northern Norway February 2017 I’ve previously worked north of the Arctic Circle in Sweden and Russia but in February I took a more relaxed ferry trip along the west and north coast of Norway from Bergen to Kirkenes, close to the Russian border.  Given the time of year it was of course very cold and the nights long but the ship was comfortable and the scenery spectacular.  However, once north of Tromsø the real show began in the form of the Aurora Borealis AKA the Northern Lights.  This natural light show lived up to expectations and with some difficulty I managed to obtain numerous images of the spectacle – the problem being imaging from a moving ship in severe cold, which with wind chill was well below -20oC – but it was worth it and made for an exciting end to my winter astrophotography.

No Date Type* Object Name
1 20/01/17 DSLR M45 Pleiades
2 20/01/17 N NGC 2244 Rosette Nebula
3 22/01/17 DSLR M45 Pleiades
4 22/01/17 N IC 434 Horsehead & Flame Nebula
5 21/03/17 N NGC 2244 Rosette Nebula
6 21/03/17 B M65 Leo Triplet
7 24/03/17 B NGC 4874 Coma Cluster
8 25/03/17 N M42 Orion Nebula
9 27/03/17 N IC 434 Horsehead Nebula

Record of quarterly photographic images taken in 2017

*Type: DSLR colour, B Broadband LRGB, N Narrowband Ha-OIII-SII, V Video


The period from April until the end of July can be a frustrating time of the year for astronomers, except those with an interest and the equipment for solar imaging.  Other than just giving up for a while, the secret is to abandon normal pursuits and just make the best of whats on offer, which is exactly what I did this year.  After limited success  attempting some of the larger galaxies in early Spring, I moved on to webcam imaging Jupiter and Saturn, insofar as is possible with my small telescope.  At about this time I also managed to capture the comet C/2015 V2 (Johnson), my second one after previously imaging C/2014 Q2 Comet Lovejoy in early 2015.  As I had not attempted such objects for more than two years and was more than a bit rusty with the different imaging and processing techniques, the results were varied but is was still good fun, which I hope to repeat in 2018 depending on what’s around at the time.

I also used the much improved weather and extra spare time afforded to go over the basics of my mount-telescope-computer set-up: balance, leads, equipment alignment, computer updates etc.  I inspected and replaced some old cables, wherever possible using cold-resistant silicon leads.  Following last year’s catastrophic camera power lead failure, I am now aware of the damage that cold can do to cables and pay greater attention in order to avoid repeating such problems.  I was also aware that with the change to the ZWO camera and using autoguiding routinely there had been a noticeable increase in cables, which I therefore tidied and strapped with Velcro bands to restrict unnecessary movement and snagging.

IMG_20170324_194502542 (Medium) The overall impact of these changes has transformed my working practices, making set-up and dismantling quicker, more efficient and more effective, itself a huge improvement.  In addition, I’ve also been able to move the mount and image capture controls indoors, which being more convenient and comfortable has made operating conditions and results much better.  Astrophotography inevitably becomes more complex and working in a warm environment with access to a cup of tea really does improve the outcome when working, in particular when resolving problems.  Given the significant benefits achieved from this housekeeping, in the future I intend to repeat this exercise each summer – it really pays off.

Veil SHO GxCcropHub

Eastern Veil Nebula in SHO – for Will| 21st June 2017

Notwithstanding these virtues, by June I was eager to start imaging again with the ZWO1600MM-Cool and with good weather and some very late nights I was able to obtain a few narrowband subs of the Eagle and North America nebulae.  To my surprise on the morning of 21st June I even briefly managed to image the Eastern Veil Nebula in narrowband; who would have thought imaging the Veil on the Summer Solstice?  Once again the results of just a few subs from the new camera continued to show great promise.

No Date Type* Object Name / Type
10 02/04/17 B NGC 2903 Galaxy
11 02/04/17 B M61 Galaxy
12 18/04/17 B NGC 4438 Markarian’s Chain
13 14/0517 V Jupiter Video Sequence
14 25/05/17 V Jupiter Video Sequence
15 26/05/17 DSLR Comet C/2015 V2
16 11/06/17 V Saturn Video Sequence
17 14/06/17 V Jupiter Video Sequence
18 19/06/16 N M20 Eagle Nebula
20 20/06/17 N NGC 7000 North America Nebula
21 21/06/17 N NGC 6992 Eastern Veil Nebula


After a taste of the ZWO1600MM-Cool at the start of the year and briefly around the Summer Solstice, the end of July finally brought the return of astronomical darkness, more suitable DSO targets and at last the opportunity to get serious with narrowband and broadband imaging.  Combined with some exceptionally good weather and clear skies this period was very productive and successful.  Without plate solving the maximum imaging time I can achieve at the moment is about two hours before or after the Meridian but using a high Gain of 300, 180 second exposures and autoguiding, for the first time I was able to get some very decent subs of various nebulae – now it was really getting exciting!

At the time of purchase I wavered between the ZWO EFW x5 filter or the soon to be released alternative x8 version and in the end waited for the larger version, together with the matched LRGB, Ha, OIII and SII filter bundle.  There were initial problems controlling the EFW and camera, inevitably resolved after some time with a new driver code but in the end the x8 EFW and camera have proved to be an excellent combination.  I have especially found narrowband imaging to be a revelation and when possible have so far mostly concentrated on this technique; its use when the Moon is about is an added and somewhat pleasing bonus.  The detail shown in Ha-subs can often be quite spectacular and for the best results I’ve discovered that more aggressive stretching is needed.

