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.

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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.

Another Side Of the Veil

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Veil Nebula / Cygnus Loop WO GT81 & modded Canon 550D + FF | 30 x 180 sec exposures @ ISO 1,600 | 19th September 2015

I first imaged the Western Veil in October 2014 and return each year to the so called Witch’s Broom and other parts of this faint supernova remnant that stretches over 3-degrees of the night sky for the next four months.  Located in the Cygnus constellation, the Veil Nebula is high in the sky and at this time-of-the-year is only just visible late in the night being some 80o east of The Meridian; short nights and lack of darkness further complicates imaging at the moment.  However, with the weather set fair and having just completed some other good targets, I couldn’t resist a few frames of the Eastern Veil using the new ZWO1600m-Cool camera and narrowband filters before going to bed.

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Eastern Veil Nebula (NGC 6922 & 6995): WO GT81 & modded Canon 550D + FF & guiding | 10 x 300 sec @ ISO 1,600 + darks | 11th September 2016

With Nautical Darkness due to end at 2.40 a.m. imaging time was at a premium. In the event I managed just 40 minutes, towards the end of which the sky perceptibly lightened – it was after all mid-summer day and the Summer Solstice beckoned!  The limited imaging time inevitably impacted on the quality of the final image but I am nevertheless pleased to have seen and imaged another side of the Veil nebula so soon in the year on 21st June – certainly the sensitivity of the camera helped a lot in achieving this.

Veil HSO Hub


Veil Bi Col Hub

Bi-colour Ha+OIII+OIII

Eastern Veil Nebula – narownband images: All images taken using WO GT81 + Field Flattener & ZWO 1600MM-Cool camera + either Ha (6 x 180 sec), OIII 3 x 180 sec or SII 3 x 180 sec at -20C set at Gain 300, Offset 10 & full calibration | 21st June 2017 

I am still experimenting with narrowband imaging and therefore using colour mapping processed the three wavelengths into three different final image formats.  The HSO and Ha-OIII Bi-colour are interesting but my favourite is the SHO version shown below, which shows interesting and attractive details of the Veil’s nebulosity in ways that were previously not possible with a DSLR camera.  Though short, it was a very productive evening for imaging and for a variety of reasons will be a night to remember for a long while.

Veil SHO GxCcropHub

Eastern Veil Nebula in SHO – For Will


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

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.


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.


Great Balls Of Ice


The next couple of months can be frustrating for astronomers in the Northern Hemisphere.  We have just entered the period of summer during which there is no astronomical darkness and for those of us who enjoy the spectacle of a DSO there are also few around to image, especially of the larger Ha-type that my equipment is currently best suited to.  However, there are compensations and with some imagination and a change of tack, it can be a useful time in which to do some housekeeping and return to objects not usually viewed.

I recently noticed that dust and the odd stray fingerprint had appeared on the object lens of my William Optics GT81! Opinion on how to clean this critical element is varied but all advice says: (i) be very careful, and (ii) do nothing unless you absolutely have to; in particular opinion is divided on whether to use alcohol-free cleaner.  I therefore purchased some Baader Optical Wonder Fluid which comes recommended by many but for now confined cleaning to the use of a brush and compressed air to remove the dust and a Lenspen to gently polish the glass surface – the Wonder Fluid will have to wait until another day.

Warm temperatures that accompany summer are also a more comfortable time in which to undertake important tasks outside, such as re-setting equipment alignment, balancing, cable routing etc.  I am therefore also replacing the mount power cable and EQDIRECT adapter cable, both of which look the worse for wear.  Truth is the original cables were poor quality and, mindful of my disastrous camera cable problems this time last year, if possible I now intend to upgrade both these critical items.  The experience of last year’s meltdown showed how prone cables are to low winter temperatures and I now see there are alternative silicon cables on the market – obviously I’m not the only one who’s suffered!

Of course we all want to be outside imaging and observing and a recent spell of very fine, clear, warm nights provided just such an opportunity – but what to do?  There are some popular objects within the Solar System that are worthy of attention at this time of year, which for a change I therefore once again tried my hand at imaging, on this occasion a comet.

There have recently been no less than three notable comets in the night sky:

  • 41P/Tuttle–GiacobiniKresák:  first discovered in 1858, the comet orbits the Sun every 5.4 years and this year was seen from Ursa Minor – Draco – Lyra between March and May.
  • C/2017 E4 (Lovejoy):  only discovered earlier this year by the inimitable Australian comet hunter Terry Lovejoy, the comet rises in the east-northeast above the star Enif in the early morning sky.
  • C/2015 V2 (Johnson): probably this year’s most popular comet, was at full magnitude in Hercules during April but is still clearly evident to the east of Bootes from about 11pm – see below.

