Hunting Orion

Combined +180 degrees 3+5min HaLRGB (Large)

In Greek mythology it is said that Zeus, the god of thunder, placed a giant huntsman amongst the stars as the constellation Orion.  Today it is one of the most recognizable of the 88 constellations in the night sky and certainly one of the most popular amongst astronomers.  Towards its extremities it is defined by the red supergiant star Betelgeuse at the top-left and the massive blue supergiant Rigel lower-right, divided in the centre by Orion’s so-called ‘belt’ formed by the line of bright stars from left-to-right: Alnitak, Alnilam and Mintaka.  These and the other stars that make up the constellation of Orion are of great interest to astronomers and also make an attractive widefield image with a standard camera.  But the more serious astrophotographer is mainly interested in the panoply of exciting DSOs that lie within and around Orion that I have therefore been pursuing myself since late January.

My quarry started with the Horsehead and Flame nebulae imaged in narrowband processed using the Hubble Palette technique in SHO to great effect.  Much to my surprise a spectacular period of warm weather and clear skies four weeks later then allowed me to capture the Great Orion Nebula over three nights in HaLRGB with an equally good result.  Such was the fine weather conditions that I was then able to continue over a further two nights – five consecutive nights of imaging in the UK in late February, unprecedented in my experience – with the objective now being the reflection nebula M78.

M78 is the brightest diffuse reflection nebula of a group that belongs to the Orion B molecular cloud complex but with an apparent size of 8 x 6 arc seconds it is a something of a challenging target with my equipment.  Notwithstanding, with the mono CMOS ZWO camera and the opportunity of obtaining increased integration times I considered it worth a try and was not disappointed with the outcome.

I generally like to present images in their natural orientation but this time I’ve chosen to rotate the it 90o anticlockwise, thus allowing the wider horizontal framing to better show M78 and the dramatic red Ha-light of nearby Barnard’s Loop together.   As with M42 previously, I first stacked and processed two exposure sets, short 60 second and long 300 second subs, before then combining them so as to tease out subtleties within the reflection nebula itself and provide greater control of the otherwise dominant Barnard’s Loop.  Despite my concerns about equipment and scale, I’m very pleased with the outcome of the main image (top-of-the-page), which beautifully shows off both the aforementioned objects to great effect and has even extracted some of the colour and detail of associated star clusters within and around the nebula.  Not surprisingly the cropped version of M78 itself starts to look a little noisy but is nonetheless interesting (below).

Combined crop 3+5min HaLRGB (Large)

After a very unpromising few months, the weather, Orion and my astroimaging took a surprising turn for the better from the end of January.  As a result of much longer integration times using plate solving over multiple sessions, combined with varied exposure times and more complex processing, I successfully managed to bag three classic deep sky objects of the Orion constellation – what’s not to like?

IMAGING DETAILS
Object M78 Orion reflection nebula
Constellation Orion
Distance 1,350 light-years
Size 8’ x 6’   
Apparent Magnitude +8.3
 
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   
EFW ZWOx8 + ZWO LRGB & Ha OIII SII 7nm filters 
Capture & Processing Astro Photography Tool + PHD2 +  Deep Sky Stacker & Photoshop CS3
Image Location              & Orientation Centre  RA 05:47:37      DEC 00:20:59                     

Top Left = North  Bottom Left = East 

Exposures (A)    LRGB 8 x 180 sec  Ha 10 x 180sec       (Total time: 1hr 24 min.)

(B)    HaLRG 12 x 300 sec B 17 x300 sec      (Total time: 5hr 25 min.)   

  @ 139 Gain   21  Offset @ -20oC    
Calibration 10 x 180 sec & 5 x 300 sec Darks  20 x 1/4000 sec Bias  10 x  HaLRGB Flats               @ ADU 25,000
Location & Darkness Fairvale Observatory – Redhill – Surrey – UK        Typically Bortle 5-6
Date & Time 25th  26th 27th February  2019 @ +19.45h  
Weather Approx. 8oC   RH 60 to 80%                  🌙  ½ waning

Eleventh Hour

HaLRGB2FINALcrop (Large)

As outlined in my last post Horseplay, it seemed like plans for imaging over the winter were going to be completely scuppered this year, with weeks of cloud cover from mid-November through to late January.  I was therefore very grateful for three clear nights at the end of January that finally enabled me to carry out my principal winter imaging project of the Horsehead and Flame nebulae in narrowband.  Notwithstanding, given the preceding bad weather and the onset of galaxy season, I reckoned that this was likely to be the end of my imaging for a while, which could not have been further from the truth as more than two months of good night skies (on-and-off) then followed.

Although by late February Orion is crossing the Meridian early in the evening, darkness is still prevalent at the same time and with the aforementioned good conditions it’s been a bonus to catch more of Orion’s objects before they finally disappear for the year.  I’ve successfully imaged some parts of Orion before with the ZWO1600MM-Cool camera but for various reasons they’ve mostly been short integration times in narrowband.  It was therefore obvious that given this unexpected opportunity, on this occasion I should attempt to image everyone’s astrophotography favourite – M42 the Orion Nebula in LRGB.

At some 1,500 light years distance, M42 is the closest large star forming nebula to Earth and always holds great promise when imaging.  I’d previously obtained some good images of the Orion Nebula with a modded-DSLR camera and more recently a few narrowband images in 2017 showed the promise of using the new ZWO CMOS mono camera.  Now with unusually good weather I wanted to try and achieve an image that really showed off M42 and its neighbours M43 and the Running Man Nebula (SH-279) in all their glory, paying particular attention to the more difficult inner structures and associated Ha nebulosity.  In order to achieve this I first imaged in HaLRGB at 180 sec exposures with Unity settings for 5½ hours and then at shorter 60 sec exposures for 1 hour over three consecutive nights.

With much longer integration times than before, careful processing and manipulation to bring the long and short exposure images together, I’m very happy with the final result, which I believe achieves most of the aforementioned objectives.  Internal structure and colour is shown to good effect but I’m especially pleased with the addition of the Ha data, which dramatically enhances those areas where present together with interstellar dust within and around the main objects; I’m already planning to add more Ha data next year to further intensify the aforesaid impact.

