Located within the Orion Arm of the Milky Way galaxy is the Gamma Cygni nebula, a diffuse emission nebula that surrounds the star of the same name, otherwise better known as Sadr. Moreover, this large area forms part of an even bigger HII-region that is mainly (80%) located in the north and east quadrants of the so-called Cygnus Cross, which is defined by the stars Deneb – Sadr – Delta Cygni – Albireo – Aljanah (see below).
This vast area passes directly high overhead at this time the year before disappearing behind the house roofline in the early morning hours and has already provided many exciting imaging opportunities for me in the past. The heart (not the centre) of the region is the supergiant star Sadr and I first imaged this area in autumn 2015 using my modded DSLR camera. A return visit was therefore long overdue and this time I set out to better capture the so-called Butterfly Nebula in narrowband wavelengths.
The resulting data has been processed to good effect as an SHO image (see top-of-the-page) using the Hubble Palette techniques. Other than the dominant supergiant star Sadr and widespread colourful nebulosity, two significant features are worthy of note in the final image. Either side of the almost central dark rift that divides the image laterally, are two large bright areas which together form the ‘wings’ of the so-called Butterfly Nebula IC 1318-C (right = south) and IC 1318-B (left = north). Furthermore, just beyond the Butterfly’s left wing north of Sadr is the young, bright open star cluster NGC 6910.
Finished well with submersible water pump & floodlight (turned off for astronomy!)
I’m very pleased with this image, which is my first since the end of March, in part because nowadays I take an astronomy break during the long late spring / summer days when astronomical darkness is largely absent. However, this year the pause has been protracted as the patio on which Fairvale Observatory is situated was re-laid, during which a hitherto unknown water well was discovered. Thereafter one thing led to another and turned into a summer project to recommission the well, thus delaying completion of the patio. As a result I’ve only recently been able to reinstate the astronomy equipment, a job that is still ongoing. The new patio is firm and flat, providing a much better surface for the mount than before and I’m hopeful that once recalibration is completed will result in improved tracking results – watch this space!
IMAGING DETAILS
Object
IC1318-B & IC1318-C Gamma Cygni Nebula or Butterfly Nebula NGC 6910 Open cluster
Constellation
Cygnus
Distance
3,700 light-years
Size
1Approximately 100 light-years
Apparent Magnitude
Varies
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding
William Optics 50mm guide scope
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
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
Somewhat tongue-in cheek, astrophotography is often referred to as something of a dark art and to be fair it sometimes seems that way, particularly when it comes to processing. My main interests in astrophotography are Deep Sky Objects such as emission nebulae, galaxies and planetary nebula but have long aspired to capture a more elusive category that abounds throughout the Universe – dark nebula.
Popular with astrophotographers, emission nebulae consist of vast clouds of ionised gases and regions of interstellar dust which reflect light from the said gases and or from stars and stellar nurseries that lie within – depending on their make-up the results are colourful in both broadband and narrowband wavelengths. Dark or absorption nebulae are also a type of interstellar cloud but are so dense they completely obscure and / or soak-up visible light emitted from objects behind or within, which as a result contrasts with general light flux of the Universe forming large dark regions. Because of their darkness they are usually faint, hard to see and moreover, difficult to image, especially from locations with light pollution.
The Horsehead Nebula is a dark nebula that has formed a part of my previous images but I’ve only imaged an isolated dark nebula once before – Barnard 142-3, which for obvious reasons is also known as the E-nebula (see above & here). Larger more complex dark nebulae require much darker skies to image than prevail at Fairvale Observatory, such as in New Mexico, USA where the Deep Sky West observatory is located and on this occasion has produced my first ‘serious’ image of a stand-alone dark nebula.
Cepheus & the aproximate location of LDN 1250 image indicated by the red square
Lynds Dark Nebula (LDN) catalogue of dark nebulae was compiled by the eponymous Beverly T. Lynds in 1962 and is based on the study of red and blue photographic prints from the National Geographic-Palomar Observatory Sky Atlas. Situated in the north close to Polaris, the constellation of Cepheus has a number of dark nebulae, of which LDN 1250 is part of a huge complex of dark nebula surrounded by dust and scattered light from the stars of Cepheus.