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To my surprise, I’ve so far found LRGB broadband imaging more difficult than expected, both to capture and in post-processing.  It’s apparent that Gain and Offset settings are more critical than narrowband, perhaps because such objects tend to be brighter, with more contrast and often greater complexity?  I had been looking forwards to imaging the Andromeda Galaxy in LRGB and as is often the case with M31, first thought that my subs were overblown.  However, after dialling down Gain, Offset and exposure time the alternative result was even more disappointing.  It was instructive that by returning to the original data and applying greater care during processing, I was able to tease a good image from the subs after all.

No Date Type* Object Name / Type
22 27/07/17 N M20 Trifid Nebula
23 31/07/17 N NGC 6960 Western Veil Nebula
        & Pickering’s Triangle
24 10/08/17 N IC 5070 Pelican Nebula
25 11/08/17 N IC 1318 SADR Region
26 11/08/17 N NGC 6888 Crescent Nebula
27 13/08/17 DSLR Perseids  
28 19/08/17 N NGC 6995/ NGC 6992 Eastern (Bat) Veil Nebula
29 20/08/17 B M15 Globular Cluster
30 27/08/17 N NGC 7000 North America Nebula
31 28/08/17 B M31 Andromeda Galaxy
32 28/08/17 B M33 Pinwheel Galaxy
33 15/09/17 DSLR Milky Way  


From the experience of the new camera to-date I had arrived at two critical questions:

  • What are ‘right’ Gain and Offset settings?
  • What are the ‘best’ methods for LRGB imaging and post-processing?

Imaging during the final quarter then turned out to be something of a mixed bag trying to answer these questions.

I have a general feel about Gain, Offset and the related ADU values but if I’m honest despite reading around the subject I’m still mainly in the dark – no pun intended!  Such are the new challenges posed for all by the features of the ZWO1600MM-Cool it seems to me that even after 12 months the jury remains out over the answer to the first question – so it’s not just me!

The manufacturer provides value guidelines but based on experience, three schools of thought seem to have emerged from users:

  • Use Unity Gain 139 setting and vary exposure times – longer for nebulae, shorter for brighter objects such as M31;
  • Use low Gain for bright objects and higher Gain for faint objects + short and longer exposures, mindful of achieving a relevant ADU level across the resulting sub;
  • Use very high Gain and take lots and lots of short to moderate exposures.

I’m still experimenting with each of these techniques but increasingly lean towards higher Gain and varied exposure times of between 60” and 300”.  I have certainly found that lower Gain and short exposures didn’t work well for me when applied to the Andromeda Galaxy and California Nebula.

One issue when taking shorter exposures with the ZWO camera compared to a CCD is that many more subs are required, which inevitably needs very large storage and processing memory requirements – it’s a small price to pay for such quality and other advantages.  My laptop was already well specced for processing, with an Intel i7 64 bit chip 16GB RAM and to store the extra data I purchased a 4Tb external hard disc at a very reasonable cost = problem solved.

Picture saved with settings embedded.Like most people M42 has long been one of my favourites but like M31 I’m still struggling achieve a decent broadband image with the new camera and M45 is a similar problem; there’s nothing wrong with the camera, I just haven’t mastered the technique required yet.  However  narrowband images of M42, the Horsehead and Monkey Head nebulae all worked well at my standard default used of Gain 300 and Offset 10.

In preparation for further experimentation, at the beginning of  November I took time to compile a more comprehensive calibration library at various Gain, Offset and exposure settings.  Like most CCD cameras the new ZWO camera incorporates cooling to -45oC below ambient in order to reduce noise that is associated with all photoelectric sensors; I have been using the camera at a nominal temperature of -20oC.  By having such control it is therefore possible to obtain the aforementioned calibration frames irrespective of the ambient temperature and at any time.  Since June I’d already been successfully using another calibration set which has saved considerable time during each imaging session, unlike DSLR imaging which generally has to be undertaken at the same time + every time to ensure the same conditions.

Passing Shot: I’m posting Reflections later than usual this year having just returned from a protracted trip to New Zealand over the Christmas and New Year period.  The night sky down under was spectacular and I managed some good widefield imaging using a basic DSLR and tripod set-up; more on astronomy in New Zealand at a later date – Watch This Space Man! In the meantime below is a taster of the results taken whilst staying at my daughter and son-in-law’s house in Ohaupo, North Island.  Other than the beautiful Milky Way itself, note the Southern Cross just above the roof line and especially the large and Small Magellanic Clouds.

IMG_9984 (Large)

No Date Type Object Name / Type
34 12/10/17 B M31 Andromeda Galaxy
35 13/10/17 N NGC 1499 California Nebula
36 28/10/17 B NGC 2174 Monkey Head Nebula
37 28/10/17 B IC 434 Horsehead Nebula
38 30/10/17 B M45 Pleiades
39 30/10/17 B M42 Orion Nebula
40 01/11/17 N NGC 1499 California Nebula
41 13/11/17 DSLR Jupiter-Venus Conjunction
42 25/11/17 B NGC 1333 Reflection Nebula / Perseus
43 26/11/17 N NGC 2264 Cone Nebula


Once again my astronomy year was often shaped by other events and related matters.  Throughout the first quarter I completed an online MOOC course at Edinburgh University on the Higgs Boson and Particle Physics hosted by a wide variety of relevant experts, including no less than Peter Higgs himself.  It’s relevance to astronomy only came right at the end but was well worth waiting for.  Based on the theories of particle physics, the Higgs Boson, scalar fields and inflation, cosmologist Professor John Peacock ably demonstrated:

  • There was no Big Bang;
  • The existence of a multiverse – of which our Universe is but a part.

Intuitively I’ve long wondered about such possibilities and Professor Peacock’s lectures were by far the most convincing case I have seen for such a model.  Of course the implications of these conclusions are  profound and I’ve continued to think about this for the rest of the year.