M42 180s Ha StretchNR (Large)

M42 Ha data

Obtaining such results at this late stage of February was completely unexpected and, I thought, would effectively mark the eleventh hour this year for Orion and the rich collection of other DSOs that are found across the winter sky.  But no, there was much more to come – watch this space!

IMAGING DETAILS
Object M42 Orion Nebula + M43 & Running Man Nebula (SH2-279) etc.
Constellation Orion
Distance 1,500 light-years
Size 65’ x 60’  or 24 light-years (M42 only)
Apparent Magnitude +4.0
 
Scope  William Optics GT81 + 0.80 x 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   
EFW ZWOx8 + ZWO LRGB & Ha OIII SII 7nm filters 
Capture & Processing Astro Photography Tool + PHD2 +  Deep Sky Stacker & Photoshop CS3
Image Location              & Orientation Centre  RA 05:35:09      DEC -05:08:31                     

Top Right = North   Top  = North East   Bottom Left = South   Bottom = South West 

Exposures (A)    L 20 x 180 sec  R 24×180 sec  G 25 x 180  B  24 x 180sec  Ha 17 x 180sec                            (Total time: 5hr 30 minutes)

(B)    12 x 60 sec HaLRGB (Total time: 1hr)   

  @ 139 Gain   21  Offset @ -20oC    
Calibration 10 x 180 sec & 15 x 60 sec Darks  20 x 1/4000 sec Bias  10 x  HaLRGB Flats               @ ADU 25,000
Location & Darkness Fairvale Observatory – Redhill – Surrey – UK        Typically Bortle 5-6
Date & Time 23rd 24th 25th February  August 2019 @ +19.40h  
Weather Approx. 7oC   RH <=75%                  🌙 ¾ to ½ waning

Reflections 2018

Reflections is a summary of my astronomy and astrophotography during the past year, plus some thoughts about what might happen in going forwards.  In some ways it’s a bit of a chore to compile but as it provides me with some perspective on what I’ve achieved year-to-year, I do find it to be a worthwhile exercise.

Watch This Space (Man) started in 2015 as a personal record of my astronomy journey. Notwithstanding, the blog has so far attracted 15,000 views from all over the world, including various locations in 64 countries over the past year (see map below for visitors in 2018).   I do like to hear from anybody out there – comments, questions, help or just to say hello  – and can be contacted via details in the ABOUT menu section or alternatively  just leave a comment on any item if you prefer.

 

WTSM Map 2018

 

I’m always tinkering with the website where apart from the main blog, there are also links to other astrophotographers, astronomy tools, astronomy weather, scientific papers etc.,  so even if you’re a regular visitor please take a look around from time-to-time.  Looking back I see I did not file any reports this year  under the new Astrobites section, on the other hand look out for more notable occasional image that now appears in the right-hand column under the heading Screenshot, which this year included: the Eskimo Nebula, Jupiter, the Moon & Jupiter in conjunction and Venus etc.         

Whilst there is a photo gallery of my work, for a more summary view of some of my better images there’s a FLICKR album link which is accessible from the GALLERY menu.  Following the change to mono imaging techniques in 2017, for reference each image is now accompanied by a detailed tabulation of the technical information; personally I find this information invaluable when looking at other astrophotographer’s images as a guide to settings and issues when imaging the same object myself for the first time.

Reflections Banner

Overview, Images & Goals for 2019

Since getting to grips with autoguiding in 2017, I’m pleased to say all the basic processes worked well throughout 2018, resulting in a marked improvement of individual image subs.  Long imaging times are difficult to achieve in the UK with poor skies being the norm but the successful adoption of Plate Solving this year marked a very significant breakthrough and holds great promise for ever longer integration times in the future.  Re-configuring the equipment and operating set-up in 2017 now enables operating from indoors most of the time, which apart from improving working conditions, has also made operating itself much more efficient.

I’m especially pleased that after more than 4-years astrophotography I finally manged to establish a new imaging location at the bottom of the garden this year, thereby for the first time enabling imaging of the north sky, literally opening up a new world!  For another perspective I was also fortunate to experience some excellent night skies in New Zealand, France and Cornwall during the year, which was great fun and led to some excellent images too (see 2018 CHRONICLE later in this blog).

Favourite Images

Apart from the odd DSLR shot of the night sky, my astrophotography at Fairvale Observatory in 2018 was entirely carried out with the ZWO1600MM-Cool mono CMOS sensor camera & EFW, combined with the William Optics GT81 scope, in both narrowband and broadband wavelengths.  The new camera has in every sense been a game changer and a lot more work but, in my opinion, the images this year show substantial improvement.  I also made progress using more complex processing techniques in Photoshop and improved colour and detail by combining Ha with LRGB or adding RGB and narrowband wavelengths.  With these advances I submitted a number of images to the British Astronomical Association which, I’m pleased to say, were chosen for publication on their website at various times throughout the year (see Astroimaging Record 2018 at end of blog for details).

A few of my personal favourites are shown below, in no particular order:

GR Final HaLRGB

M74 Phantom Galaxy (HaLRGB)

RGB HaOO XXX2

Rosette Nebula (HaOO) 

M13 LRGB Close-up

M13 Great Globular Cluster of Hercules (LRGB) 

Sombrero Galaxy

M104 Sombrero Galaxy (LRGB)

HHOO hlvg (Large)

Heart Nebula (HaOO)

RGB2 GxFinalX (Large)

M45 Pleiades (LRGB)

 

RECORD CARD – 2018
Goal Specifics / Results Outcome
Improve broadband and narrowband imaging

 

Improved understanding and use of the ZWO1600MM-Cool mono camera leading to better subs.  Major breakthrough with Plate Solving enabling a significant increase in image integration times and overall quality. MUCH BETTER

 

 

Improve processing Continuing to make improvements and achieving noticeably better narrowband images but with more work to do in broadband. Much greater use of various Photoshop techniques is improving detail, colours and final quality. BETTER

 

 

Expand & Improve Widefield Imaging Despite some good images of the Milky Way in the UK and NZ I barely used the Vixen Polarie tracking mount and did not make it to any dark sky sites in the UK. FAILED

 

 

I think it helps to set new goals each year, so here goes for 2019:

  • Imaging: (i) There’s lots of scope to improve imaging techniques but probably most of all I now need to improve guiding quality and then increase exposure and image integration times further. (ii) Start mosaic imaging using Plate Solving.
  • Improve processing: Despite progress, I expect this will continue to be a major challenge for some time to come. Working with Olly Penrice in France and using Steve Richards’ new book Dark Art or Magic Bullet provided lots of opportunities to learn more but I’m still considering a move to new software for pre- and post-processing – we shall see.
  • Other: (i) Widefield imaging – Since acquiring the Vixen Polarie two years ago I’ve done little more than dabble in the occasional night sky shot. Maybe just set my sights lower this year and just see what happens! (ii) Do more observing – I had been thinking of getting something bigger like a Dob for observing whilst imaging is underway but frankly now thinking just do a bit more when I can with what I’ve got.  (iii) Notwithstanding weather issues at Les Granges observatory in France, get back to at least one good dark sky site next year.

