Astrophotography – deep sky

Another DSO challenge – the Hickson catalogue

The appearance of Pegasus reminds me that there are a couple of well-known compact galaxy clusters in that constellation. One of them, Stephan’s Quintet is included in a catalogue of galaxy clusters – the Hickson catalogue

http://www.reinervogel.net/pdf/Hickson.pdf

It is a pretty challenging set of targets for all you astrophotographers out there! There is a sub-set of the easier ones (!) at

http://www.astronomy-mall.com/Adventures.In.Deep.Space/hicklist.htm

I have only managed to image 3 out of this list, so far, and here are some PD images from my archive to wet your appetite.

Hickson 44, comprising NGC3187, NGC3193, NGC3190 and NGC3185

Hickson 68, comprising NGC5350, NGC5354, NGC5353, NGC5355 and NGC5358

Hickson 92 (including Stephans Quintet), comprising NGC7320C, NGC7320, NGC7319, NGC7318B, NGC7318A and NGC7317

The other well-known cluster in Pegasus is the Deer-Lick group, comprising NGC7336, NGC7335, NGC7331, NGC7340 and NGC7337

Happy imaging!

 

 

GIMP, Reprocessing and C12 / NGC6946

Many thanks to Andy for posting his instructions for image processing – obviously caught the bug!

Its nice that someone else is also trying things out. The simple method there for reducing star trails had never occurred to me for example!

There are many different ways of achieving an objective once you have a general purpose toolbox, and often a combination of methods is the best option, The GIMP “pyastro” plugin is pretty good for rounding stars for instance, but doesn’t always work, especially when the stars are in front of an extended DSO.

That brings me to C12 / NGC6946. Rob has just posted a really good image of this. I posted one way back in 2015 (that is very poor compared to Rob’s) at http://www.thornett.net/Rosliston/Astrophotography/html/11-9-2015.html

It suffers from all sorts of problems such as star trails and halos, so can we do anything about it?

I’ll not bore everyone by recounting the exact sequence of processing steps, as it will be different for every image.

Suffice it to say it was a combination of despeckle / star trail reduction / and dehaloing as I described here:

The dehalo method for deep sky objects using GIMP.

Anyway, here is the original as posted, and the reprocessed version.

Still not a patch on Rob’s, of course!

Damian re-processes Andrew’s M101 image from 24/8/2019 in Nebulosity and Photoshop

Better outcome that my previous attempts. Also multiple small galaxies indentified by comparison with a better widefield image (not mine) – overlaid below – my apologies that stars don’t quite match

Andy

Damians-version-my-M101-from-240819-on-080919:

Damian’s version my M101 from 240819 on 080919 overlaid with better widefield M101 picture, showing multiple small galaxies, many of which are evident also in image above (due to poor alignment many stars appear twice close to each other):

Weekend Opportunism

Between a busy work week, family commitments and some so-so forecasts it wasn’t looking good for astronomy this weekend, but it turned out pretty well.

Friday Night:
Imaging-
Didn’t get out until about 10:30 but tried to make up for lost time by setting both the main scope going and trying out my 50mm lens on the Star Adventurer. I had high hopes for the 50mm lens- it’s another oldie (I’ve had it about 15 years), but online quite a few people are getting great results with them. Well- I’m not in that club (yet). The diaphragm only has five blades and although I stopped it down to f2.8 (it’ll open up to f1.8) all of my stars are pentagons and DSS is refusing to recognise them as stars- so no results from that. Fortunately, the main rig saved the day: I went for NGC6946 – The Fireworks Galaxy with my 200p. Throughout the session low clouds were interrupting the view, and around half the subs were lost, but the ones I did hang onto gave the result below. Over the summer I’ve picked up a second hand Canon 550d that has been home modified with a Peltier cooler and put into a metal case- it’s not pretty, but it seems to be effective. This is 13×4 minute subs and throughout this session it held the temperature down to around 7-8 degrees which I’m pleased with (a couple of degrees below ambient, my 600d usually runs about 10 degrees above ambient and is consequently much noisier). The target itself is quite a bit smaller than I’d anticipated- this is a crop of about 20% of the frame. Despite the small size- I think this is a lovely target- both for its colours and the asymmetry in the arms.

Observing-

Whilst the cameras were doing their stuff I had the Dob out on the following objects:

The Double-Double- I used Vega to get the finders lined up then dropped down to Epsilon Lyra to check out the seeing. It was a straightforward split, but I could see that the transparency was not great.

M13 & M92 – I often start with these and never get tired of them. In Binoviewers at about 260x they fill the field of view and appear 3 dimensional. For me these are the only types of objects that actually look better in the eyepiece than in a photo; I love the difference in their appearance- M13’s great with lots of features, but a bit of a mess with arms everywhere, whereas M92 is compact and very neat. Just wonderful.

The Veil – I was reading a thread on SGL recently which referenced a Sky and Telescope article on The Veil (https://www.skyandtelescope.com/astronomy-blogs/explore-night-bob-king/explore-veil-nebula/) . Using this as a guide, and with an Oiii filter a 30mm eyepiece (55x) and a coat over my head I managed to explore just about the whole thing. I’m a bit prone to hopping from object to object whilst observing, so it was great to really take my time in the tranquillity of the small hours and drink it all in with nothing but the odd clunk of a shutter release and that American woman with the nice voice who commentates on APT saying “Dithering started…” softly in the background. Ahhh… a very nice dither contemplating the remnants of a supernova.