LDN 1250 luminance – RGB wavelengths are also strong
Imaged here in LRGB the features come out well in all wavelengths, however, such are the subtleties of the dark nebula components I found processing difficult and required plenty of ‘dark art’ techniques. The final image at the top of the page shows to good effect the main dark nebula, togeher with widespread but less opaque nebulosity and star colours, as well as some distant galaxies lurking in the background that together has produced a satisfying and very interesting outcome.
Originally thought to be a planetary nebula, Abell included this object in his catalogue as Abell-85 but later in 1971 it was revised as a supernova remnant (SNR) and renamed CTB-1, thus also denoting it as a radio source. The overall structure is a circular shell with a conspicuous rupture towards the north (bottom right of image). The main red Ha-shell is composed of multiple interlocking filament limbs, with a blue / green OIII arc along one side (see main image above).
I experimented extensively processing the data because of its overall complexity and is an interesting object, which is therfore also presented below as greyscale Ha-wavelength only and starless versions. The main Ha and OIII data is shot at long 1,800 second exposures, which together with RGB adds up to a whopping 29 hours of integration time. However, CTB-1 is an extremely faint object, which probably still requires considerably more time – I’ve seen somebody else’s 61-hour integration which they described as “not enough” and despite the quality of their image I’d probably have to agree.
CTB-1 is a very exciting object, which might have been what Douglas Adams had in mind when creating Milliways or The Restaurant At The End Of The Universe in the Hitchhiker’s Guide, from which such spectacular events could be ordered to view with your meal!
Discovered as recently as 2011 by French astronomer Nicolas Outters, is the very faint OIII emission nebula Ou4. Located in the constellation of Cepheus , this somewhat elusive object requires very long exposures and integration time to successfully image. For obvious reasons Ou4 has become known more commonly as the Giant Squid Nebula and belongs to the difficult but must-do objects list of astrophotographers. Moreover, the Squid lies within the much larger SH2-129 HII emission region or the Flying Bat Nebula, only part of which is shown here. In this case some 40-hours of exposure, of which the Squid is 15-hours, combined with careful processing has produced a wonderful image of both these exciting objects.
Initially considered to be a Planetary Nebula, Ou4 is now thought to be a bipolar outflow that was discharged 90,000 years ago from the hot massive triple star system HR 8119 situated within the Sh 2-129 HII-region, which is also responsible for ionizing the red emission nebula itself. The Squid consists of two collimated lobes with arc-shaped tips of enhanced OIII emission that resemble bow-shocks seen in stellar outflows and a few bubbles and filamentary arcs. The bipolar Ou4 lobes measure some 50×8 light-years, which though faint forms one of astrophotography’s great spectacles.
About this time of the year as astronomical darkness is lost for a few months I tend to take it easy, astronomically speaking. However, this year’s an exception as I have a large backlog of image processing to complete courtesy of the Photon Factory. With continuously bad weather prevailing across Europe back in February, it was more than four months since I’d been able to undertake any astrophotography here at Fairvale Observatory – of course such problems go with the hobby but this was ridiculous and somewhat disheartening. There were three solutions to the situation: continue waiting, give up all together or look further afield where the skies are reliably clear and dark, which like many others nowadays is what I did and thus joined the ever increasing band of remote imagers.
About 2-years ago I considered establishing equipment at one of the growing number of astrophotography host sites in southern Europe. However, after some research I concluded that whilst such a facility would be great to have it was probably too expensive for now and moreover, I first needed to spend more time improving my processing techniques before embarking on such a plan. Thus having since taken steps towards this goal, which included learning PixInsight, I felt the time was right to sign-up with Deep Sky West (DSW) situated in the state of New Mexico, USA. DSW were one of the early remote hosting observatories established and have a good reputation, reasonable prices and a wide choice of quality equipment. I therefore signed up for one year’s imaging with the following set-up:
QSI1683-WSGA camera 5.4 nm pixels & Astrodon 5nm filters
Paramount MyT mount
Deep Sky West is located about 35-miles south east of Santa Fe, at an elevation of 7,400ft on the Glorietta Mesa (see above map). Established by Lloyd Smith and Bruce Wright in 2015, there are now two large bespoke roll-off sheds (Alpha & Beta – see picture below) housing up to nearly forty rigs which are used by astrophotographers from across the world – you could call it a photon factory. DSW has since established a premier reputation as an observatory producing high quality data. Building on this success and the burgeoning demand for remote imaging, DSW are now expanding their service into Chile.