I’m very pleased to say 2018 was again very good year for astrophotography, almost certainly my best yet, which was especially defined by two positive developments that are already transforming my astrophotography and hold further promise in 2019 (I said the same last year but it’s true):

  • Starting to Plate Solve has opened up whole new possibilities, in particular: Meridian flips and multiple imaging over different nights; Mosaic imaging.
  • Fairvale Observatory South – The ability to see and image the north sky from the new location expands imaging possibilities very significantly – should have done it sooner.

You can’t ask for more than that and hope that WTSM’s Reflections 2019 will record further such success.

Watch this space!

wtsm logo

2018 CHRONICLE

Below is a quarter by quarter summary of my astronomy and astrophotography for the year 2018, followed by an imaging record.  It’s interesting but not surprising that I recorded about 50% less objects than in the previous year but, as explained, integration times have increased markedly – “never mind the width, feel the quality”!

JANUARY TO MARCH

The year started with a new perspective on astronomy – upside down!  A six week trip to New Zealand over the Christmas period produced some wonderful views of the night sky in the Southern Hemisphere. Using my basic DSLR and a GorillaPod, I was able to obtain some good images of the Milky Way, accompanied by the Large and Small Magellanic Clouds, which are unseen in the Northern Hemisphere.  New Zealand’s weather conditions and terrain also produced opportunities to see various noctilucent cloud formations, particularly on South Island (below).

IMG_9102 (Large)

Being Down Under for much of January I was unable to start astroimaging until February but it was worth the wait, which resulted in an excellent narrowband image of the Rosette Nebula with which to start the year .  From the experience and advice gained in 2017, in narrowband I now tend to stretch each Ha-OII-SII wavelength more aggressively prior to post-processing and, as a result, obtain better detail and contrast.  In this case the resulting HaOO version of the Rosette (see Favourite Images section above) was particularly good and for the first time was included on the British Astronomy Association’s website 🙂

BAA PotW

Since obtaining the ZWO1600MM-Cool mono camera narrowband imaging has been nothing less than a revelation to me.  Whilst tone mapping using the Hubble Palette produces quite spectacular and colourful results, applying the aforementioned stretching to the just the stacked Ha-wavelength subs can often result in equally exciting black and white (grey) images which show exquisite detail.  One such image taken in March was the Cone Nebula, which showed the more extensive nature of the HII-region as well as the Cone and Fox Fur Nebulae (below).

Picture saved with settings embedded.

With the passing of winter’s narrowband targets by the end of February, I moved on to broadband imaging in March.  Of all the DSO features, I am perhaps most fascinated by globular clusters but had previously obtained mixed results with a DSLR camera.  Using the CMOS based ZWO1600 mono camera, I was now able to obtain much noticeably better colour and detail of these exciting but enigmatic objects (see Favourite Images section for M13 & below for M3).

M3 LRGB Crop (Large)

I can be put-off by some of the more technical requirements associated with astrophotography and, I‘m ashamed to say, that my approach is first to – ignore it, then maybe undertake some research but do nothing, then consciously put it off again and then, when there’s absolutely no alternative – give it a try.  I am not a technophobe, quite the opposite, but often find technology and the people who design and write about it unclear to the point of making no sense sometimes or at least misleading; it seems  somewhat paradoxical that I even got onto astrophotography given these issues! Notwithstanding, when I eventually summon the courage to tackle such problems, almost always I get it to work, eventually.  Such has been the case with Plate Solving this year.

With sight lines limited by houses, hedges and tall trees to the east, south and west, I’ve hitherto had to make do with average imaging windows of up to 2-hours, either to the east or west of the Meridian and depending on the object’s declination – a lower levels  the Meridian view is itself hidden by two tall trees, obscuring up to 30o vertically and 10o either side.  Naturally these constraints limit the image integration times severely, with an inevitable impact on the quality of images, notably with higher noise, less colour and detail.  The answer of course is plate solving and during February this year I finally bit the proverbial bullet.

Since changing to the ZWO 1600MM-Cool camera I have used Astro Photography Tool (APT) for image capture and camera control, with great success.  The software is quite comprehensive and it is excellent to use, though like most software can be a little idiosyncratic in places.  This is the point where I either give-up, try other software or, as is the case with APT, turn to their excellent product Forum.  Armed with the APT manual and answers from the Forum, I soon managed to plate solve and obtain images of the Leo Triplet over two consecutive nights, which subsequently aligned and stacked well – at last!

APRIL TO JUNE

For the past year or more I’d been thinking about the possibility of moving the observatory to the end of the back garden during the spring and summer period, so as to provide a platform from which to view the northern sky, which as previously mentioned is otherwise completely obscured by my house.  The principal issue was how to operate the equipment some 30-metres away?  From the experience of others it seemed that both WiFi and Bluetooth can have big reliability issues and I am always keen to keep it simple, so for now I chose to try and use a long ethernet cable to link the operating / capture computer with a control computer indoors.

I had intended to set-up on the lawn but after I had recently extended the paving around a nearby shed in the corner of the garden, cut back some of the bushes and cleared out the shed it, was obvious that this was a preferable location; the paved base was more stable and provided a dry foundation on which to work but, furthermore, the adjacent shed could house the operating computer.  Despite successful tests indoors using an ethernet cable between the two computers and Teamviewer software, only when the equipment was set-up in position outside did I finally discover it no longer worked; I still don’t know why and the problem remains work in progress (when I can be bothered to look at it again).

