Summer Triangle Widefield Imaging – First Attempt

At mentioned in my last post, I ended up with 263 frames of the Summer Triangle. I thought I’d have a go at processing one of these to see if I could get more detail out.

So here’s my starting image.

I hadn’t realised quite how bad my light pollution was until I saw this.
It’s a 30 second exposure, sunlight white balance at ISO400 taken on a Canon EOS400D with a Sigma zoom set at it’s widest 18mm focal length.
faintest stars you can see here are about magnitude 4.
I then tweaked it a bit in photoshop, adjusting levels to bring out fainter stars up to about magnitude 7. I removed the colour cast as best I could, although I think I went a bit too at as it’s quite blue now.

Now I know this is far from perfect. It’s a first attempt and I can see quite a few problems.
Stars aren’t quite in focus. I’d focused manually and it’s difficult to know in the dark through the camera eyepiece.
Next time I’ll lock the mirror up to prevent that causing a bit of shake.
Exposure is only 30 seconds but I don’t think I can do longer without the stars blurring with motion. I could, if I put the camera on the telescope’s mount. There is a piggy back mounting screw.
I think I need to really up the ISO, perhaps up to 1600 to captured the fainter stars. I’d held back because I thought I’d end up overexposed with all the light pollution. I think though, that I can fix that with levels in processing.
I need to investigate stacking multiple images too, as that seems to be how many people do it.

Finally I annotated the final image in Skitch on the iPad to identify the various constellations and stars. That was an fun and educational thing to do. I hadn’t noticed the small constellation Delphinus creeping in just below Cygnus for instance, and on zooming in and around the shot, I also noticed Collinder 399, Brocchi’s Cluster aka the Coathanger sneaking in.

Observations – Thursday 9 August 2012

Location: Home, on the lawn, rather than up by house. It’s closer to the street light but shaded by a laburnum tree.
Weather: A sunny clear day leading to a mostly clear sky. Some thin high cloud. Seeing is poor.
Highlights: M57 Ring Nebula, M27 Dumbell Nebula, M71 globular cluster, Collinder 399- Brocchi’s Cluster – the Coathanger.

21:45 Set up on the lawn this evening. Despite being closer to a street light it’s shaded soemwhat by a tree The positon also gave me visibility of the sky to the north above the house so I could do a trial run for meteor watching with a camera. It’s the Perseid meteor shower around now with the peak expected this weekend. There was an article in the August edition of Sky at Night magazine on photographing meteors which I want to try. I’ll outline the gist of the procedure here.

• I put an 18 to something zoom on it’s widest setting on the SLR and set it up on a tripod pointing up at about 60deg facing north-ish. The Perseids should be radiant on the constellation of Perseus which was approximately in that direction.
• I put the camera, a Canon EOS400D into shutter priority (Tv) mode.
• I focussed manually to infinity and took a test shot of a few seconds to check.
• The article in Sky at Night magazine says to up your ISO to 1600 or so but I found that this caused the sky to be too bright on long exposures so I stuck with ISO 200. I can always change this later if I find myself with darker skies.
• I set the exposure time to 30 seconds and the shooting mode to continuous.
• I then fired the camera with a locking remote shutter and left it running for as long as batteries and memory cards (I have spares of both) will allow. Every 30 seconds it would then take another shot.
• The idea is to leave this running like that throughout the observing session and whilst there will be a lot of frames of just sky there should be some with meteor streaks across them. Reviewing the shots on the camera afterwards, there weren’t any last night but I am a bit early. The point was to test the procedure anyway.

So while the camera was clicking away, I got on with some observing.

22:05 Started with M57, the Ring Nebula, in Lyra tonight. It was just a smudge in the 17mm Plossl eyepiece with a light pollution filter. The ring was visible in the new 6mm ultra-wide eyepiece when I was using averted vision.

22:15 Started to starhop from Albireo to M27, the Dumbbell Nebula in Vulpecula. Seeing is poor tonight. I was there within minutes this time and got there by memory too. I observed it through 17mm with light pollution filter. My awareness is increasing. I wasn’t confident yesterday evening but it was definitely there tonight. It is indistinct though, guess that’s why it’s a nebula. It’s a strange sensation – more being aware of something than actually seeing it. I found Let it drift across the eyepiece a few times I got a better view. It’s also larger than I expected.

22:44 My next target was M71, a Globular Cluster in Sagitta. I tried to get there yesterday from Altair in Aquilla, but tried a different path tonight, just a short hop down from M27. Again, I’ll attempt to share the starhop route I took, together with some screenshots from SkySafari3+. I recognise this isn’t the most obvious starting place but if you consider it the next step on a route then it’s a reasonable way to go. If you need to know how to get to M27 then take a look at yesterday’s post.

Starting with 14 Vul, which is close to M27, in the centre of the finderscope, I moved the scope down on the dec axis until 14 Vul was just about to disappear from the top of the view finder. Gamma Sagitta and Eta Sagitta were in view. (I need to work out how to do greek alphabet on here) Gamma Sagitta was my target to centre in the finderscope.

Next step was to find 9 Sagitta which is close to M71 and get that centred up

Time then to switch to the main telescope OTA which I had a 25mm eyepiece in. The following section is from the notes I took at the scope.

Have i found it? Can only see a few stars – probably clusered together. Certainly not a ball of them in a haze as is described. Losts of very faint stars in the background. Guess i’m in the band of the Milky Way here. Consulted some other stuff. Not looking like it from the black on white Messier sheets TBH. Think I’m lost actually.

So I went back up to M27 to try again. As a distraction the Dumbbell was quite distinct in 25mm (no LP filter) this time. In fact the Dumbbell was looking wonderful. Just goes to show magnification isn’t everything.

So I tried again. Got back down to 9 Sagitta. Those were just stars I was seeing. It needed to be more fuzzy…. So I started looking differently. I was definitely in the right place but M71 was just being elusive. Knowing what to look for and how to look for it is part of the challenge, I’m discovering.
Again from my notes.

23:20. Found it! So I was looking for a faint fuzzy all along. Just NE of 9 Sagitta. Line of 3 stars and then off to the side a round smudge, just like the drawing on pg 139 of Turn Left At Orion. The book says it’s quite dim. It’s very dim for me. I need to get out to a dark site to see these things better. It may or may not be a globular cluster apparently. So I need to look up and understand what a globular cluster is. So far my previous 2 Messiers were Planetary Nebula and I think I know what they are/were. Anyway 3/110 of the Messier objects.

23:32 Finished off with a visit to Collinder 399 – The Coathanger, or Brocchi’s Cluster. A nice asterism to end the evening on and one I hadn’t visited before. It was a short hop across Sagitta and Vulpecula. I found it easily. it just fits in the 25mm eyepiece’s FOV. 6 stars across base 4 for hook. All blueish stars apart from one orange according to SkySafari. Not seeing the orange star though. Sky Safari tells me it’s 4 Vul, a double star at the top of the hook (bottom really -it’s an inverted coathanger) Can’t split it either even in the 6mm though, the seeing is too poor.

A very sucessful couple of hours I think. Got the hang of starhopping and am learning to see what is almost perceptible. Revisiting the M27 Dumbbell Nebula and seeing more this time around tells me that there’s plenty to appreciate in going back again to build on previous viewings.