After imaging the globular cluster M53 from Fairvale Observatory in early April, it was opportune to be able to continue the same theme with my first two DSW images taken during Q1 and Q2 – the globular clusters M13 and M92, both located in the constellation of Hercules. With an angular separation of just 9o 33’, spatially the two clusters appear as neighbours but in reality M13 is some 4,560 thousand light-years closer. Spanning some 145 light years in diameter, M13 consists of several hundred thousand stars and as the brightest globular cluster in our galaxy it is generally considered to be the finest in the Northern Hemisphere. Whilst somewhat overshadowed by its more famous neighbour, M92 is still one of the brightest globular clusters orbiting the Milky Way and at +11 billion years is one of the oldest.
Since moving to mono imaging in 2017 I’ve only used a CMOS camera and therefore this is my first experience of working with CCD data, hitherto considered as the best, though more recent development of CMOS sensors suggests this is now likely to be the way forwards for amateur astrophotography. Whilst most of the techniques are the same there are minor differences such as using bias frames instead of dark flats with my CMOS camera for calibration.
The DSW equipment combination produces a field-of-view nearly 50% less than my equipment at home but with a similar resolution, thus improving the magnification and image details of smaller and/or complex features such as globular clusters. Notwithstanding, I was pleased with my previous image of M13 (above) taken from Fairvale Observatory in 2018, which after cropping compares well with the new DSW version (see main image at the top of the page). This is my first image of M92 (below), which though OK probably needs more attention, as I’m not convinced the combination of the 600 secs + 300 secs + 60 secs data has worked to its full potential.
The Takahashi 106 is one of my dream scopes and with up to 250 clear nights a year historically, the DSW location in New Mexico provides an opportunity to work with top level equipment in outstanding night sky conditions – what’s not to like with remote imaging? However, with a growing cadre of remote imagers this has become a something of a contentious issue amongst astrophotographers – there’s no doubt it produces excellent data which leads to outstanding images but as a hobby it’s still good to be hands-on. So far I’m really enjoying working with the remote data produced under optimum conditions but strangely there’s much to be said for imaging in the backyard even with or perhaps because of the problems it involves. Funny old world!
Here at Fairvale Observatory, most of the exciting deep sky objects associated with the transit of the Milky Way during winter have disappeared over the western horizon by early spring. Notwithstanding, a brief period of decent conditions at the very end of March provided a late window of opportunity to image a core area of our galaxy, which being viewed above Oirion at a higher declination in the constellation of Gemini, helped to extend the limited imaging time available. Frankly after such a terrible period of weather since last November, I was desperate to get one last image from this rich part of the night sky and try out my new Chroma narrowband filters again, which thankfully worked out well after imaging IC443 the Jellyfish Nebula over four nights, despite there being less than two hours of suitable viewing and darkness each night.
The remnant of a supernova that occurred between 3,000 and 33,000 years ago, located in the Gemini constellation the Jellyfish Nebula is some 5,000 light years from Earth. With a diameter of 70 light-years, the angular view of the nebula is some 50 arcminutes or nearly twice the size of a full moon. Overall the nebula consists of at least three distinct shells reflecting the complex nature of this Type-II supernova, which is interacting with the surrounding area of molecular clouds.
Red box indicates location and orientation of image
Acknowledging the limited time available – compounded by lingering cloud each night – I chose to image The Jellyfish in narrowband bicolour, hoping to collect some SII photons on another day to add to the Ha & OIII. At the end I also added some short LRGB subs to improve the final star colours and during processing used Ha as a false luminance layer to help bring out the complex structure of the nebula further. The image has been deliberately framed by the adjacent large stars Propus (bottom) and Tejat (top), which caused plenty of problems during processing but in my opinion form an essential component when imaging this object. Whilst IC443 is undoubtedly the main act, it is set off well by the large adjacent area of detailed nebulosity and the smaller reflection nebula IC444 to the right which is easy to overlook. Despite many issues I am very pleased with the final image that beautifully shows off this spectacular DSO and the surrounding region in all its glory, which seems all the better being something of a last chance opportunity that I thought I’d missed for this season.