Notwithstanding, it was obvious that I could instead comfortably operate the mount and camera myself from the shed and duly set about establishing what has now become Fairvale Observatory South or the Shed Observatory (see photos above); the principal observatory location by the house now becomes Fairvale Observatory North or Patio Observatory. Having established myself at the end of the garden with a not unreasonable view of the north sky over the roof of my house, I eagerly set about imaging some northern classics over the next few months.  Imaging in both narrowband and broadband I was pleased to obtain decent pictures of the Bode & Cigar galaxies and the Elephant’s Trunk Nebula before taking a break in June and July when there’s no astronomical darkness; I have imaged at this time of the year before but it’s sometimes good to take a break.

M81 B (Large)

My very first image of the northern sky M81 Bode & M82 Cigar Galaxies (LRGB)

Now I know the observatory works from this location, I plan to move there sooner in 2019 in order to spend more time with new set-up, hopefully improving on the aforementioned objects as well as trying new ones.  All-in-all the new location was a big success as well as being great fun.  Strangely I was surprised to find that the experience of guiding could be more demanding in the north sky but of course thinking about it more, as the views essentially centre on Polaris on which RA lines converge the tracking needs to be more extreme in order to move the same angular distance when compared to a southward view.  However, anxious not to upset the established settings too much, my set-up was shoddy and, as a result, guiding error was generally poor from this locality.  Next time I’ll pay more attention to this and hopefully achieve better guiding and subs.

JULY TO SEPTEMBER

After a break of nearly 8-weeks I was eager to get back to the ‘new’ observatory at the bottom of the garden.  Furthermore, much of the summer through into September was dominated by a heatwave which was accompanied by clear skies, night after night!  As a result I was able to get some very encouraging results of the Heart (see Favourite Images section above) and Soul Nebulae and finally, to my surprise, the unusual Bubble Nebula (see image below).

SHO2int3 (Large)

OCTOBER TO DECEMBER

Needless to say, once back at Fairvale Observatory North the clouds rolled in and, furthermore, suitable objects for my equipment are initially sparse at this time of the year.  Since obtaining the ZWO1600MM-Cool camera I’ve concentrated on nebulae and narrowband imaging.  Though I’ve managed a few decent LRGB images, it’s fair to say that there’s room for improvement here and therefore finished the year on M33 the Triangulum Galaxy (see below) and subsequently M45 the Pleiades.  Despite being a good size for my scope it’s become clear to me that M33 is actually a tricky object and I was not satisfied with the final image – again better guiding and longer integration next time will almost certainly help.  However, Pleiades subsequently came out well (see Favourite Images section above) but the delicate interplay of the blue star light and interstellar dust does require careful post-processing.

LRGB P2 CropXX

As it was my birthday and it’s been something of an overdue trip since first conceived in 2015, I travelled to Olly Penrice’s Les Granges Observatory at the beginning of November.  It’s a great set-up and Olly was a real pleasure to work and learn from.  As a somewhat remote location in the Hautes-Alpes region of Provence, when it’s clear the SQM values at Les Granges can exceed 22 and for the first two nights we were able to image M74 the Phantom galaxy in HaLRGB under such conditions using his TEC 140, though following some rain during the day seeing conditions were mixed on the first night.

HaLRGB mosaic (Large)

Unfortunately the clouds had followed me from the UK and for the rest of the time there we were unable to image, though it did allow me to spend some useful and enjoyable time processing with Olly.  Other than processing the M74 image and learning some new techniques, using data previously acquired by Olly and with his help, I was able to compile a wonderful 9-panel HaLRGB widefield mosaic image of the North America Nebula and surrounding region (see above).

 

Notwithstanding the mixed weather conditions, I was able to obtain my first good, face-on image of a spiral galaxy (see Favourite Images section above), which with some additional subs from Olly’s previous sessions using an 14″ ODK scope turned into a truly spectacular image (see below) of this less than popular object.

M74 ODK with TEC STARS HaLRGB Crop

 

ASTROIMAGING RECORD 2018

No Date Type Object Name
1 Jan 2018 DSLR New Zealand

 

Milky Way, Lenticular Clouds etc. 
2 09/02/18 NB NGC 2244 Rosette Nebula
       
3 11/02/18 NB NGC 2264 Cone Nebula
       
4 11/02/18 BB M44 Beehive Cluster
       
5 11/02/18 NB Abell 21 Medusa Nebula
       
6 11/02/18 BB NGC 2392 Eskimo Nebula
       
7 24/02/18 NB IC 405 Flaming Star Nebula
       
8 24/02/18 BB Moon  
       
9 19/04/18 BB M65 + M66 Leo Triplet
       
10 05/05/18 BB M3 Globular Cluster
       
11 06/05/18 BB M104 Sombrero Galaxy
       
12 06/05/18 BB M13 Globular Cluster
       
13 18/05/18 * BB M81 & M82 Bodes & Cigar Galaxies
       
14 20/05/18 NB NGC 7822 Nebula
       
15 22/05/18 NB IC 1396 Elephant’s Trunk Nebula
       
17 16/08/18 * NB IC 1805 Heart Nebula
       
18 02/09/18 NB IC 1848 Soul Nebula
       
19 03/09/18 NB NGC 7635 Bubble Nebula
       
20 09/10/18 BB M33 Triangulum Galaxy
       
21 28/10/18 BB M33 Triangulum Galaxy
       
22 2/11/18 BB M74 Phantom Galaxy
       
23 17/11/18 BB M45 Pleiades
       
24 18/11/18 BB IC 2118 Witch’s Head Nebula
       

*multiple evenings                                            Underlined = BAA published

 

Other Worlds

GR Final HaLRGB

Apart from the simple enjoyment of travel, it often opens the potential for new opportunities and experiences that more profoundly broadens one’s horizons; I’ve travelled extensively during my life which has been enriched accordingly.  Earlier this month I visited astrophotographer Oliver (Olly) Penrice at his Les Granges Observatory in the Hautes-Alps region of Provence in France, with the objectives of imaging with a more favourable dark sky and to learn from Olly’s experience.

Les Granges Location (Medium)

Situated deep in the mountains and very much off the beaten track, Les Granges is in the small (28 people) hamlet of Ètoile-Saint-Cyrice, some way from Peter Mayle’s better known Provence but nonetheless itself interesting and beautiful, with some wonderful geology to boot; after all my wife and I are also geologists.