V2 CdC

I have only once before imaged a comet, that being C 2014 Q2 Comet Lovejoy (him again) in January 2015, on this occasion I set out to image the aforementioned C/2015 V2 (Johnson).  The comet will soon reach perihelion on 12th June and thereafter leave the Solar System.  Travelling at a speed of 74,000 mph, imaging this small body of ice as it passes Earth is difficult and required going back to basics.  It was also the first time since January that I had used the DSLR camera, which despite longstanding experience required some brushing up.  At first I intended to follow the comet using the Custom Tracker facility in EQMOD but in the end this seemed unnecessary once I had the object centred in the camera and instead I resorted to a number short exposures at high ISO.

v2 orbit

V2 Track I am pleased with the results, though they are a little noisy due to some stupid mishaps on my part along the way which left less imaging time than I would have wished.  Though each comet is different, experimentation suggests that with good framing and guiding, exposures of about 2 minutes and ISO 3,200 produced the best results.  Given this exciting experience, which was also good fun,  I will hopefully not leave my return to comets so long as last time.

A New Palette


It still remains early days with the new ZWO 1600MM-Cool camera but the initial signs using the narrowband filters have been very promising and frankly good fun.  I’ve been surprised at the benefits gained using these filters and especially the new and exciting possibilities it introduces to imaging. But there’s more.

When first using a digital camera for astrophotography it came as a surprise to discover that the colours come from an RGB Bayer Matrix placed in front of the sensor.  The so-called One Shot Colour camera or OSC, provided me with many decent images and when I recently started to think about getting a better camera another OSC seemed the way to go.  Their major benefit is that you are able to just take, as it says, one shot – or multiple colour shots for stacking.  Of course there’s still much to learn when starting out but the process is relatively simple and a decent set of subs and calibration frames can be obtained in a few hours or less; subsequent processing is also straightforward with one set of subs and no more than three sets of calibration frames.

Notwithstanding, when looking at more specialized OSC cameras, it soon became clear that the benefits of moving from DSLR were limited.  Another surprise with astrophotography is that the best images are obtained using a mono camera, in combination with colour and if required narrowband filters.  Hitherto, this has meant precise guiding in order to obtain long exposures using a very expensive CCD camera.  However, last year everything changed with the introduction of completely new technology in the form of a cooled CMOS camera, which I and the astrophotography community are currently getting to grips with – the aforementioned ZWO ASI1600MM-Cool.

Whilst more complex to use than a DSLR, this camera seems to be something of a game changer for astrophotographers in that: (a) it has a larger more sensitive sensor than a CCD camera, (b) it’s cheaper (though not cheap), (c) because of its sensitivity imaging requires only relatively short exposures, thus reducing the need for ultra-precise guiding as it gathers light more quickly than a conventional camera.  It was the latter feature that convinced me to go ahead with the camera and it is already clear this was not a mistake.

I often complain about the excessive cloud cover we suffer here at Fairvale Observatory, which can often prohibit imaging for weeks or even months on-end.  The advantage of imaging quickly when the clouds do eventually part is therefore a major factor for me.  If the camera has one problem it’s probably the vast quantity of data generated, putting huge demand on computer memory and processing power – but it’s worth it.


LRGB imaging is the main format used by most advanced astrophtographers, after all the resulting colours and detail achieved can be spectacular and it was now time for me to give it a try.  I was astonished to learn that some 80% of the detail in an image is in the luminance and only 20% colour, so the advantage of LRGB imaging becomes immediately apparent.  I also purchased the ZWO x8 EFW and matching 31mm filters with the camera and initially had some problems getting it to work.  However, once sorted it has been a pleasure to use and makes image sequencing with different filters a piece of cake.

At the moment I’m using Astro Photography Tool (APT) for capture and apart from my own lack of LRGB imaging experience and some misunderstandings of the software, it works very well.  A full LRGB sequence is easy to set-up beforehand and after that the imaging automatically looks after itself!  I carry out most of the calibration frames manually but this too is generally quite easy; I did struggle at first with the flats, which is a quite different method compared to a DSLR but once I got the hang of the APT Flats Aid – courtesy of the APT Forum members – all was OK.