IMAGING DETAILS
Object
IC443 Jellyfish Nebula & IC444
Constellation
Gemini
Distance
5,000 light-years
Size
50 arc minutes ~70 light years
Apparent Magnitude
+12
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding
William Optics 50mm guide scope
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
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
For good reason spring is known as “galaxy season” by astronomers but during this period, shortly before astronomical darkness inevitably disappears for summer, there’s also another show in town. Closer to home in the denser extremities of our galaxy, over 150 globular clusters have so far been identified orbiting above and below the plane of the Milky Way within the galactic halo. Globular clusters consist of hundreds of thousands of tightly packed stars that are surely one of the more enigmatic features of astronomy, as we now know that similar clusters also are associated with other galaxies throughout the Universe. Whilst the formation of globular clusters is poorly understood, we do know that at 10.0 to 13.5 billion years they are very old. Given their age, location and density, it seems that globular clusters formed under very different circumstances to the more recent dispersed star clusters.
Image Setting / Location
Sagittarius and Ophiuchus brim with globular clusters but at the higher latitude here at Fairvale Observatory it is necessary to view those around the regions of Canes Venatici, Virgo or Coma Berenices; the Great Cluster of M13 and others such as M92 and NGC 6229 located in the aforesaid Hercules constellation move into a better view later during early summer. Having previously imaged a number of these clusters in the past, this spring I looked around for something new and different, which I found in the name of M53 (Above + left of centre – main image top of the page) . In this case it turned out to be two for the price of one, as with careful framing it was possible to include a second globular cluster, NGC 5053 (Below + right of centre – main image top of the page).
Located in the southern area of the Coma Berenices constellation, M53 (Above left of centre – main image, top of the page) is some 58,000 light years from Earth. Containing some 500,000 metal-poor stars, the cluster equates to 13 arc minutes of sky or about 220 light years in diameter, with an estimated age of 12.67 billion years. Just over 1o east of M53, NGC 5053 is 53,500 light-years away, with an apparent size of 10.5 arc minutes or 160 light-years. Although classified as a globular cluster, NGC 5053 is more irregular and dispersed in nature without a distinct bright core and is therefore dimmer than its neighbour, making it more difficult to image.
M35 Full Crop
All-in-all I believe these two globular clusters, combined with the star studded background that just includes the binary Diadem star (Upper edge + right of middle – main image, top of the page) southwest of M53, altogether makes for a rich and interesting final image.
IMAGINGDETAILS
Object
M53 & NGC 5053
Constellation
Coma Berenices
Distance
Approx.. 58,000 & 53,000 light-years
Size
13.0 & 10.5 arc minutes
Apparent Magnitude
+8.33 & +10.00
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding
William Optics 50mm guide scope
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
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
After starting astronomy in 2014, Watch This Space (Man) was launched shortly thereafter as a personal record of my then nascent astronomy journey. Apart from the main blog about my progress or otherwise, links to other astrophotographers, astronomy tools, astronomy weather, scientific papers etc. can also be found on this website; I was suprised to see that to-date 152 items have been published on this site.
I always like to hear from others – comments, questions, help or just to say hello – and can be contacted via: graham.s.roberts@gmail.com or just leave a comment at the end of any item if you prefer.
Vistor map 2020: In this most difficult of years for everyone, it’s especially heartening to see so much interest from all corner’s of the world and hope to see you and others again in 2021 – Clear Skies!
REFLECTIONS is a review of my astronomy and astrophotography during the past year, together with some thoughts on possible future developments.
2020 Overview, Images & Goals for 2021
For the world 2020 was a year like no other. Notwithstanding the obvious problems and dire consequences of Covid-19 for everyone, there have been surprising benefits for astronomy. Although I am retired, under lockdown there was even more time available for hobbies. Furthermore, as I live close to Gatwick and Heathrow airports + underneath numerous high altitude long-haul overflight paths, a massive reduction in air travel resulted in a very obvious improvement in seeing conditions, which was confirmed by guiding results. Located in a Bortle 5 to 6 area I ordinarily achieve at best average RMS error guiding of 0.90” to 1.50”/pixel, guiding improved markedly during lockdown to between 0.50” to 0.75”/ pixel. Of course such seeing conditions also resulted in better quality imaging itself and on a number of occasions I was able to achieve integration times of 10-hours or much more over a number of nights. The result was better images but less of them and inevitably, a lot more cloud throughout the rest of the year!