As previously reviewed, for two weeks in February it was my good fortune to sail along the Norwegian coastline on the Richard With, flagship of the Hurtigruten ferry line.  At this time of the year it was very, very cold being mostly north of the Arctic Circle and the weather can be rough at times but overall the journey was outstanding.  Like most, my personal goal was to see and image the Aurora Borealis, which I was successful in doing on a number of evenings.  However, it’s got to be said that such imaging from a moving ship at -20C is both difficult and very uncomfortable.  Whilst I was pleased with the photographs, next time I’d prefer to be on land, where it should be so much easier.

Inspired both by the aforementioned trip and meeting a fellow geologist on board the Richard With who worked as a guest speaker on other cruises, I subsequently attended an audition to lecture myself on astrophotography.  Whilst my talk was successful and I was chosen to join the agency’s list of speakers, I have yet to be asked to join a cruise.

Favourite Images

With only a few exceptions, the outcome of my astrophotography in 2017 reflects the transition that took place from DSLR to the ZWO1600MM-Cool mono CMOS sensor camera.  The new camera has in every sense been a game changer and the resulting images have shown just how much colour and detail can be achieved in both broadband and especially narrowband.  Some of my personal favourites taken during the year are shown below, in no particular order:

Aurora Borealis-2 Northern Norway February 2017


NGC 2244 SHO Final1

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SHO Final

Eastern Veil Nebula detail in Bicolour 19th August 2017

Western Veil Nebula (Witch's Broom & Pickerings Triangle) in Ha-OIII Bicolour July 2017.jpg

MiIky Way Isle of Purbeck Dorset September 2017




Cygnus Wall BiCol FINAL

Above Images (from top-to-bottom): Aurora Borealis off Norwegian Coast – DSLR; Leo Triplet – LRGB; Rosette Nebula – SHO; Flame & Horsehead Nebulae – Ha; Eastern Veil Nebula – SHO; Eastern Veil Detail – Bi-Colour; Western Veil Nebula & Pickering Triangle – Bi-Colour; Milky Way from Isle of Purbeck, Dorset – DSLR; Andromeda Galaxy – LRGB; California Nebula – form left-to-right, Ha-SHO-Bi-Colour; North America Nebula – SHO; Cygnus Wall – Bi-Colour 

Round-up & goals for 2017

Since resolving a number of critical issues in 2016 and finally getting to grips with autoguiding, I’m pleased to say the basic processes worked very well in 2017.  In addition to improvements in the set-up, being able to operate from indoors has greatly improved both working conditions and the results.  Not surprisingly my astrophotography last year was dominated by learning and using the new camera.  Whilst the experience of DSLR imaging and related matters was helpful, I was surprised at just how different working with a mono camera, filters and especially processing has been by comparison and I’m still learning.  Some of the minutiae can be very important and are frustratingly easy to miss but, with the assistance of those ever helpful astronomers online and perseverance the results are really starting to show in my work.



Goal Specifics / Results Outcome
Improve processing After some set-backs now successfully processing FITS files in DSS and compiling broadband and narrowband images in Photoshop – all very different to DSLR RAW! Noticeable improvements using more complex techniques in PS.



Expand & Improve Widefield Imaging For the first time I obtained some decent images of the Milky Way but otherwise barely used the Vixen Polarie and did not make it to any other dark sky sites – disappointing.   FAILED


Start LRGB  imaging Now using the ZWO1600MM-Cool mono camera + EFW with LRGB & Ha- OIII- SII filters with good narrowband and varied broadband results.   GETTING           THERE


I think it helps to set some goals for the forthcoming year, so here goes:

  • Improve processing – more: Despite some noticeable improvements in 2017 there’s always more to learn whichever software is being used. I aspire to working with PixInsight or the newly acclaimed APP but will likely persevere with various more advanced Photoshop techniques.
  • Expand widefield imaging: First – use the Vixen Polarie as had been intended last year to obtain nightscape images at UK dark-site locations. Second – look at ways of using a widefield set-up with the mount.  Having previously failed I’m hoping to be more successful in 2018.
  • Improve broadband and narrowband imaging: In considering how to progress in 2016, I came to the conclusion that the next step should be a move to a mono camera rather than a larger telescope. This has turned out to be a great decision but it’s still early days.  There’s plenty more to learn and finesse but most of all after nearly a year’s learning and experimentation it’s clear that I need to improve one matter above all – increased integration time and this means learning plate solving.  I’ve been very happy using Astro Photography Tool (APT) for FITS image capture, scheduling and filter control (the APT Forum has been very helpful), but I also own the much praised Sequence Generator Pro (SGP) and might switch or at least give it a try in 2018.

I’m very pleased to say 2017 was a very good year for astrophotography, perhaps my best yet, which was especially defined by two positive developments:

  • In general the equipment set-up was much better after some long overdue changes and in particular operating from indoors, once all the basics are completed. With a good basic starting set-up and alignment of the guidescope-autoguiding camera with the main OTA, I’m often able to just quickly refresh EQASCOM alignment models directly from the computer = no more crawling around on the ground in the dark, or at least very little!
  • Although it’s still early days and despite my reservations over the complexity (which is true) of using a mono camera and filters, it’s revolutionised and revitalised my imaging and therefore proved very worthwhile. It is a lot of fun and the improvement of my images has been both exciting and very fulfilling.

You can’t ask for more than that and holds much promise for the coming year, which I hope to record in WTSM’s Reflections at the end of 2018.

Watch this space!