IMG_1046 (Medium)

Area immediately north east of Etoile-Saint-Cyrice

IMG_1066 (Medium)

Spectacular monocline rock folding at Sisteron

Subject to time and conditions, I particularly wanted to image a target that could not be achieved at home, either because it cannot be seen from my location or is beyond the capabilities of my equipment. Before leaving for France I therefore researched the projected night sky at Les Granges and developed a short list of potential targets, number one of which was a spiral galaxy.  At the moment my equipment struggles with these faint fuzzies and I’ve long wished to bag a good image of a ‘proper’ galaxy.  With galaxy season still a few months off the choice was limited but it soon became clear that M74, the Phantom Galaxy would provide such a target: it is not commonly imaged, is somewhat faint and difficult to see but is a classic, face-on spiral galaxy – just right for Guy Fawkes Night on November 5th too!

M74 at les granges 051118 10pm

Olly’s imaging equipment consists of a Takahashi FSQ106Ns rig and a more suitable TEC 140 f/7 refractor, which when matched with an Atik 460 CCD camera was just the job for the proposed task.  Outstanding night skies at the Les Granges Observatory are commonplace, with SQM values in excess of 22 but it was raining when we arrived and the outlook seemed less than perfect.  Notwithstanding, the next two nights were clear in the early evening and so on the first night we managed to obtain 3-hours of RGB subs, followed by nearly 2.5 hours of Ha and Luminance data the following evening.  Whilst imaging we also spent time observing, in these conditions Andromeda Galaxy was clearly visible with the naked eye but using the 14″ Meade LX200 which Olly inherited from the late Alan Longstaff other objects such as M27 and M33 came to life in the eyepiece.

IMG_20181108_115731653 (Medium)

Does what it says on the tin – entrance to Les Granges observatory

Sadly the rain returned thereafter and this turned out to be the only window of opportunity for the rest of the week!  Thankfully Olly has a vast wealth of data that included some of M74, from which we were able to bolster our meagre data from the first two evenings of imaging the same object.

Since returning home I’ve worked on the recently acquired data again and am pleased with the resulting image, shown at the top of the page.  In particular, the addition of Ha-wavelength light has brought the galaxy to life where it highlights areas of star formation located within the spiral arms, in the form of distinctive areas of magenta coloured red spots – a characteristic sign of such activity within galaxies.  Olly also produced an alternative image by combining data from the aforesaid recent image with additional data previously taken with an ODK 14 inch scope.  This resulted in a total integration time of some 17-hours and produced a stunning image of M74 that I’m pleased to say I played a small part in (see below).

M74 ODK with TEC STARS HaLRGB Crop

It was disappointing that much of the time at Les Granges was spoilt by poor weather but I was able to use some of that time on processing techniques with Olly and just enjoying the wonderful ambiance that comes from being in such a location.  I hope to return again some time in order to enjoy the beauty of the area and the night sky that can be seen – when it’s not cloudy.  In the meantime, I’m more than pleased to catch some photons from another world of another world, which has resulted in stunning images of a spiral galaxy – at last.

  IMAGING DETAILS
Object M74 Phantom Galaxy
Constellation Pisces
Distance 30-million light-years
Size 10.5’ x 9.50’     
Apparent Magnitude +10.0
   
Scope  TEC 140   FL 980 mm   f7.00      (+ADK 14”)
Mount Mesu 200
Guiding PHD2 
Camera Atik 460 CCD  Pixels 4.50 ɥm
  FOV 43.80’ x 35.04’  Resolution 0.96”/ pixel     
Capture & Processing Atik software capture, Astroart pre-processing, PixInsight and Photoshop CS3 post processing
Image Location RA 01:36:41    DEC 15:47:01                       
Exposures 6 x 600sec RGB + 5×900 sec L & Ha  = 320 minutes  @ -20o
Location & Darkness Ètolie-Saint-Cyrice, Hautes-Alps Provence, France        SQM <=21.50 – 22.00
Date & Time 2nd & 3rd November 2018 @ +20.30h  
Weather <=8oC    RH% high

Boreal Breakthrough

 

M81 LRGB Final HLVG

I have often written about imaging difficulties here at Fairvale Observatory, which apart from overflying aircraft from Gatwick and Heathrow airports, 24/7 helicopters from Redhill aerodrome and general light pollution, also consists of numerous sightline obstructions in the form of large trees to the east and south, high garden hedges and the complete obstruction of the north sky by my house!  I have toyed with the idea of moving onto the lawn so as to look back northwards over the house but was concerned by all the faffing about to get the equipment down and back up a flight of steps, as well as added complications with equipment control and dew problems; I concede that many do operate successfully in this way but with plenty of other problems to cope with, I like my hobby to be as easy and convenient as possible.

Last year I enjoyed working outside during the summer months – notwithstanding the lack of darkness during much of this period – and therefore over the past winter finally considered how such a garden-based set-up could be achieved, primarily for use between May and September.  The resulting Plan-A was to place three paving stones within the lawn to support the tripod and run a USB-cable back to the house for control.  However, after recently expanding a small paved area outside the shed at the end of the garden and looking at the potential sightlines from this location, it was obvious that a Plan-B set-up here could also work.  Whilst not quite as good viewing angles as the original location, there are a number of other worthwhile benefits:

  • Being off the lawn on paving it seemed likely that dew could be less of a problem;
  • Working on the paving around the mount would be more convenient and dry;
  • By clearing out the adjacent shed it could be used as a dry location from which to control the equipment.

And so early in May I set about establishing Plan-B and soon afterwards putting it to work.

Pan1 Comp (Medium)

The view from the shed looking northwards is surprisingly quite good (see above) and I don’t know why I hadn’t considered this before. There are a few large trees to the north east, a high hedge along the western boundary and of course my house is still somewhat in the way but altogether it’s not too bad and for the first time I have a clear view of Polaris, as well as a whole new plethora of imaging targets!  Whilst this direction looks directly towards south London, being on the southern slope of the Greensand Ridge the worst of the city’s glow is fortunately obscured by the hill.  Furthermore, it is ironic that my house and the hedges also provide considerable protection from the local street lights, which I’m pleased to say are now turned off after midnight anyway.