I was on the Veil for over half an hour and loved every minute of it, but decided with to move on with the Oiii filter and go check out M27. This is normally not a problem, but by this point the transparency had deteriorated so much I was unable to hop to it. Altair was the only nearby star that was naked eye visible and despite several attempts I just couldn’t find the stars in the finder to hop up to M27. Reluctant to retire I switched up to the North East to check out M31 as the skies looked better in that direction. Before I could get to it a bank of cloud blotted it out. Time for bed…

Saturday:

I managed to pop out briefly whilst doing other things on Saturday evening and set the imaging rig running on M13. This was a bit of an experiment: I’ve imaged M13 before, but with my guide camera on a smaller scope using the short exposure method. Whilst I was quite pleased with those outcomes (see https://roslistonastronomy.uk/catching-up-on-images) , I wanted to see how it would look with more integration time and a DSLR chip. This is 22x 4 min subs plus calibration frames and I am really pleased with it. As a bonus for the last half-hour it was running I sat outside with Sam observing the sky primarily with Mark 1 eyeballs. After a while we were both able to pick out the Milky Way running up through Cassiopeia and Cygnus despite the local light pollution. A real pleasure!

Clustering 08/09/2019

I wasn’t ambitious enough to go hunting local group galaxies last night, but it occurred to me that I hadn’t got a half decent image of the Perseus double cluster, for all the same reasons I hadn’t got an image of M31. So, equipping the PD with the 5-100mm zoom lens again, I tried to rectify the situation. Here is NGC669 / NGC884 / or C14, as you choose.

 

By this time, the Pleiades (M45) had come into view. Although that means winter is coming, it is always nice to welcome back and take a snapshot of old friends.

 

Here is another version with the nebulosity suppressed a bit:

Local project?

How about this for a project?

Observe/sketch/image as many of the Local Group of galaxies as possible.

Meet the Shy Side of the Local Group

They are well placed at the moment. There is the obvious M31, M32, M110 and M33. There is also the rather less obvious NGC147 and NGC185 (C17 and C18). There are also others.

Here are images of M32 and M110 I have extracted (not too successfully!) from existing images of M31,

and here is a reprocessed image I obtained last year of NGC185. So far I have never managed NGC147.

Anyone up for a challenge?

 

Bird table observatory and more reprocessing

In my post https://roslistonastronomy.uk/m31-on-the-cheap, Rob commented

“I am now looking forward to your results from the Bird Table Observatory (fits in small spaces), the Chimney Observatory (excellent horizons) and the Picnic Rug Observatory (good on holiday with you)!”

Well, as it happens – – – !

3 or 4 years ago we, and the window-sill observatory had some holidays in the West Country (see  http://www.thornett.net/Rosliston/Astrophotography/html/dsos_1-10-16.html and http://www.thornett.net/Rosliston/Astrophotography/html/deep_sky_objects_from_the_west_country_8-10-2015.html)

and in 2016, here are a couple of images of NGC 1499, the California nebula, and M45 from a “bird table observatory”! Admittedly this bird-table was a sawn-off tree trunk converted into a bird-table. Incidentally, a sawn-off tree trunk makes a really good very stable well-damped scope pier, it just takes a while to get to the end product! I also took the opportunity to do a bit of reprocessing.

The previous year we were in Cornwall and here are a couple from the “Picnic Rug Observatory” Again admittedly the rug was spread on a patio table. Anyway here is M33 and M45 again, with a scope this time.

No “Chimney Observatory” as yet though!

The Cygnus Rift

Another clear moonless sky last night and I initially had a plan to do some galaxy imaging with my 8 inch Newtonian. For whatever reason I simply could not align the scope (suspect the issue was tiredness after a long day, plus the previous night’s observing an Brankley Pastures, causing me to do something stupid), so rather than feed my frustration any further I decided to stop and instead put the camera on the Star Adventurer mount and do some widefield imaging. The joy with this is that you polar align and then manually aim- no computer and no guiding so perfect for when you’re a bit hard of thinking!

The previous night, before the clouds rolled in, we’d had a wonderful clear naked eye view of The Milky Way showing clouds of stars and the dark river between them and I wanted to try and capture it. I’d tried at the time, but couldn’t focus and then clumsily messed up the polar alignment. Having resolved the focusing problems, I took this in my back garden with my modded Canon 600d SLR with a light pollution filter on it and using an 18-55 zoom lens that I’ve for many years now- although this is its first venture into proper AP. I took 17 2 minute subs plus darks and bias. I tried taking flats, but couldn’t defocus enough to make my flats panel blank.

I must admit I’ve really enjoyed looking at this one- the field of view covers almost all of the Summer Triangle (Altair was originally on there, but I cropped it out due to some weird effects that I suspect are a consequence of not having flats). Among the more prominent objects visible on here are the North America nebula, the Pelican, the Elephant’s trunk, the Veil, the Butterfly and the Coathanger asterism- but there are many more!