The ones that got away:  Imaged but not seen in WTSM this year (warts and all)

NGC 2174 281017

Pleiades 301017

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M15 Crop 200817

Above Images (from top-to-bottom): M42 Bi-Colour, Ha & SHO; Monkey Head Nebula Bi-Colour; Crescent Nebula SHO & Bi-Colour; Pleiades LRGB; Sadr Region Ha; M15 Globular Cluster LRGB    

The Wall


I first had a peek of the North America Nebula shortly after I started my then nascent astronomy hobby in August 2014.  With a Skywatcher 150PL Newtonian reflector and DSLR camera, I just managed to capture the edge of this very large nebula.  It was a very poor image and obviously navigation and framing were not my strong point but the mere glimpse of such Ha nebulosity was at the time something of an epiphany.  Hitherto I didn’t know such things existed, let alone their size and grandeur and the potential to catch even a part of it on camera was very exciting – that excitement has still not left me.

NGC 7000 240914 FINAL + Red (Medium)

NGC 7000 unmodded Canon 700D DSLR | September 2015

Armed the following year with a AZ-EQ6 GT mount and William Optics GT81 refractor, I managed to image most of the ‘continent’ and ‘Gulf’ (see above), although ‘Mexico’ was still missing; the title of my related blog at the time encapsulated my emotion at the time – WOW!  Since then I have often returned to NGC 7000 and with the combination of a modded DSLR, computer control and guiding gradually improved my technique so as to obtain better images.  However, the outcome of imaging the North America Nebula this year with the ZWO1600MM-Cool mono camera has been a revelation, resulting in perhaps some of my best images so far.

I’ve recently been spending time improving post processing methods, which together with increased knowledge gained from using the new camera for more than 6-months is now starting to pay off.  Being a very large HII-region the North America Nebula responds well to narrowband wavelength filters and I therefore took Ha-OIII-SII subs, which have subsequently combined well into Bi-colour (below) and SHO images that far surpass what I’ve previously achieved.


I was particularly keen to capture the Cygnus Wall for the first time, located along the ‘southern California’ and ‘Mexican’ coasts – so to speak.  In both cases the Wall shows up very well in detail (below in bi-colour), with its W-shaped edge dramatically illuminated by star forming regions from within.  I am particularly pleased with the SHO image (top of the page), which apart from the Wall illustrates delicate details across the entire nebula.

Cygnus Wall BiCol FINAL

Greater care during processing is improving such images but now that I’ve experienced this new camera across a number of different objects, it is clear that further enhancements are likely to be incremental and more difficult to achieve.  The one important factor that I suspect will still provide a noticeable improvement to my images will be longer integration time, which requires plate solving.   I’m already starting to learn this process and hope to adopt its use in the New Year.  In the meantime I feel recent imaging results and especially these narrowband images of the North America Nebula mark a very satisfying climax to my astrophotography year, progress over the past few years is very evident and I’m eagerly looking forwards to 2018.

Object North America Nebula – NGC 7000   
Constellation Cygnus – near Deneb
Distance 1,600 light-years
Size Approx. 50 light-years or 2o
Apparent Magnitude +4.0
Scope  William Optics GT81 + Focal Reducer FL 382mm  f4.72
Mount SW AZ-EQ6 GT + EQASCOM computer control
Guiding William Optics 50mm guide scope
  + Starlight Xpress Lodestar X2 guide camera & PHD2 control
Camera ZWO1600MM-Cool (mono)   CMOS sensor
  FOV 2.65o x 2.0o   Resolution 2.05”/pix   Max. image size 4,656 x 3,520 pix   
EFW ZWOx8 + ZWO LRGB & Ha OIII SII 7nm filters 
Capture & Processing Astro Photography Tool,  Deep Sky Stacker & Photoshop CS2
Exposures 18 x Ha, 8 x OIII & 8 x SII @ 180 secs  (Total time: 102 minutes)
  @ 300 Gain 10 Offset @ -20oC  
Calibration 5 x 180 sec Darks 10 x 1/4000 sec Bias 10 x Flats Ha, OIII & SII  
Location & Darkness Fairvale Observatory – Redhill – Surrey – UK      Typically Bortle 5
Date & Time 27th August 2017 @ 21.50h

AstroBites-3: Conjunction

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I was up early this morning in order to view and image the rare visual conjunction of Jupiter and Venus.  Unfortunately I cannot see the eastern horizon from here but from the top of Redhill Common adjacent to Fairvale Observatory there is an excellent view and just before 6.30 a.m. I climbed to experience the spectacle.

Following a cold, clear night the early morning weather was excellent and I was able to obtain a number of images as well as a good view using binoculars.  It was a short but worthwhile event, as shortly after 6.50 a.m., with growing brightness from the impending sunrise due at 7.14 a.m., the view of the conjunction was soon lost.  The next Jupiter–Venus conjunction will be on 30th April 2022, so time to recover!

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Galactic Neighbours

M31 LUM ProcessedX (Large)

I continue to be very impressed and pleased with the William Optics GT81 triplet refractor and ZWO1600MM-Cool camera combination, which has unleashed an exciting  new era in my astrophotography.  Still less than one year since acquiring the camera I continue to learn about its features, as well as master the increasing complexity of using a mono camera and filters; I am particularly pleased I waited last year for the release of the larger ZWO x8 EFW and matching 31mm filters.  Armed with this new set-up I’m working through my list of favourite targets that were previously imaged with a modded-Canon 550D DSLR, the difference is often nothing less than quite spectacular revealing previously unseen details and colours.