Set-up

Local equipment layout the same as previously

I cut-back some of the adjacent vegetation to improve sightlines and ran a power cable from the house to the shed otherwise it’s exactly the same set-up which was being used at the main, south looking location on the patio by the house.  I looked into WiFi-control of the equipment but from the experience of others concluded it could be unreliable and instead considered using Teamviewer software via a USB Cat-5 repeater cable from the mount / shed computer to a second computer in the house.  However, given the distance of some 30 metres I finally decided to adopt a more robust LAN Cat-6 ethernet cable for this purpose. Unfortunately whilst this had worked successfully during testing in the house, I have so far been unable to get it to work outside and for now have had to operate the equipment from inside the shed, which has nonetheless proved to be a comfortable and effective alternative.

Being lazy and cautious about changing too much about the set-up, I levelled, aligned and reset the new location data of the tripod but kept all other settings the same for now.  I realise this is not ideal but initially just wanted to experience the new location and north sky to understand what was possible within the given field-of-view and identify any obvious problems.  Fortunately a settled period of good weather allowed me to try out the new location soon thereafter.

North Sky ViewX

White area shows optimum imaging area from Fairvale Observatory South – AKA ‘The Shed’

What I hadn’t expected on first use was that slewing and tracking would become more difficult and takes noticeably longer at higher latitudes, especially approaching Polaris.  Following subsequent enquiries and with some further thought it now makes sense.  At higher latitudes near and above about 70 degrees as the lines of Longitude are closer together, it makes the RA slew rate bigger and bigger the closer you get to the North Celestial Pole.  Of course the celestial pole is not coincident with the terrestrial pole, which means that those objects within the latitude of 90o minus the observer’s latitude – in my case this equals 39o – means that all those objects above 39o will be circumpolar from my point-of-view i.e. will rotate over the year around North Celestial Pole.  This is basic astronomy but hitherto I had not considered the implications for tracking and guiding before and will need to bear it in mind when selecting targets in the future.

M81 B (Large)

I had one particular target in mind but as it was only viable much later in the night, on this occasion I chose to start imaging the north sky for the first time with Bode’s Galaxy AKA M81 and the nearby Cigar Galaxy AKA M82; for comparison using low gain, long exposure on the first night (top of the page) and high gain, short exposure (below) on the following night.  Given the target’s DEC position of 70o I soon discovered the aforesaid tracking difficulties, which resulted in the RMS guiding error varying from 3’ to 20’ and deleterious consequences for the images!

 

Whilst I’m pleased with my very first north sky images, it is obvious I’ll need to return again with better guiding and much longer integration time.  On a positive note the general set-up worked very well and the shed provided an excellent place from which to operate the control and image capture equipment.  Furthermore, despite a few restrictions the overall view of the northern night sky is good and holds much promise for future, hitherto inaccessible imaging objects.  As a result of establishing this new site I intend to name the new north looking location Fairvale Observatory South or ‘The Shed Observatory’ (see mosaic above) and the principal, south looking location by the house Fairvale Observatory North or ‘The Patio Observatory’.  Altogether this marks a major breakthrough for my astronomy and I eagerly await the return of astronomical darkness on 20th July onward.

AstroNet ResultX

IMAGING DETAILS
Objects Bode’s Galaxy M81  &  Cigar Galaxy M82     
Constellation Ursa Major
Distance M81  11.8  &  M82  11.4 -12.4 million light-years
Size M81 26.9’ x 14.1’   &    M82 11.2’ x  4.3’
Apparent Magnitude M81 +8.0  &  M82 +8.4
 
Scope  William Optics GT81 + Focal Reducer FL 382mm  f4.72
Mount SW AZ-EQ6 GT + EQASCOM computer control
Guiding William Optics 50mm guide scope
  + Starlight Xpress Lodestar X2 guide camera & PHD2 control
Camera ZWO1600MM-Cool (mono)   CMOS sensor
  FOV 2.65o x 2.0o Resolution 2.05”/pix  Max. image size 4,656 x 3,520 pix   
EFW ZWOx8 + ZWO LRGB & Ha OIII SII 7nm filters 
Capture & Processing Astro Photography Tool + PS2,  Deep Sky Stacker & Photoshop CS2
Image Location Centre Image-B    RA 09:55:13.46    DEC 69:21:08.36  (19/0518) 
Exposures                       

                                       

                                         

A 18/05/18   10 x 180 sec L  + 5×180 sec RGB  (Total time: 75 minutes)    @ 139 Gain   21  Offset @ -20oC

B 19/05/18   45 x 60 sec L    + 15 x 60 sec RGB  (Total time: 90 minutes)    @ 300 Gain   50  Ofsett @ -20oC    

Calibration                    

                                        

A 15 x 180sec Darks  20 x 1/4000 sec Bias  10 x Flats LRGB  @ ADU 25,000  

B 15 x 60sec Darks     20 x 1/4000 sec Bias  10 x Flats LRGB  @ ADU 25,000  

Location & Darkness Fairvale Observatory South – Redhill – Surrey – UK       Typically Bortle 5
Date & Time (A)    18th  &   (B) 19th May 2018 @ +23.45h approx.

 

 

Star Struck

 

M13 LRGB F2 CROP (Large)

Of all the things I’ve discovered since taking up astronomy, perhaps it is the presence and nature of globular clusters that has most surprised me. Bound closely together by gravity, these massive spherical collections of stars orbit the galactic core perpendicular to its plane.  In the case of the Milky Way there are 150 globular clusters but they can be much larger in other galaxies, such as M87 which has some 13,000; clusters of clusters have also now been discovered in the Universe!  Typically each cluster might contain a few thousand or tens of thousands of stars, although in some cases they can be much larger.  Omega Centauri is the largest globular cluster in the Milky Way, being 150 light-years in diameter it contains 10 million stars; though clearly visible from Earth it can only be viewed from the Southern Hemisphere, which we unfortunately did not see when in New Zealand earlier this year.