Having previously got to grips with plate solving, using the new CdC planning function I intended to develop the use of mosaics this year. However, such is the weather in the UK (see above) that it’s obvious to me that creating mosaics is probably not the best use of what imaging time we get. Undeterred, during January I planned and shot a 15x panel mosaic of Barnard’s Loop in Ha-wavelength. Unfortunately the unpredictable occurrence of patchy cloud invalidated some of the panels, though I was finally able to compile a 7x panel mosaic of the upper easterly section of Barnard’s Loop – see below. Notwithstanding, there were lessons learned: (i) restrict mosaics to one or two panels and / or (ii) where wider view images are required use a wide FOV set-up rather than a large mosaic.
Most of my other objectives for 2020 turned out to be pipedreams e.g. a new observatory or perhaps a larger telescope or dual rig. Despite this there were important developments on other fronts.
After eventually coming to the conclusion that mosaics were probably an unwise way to go considering UK conditions, it became clear that a suitable high-quality camera lens might produce similar coverage with less imaging time and hassle. Thus also inspired by the images of others on the SGL Forum using such equipment, I set out to build a new rig based around the excellent Samyang 135 f2 lens. This project remains work-in-progress but so far using the lens with a bespoke 3D printed rig and micro focuser made by Astrokraken and a modded DSLR, it’s apparent that this lens produces excellent widefield images in a relatively short time.
Initial Samyang 135 f2 set-up with modded DSLR
With the time and ‘opportunity’ afforded by lockdown throughout most of the year, I finally decided to do something about improving my processing, namely learning PixInsight. Unfortunately the rumours were correct – it is a steep learning curve and altogether a less than user friendly software. However, after many weeks of toil and expletives I’m pleased to say I can now process an entire image with PixInsight, the impact of which has been nothing less than profound. However, whilst PixInsight is an excellent processing facility, I’ve come to the conclusion that it is often best used together with other process software where appropriate for specific tasks:
Deep Sky Stacker for calibration, alignment and stacking; the equivalent PixInsight process is just too complicated and time consuming;
Photoshop can be very helpful finessing colours and stretching (Levels & Curves);
Starnet++ is useful for creating starless images, which then help to get the best from processing nebula separately before re-combining with the stars;
Topaz AI Denoise has been very effective and easy to use for noise reduction and sharpening at any point during the workflow.
This combination for processing has turned out to be something of a game changer and almost certainly was the most important astrophotography development of the year for me, which augurs well for 2021 and beyond.
Favourite Images
Continuing with the theme of less is more, I imaged just 13 objects this year – of which three were experimental & three with a DSLR – but still with a total integration time of 80 hours (2019 17 objects & 65 hours, 2018: 25 objects & 43 hours). Having worked through many of the astronomer’s favourites by now, images in 2020 consisted of: a new approach to old favourites, difficult / small objects for my equipment e.g. galaxies or less popular and widefield targets.
I’m pleased to say that most of these images turned out well and it’s difficult to choose a favourite. The so-called ‘favourites’ below therefore represent those images from this year that portray an important development in my astrophotography journey. More detailed reviews of these and all other images from 2020 can be found in specific articles that can be accessed using the links found below or via the Blog Index, located under the dropdown menu ABOUT.
Heart Nebula: Although imaged in 2018, this version has been re-processed using mainly PixInsight, thus transforming the original SHO Hubble Palette image from something rather dull to one with warm, vibrant colours, as well as much great detail – demonstrating the significant impact of my new PixInsight based processing abilities.
LBN 325: Numerous emission nebulae populate this small part of a very extensiveHII-Region, which forms an exciting LRGB image. Processing was complex and difficult, in order to bring out exciting features that abound in this spectacular but less popular area of the Cygnus constellation. Integration time of 10-hours was obtained over three nights and is my first LRGB image processed using PixInsight.