As the autumn equinox approached and the skies darkened again and imaging opportunities have thankfully greatly improved, subject to clear skies of course!  Whilst the scope-camera combo is excellent for larger DSO targets and especially nebulae, it is unable to tackle most of the galaxies which are usually small and require greater power than this provides.  However, there are a few exceptions, most significant of which arrives here towards the end of August if you are prepared to stay up very late.  It is our nearest neighbour M31, the Andromeda galaxy and smaller friends.  I think I’ve been quite successful imaging M31 before with a DSLR but now it was time to get to grips with the new camera and LRGB!1600-Gain-RN-DR-FW-vs-gain-716x1024

I’m new to the issue of Gain, Offset and ADU and am still experimenting with these settings on the ZWO1600.  As the camera performs quite differently to a more conventional CCD sensor, it’s fair to say that most other users, even those with CCD experience, are also on this learning curve.  After little more than a year since this revolutionary CMOS-based camera was introduced in the UK, only now are users starting to agree on suitable operating parameters.  Unity at 139 and has become the safe Gain setting but many have obtained some exciting results using either high gain and very short exposures or low gain and long exposures.  Given its size, apparent magnitude and high contrast core, it was clear that Andromeda was going to pose some new problems with the ZWO camera.




0 10 400
75 12 550
139 21 850
200 30 1690
300 50 2650

Current popular guidance on ZWO1600MM-Cool settings

In view of the galaxy’s characteristics the obvious adjustment would be to reduce Gain but I continued to use my standard setting of 300 and Offset 10; the offset should be higher but for some reason I was initially successful with this level and have also conveniently stored a good set of matching calibration subs too.  My initial impression afterwards was that the subs were overcooked, blown-out in the centre and lacking detail in the spiral.  Enquires on the SGL Forum seemed to confirm that I needed to turn down the Gain for the core whilst seeking a target ADU count of about 500 to 600.  Shortly afterwards I therefore imaged M31 again but this time using two different settings for the core and the spiral:  Gain-O Offset-3 + Gain-100 and Offset-17 respectively.

Green Mud

The ‘disc of green mud’ during processing! Clearly lower Gain and Offset settings combined with shorter 30 second exposure was not working.

Despite these changes initial processing of the subs obtained from the second imaging session resulted in an even worse outcome, with the galaxy now looking more like a disc of green mud! As a result I returned to the original subs and with care and perseverance teased a decent image of Andromeda (top of page) – patience and care is everything with astrophotography, if at first you don’t succeed try and try again.

Object M31 Andromeda Galaxy + M32 & M110  
Constellation Andromeda
Distance 2.5 million light-years
Size Approx. 3.17o x 1.0o or 220,000 light years
Apparent Magnitude +3.44
Scope  William Optics GT81 + Focal Reducer FL 382mm  f4.72
Mount SW AZ-EQ6 GT + EQASCOM computer control
Guiding William Optics 50mm guide scope
  + Starlight Xpress Lodestar X2 guide camera & PHD2 control
Camera ZWO1600MM-Cool (mono)   CMOS sensor
  FOV 2.65o x 2.0o Resolution 2.05”/pix  Max. image size 4,656 x 3,520 pix   
EFW ZWOx8 + ZWO LRGB & Ha OIII SII 7nm filters 
Capture & Processing Astro Photography Tool,  Deep Sky Stacker & Photoshop CS2
Exposures 60 sec 40 x L + 20 x RGB  (Total integration time: 100 minutes)
  @ Gain 300 Offset 10 @ -20oC  
Calibration 5 x 60 sec Darks + 10 x 1/4000 sec Bias + 10 x  LRGB Flats  
Location & Darkness Fairvale Observatory – Redhill – Surrey – UK   Typically Bortle 5
Date & Time 28th August 2017 @ 00.00h

AstroBites-2: Home Sweet Home

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From time-to-time I’ve been fortunate to see the Milky Way but due to the lack of dark skies, rarely in the UK.  With a move towards urbanisation taking place throughout the world, light pollution is a major obstacle to such views and astronomy in general and it is only in more remote, unpopulated locations that such sights are now possible.  On such occasions a view of our galaxy from within is always striking and usually memorable. I’ve been fortunate to visit many such remote places but either didn’t look upwards (why not?) or was hindered by the inevitable cloud.  Recently on a trip in 2016 to Arizona and Utah in the South West USA, such views were hampered by the full moon – timing is everything!  However, there have been two occasions when the darkness was so complete that I found the view of the Milky Way to be not only incredible but quiet profound – first in the Kalahari desert in Botswana and subsequently on a scuba diving trip whilst motoring southwards along the middle of the Red Sea at night with the boat’s lights turned off.

Notwithstanding, since my interest in astronomy started a few years ago I have yet to successfully image the Milky Way, which has remained resolutely elusive to my camera sensor.  I have tried a few times at Fairvale Observatory but the night sky here at best rates 5 on the Bortle scale and makes such imaging almost impossible.  Then whilst in the Arizona desert last year (see above) and on other occasions I have been thwarted by a full moon.  Apart from the obvious problem of light pollution I was beginning to wonder if I was doing something wrong but no, it was the sky conditions.

Finally during September this year, whilst camping in Dorset on the Isle of Purbeck just west of Corfe Castle, I at last managed to image the all elusive galaxy – our galaxy (see top of page).  Looking south across the Purbeck hills towards the English Channel, the Milky Way was revealed in all its glory traversing the clear, very dark sky which itself was pierced by the vivid light of the myriad of stars; it is on such occasions I realise just what I’m missing at home.  Once accustomed to the darkness the form and some detail of the Milky Way could be clearly discerned with the naked eye but of course the camera saw a lot more.

Picture saved with settings embedded.

Some processing shows good detail of the Milky Way but at ISO 6400 is too noisy

Using my unmodded Canon 700D DSLR and an ultra wide-angle 10mm lens, for the first time I was able to capture some reasonable images of the Milky Way.  All were shot on a static tripod between 15 and 20 second exposures at ISO 6,400; I had set-up the camera on the Vixen Polarie for tracking but could not obtain a favourable view of the galaxy in this way.  From this experience next time I would reduce the ISO to at least 3,200 or less and increase the exposure time based on the ‘Rule of 500’ to about 30 seconds.  However, for now I’m happy with the result and hope the next opportunity doesn’t take another  lifetime coming.