Notwithstanding, at first I was concerned by large concentric light and dark halos in the flats.  I have long used the combination of a flowerpot, LED and T-shirt for taking flats, which has always worked well.  I therefore expected the flats from the new camera using APT would not be a problem.  However, as mentioned taking flats with this camera is a whole new ball game which has taken some time to master, or at least learn.

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The flower pot flats set-up has always worked well before.

Unlike the DSLR, which just requires changing to the AV mode, it is necessary to calculate an exact exposure – to five decimal places – using a mid-range ADU setting of between 20,000 and 25,000 for each different LRGB filter.  Sounds awful and it does generate a lot of frames but now I’ve got the hang of the Flats Aid it is much easier and very effective; on average I have so far found the required exposures vary from 0.00145 sec to 0.00792 sec.  I did discover some minor light leakage in the optical train when testing the flats taken in daylight but by doubling up the T-shirt material and adopting a more careful set-up of the flower pot directly in front of the telescope object lens, the halos now seem to have disappeared.

The other new ‘toy’ with this camera is cooling.  Despite the camera’s low noise and high sensitivity, like all digital cameras there is an inevitable amount of unwanted signal and currents created by the sensor.  Apart from applying calibration frames, this problem can be significantly reduced by cooling the sensor when imaging.   APT also has cooling and warming aid controls to avoid thermal shock but at first I struggled to get these working – turns out I forgot to plug the power lead in!  After that it has worked like a dream and I am now routinely imaging at -30oC.  The one drawback is that cooling down and warming up adds another 10 or 15 minutes to the set-up and take-down times, which can be annoying at 2.00 a.m. when you want to get to bed!

Unfortunately, now I have this camera working suitable imaging targets are in short supply for the moment.  At first I was able to carry out some narrowband imaging of the remaining late winter nebulae just before they disappeared for the season but I must now wait for a few months until later in the year for similar objects to appear again. Meanwhile, whilst the night sky in spring abounds with some wonderful galaxies, most of these are really too small for my set-up to resolve properly.  However, in the absence of larger DSO objects I have had to make do with these and have been pleasantly surprised by some of the results obtained.

The outcome of Leo Triplet and Markarian’s Chain were particularly good and demonstrate the superior abilities and power of the camera.  Compared to the Canon 550D, when used with the William Optics GT81 refractor and a x0.80 field flattener, the ZWO 1600MM-Cool’s sensor produces a notably larger image with much greater sensitivity.  As a result detail of all three galaxies that form the Leo Triplet M65, M66 and the end-on view of NGC 3628 is quite apparent and in another image, the spirals of the very small M61 galaxy can be clearly seen, though the quality is poor.


Leo Triplet – M65 (top right) M66 (centre right) NGC 3628 (lower left) Leo Constellation: William Optics GT81 & ZWO 1600MM-Cool + x0.80 field flattener | 60 sec 20 x L, 5 x RGB + full calibration, Gain 300 Offset 10 @ -20C | 21st March 2017

As expected the size of the data set from LRGB imaging with the camera is prodigious and furthermore, requires great care to organise before processing if mistakes are to be avoided.  In the case of Markarian’s Chain I experimented with binning – only to learn later that it has no effect with CMOS sensors – which reduced the file size of the RGB and calibration images.  Nonetheless, in all there were still 140 images with a combined file size of 1.6 Gigabytes!  Notwithstanding, the benefits of LRGB imaging with this camera and EFW outweigh such problems and nowadays an extra storage disk is relatively inexpensive.  Only processing power could perhaps be a problem if using an older PC but my 64-bit + i7 chip +16 GB RAM laptop computer has so far dealt easily with data processing very well.

lrgb data

The difference between imaging and processing with a DSLR and the ZWO CMOS mono camera has been much greater than I anticipated and required more adjustment which I am still dealing with – the learning curve is steep!  Notwithstanding, the experience previously gained using a DSLR has proved invaluable and I would not like to take-on LRGB imaging from scratch; I’d like to think that my adage of walk before you run once again has paid off.  This camera is very exciting and I am confident that when the autumn and winter skies eventually return the new palette now in my hands will reap great rewards – can’t wait.