M63 Sunflower Galaxy: At 12.6’ x 7.2’and apparent magnitude of +9.3,this small flocculent galaxy in the Canes Venatici constellation is a challenge for my equipment. However, with 8 hours 20 minutes exposure over three nights in April and careful processing, the all-important detail within the galactic disc is clear. Topaz Denoise AI and Gigapixel software played an important role in maintaining the colour and delicate detail in this +50% cropped image.
Taken from last year’s REFLECTIONS 2019:
“Although you never know, I don’t see any major breakthroughs in the coming year”. Just goes to show what I know, fewer but better images were obtained in 2020:
RECORD CARD 2020
Goal
Specifics / Results
Outcome
Improve image capture
Further Improvements in overall quality + much longer integration times + better guiding accuracy = less but better images.
MUCH BETTER
Better processing
Using PixInsight software combined with Photoshop, Starnet++ and Topaz Denoise AI has led to major processing improvements and much better final images.
MUCH MUCH BETTER
Widefield Imaging
Initial results from new imaging rig based around Samyang 135 f2 lens were very promising but there’s more to do.
BETTER
My main objectives for 2020 were largely fulfilled (see above), so what about 2021?
Imaging: Other than maintaining the aforesaid improvements achieved over the past two years – guiding & longer integration times – two items that still need to be addressed are: (i) upgrade filters to remove star bloating and all round better images, (ii) improved focussing.
Widefield: Complete Samyang-rig build and switch from DSLR to CMOS mono camera.
Consolidate processing improvements: Whilst the move to PixInsight and other software was very successful in 2020, I’m still only scratching the surface of what’s possible.
Upgrade mono camera – there’s a new generation of colour CMOS cameras starting to appear, hopefully soon to be followed by their mono equivalents !
Hardly a year I and the rest of the world will want to remember, though more than ever astrophotography played a big role in providing relief from the trauma going on around us all.
The major increase of integration times achieved and the use of PixInsight has proved transformative for my astrophotography and will justify returning to reimage some old favourites in future years. I had often thought about upgrading my OTA to something bigger but given the lack of a permanent observatory here at Fairvale Observatory, combined with long periods of bad / cloudy weather, the penny finally dropped and I now have high hopes for the little wonder that is the Samyang 135 f2 lens when I complete its set-up in 2021.
Looking back I have to be happy with my astrophotography in 2020 but more importantly, look forwards to an even better year which holds great promise building on the positive developments of the past 24-months. Moreover, I hope for the sake of everyone that we will be able to deal with Covid-19 soon and return to something of a normal life once again. These are big ambitions and I hope that WTSM’s Reflections 2021 will record such success.
Watch this space!
ASTROPHOTOGRAPHY INDEX OF 2020
To access each blog, click on the title required below highlighted in RED:
I’ve been very happy with my main imaging set-up for nearly 4-years: Skywatcher AZ-EQ6 GT Mount + William Optics GT81 + ZWO1600MM-Cool mono camera. Nevertheless, thoughts inevitably stray towards the big and usually expensive question – what next? Given the said equipment, a natural move is likely to be the addition of a larger telescope to get at those faint fuzzies and I have been toying with such an idea for some time – probably another refractor in the 100mm to 130mm range. However, I’ve always been held back by a number of nagging issues:
Without a sightline of Polaris for polar alignment from the main location at Fairvale Observatory, guiding is always going to be sub-optimal – I can get away with it with the smaller William Optics but a larger aperture / focal length would be more challenging;
Being a set-up / take-down observatory each night, the increased technical demands of a larger OTA would certainly take longer and in general be more difficult to undertake – as I get older moving the mount is already taking its toll on my back;
Time is short as there’s simply no getting away from the problem we all suffer in the UK – cloud and lots of it! It’s been normal to go weeks, even months without a clear night sky and as a result last year I managed to image just 18 objects over some 27 nights, of which some were only over a few hours before the clouds rolled in;
A static observatory would help enormously but my garden is unsuitable: apart from the aforesaid problem that my house obscures a northerly view, there are also houses and substantial trees and very high hedges on all the other sides.