Eastern Promise

SHO Final

Eastern Veil Nebula NGC 6992 & NGC 6995 in SHO narrowband*

The East traditionally evokes connotations of the exotic and a promise of excitement.  This year the late Summer delivered plenty such opportunity for astrophotography combined with long, warm and clear nights, making for a productive and very enjoyable time.  Furthermore, this being the first year I’ve owned the mono ZWO1600MM-Cool camera, I’m mostly revisiting objects previously imaged with a modded DSLR and as a result am discovering details of hidden interest and beauty within the new images; on this occasion the object of my desire was the Eastern Veil Nebula in the Cygnus constellation.

Desperate to start re-imaging suitable targets with the ZWO camera, I briefly flirted with the Eastern Veil on the morning of the summer solstice this year.  But with limited darkness of any sort and coming just before dawn, imaging time was very limited.  I was still pleased with the result which bode well for longer, darker night conditions with the potential for extended imaging time.  In June I was only able to capture 18 minutes of Ha and 9 minutes each of OII and SII wavelengths, compared this time with a whopping 30 minutes for each!  OK it’s still quite short and for a standard CCD camera might only amount to one or two subs but given the unique sensitivity of the ZWO1600 operating at -20oC – itself a game changer in so many ways – the additional integration time achieved resulted in much more detailed and dramatic images than before.

Bicolour FINAL

Eastern Veil Nebula in Ha-OIII BiColour*

For the moment I’m very pleased with the outcome but it’s obvious that greater imaging time holds the prospect of even better images – although such improvements are likely to be less dramatic and more incremental in nature.  Due to practical limitations at this site I’m limited to about 2-hours dedicated imaging time each side of the Meridian and will only be able to increase the integration time beyond this barrier by using plate solving, thus enabling meridian flips during a session or cumulative imaging of the same object over different nights.  With plenty to learn and enjoy with the ZWO1600 camera, plus Orion already reappearing over the eastern horizon – my personal favourite, this is unlikely to occur before next year.  In the meantime, the Eastern Veil points towards a very promising future – Watch This Space!

NGC 6992 Bicolour The Eastern Veil Nebula detail in Ha-OIII BiColour*

Bicolour FINAL BAT

The Bat Nebula IC 1340 detail in Ha-OIII Bicolour*

Object Eastern Veil Nebula   AKA Caldwell 33      NGC 6995, NGC 6992 & IC1340   
Constellation Cygnus
Distance 1,470 light-years
Size Approx. 80’  vs Total Veil Nebula 3o
Apparent Magnitude +7.0
Scope  William Optics GT81 + Focal Reducer FL 382mm  f4.72
Mount SW AZ-EQ6 GT + EQASCOM computer control
Guiding William Optics 50mm guide scope
+ Starlight Xpress Lodestar X2 guide camera & PHD2 control
Camera ZWO1600MM-Cool (mono)   CMOS sensor 
FOV 2.65o x 2.0o   Resolution 2.05″/pix  Max. image size 4,656 x 3,520 pix
EFW ZWOx8 & ZWO LRGB Ha OIII SII 7nm filters 
Capture & Processing Astro Photography Tool,  Deep Sky Stacker & Photoshop CS2
Exposures 10 x 180 sec Ha, OIII & SII  (Total time: 90 minutes)
@ 300 Gain 10 Offset @ -20oC  
Calibration 5 x 180 sec Darks 10 x 1/4000 sec Bias 10 x Flats Ha, OIII & SII  
Location Fairvale Observatory – Redhill – Surrey – UK
Date & Time 19th August 2017 @ 22.38h


New Broom


Converting from a DSLR to the ZWO1600MM-Cool camera feels in part like I’m starting out all over again and is exciting.  I’m getting used to the new field-of-view and its implications for framing, which is complicated further by using separate mono filters that can often make it difficult to identify on screen the chosen imaging target.  I’m also learning to use Astro Photography Tool (APT) for image capture, which is turning out to be an excellent programme, though at times somewhat idiosyncratic in nature.  APT contains useful Histogram and associated Stretch tools, which when applied to test shots prior to data capture can reveal underlying target detail which is otherwise unseen and thus enables suitable framing to be chosen.

With a set mount location, better polar alignment, calibrated PHD2 and a basic star alignment model established in EQ-ASCOM early in the summer, the process of imaging has now become much more efficient. After adding a few supplementary alignment points local to the target and some other minor adjustments, I have recently been able to set-up and start imaging in much less than one hour; excluding the physical set-up, imaging is possible within 30-minutes.  Contrast this with one or two hours when previously using various Synscan handset procedures and setting up the DSLR camera, I think it’s fair to say I have at last crossed the proverbial Rubicon!  Using a cooled sensor and compiling a calibration library has also been very helpful in streamlining imaging sessions, which all-in-all has made my astrophotography much more productive – qualitatively and surprisingly quantitatively too, despite all the extra subs and calibration required.

I’m currently working through familiar targets with Ha-OIII-SII subs to produce Hubble Palette based images.  It’s true to say that the use of narrowband filters has also been nothing less than a revolution for my imaging, in terms of process and results.  I’m particularly pleased that I purchased the ZWO x8 EFW and matching LRGB + narrowband filters with the new camera – 31mm parfocal filters also help minimize the need to re-focus for different wavelengths.