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Markarian’s Chain | Subs 60 sec – see table for details Gain 300 Offset -30C | 18th April 2017


M61 piral Galaxy in Virgo Cluster | William Optics GT81 & ZWO 1600MM-Cool + x0.80 field flattener | L 30 x 40 sec RGB 3×20 sec + full calibration Gain 75 Offset 15 -30C | 2nd April 2017

Brave New World

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In my quest to understand astronomy and in particular the big picture, I have just successfully completed another MOOC course at the University of Edinburgh on the Higgs Boson and particle physics.  From earlier studies which included the Special Theory of Relativity and the Universe, the next step was obvious: moving from the very big to the very small in order to better grasp where we might be with the elusive unified theory and I was not disappointed. An added bonus to the course was the participation of Professor Peter Higgs himself, in which he discussed how he had arrived at his conclusions and the development of subsequent matters that led to the actual discovery of the Higgs Boson at the Large Hadron Collider in Cern, Switzerland in 2012; watching and listening to him speak felt like having a personal chat with Einstein and was quite a privilege!


A chat with Professor Peter Higgs!

Frankly I found the nature of the subject very difficult and at times bewildering but its potential impact on astronomy was finally something of an epiphany for me.  The Higgs and related items results in two profound results:

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

I am not sufficiently able to articulate how these conclusions are arrived at nor is this the place, but when the full content of particle theory, the Higgs, General Relativity are applied to cosmology, the aforementioned outcome is, like all good science, simple and beautiful – click here for lecture notes Higgsmooc part1  + Higgsmooc part2  and accompanying presentations 7.11_Quantum Vacuum_& Cosmology + 7.12_The HB_scalarfieldsand inflation.

I’m pleased to say there have also been other breakthroughs for me since achieving first light with the ZWO 1600MM-Cool CMOS camera.  I am still at the experimental stage and with the spectacle of the winter sky rapidly departing, suitable objects are much more limited, with the few remaining HII objects low and very far to the west of the early evening sky.  However, before the Milky Way disappeared completely I managed to obtain some useful imaging experience by targeting some old favourites.


Passing Shots: Orion & Rosette Nebulae

Having already battled a number of issues with the new camera – basic LRGB image capture, using Astro Astronomy Tools, achieving focus, guiding, alignment, processing and post-processing – for the moment everything has come together, including some warmer nights and clear skies.  Over a few evenings I therefore undertook imaging in LRGB as well as Ha, OIII and SII, with some excellent results that augur well for the future.

The camera’s sensitivity and ability to image at short exposures enables much less imaging time than conventionally used with CCD cameras – one of the reasons I decided to purchase this camera.  In addition, shorter exposures make perfect alignment and tracking less important, though still a desirable set-up.  The downside is it produces a prodigious number of images, which leads to a somewhat challenging processing burden – but it’s worth it.

Despite my DSLR experience, CCD processing and especially post-processing, is significantly more complex.  I was surprised to find only one decent online video on LRGB processing by Rankin Studio, without which the task would have been even more difficult and taken much longer to learn – thanks David.  Ironically I have found narrowband processing easier, probably because there are just less filters and resulting image sets required, however, the restricted wavelength also provides whole new opportunities that I’ve already started to exploit.

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Orion Nebula + M43 & Running Man Nebulae in Ha: William Optics GT 81 & ZWO 1600MM-Cool + x0.80 field flattener | 15 x 180sec Gain 139 Offset 21 @ -18C & full calibration | 25th March 2017

Just before they disappear from our night sky until next winter I was fortunate to be able to image both the Horsehead and Orion nebulae, everyone’s favourites and I’m no exception.  With limited time available in the early evening sky it was only possible to capture a limited number of images before it moved outside my view in the west but even with these few images the power of the camera has already become self-evident.

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Horsehead Nebula in Ha: William Optics GT81 & ZWO 1600MM-Cool + x0.80 field flattener | 19 x 180 secs Gain 139 Offset 21 @ -18C & full calibration | 27th March 2017

Given the need to use less filters and thus less time I have started out with narrowband imaging – as a completely new medium for me that holds great promise aesthetically and scientifically, I was also keen to give it a try and on this occasion used Ha and OIII.  Having sorted an earlier problem with the EFW managing the filters is a breeze and can easily be automatically sequenced in the APT capture software.  Notwithstanding, as previously indicated image capture is really only just the start – though good data is always the key to the final image – and processing and post-processing is both complex and takes considerable time.

M42 Bicolour & balance

Orion Nebula in bi-colour: Ha red channel + OIII green and blue channels

On this occasion the individual Ha subs are themselves very revealing, showing new details when compared with previous DSLR images.  But it is with the bi-colour image that the exciting opportunities provided by using narrowband imaging become apparent – I can see I’m going to enjoy this!  I’ve also taken the opportunity to further explore and understand the nature of these types of images and their constituent parts by manipulating the colour channels, with some startling results.

