Return To The Moon

It's been a while since I last pointed my trusty ToUCam Pro webcam at the Moons surface - too long to be honest! I find there's something very satisfying in this day and age of expensive equipment of putting a humble webcam at the prime focus of my telescope. The instant gratification of seeing a small section of the Moon surface shimmering away on your laptop screen cannot be underestimated in my book!

I was having a torrid time with my 20D's first outing - I always forget something, and this time it was the USB cable to connect it to my laptop for long exposures. The night was superb, and once the Moon had risen over the observatory dome I couldn't help but have a go at imaging it "for old times sake", plus I know that at least I could take home something good from the night!

Times have changed since I first started webcaming - we can now update the firmware on the ToUCam to remove the automatic sharpening, and even remove the automatic debayering algorithm as well. The result? Much smoother, sharper images that give fantastic results. Unfortunately I did not pay enough attention to getting the correct exposure :( It's all too easy with the Moon to get this wrong due to its huge dynamic range - ideally you should take a number of exposures and blend them together to get best results, but on this night I as just wanting to grab a quick image. I really should learn that this is not a good idea! Anyway, here's the resulting image:


Still, I'm impressed with the result. Another great thing about webcams is that a mosaic stacks up the mega-pixels pretty darn fast! Back in 2002 I spent an evening with my 8" Meade Starfinder and 2x Barlow lens capturing over 60 sets of avi files to produce a massive image that I had printed out and now proudly hangs on my wall at an impressive 2 foot square. I think it took me well over a week to process that bad boy! It's like having my own personal Lunar Atlas on the wall, and I love it :)

Anyway, back to this image! Now, I don't know why, but Registax really, really, winds me up! It just never quite works the way I want it to. For this image I simply wanted to multi-point stack all 8 frames using sigma clipping. I gave up on the multi-point aspect as it just did not work :( I'm not sure I really needed it anyway for this project. The stacked images were then dumped into Photoshop, clipped to a clean edge, feathered out, and mosaiced together. I used the exposure image adjuster to level out the variable transparency that occurred during the capturing process, and a liberal use of the eraser tool removed a few alignment oddities. With a clean base image, I ran the smart sharpen filter to bring out a bit of the detail (I'd love to use a deconvolution filter in Photoshop, but I don't have one) and then ran three sets of high-pass filtering of reducing filter size (7.5, 3.2, 1.4) to increase the tonal range and contrast without introducing too much noise into the final image. The end result, a rather pleasing lunar mosaic and an urge to do it again - but this time properly :)

Cygnus Widefield

Continuing with my 20D and 50mm setup, I moved on from the Double Cluster to the region around Deneb (alpha Cygni) and the nebula with the most canny resemblance to its namesake, the North American Nebula. I've tried this region out with my 10D in the past, and have been pleasantly surprised with the results, so I was hoping for better things this time.

Set up in my back garden, equipped with an Astronomix CLS light pollution filter, I pointed the camera straight up and let it record 50 frames, each of 60 seconds - as with the Double Cluster, any longer and there was no benefit due to the quarter moon rising. Incidentally, while this was going on I actually undertook some visual observing for once! Lying on the sun lounger I worked my way around the familiar clusters and double stars of the summer sky, and also undertook some detailed observations of the Lunar terminator as well (more on that in another post perhaps). Anyway, a couple of hours later and the light and dark frames had been safely captured and I could retire for the night. Job done (for now!).

Stacking was done using the excellent Deep Sky Stacker, and most of the processing with PixInsight LE and final composition and balancing with Photoshop. Yet again, I was impressed with what such humble equipment could achieve! There are just sooooo many stars in that region of the Milky Way! Here's the results at any rate.