MW &amp; globs

Despite all the advances being made in cosmology, the origin of globular clusters still seems to remain quite uncertain.  Characteristically the stars are all very old, typically in the region of 8 to 12-billion years and are of low metallicity i.e. they contain a low proportion of elements other than hydrogen and helium.  At least some, such as Alpha Centauri, are thought to have condensed from dwarf galaxies and such a process may currently be taking place within the large Magellanic Cloud – which we did see in New Zealand!  In other cases it is thought that the clusters have probably originated independently and were subsequently captured by the relevant galaxies.  However, their very old age – sometimes nearly as old as the universe itself – origin and relationship to galaxies remains intriguing.  For these and many other reasons I personally find globular clusters fascinating, probably more than any other astronomical feature, amazing as they too may be.

GlobsX

Globular Clusters May 2018: M3, M13 & M92 (red circles) + Others (yellow circles)

From time-to-time I’ve tried imaging various globular clusters but have not been satisfied with the outcome.  Now using guiding, plate solving and the high-resolution ZWO1600MM-Cool camera, it was time to give it another try this spring, when some of the best clusters are present in the northern night sky.

M3 LRGB Final (Large)

First up was M3 (Final image above), the very first Messier Object to be discovered by Charles Messier himself in 1764.  Consisting of 500,000 stars, between 8 and 11-billion years old and spanning some 220 light-years, M3 is one of the largest and brightest (absolute) globular clusters associated with the Milky Way – about 300,000 times brighter than our Sun.  It is noteworthy that the cluster contains some 274 variable stars, the highest number of any clusters, as well as a relatively high number of ‘blue stragglers’ – young main-sequence stars that appear to bluer and more luminous than the other stars in the cluster and are thought to be formed through stellar interaction of the older stars.

M3 LRGB Crop (Large)

With these attributes it is not surprising that M3 is considered a popular target in astrophotography (cropped image above), likely surpassed however by M13 AKA the Great Globular Cluster in Hercules (cropped image top-of-the-page), which conveniently follows M3 in the same area of the sky about 3-hours later (together with nearby the globular cluster M92).  And so having bagged M3 it was time to turn the telescope and camera towards M13 (Main image below).  Discovered by the eponymous Edmond Hailey in 1716 (he of Hailey’s Comet), seen from Earth M13 is slightly brighter than M3 with a wide range of star colours that certainly makes for an exciting image.  At 11.65 billion years old, M13 has been around almost three times as long as the planet Earth.

M13 LRGB Final (Large)

Since starting astrophotography I like to try my hand at imaging a globular cluster at least once each year but hitherto with disappointing results.  This time I’m pleased with the outcome, especially M13 which is surely one of the most magnificent objects in our night sky; as a bonus there are also a few galaxies in the background of both the M3 and M13 images too.  It is therefore fortunate that for those of us in the higher latitudes of the northern hemisphere the Great Globular Cluster in Hercules can be seen all-year round, though is at its highest and therefore best position between May and September – thereby inaccessible for the Kiwis who are instead compensated by Alpha Centauri!  I expect to be back again next year to marvel at these amazing and enigmatic objects, if not before.

M3 Location Crop

IMAGING DETAILS
Object M3    (NGC 5272)     
Constellation Canes Venatici
Distance 33.9 million light-years
Size 18.0’ or 220 light-years     
Apparent Magnitude +6.2
 
Scope  William Optics GT81 + Focal Reducer FL 382mm  f4.72
Mount SW AZ-EQ6 GT + EQASCOM computer control
Guiding William Optics 50mm guide scope
  + Starlight Xpress Lodestar X2 guide camera & PHD2 control
Camera ZWO1600MM-Cool (mono)   CMOS sensor
  FOV 2.65o x 2.0o Resolution 2.05”/pix  Max. image size 4,656 x 3,520 pix   
EFW ZWO x 8 + ZWO LRGB & Ha- OIII-SII 7nm filters 
Capture & Processing Astro Photography Tool + PS2,  Deep Sky Stacker & Photoshop CS2
Image Location Centre  RA 13:42:23     DEC 28:22:50  
Exposures 24 x 180 sec L + 10×180 sec RGB  (Total time: 162 minutes)   
  Unity @ 139 Gain   21  Offset @ -20oC    
Calibration 10 x 180sec Darks  20 x 1/4000 sec Bias  10 x Flats LRGB  @ ADU 25,000  
Location & Darkness Fairvale Observatory – Redhill – Surrey – UK        Typically Bortle 5
Date & Time 5th + 6th  May 2018 @ +23.00h

M13 Location Crop

IMAGING DETAILS
Object M13     (NGC 6205)
Constellation Hercules
Distance >=20,000 light-years
Size 20’  or 150 light-years
Apparent Magnitude +5.8
 
Scope  William Optics GT81 + Focal Reducer FL 382mm  f4.72
Mount SW AZ-EQ6 GT + EQASCOM computer control
Guiding William Optics 50mm guide scope
  + Starlight Xpress Lodestar X2 guide camera & PHD2 control
Camera ZWO1600MM-Cool (mono)   CMOS sensor
  FOV 2.65o x 2.0o Resolution 2.05”/pix  Max. image size 4,656 x 3,520 pix   
EFW ZWOx8 + ZWO LRGB & Ha OIII SII 7nm filters 
Capture & Processing Astro Photography Tool + PS2,  Deep Sky Stacker & Photoshop CS2
Image Location Centre  RA 12:39:59    DEC -11:37:20  
Exposures 20 x 180 sec L + 15×180 sec RGB  (Total time: 195 minutes)   
  @ Unity 139 Gain   21  Offset @ -20oC  USB 40 
Calibration 10 x 180sec Darks  20 x 1/4000 sec Bias  10 x Flats LRGB  @ ADU 25,000  
Location & Darkness Fairvale Observatory – Redhill – Surrey – UK        Typically Bortle 5
Date & Time 6th + 7th + 9th May 2018 @ +00.30h  

 

Chapeau!

LRGB GxC Crop-2 (Large)

 

I always had a general interest in astronomy but was eventually sparked into action after viewing Saturn through the Thompson 26 inch refractor at Herstmonceaux observatory in 2014.  The beauty of the planet and its unique rings is captivating and like many others it remains my favourite planet to this day.  One year on and looking further afield at Joan Genebriera’s Tacande Observatory on the island of La Palma, I discovered what is now  one of my very favourite Deep Sky Objects – M104 or the Sombrero Galaxy; until recently I used the resulting picture obtained whilst at La Palma as the main banner image for this website.  Though perhaps not as spectacular as the Orion Nebula or certain spiral galaxies, the sombrero-like galaxy (with a passing resemblance of a flying saucer too), is beguiling in its own unique way and ever since then I’ve been eager to return to The Hat and image it myself from home.