NGC 2244 HOS-1LCLCrop (Large)

Rosette Nebula in HOS: William Optics GT 81 & ZWO 1600MM-Cool + x0.80 Field Flattener | 15 x 180 sec Gain 300 Offset 10 Ha, OIII & SII @ -20C + calibration | 24th March 2017

Not far from M42 is another of my favourites which I’d already used to achieve First Light with this camera using Ha – the Rosette Nebula (NGC 2237, 2238, 2239, 2244 & 2246).  This time I decided to use all the narrowband filters – Ha 656nm, OIII 672nm, SII 500nm all 7nm bandpass – and subsequently experimented with processing using the Hubble Palette with stunning results.  As the name indicates, this technique was originally developed for processing images taken with the Hubble Space Telescope which put simply, uses different mixes of each narrowband filter in different processing channels e.g. Ha in the red channel, OII in green and SII in blue, for short known as HSO.

NGC 2244 SHO Final1

Rosette Nebula in  SHO

The outcome of my new adventure into narrowband imaging has been nothing less than a revelation.  Like so much of my preceding astroimaging, I knew about much of it before but doing it yourself and seeing the results is both exciting and very satisfying; like Peter Higgs I feel I have entered a new world!

First Light


If nothing else, I have learned from life – walk before you run.  I have spent the past three years trying to learn about astronomy and astrophotography using a DSLR but late last year decided it was time to raise my game.  I was reluctant to go to a CCD mono camera as it involves greater complexity and, perhaps more significantly, during the aforesaid period clear skies have been in very short supply – making long, guided exposures over protracted periods something close to impossible where I live.  However, with the recent advent of the new CMOS cameras and their rave reviews, against my better judgement I took the plunge and bought a ZWO ASI 1600MM-Cool with a matching ZWO x8 EFW and 31mm LRGB, Ha, OIII and SII filter set.

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Wow! As expected, it’s a whole new world compared to DSLR and, as well as continuing week-after-week cloud cover, I have been battling with numerous set-up and processing issues. Still, rule number one with this hobby is patience and perseverance and I’m pleased to say I have just achieved First Light with the camera.

At first I set up the camera indoors on a tripod to test the equipment and quickly found that the camera and EFW would not work together; in addition to a USB 3.0 data socket, the camera also has two useful USB 2.0 sockets which can be used to power and control other equipment.  After more than 3-weeks, much help online and a mixed response from the manufacturer, ZWO suggested I try another USB driver which they sent me and it worked – so why not supply that in the first place or ensure users are aware of the issue and provide a solution from the outset?  Whilst the actual equipment is well specced, well made and well priced compared to CCD camera – though far from cheap, I found ZWO’s web-based technical guidance and general support poor and would expect better with such expensive equipment.  In retrospect, perhaps it is not a surprise as I had a USB problem when I purchased their ZWO ASI 120MC camera, with a similar response and outcome i.e. there is a theme here, which is a pity as their equipment itself is innovative and very well made.

During brief periods between the clouds I subsequently managed to try-out the camera in order to understand focus, capture and processing. Despite prior experience with the DSLR and software, this turned out to be new territory which I am still exploring. Briefly:

Focus – With the new camera I was faced with two fundamental focusing issues:

  • Establishing the correct optical train – I want to continue using the William Optics x0.80 focal reducer with the ZWO camera, thereby increasing the speed of the scope from f5.9 to f4.72. I therefore purchased a Canon EOS adapter to use with the existing EOS convertor which has previously worked successfully with the DSLR.  Despite the apparent complexity, the resulting set-up is within 0.50mm of the optimum distance and seems to work OK – with one exception. Whilst the locking pin on the EOS adapter works i.e. it locks, there is some unacceptable lateral play, which for now I have solved with the addition of a piece of electrical tape! I’m advised this is normal for such adapters but it seems like a poor product to me if this is the case.    ZWO cam_EFW_FF_annotated (Large)
  • Operating focus – after months of battling with focus when I started out DSLR imaging, I eventually discovered the Bahtinov mask and assumed this wonderfully simple method would work just as well with the new ZWO camera; of course, after my initial trials it was apparent this wasn’t going to be the case.  Not that the mask doesn’t work but in order to achieve good focus with the smaller pixels of the ZWO ASI 1600 requires much greater accuracy, which I’m pleased to say has now been achieved by using APT’s Bahtinov Aid (based on Neils Noordhoek’s Bahtinov Grabber), so that I am now getting much better results.  However, as the focus point can change with seeing conditions and when using different filters, it is apparent that I’ll need to return to this matter again to finesse the operation, probably by using an electronic focuser.