Regretfully I have therefore always come to the same conclusion, that unless I moved house it was best to continue with my current set-up – until now! Inspired by a fascinating thread on the Stargazers Lounge Forum the solution was blindingly obvious, or at least it was once I understood there was another way, a larger field-of-view rather than larger telescope, achieved with a traditional though far from ordinary camera lens.
As a life-long photographer on land and underwater, astrophotography surprisingly came as something of a shock, as it’s just so contrasting to the aforesaid disciplines and requires quite different technical knowledge and aptitude. Of course, I’ve often used my camera equipment to image the night sky, particularly the Milky Way and started out astrophotography using a modded DSLR but otherwise did not consider that a camera lens could form the basis for my astrophotography going forwards – then I discovered the Samyang 135 f2 lens. Moreover, looking at what others achieved matching this lens with a tracking mount and mono camera, the decision to join the Samy club was a no brainer.
Located in South Korea, Samyang Optics has been manufacturing good camera lenses since 1972. Also sold under the Rokinon brand name, the Samyang 135 f2 stands out for two reasons:
The optics of the lens are top drawer, consisting of 11-elements in 7-groups using very high quality glass;
The lens is very well suited to gathering photons with a maximum f2 aperture – though most users stop down to 2.8 in order to achieve good star shapes right into the corners.
The optical quality produces sharp image quality from corner to corner but combining this with a 135mm focal length achieves an enormous 9.45o x 6.30o field of view @ f2 with a Canon 550D compared with my current set-up of 2.67o x 1.78o, opening up whole new imaging possibilities.
Inner rectangle: FOV using William Optics GT81 + focal reducer & ZWO 1600MM-Cool camera Outer rectangle: FOV using Samyang 135 f/2 & CAnon 550D DSLR camera It would take approximately a 9 x panel mosaic from the WO to cover the Samyang area!
Furthermore, this much smaller rig is lighter, easier and thus quicker to set-up and break-down. Put together it’s a powerful combination that I hope to fully exploit in the future.
Camera
Equipment
FOV
Resolution
ZWO ASI1600MM-Cool
WO GT81 + 0.80 FR*
2.65o x 2.00o
2.05”/px
Samyang 135 f/2
7.50o x 5.67o
5.80”/px
Canon 550D DSLR
WO GT81 + 0/80 FR*
2.67o x 1.78o
1.85”/px
Samyang 135 f/2
9.45o x 6.30o
6.45”/px
*Current set-up
By today’s standards this lens might be considered somewhat old fashioned with no autofocus or image stabilisation etc., but the intrinsic high manufacturing standards and manual focus are excellent for those who know how to handle such a lens and perfect for astrophotography. For such a purpose users generally either create their own rig by adapting various astronomy bits and pieces or use one of a growing number of bespoke brackets that are being made for this increasingly popular lens.
For the moment I chose to use a 3D printed bracket and integrated manual microfocuser, made by the French company AstroKraken and its founder Philippe Leca. Therein the lens is cradled by two hinged rings, which when screwed down hold the lens firmly to either a Vixen bar or Losmandy plate. The microfocuser then fits snuggly around and then clamps onto the focus ring, so that two screws on either side can be adjusted so as to push against a bridge located above and between the two rings, thus providing fine control over the focus ring; the said bridge also has a Synta fitting shoe on top to fix a finder / guide scope. Altogether it’s a neat and very effective design that provides an easy-to-use tailor made platform for the lens, which can then be combined either with a DSLR or mono camera on the back; users of mono cameras tend to recommend changing the lens’ bayonet for a screw fitting and possibly add a third ring for the camera in order to eliminate the possibility of any flexure.
Whilst the AstroKraken bracket works well, the structural layout is inevitably tight making it difficult to view the focus ring settings but once established close to focus, subsequent use of the microfocuser is excellent in finessing the job of focussing before locking down the adjustment screws. In addition, I’ve acquired a second Starlight Express Lodestar X2 autoguiding camera for use with a Skywatcher Evoguide 50ED guidescope but so far have not needed it with short exposures currently being used.