Chart_1.cdc3

However, imaging the Sombrero from the UK and especially at my location just south of London is quite another matter to La Palma.  Aside from light pollution, being at 51o north compared to 28o in La Palma, M104 is considerably lower in the sky when viewed from Fairvale Observatory in Redhill; at the time of imaging in early May it was about 26o above the southern horizon.  Furthermore, my sight lines are obscured on three sides by 15-foot hedges and directly south by two 45-foot conifers – see below SE to SW view of M104 imaging track at Fairvale Observatory.

M104 Track crop

As a result, only after it emerges from behind the western edge of the aforesaid conifers can M104 (just) be imaged, as it moves along the top of the hedge for just over an hour before disappearing from view once again.  Of course this is far from ideal but with my enthusiasm for the Sombrero, a high-resolution ZWO1600M-Cool camera and newly acquired ability to plate solve, I gave it a try over three consecutive nights.

 

RGB GxC crop (Large)

 

An unbarred spiral galaxy, the hallmark of M104 is its bright bulbous centre encircled by dark dust lanes, which when viewed from Earth tilted at just 6-degrees above the equatorial plane creates the appearance of a sombrero hat (see cropped image above).  With the much higher resolution of the Hubble telescope some 2,000 globular clusters have been identified with M104, ten-times that of the Milky Way.  In 1912 the galaxy was found to be moving away from Earth at 700 miles per second, providing an early indication that the Universe was in fact expanding in all directions.

All-in-all the Sombrero galaxy is a fascinating and unusual object, though small and all-in-all a challenging imaging target, especially seen from Fairvale Observatory.  Notwithstanding, at last I am very pleased to obtain my own exciting image of the Sombrero – chapeau!

M104 Location

IMAGING DETAILS
Object Sombrero Galaxy  M104     
Constellation Virgo
Distance 29 million light-years
Size 9’ x 4’  or  50,000 light-years
Apparent Magnitude +8.0
 
Scope  William Optics GT81 + Focal Reducer FL 382mm  f4.72
Mount SW AZ-EQ6 GT + EQASCOM computer control
Guiding William Optics 50mm guide scope
  + Starlight Xpress Lodestar X2 guide camera & PHD2 control
Camera ZWO1600MM-Cool (mono)   CMOS sensor
  FOV 2.65o x 2.0o Resolution 2.05”/pix  Max. image size 4,656 x 3,520 pix   
EFW ZWOx8 + ZWO LRGB & Ha OIII SII 7nm filters 
Capture & Processing Astro Photography Tool + PS2,  Deep Sky Stacker & Photoshop CS2
Image Position Centre  RA 12:39:59    DEC -11:37:20  
Exposures 25 x 180 sec L + 3x5x180 sec RGB  (Total time: 120 minutes)   
  @ 139 Gain   21  Offset @ -20oC    
Calibration 10 x 180sec Darks  20 x 1/4000 sec Bias  10 x Flats LRGB  @ ADU 25,000  
Location & Darkness Fairvale Observatory – Redhill – Surrey – UK        Typically Bortle 5
Date & Time 5h + 6th + 7th  May 2018 @ 23.30h  approx.

 

 

Hive Of Activity

 

M44 Crop (Large)

Identified by Ptolemy in the second century AD, the open star cluster was known in Greek and Roman mythology as Praesepe (The Manger). Soon after developing the so-called ‘Dutch Gadget’ for use in astronomy as a refractor in 1609, Galileo became the first person to properly observe through the telescope what is now known as The Beehive Cluster and thus detect some 40 stars.  In 1769 Messier added the cluster to his growing catalogue as the 44th object and thus became M44.  More than 400 years since Galileo’s first view, the Beehive Cluster AKA M44, Praesepe or more prosaically NGC 2632, is now known to consist of approximately 1,000 stars and forms one of the imaging targets at or about the time of the Spring Equinox each year.

M44 Locate

Located in our galaxy relatively nearby within the constellation Cancer, between 520 and 610 light-years away and 3-times the Moon’s diameter or 1.5o, The Beehive can be seen with the naked eye as a blur in dark skies and with a telescope becomes an excellent imaging target.  Last imaged with the modded Canon 550D DSLR in 2015, the LRGB image obtained this time shows improvement but with only 20-minutes integration time lacks the colour seen in other examples, which however consist of more than 17 hours! Truth is that this was a brief experiment carried out between imaging two other objects on the same night and I’m encouraged that by increasing my time significantly I can eventually tease out better quality and the spectacular colours that make The Beehive such an attractive open cluster.

IMAGING DETAILS
Object The Beehive Nebula   (Praesepe, M44, NGC 2632)     
Constellation Cancer
Distance 520 – 610 light-years
Size 1.5o  
Apparent Magnitude +3.7
 
Scope  William Optics GT81 + Focal Reducer FL 382mm  f4.72
Mount SW AZ-EQ6 GT + EQASCOM computer control
Guiding William Optics 50mm guide scope
  + Starlight Xpress Lodestar X2 guide camera & PHD2 control
Camera ZWO1600MM-Cool (mono)   CMOS sensor
  FOV 2.65o x 2.0o Resolution 2.05”/pix Max. image size 4,656 x 3,520 pix   
EFW ZWOx8 + ZWO LRGB & Ha OIII SII 7nm filters 
Capture & Processing Astro Photography Tool,  Deep Sky Stacker & Photoshop CS2
Exposures 4×5 x 60 sec LRGB (Total time: 20 minutes)
  @ 139 Gain  21 Offset @ -20oC  
Calibration 5 x 300 sec Darks  20 x 1/4000 sec Bias  10 x Flats Ha, OIII & SII @ ADU 25,000  
Location & Darkness Fairvale Observatory – Redhill – Surrey – UK        Typically Bortle 5
Date & Time 11th February 2018 @ 21.30h approx.

 

Galactic Neighbours

M31 LUM ProcessedX (Large)

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

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

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

GAIN

OFFSET

ADU

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

Current popular guidance on ZWO1600MM-Cool settings

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

Green Mud

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

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

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