NGC 6960multiplelevelsonecontrast FINAL(Medium)

The Witch’s Broom (NGC 6960): WO GT81 & Canon 700D camera + 0.80x Focal Reducer | 20 x 90 sec + calibration @ ISO 800 | October 2014

It’s about 4-years since I embarked on my nascent astrophotography journey and soon thereafter I first attempted to image the notoriously difficult Veil Nebula – which of course is why I had to try.  At the time I did not know one end of the Veil from the other of this very large but faint and widely dispersed supernova and was pleased to achieve a recognizable image of the Western Veil or Witch’s Broom (NGC 6960).  This July I set out to re-image the same feature for the first time using the ZWO1600MM-Cool camera in narrowband.


The Veil Nebula AKA Cygnus Loop: Ultraviolet view ref. NASA

The full extent of the Veil is broadly demarcated by the Western and Eastern Veil Nebulae, with other generally more diffuse but related areas in between.  All-in-all the entire feature is some 3o or 110 light-years across.  The ZWO1600MM-Cool has two notable features that differentiate it from conventional CCD mono cameras, those being larger sensor size and high sensitivity when using only short exposures.  Unity of the sensor is 139 but like many other new users I’ve successfully been using a much higher Gain, in my case 300 with an Offset of 10; others have reported very good results as high as 600 Gain at just 30 second exposure, which though data heavy is very useful in helping to circumvent the UK’s fickle weather conditions and the need for perfect polar alignment, which was a major factor in deciding to purchase this type of mono camera.

Being still unfamiliar with the camera’s field-of-view using the William OpticsGT81 refractor and x0.80 focal reducer combination, on this occasion I centred the Broom just above the centre of the frame, thus adding the possibility of capturing other parts of the nebula located to the east and just below the Broom in this case.  As I’ve yet to master or even attempt mosaics or a Meridian flip with plate solving, for the moment my imaging is limited by the transit period defined from about 110o east to the Meridian or similarly to the west and between a 30o to 80o azimuth, which equates to just over 2 hours per target each side of the Meridian.  The nature of the object and lack of darkness at this time of the year can often restrict this available time even further.  Notwithstanding, on this occasion I was able to obtain 20 x Ha and 18 x OII 180 sec subs in order to produce a final bicolour image.


The Witch’s Broom NGC 6960 & Pickering’s Triangle NGC 6979 Ha-OIII-OIII Bicolour: WO GT81 & ZWO1600 + 0.80x Focal Reducer | 180 sec x 20 Ha & 18 OIII Subs + calibration @ Gain 300 , 10 Offset & -20C | 31st July 2017

With a good set of subs the stacked and collated Ha-OIII image has turned out well, with nebulous filament details typical of the Veil that had not previously been clear when using a modded-DSLR camera now clearly visible.  Furthermore, on this occasion the aforesaid framing included detail of both the Broom and as something of a bonus Pickering’s Triangle, altogether forming a very pleasing image.

At this stage I would usually crop the Witch’s Broom and finesse the resulting image in Photoshop.  However, following a prior line of thought and questioning on the SGL Forum, this time I tried to use the Drizzle_technique during stacking to enhance the quality of The Broom itself.  Unfortunately it didn’t take long to discover that, as so often is the case with astrophotography, drizzling is a good deal more complicated than just placing a check in the Drizzle box.

Originally developed for use with the Hubble Space Telescope, drizzle is a digital processing method for the linear reconstruction of under-sampled images, thus improving the apparent resolution of the image.  Deep Sky Stacker is an excellent piece of software and provides the facility of x2 and x3 Drizzle but unlike some commercial packages has limited memory that is used for this task.  As a result after attempting to use Drizzle whilst stacking a number of times in DSS, the process crashed at the end of each sequence.  Finally another SGL Forum query provided the answers: (i) DSS lacks memory required to stack and process the original sub using Drizzle, but (ii) Drizzle will work by applying the Custom Rectangle Mode in DSS to a select a specific, smaller area of the sub.  It took me a while to figure this out but eventually I manged to process the Witch’s Broom area of the image successfully.  I’ve concluded that Drizzle is certainly a feature worth deploying during stacking from time to time but only where the main target is poorly sampled and where the specific object will fit within the Custom Rectangle Mode defined by DSS – it should also be noted that the resulting data size also increases very substantially when using Drizzle.


Witch’s Broom (as above) + 2x Drizzle

All-in-all it continues to be a great surprise just how different and often complex the techniques are with a mono camera and filters compared to a one-shot DSLR camera, both during capturing and processing.  I was previously aware of these issues and some related shortcomings but so far the results have justified the additional effort; I’m not sure I would say the same about a conventional mono CCD camera, that requires much longer imaging times which in my opinion are not suitable for the average user and weather conditions in the UK.  I know there’s still much to master – Plate Solving + Mosaics + Meridian Flips + Sequence Generator Pro etc. – and I’ll soon need to start a completely new alignment star model for winter and recalibrate PHD2 guiding but the past few months have really been good fun and very productive.

Cosmic Nursery


With the summer arm of the Milky Way now starting to dominate the late evening sky I’m slowly returning to imaging DSO objects, this time literally in a new light using the ZWO1600MM-Cool camera.  Because of the inclined orientation of the Milky Way it is the lower altitude objects that first become accessible, which is unfortunate as seeing conditions will generally always be poor at these levels.

South Overview copy

However, the problem is compounded here at Fairvale Observatory by high hedges and numerous large trees that obscure much of the southern horizon below about 28and in this case also severely restricting imaging time.  It’s a real pity as the constellation Sagittarius that is located in this region of the sky abounds with some wonderful objects.