Capture – At the heart of my philosophy is the KISS principal – Keep It Simple Stupid! When working with the DSLR I therefore only ever used the Canon EOS Utilities software for image capture – it is simple, did what I needed and worked.  Moving to a mono camera with filters, the increase in complexity is exponential and inevitably requires more sophisticated image capture software.  Judging by the experience of others Sequence Generator Pro seems to be one of the best low cost programmes that will do this job and I have purchased a copy for US$99 and the accompanying Framing and Mosaic Wizard for an additional US$39.  However, in applying the KISS principal during the early stages of getting to know and understand the new equipment and processes, for now I’m using Astro Photography Tool (APT) – something I’ve had for a while but not used before.  It is a very capable programme that manages sequencing, cooling, filter management etc. well, with excellent support from its author Ivo but importantly seems easier to use than SGP, albeit inevitably with its own idiosyncrasies.  It’s early days but so far so good.

Processing – Mono images differ in a number of fundamental ways to DSLR other than just colour, which requires a quite different approach to processing and post-processing, in particular:

  • the images are FITS not RAW;
  • mono images are taken with a variety of filters which subsequently need to be compiled.

Despite successfully working with Deep Sky Stacker (DSS) for some time, I was not aware of any changes required when processing FITS files, which are the product of the ZWO 1600 camera; useful pre-assessment of the files can be carried out using the ESA/NASA free Fits Liberator software.  As a result my first try of the Beehive Nebula based on just Luminance subs was covered in bizarre ‘green spider-like’ artefacts after stacking in DSS.  These disappeared when transferred into Photoshop but then became covered in Bayer matrix-like coloured squares!

Thanks to help from the SGL Forum it was apparent that I had failed to turn-off the FITS colour option in Settings before stacking – unchecking this and restacking immediately resulted in a half-decent image of the open star cluster.  Meanwhile, since purchasing the ZWO camera I have read and watched numerous videos on post-processing and using LRGB files available online for practice, I have been able to start experimenting with this technique prior to obtaining my own data from the new camera.  It is much more complex and I’ve got a long way to go but the experience gained from DSLR processing has nevertheless helped immensely; walk before you run pays off in the end!

And so last week I managed my first reasonable image of the Rosette Nebula (NGC 2244) using only Ha-subs, which this object has in abundance.  I consider this marks the camera’s First Light and am pleased with the result but realise there’s still much more to learn, weather permitting!

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Rosette Nebula in Ha | William Optics GT81 + ZWO ASI 1600MM-Cool & x0.80 focal reducer + guided | 15 x 180 secs + darks & bias calibration Gain 300, Offset 10 | 21st March 2017

  • This guided image is 15 x 180sec Ha-subs + darks and bias, gain 300, offset 10 + minor stretching in Photoshop. The corners – particularly the bottom right – look like there may be some vignetting in the stacked image?  I haven’t managed to achieve any decent flats yet (another story) but I assume these would help eliminate this effect? However, I am surprised as I’m using the ZWO x8 EFW with larger 31mm filters, which with the focal length of 382mm (f4.72) should not result in vignetting.
  • Clearly my experimentation is ongoing with this new technology and I particularly need to understand better what is the ‘best’ gain and offset setting for different types of objects.
  • Whilst the CMOS chip is bigger than standard CCD sensors it is still smaller than a standard DSLR and with smaller pixels too (3.80nm v 4.30nm), the result when used with the focal reducer is a 29% reduction of the field-of view from 3.34o x 2.23o to 2.65o x 2.0o, which on-screen translates to increased magnification and allows me to get at some of the galaxies which hitherto have been too small; the benefit is minor but is worth having nonetheless.




From Cloudy Nights Forum – compiled by Jon Rista

All-in-all the ZWO ASI 1600mm-Cool is an excellent piece of kit that has the potential to open up new vistas for my astroimaging.  At a fundamental level it does all the basic stuff very well and the addition of cooling is a major improvement which  reduces noise still further.  I’m particularly looking forwards to experimenting with narrowband and bi-colour imaging – not least in order to keep working when the Moon’s about, unlike broadband imaging.  However, the cameras intrinsically low read noise and ability to capture fine detail using only short exposures is surely set to mark the next revolution in astrophotography and furthermore reduces the need for very precise guiding; it’s clear the other manufacturers are scrambling to catch-up with this leading edge technology.  Timing is everything in life and I’m pleased to be part of this hobby at such an exciting moment.