As a project for the new rig I had intended to spend the late summer imaging the suitably large Cygnus HII region but in the end conditions limited my time on this wonderful area of the sky at this time of the year and will have to wait for another time. Notwithstanding, first light using my modded Canon 550D DSLR camera of the said Cygnus area was briefly achieved at the end of July, with promising results (see above – uncropped). More recently, in early September I was able to obtain images of the Veil Nebula (see below – cropped to 70%) and North America Nebula (see top-of-the page, cropped to 80%), in all cases taken at 120sec exposures and ISO 1600. Unfortunately all integration times have been just under 60 minutes for each target and in the long run the real magic of this lens will be unlocked with the addition of a mono camera and much greater imaging times.
Looking back personally and professionally, it’s apparent to me that the concept of the big picture, metaphorically or otherwise, has played a central role in my life and is an area I like to work with; it’s the big picture that provides context, understanding and opportunity. Perhaps it should therefore not be a surprise that in the end my next step in astrophotography will now follow such a path. The detail provided with my current equipment is fulfilling and beautiful but the additional context provided by the Samyang’s extensive FOV can be more insightful and even breathtaking in scope. After something of a slow start, I’m now really looking forwards to spending more time with this new and exciting rig in the future.
Following a very poor winter period, spring has been nothing less than spectacular and provided many clear nights for astronomy, ironically made all the better by the covid-19 lockdown. With the near absence of road traffic and especially aircraft – Fairvale Observatory is badly affected by flights from nearby Gatwick, Heathrow and Redhill aerodrome – it has resulted in noticeably better seeing, as well as a quieter and more enjoyable environment overall; it’s worth noting that after experimenting with Deep Sky Stacker (DSS), increasing the Kappa-Sigma clipping parameter from 2.0 to 2.50 for the light subs, in all but the worst cases eliminated aircraft tracks in the final stacked image. Resulting from these favourable conditions, I’ve recently been able to image four otherwise difficult targets, amounting to some 40-hours total integration time, literally unprecedented conditions in the +30 years I’ve lived here.
Apart from a brief diversion imaging the Leo Triplet, my attention has otherwise been centered on the constellation of Canes Venatici, AKA the Hunting Dogs. At this time of the year the constellation starts to come into view high overhead from the east at about 10 p.m. and crosses the meridian about three hours later. Located below Ursa Major and above Bootes, the relatively small Canes Venatici hosts five Messier objects, four of which are galaxies and it is these I’ve been drawn to. From earlier test shots I determined that the M94 galaxy was unlikely to be suitable for my equipment but I did obtain and have already described images of first M106 and then M63. Notwithstanding, I had unfinished business with the last of the four galaxies, which I therefore now turned to.
In 2019 I was pleased to acquire my first ever image of the wonderful M51Whirlpool Galaxy and its smaller companion, NGC 5195. However, I noted then that the final LRGB image still needed much more integration time than just 2hr 18min. achieved, plus the addition of Ha-subs and that I hoped to return to the Whirlpool and its neighbour as soon as possible for this purpose.
It was therefore a great pleasure to image M51 over no less than seven nights in March and April this spring, which combined with last year’s data resulted in over 16 hours integration time, substantially longer than any previous image I’ve compiled before. Moreover, the quality of seeing also benefitted SNR and guiding quality, thus achieving RMS errors of at least 0.80 arc seconds or better. I did encounter some plate solving issues and had to resort to manual framing on a few nights but fortunately DSS software dealt with alignment OK and the final image is all I could have hoped for (see above + top-of-the-page cropped). Naturally the interaction of the two galaxies is the signature feature of this image but it is the improvement in general colour, detail and addition of Ha-subs highlighting regions of new star formation, that have been most transformative in portraying these objects in all their glory.
Using my current set-up it seems unlikely that the image would benefit significantly from any further data acquisition but I’d like to think I’ll return another day using a larger telescope and higher resolution with which to capture and enjoy even more detail of all these exciting objects of Canes Venatici. It is said that “it’s an ill wind that blows no good” and I am doubtful we’ll ever have such good conditions here again but for now I was delighted to be able to positively exploit this otherwise difficult time in lockdown.
IMAGING DETAILS
Object
M51 The Whirlpool Galaxy & NGC 5951
Constellation
Canes Venatici
Distance
23 million light-years
Size
11.2’ x 6.9’ 77,000 light-years (M51 only)
Apparent Magnitude
+8.4
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding
William Optics 50mm guide scope
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
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
WATCH THIS SPACE(MAN) 