M20 Location

On this occasion my primary target was M20, the Trifid Nebula (NGC 6514). At some 28” size and an apparent magnitude of +6.3 it is just feasible with my equipment, so long as I could overcome the obstructions along the southern horizon!  Located 5,000 light-years from Earth in the Scutum spiral arm of the Milky Way, at about 300,000 years old M20 is one of the youngest star forming regions in the sky.  The feature is a combination of open star clusters, emission nebula and reflection nebula separated by dark dust lanes, that together form three lobes i.e. Trifid.  As a stellar nursery, close to the centre the most massive star is twenty times the size of the Sun surrounded by a cluster of 3,100 young stars.

M20 BiColour MasterC2HP (Large)

M20 Trifid Nebula & western edge of M8 Lagoon Nebula in Ha-OIII bicolour | WO GT81 & ZWO1600MM-Cool camera + 0.80 focal reducer | 180 sec x10 Ha x5 OIII x3 SII + full calibration Gain 300 Offset 10 @ -20C | 27th July 2017


M20 BiColour MasterC2HP CROP (Large)

M20 Trifid Nebula in Ha-OIII Bicolour (cropped)

Despite the limited imaging time available and other difficulties, I’m pleased with the resulting images, which have been processed in SHO and Ha-OIII bicolour.  Furthermore, just evident along the left side of the main image is the western edge of the much larger Lagoon Nebula or M8; unfortunately being even lower in the sky I don’t think I’ll ever be able to image M8 from this location.

M20 SHO Master GxHP crop (Large)

M20 Trifid Nebula in SHO narrowband (cropped)

Together with the recent success of the Eagle Nebula and Eastern Veil, things are shaping up well for astrophotography once again as the Milky Way and other features pass across the night sky over the coming increasingly dark weeks.  I’m certain to return to M20 again as it’s a wonderful object, hopefully from a better vantage point next time that will allow imaging of some of its neighbours.  I have long been aware of M20 and in my ignorance was going to call this blog Gardener’s World but now realise that it is the Trifid not Triffid nebula!


That’s Trifid not Triffid!


The Dutch Gadget

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I have just finished reading J.L. Heilbron’s biographical tome on Galileo, which though very interesting I found a difficult book and somewhat academic in style.  In 1609 Galileo became aware of a Dutch spectacle maker’s device that made distant objects appear closer.  He subsequently became known for developing the so-called ‘Dutch Gadget’ into what we now know as the refracting telescope and moreover, applying its use to understanding the Solar System with the discovery of Jupiter’s four largest moons, confirmation of the phases of Venus and the observation and analysis of sunspots; the word telescope was subsequently coined in 1611 from the Greek tele “far” and skopein “to look or see” i.e. far-seeing.  In so doing he also helped to confirm the then controversial truth of the heliocentric astronomical model, whereby the Earth and planets orbit the Sun.  Against this background it is no surprise that Galileo is today much revered by mankind and has become known as the father of observational astronomy.


Drawn into the complexity of obtaining images of the Solar System and beyond, it is the curse of astrophotography that we inevitably neglect observing the spectacle itself.  Notwithstanding, I am sure that Galileo would understand the power and beauty of today’s astrophotography, which in its own way is producing a quantum leap in our understanding of the Universe comparable to the impact of the original application of the telescope.

This summer the Solar System will hopefully provide both good observational and astrophotography opportunities here at Fairvale Observatory: Jupiter, Saturn, Comet C/2015 V2 (Johnson), the Perseids meteor shower and the Sun – sadly though I will not witness next month’s solar eclipse which takes place mainly over North America.  During recent summer months the lack of astronomical darkness, short nights and absence of DSOs has frustratingly continued to limit potential imaging targets for my new ZWO 1600MM-Cool camera but utilising a period of good weather there have recently been a few fleeting opportunities just before dawn related to the appearance of the summer arm of the Milky Way on the eastern horizon.

solstice sky

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NGC 7000 The North America & Pelican Nebulae WO GT81 + modded Canon EOS 550D + FF | 30 x 120 secs @ ISO 1,600 + calibration | 19th September 2015

I first imaged the North America Nebula (NGC 7000) in 2014 and have since returned each year to image the nebula or its various parts using a DSLR camera.  Being a very large Ha-object the nebula is an ideal target for the ZWO1600MM-cool camera and I have been anxiously waiting its arrival again this year.  On this occasion, early on the morning of the summer solstice, high in the sky and 90o east the nebula was only just visible from my location, being very close to the roof-edge of my house!  Consisting of just six Ha-frames plus three OIII and SII taken just before dawn broke, the resulting image was never going to be my best but is nonetheless interesting in SHO format and quite different to previous DSLR images.

NGC 7000 BiCol (Large)

North America Nebula in Ha-OIII Bicolour

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North America Nebula in SHO

At the other extreme, located low on the southern horizon and only briefly visible as it passed between the trees at the end of my garden is the Eagle Nebula AKA M16, home of the Pillars of Creation.  At 7-arcminutes in size and an apparent magnitude of +6.0, the nebula is at the lower end of possible for my set-up and at some 27o altitude with just 40-minutes imaging time between the trees it was a challenging target.  Notwithstanding, I’m pleased with the Ha and SHO narrowband images obtained, which quite clearly show the Pillars too.

M16 SHO1 (Large)

M16 Eagel Nebula in SHO: William Optics GT81 & ZWO1600MM- Cool & Field Flattener | 6 x 180sec Ha, x3 OIII, x3 SII Gain 300 Offset 10 + full calibration | 21st June 2017

As astronomical darkness is now slowly returning and with clear skies and weather permitting, I hope to attempt longer imaging sessions of both these and other targets during the rest if the summer and into autumn – I might even get to see M16 again as it eventually emerges from the other side of the trees!  Thanks to the development of the Dutch Gadget and modern cameras it is now possible for amateur astronomers to image such spectacular objects – I’m sure Galileo would be impressed and highly approve.