Arctic Antics


The globe pictured above on the island of Vikingen marks the location of the Arctic Circle off the western Norwegian coast.  However, surprisingly the position of the Arctic Circle is not fixed – as of 28 February 2017 it was 66°33′46.6″ north of the Equator but changes depending on the Earth’s axial tilt, which itself varies within 2° over a 40,000-year period due to differing tidal forces that occur as the Moon’s  orbit changes around Earth.  The region north of the Arctic Circle is famous for the midnight sun in the summer and its corresponding 24-hour darkness during the winter months, with major implications for life itself, as well as contrasting scenery and photographic conditions unique to this hostile region.


During the last two weeks of February, when the return of limited daylight has just begun to mark the end of winter, I travelled by ship along the entire western and northern coast of Norway close to the Russian border, spending much of the time within the Arctic Circle.  The area is famous for its beautiful scenery, in particular the fjords which typify the coastline and for time immemorial have posed a significant challenge to all seafarers passing this way.

Our ship, the Richard With, was named after the Norwegian captain who in 1893 pioneered this difficult sea passage which we took from Bergen to Kirkenes and back.  Today a fleet of 12 ships are operated by the original Norwegian company Hurtigruten on a daily basis providing ferry transport for goods, vehicles and personnel, as well as a base for tourists seeking a view of the Northern Lights – in all the ship stops at over 30 ports in each direction.


Apart from the scenery, during the winter months the area north of the Arctic Circle is probably best known for the occurrence of the Aurora Borealis or Northern Lights (Norwegian – Nord Lys).  A view of this feature is treasured by all who see them but for astrophotographers it will be one of their ‘must do’ images to acquire.  The Aurora is caused by a solar wind originating from the Sun that consists of charged particles, which when drawn downwards at the Earth’s poles by the planet’s magnetosphere ‘excites’ atmospheric atoms which produce different coloured lights depending on the type of gas which is excited by the charged particles; a similar feature occurs around the South Pole called the Aurora Australis and is also now known to occur on Saturn and Jupiter.  The lights are mostly green in colour (ʎ 557.7 nm), sometimes red (ʎ 630 nm) or blue (428 ʎ nm) and less commonly pink, ultraviolet or yellow, depending on the altitude and type of excited gas – which is mostly either oxygen or nitrogen.  The resulting aurora takes the form of rapidly moving clouds or often curtains of light that dart across the night sky, constantly changing shape under the influence of the Earth’s magnetic field and does not disappoint when seen.

The Northern Lights are best imaged with a standard DSLR camera on a sturdy tripod, using a wide angle lens at full aperture, set at between ISO 800 to 1,600 and exposures of about 8 secs to 25 secs, depending on the brightness and quality of the light and the speed of movement of the aurora; focus and all other control needs to be operated manually for best results.  On land a tracking mount, such as a Vixen Polarie, could be used to improve sharpness but on a moving ship set-up and technique is a more difficult.

In this case exposure needs to be carefully balanced in order to account for the ships movement – forwards + up-and-down on the water – and the quality of the aurora light.  As exposures will always need to be greater than a few seconds, star trails are unavoidable and have to be dealt with in post processing as best as possible. I found imaging directly forwards or to the rear of the ship helped minimise this effect but still trails were still inevitable. Experimenting with various settings I found about 12 to 15 seconds exposure and ISO 1,600 generally worked quite well but varied depending on the sea conditions and nature of the aurora at any time.

At such high latitudes it is still very cold in February and warm head-to-feet-to-hands clothing is absolutely essential.  On this occasion, together with wind chill the temperature at the ships bow ranged from between -20oC to -30oC (that’s a minus sign!), making camera control very difficult and uncomfortable!  I tried using an intervalometer for remote shooting but as settings have to be changed frequently by hand it was not very practical; I’m sure on land it would prove much more helpful.  Furthermore, much of the time I had to hold the tripod down with some force as the wind was very severe.

Notwithstanding, I’m very pleased with the results shown below and would love to return again one day, perhaps in the summer – it is a truly different and very special part of the world – hat’s off to Richard With and all those who still sail these waters.






The latter part of 2016 was very productive, especially around the end of November and early December.  Remarkably the clouds were completely absent for over a week, it was cold but the air was unusually dry and furthermore it was only just past the New Moon, all-in-all excellent conditions for astrophotography.  With Orion starting its Christmas-New Year parade across the night sky it was also a good time to investigate other parts of this fascinating constellation which I had not previously imaged.