Just as normal, I like to fire up Patrick Chevelley's excellent Cartes du Ciel (Sky Charts) to see what I've captured. NGC7000 was immediately obvious - being the brightest hydrogen alpha region in the area that was to be expected! There was also a massive cloud of stars just further down away from Deneb which I'm sure must have some name or designation ... it does contain NGC 7039 - an open cluster - but when seen in this image it looks hard not to think the cluster is just part of another, more massive, grouping out there. One assumes that NGC 7039 is gravitationally bound and the rest of the stars are just a line of sight efffect looking through the plane of the Milky Way. There even seem to be darker dust lanes just eating into the side and edging into the middle of the stellar collection in places. Before I go further, here's an annotated version to compare my notes with.



The Pelican nebula (IC 5070) and adjoining IC 5068 are readily visible, as is the wonderfully sounding (and looking) Butterfly Nebula (IC 1318). Definitely worth a closer look at some point in the future! Continuing past the Butterfly along the main body of Cygnus you come to the area that houses the Crescent Nebula - too small to be seen directly here, but the hydrogen alpha complex it lies in s visible as a small reddish blob. In fact, there is lots of nebulosity around this region, including IC 1311, but with the current response of my 20D to this hydrogen light, that's about all I'm going to be able to see for now.

One final capture was that of the edge of the Veil Nebula on the extreme right hand edge of the image - again, another future target to explore!

I'm rather enjoying this imaging lark - there's just so much that you can do without having to spend massive amounts of money on fancy kit. I've not even attached it to a telescope yet :) So, the next logical stop must be to use my ED80 refractor as a lens and shoot through it at prime focus .... we can then get a bit closer to a number of these interesting objects in the summer skies!

The Double Cluster

I finally splashed out on a Canon 20D from eBay to upgrade from my 10D - something I have been pondering over for a while now. Why? Well, the CCD is quite a step quieter than that of the 10D, there are obviously more pixels, and the price was pretty good as well! As much as I'd love to buy a new top of the range camera, for my astronomical needs it's not the best return on investment as the 20D upgrade.

Anyway, I set up in the back garden with just my trusty f/1.8 Canon 50mm lens mounted on a Vixen mount for tracking. I had just finished building a long exposure cable (parallel port to cable release) so my laptop can queue up a sequence of shots whilst I go indoors and keep warm, so I used that to capture 10 60 second frames of the Double Cluster in Perseus - spurred on after hearing a talk at the Bristol Astronomical Society about it. The quarter moon was not far away and raised the background level tremendously, but I could still cut through enough of it to capture the cluster.



I'm rather pleased with the results to be honest. Considering I was pushing it with ISO1600, the noise was relatively low - a lot lower than I would have got on the 10D at any rate.

What I didn't realise was that I'd actually captured the faintest of glimpses of IC 1805 and 1848 - slightly better known as the Heart and Soul nebula. It's really faint, and you can only just see it if your monitor is calibrated correctly, but it is definitely there! Here's an annotated version to show it better along with a few other surprise visitors in the frame! - Note: It appears that Blogger has re-compressed the JPG's after uploading, and the Heart and Soul nebulae are even harder to spot than before :(



The 20D (and other EOS Canon models) all have the intrinsic problem of the internal IR filter cut off curve being somewhat broad, causing hydrogen alpha to be clipped by well over 50% I believe. One day I may pluck up the guts to modify it and replace with a more forgiving IR filter, but that's for another day! Until then, these lovely hydrogen alpha clouds are going to remain a little elusive to me!

Some people say that imaging is not "true" astronomy, but I learn more about the night sky from my own adventures in astrophotography that I do from any book or magazine. The realisation of just how faint some things are and how big or small they are from a picture give much more understanding and weight than just a hard magnitude or arcsecond number - or at least it does for me! I like to think of it as Practical Learning :) I certainly would not have though to go looking for the other Stock clusters if it wasn't for capturing then whilst imaging something completly different .... nothing beats the knowledge that you have captured photons from far away places, travelling for more years than one cares to imagine, and have preserved their legacy for ever more in a photograph hanging on your wall.