Depicted in Greek mythology as Orion the Hunter, attention is most often given to the ‘sword’ that hangs from his belt – formed by three open star clusters which notably includes M42 the Orion Nebula.  Located just above, in the eastern region of the Hunter’s so-called belt and is NGC 2014 the Flame Nebula and the nearby Barnard 33, or as it is more famously known – the Horsehead Nebula.  I have imaged these and other targets such as the reflection nebulae M78 just above the aforementioned Flame Nebula and the difficult to image IC 2118, better known Witch’s Head nebula, situated just beyond the bright star Rigel which forms the Hunter’s left foot.

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Barnard’s Loop & Lamda Orionis Nebula + Rosette Nebula on far left (east) : Vixen Polarie & modded Canon 550D + Sigma UWA lens @ 20mm | 14 x 240 secs @ ISO 800 | 14th January 2016

However, a much wider view of Orion shows the presence of very large regions of HII nebulosity enveloping the main constellation, which altogether form the Orion Molecular Cloud Complex.  Most notable of these areas is Barnard’s Loop, a large HII cloud that arcs across some 10o of the sky encircling the lower, eastern section of the Orion star asterism.  I have had some limited success imaging the Loop before but on this occasion I tried some of the other areas of HII nebulosity which are located within the higher parts of Orion the Hunter.

The combination of the William Optics GT81 and their x0.80 field flattener reduces the focal length from 478mm to 387mm and increases the speed from f5.9 to a fast f4.72.  Apart from removing distortion at the periphery of the image, when used with the Canon 550D DSLR the field flattener increases the field-of-view by a staggering 64% or from 2.67o x 1.70o to 3.34o x 2.23o.  This has its shortcomings when imaging galaxies which generally have a small FOV but is perfect for large DSOs such as my first target.


The basic ‘anatomy’ of the Hunter is outlined by a number of stars that form his legs, waist and arms, with a club held above in his right hand and either a shield, lion’s pelt or bow held outstretched in his left hand.  On this occasion I first attempted to image his head; catalogued as SH2-264 it is otherwise known as the Lamda Orionis Nebula or sometimes the Angelfish Nebula. This very large HII cloud is located, as would be expected, at the top of the Hunter’s body and should be a good target for the aforementioned equipment with a modded camera, now aided by the longer exposures from my newly found PHD2 guiding expertise.


Upper Orion constellation & Lamda Orionis setting

This HII-feature is broadly centred on the giant double star Meissa or Lamda Orionis, which is itself at the apex of a triangle with the red giant superstar Betelgeuse to the east and blue giant star Bellatrix to the west and thus forms the outline of the Hunter’s shoulders. Some 8o in its entirety, the Lamda Orionis Nebula is enormous but consists mainly of very faint Ha-light, so that despite good imaging conditions, long exposures and good framing I was unable to obtain any sign of its presence on this occasion.

Frankly I was surprised there wasn’t at least a vestige of red Ha-light somewhere in the image but for now I will have to admit defeat.  However, looking back I can see the Hunter’s head in previous wide-field nightscapes of Orion taken in January 2015 and 2016.  Notwithstanding, together with other nearby stars Meissa forms the open star cluster Collinder 69, which on this occasion fortunately produced something of a pleasant alternative image.

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Meissa double star & Collinder 60 open star cluster | William Optics GT81 + modded Canon 550D & 0.80 FF + Guiding | 14 x 300 secs @ ISO 800 & full calibration | 4th December 2016


Subsequently I slewed the telescope and camera to another, nearby HII-cloud, this time situated along the Hunter’s right arm, just above his elbow.  Discovered by amateur Californian astronomers Harold and Charles Lower in 1939, at about 45’ x 45’ size H2-261 or Lower’s Nebula is much smaller than the Lamda Orionis Nebula but also faint and difficult to image.  However, here I did manage to capture something of the Ha-feature, albeit that the image was rather noisy when processed and yes I did apply Gradient Exterminator, though it doesn’t look like I did.

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Lower’s Nebula SH2-261 | William Optics GT81 & modded Canon 550D + FF + guiding | 12 x 30 sec @ ISO 800 | 4th December 2016

The Orion Molecular Cloud Complex is one of the best known areas for star formation that is closest to Earth and provides an abundance of wonderful imaging targets at this time of the year.  However, as previously experienced with Barnard’s Loop, the large areas of HII cloud that encircle much of Orion’s constellation can be elusive and difficult to image, which will probably require a camera of greater sensitivity and many more exposures to achieve success.  However, on this occasion the image of Lower’s Nebula was some consolation as I continue my quest for Orion’s scalp.