Thursday, 1 September 2016

3 Sessions - 1 Post

3 Sessions - 1 Post.

Good evening fellow amateur astronomers.  We've had a run of clear evenings recently in Herefordshire, and while we still have to wait for a while before the sky is dark enough to start observing, I have managed to get a few sessions in.  I've been out twice imaging and once observing, all from the back garden.  So, to kick off part one of this posting.

Session 1 - 26th August 2016

My first session recently was an imaging one.  I am still getting used to the AVX mount, so any opportunity I can get to use it, I set it up and try out some new things.  Rather than whizzing around the sky in all directions, I'm targeting objects which aren't too dim and can be seen with ease from the mount position in the back garden.  I had two in mind for this session.  M51 The Whirlpool Galaxy, and open cluster M103.
Seeing conditions weren't brilliant it must be said with alot of moisture in the atmosphere.  This meant that the stars were twinkling a great deal, and some of the dimmer stars that I can usually see were not visible to the naked eye.
The first set of data I collected was for the M51, Thie Whirlpool Galaxy.  I collected the following exposures:
20 x 60 sec iso 400 light frames.
3 x 60 sec iso 400 with cap on dark frames.
3 x 1/14000 sec iso 400 with cap on bias frames.
All the frames were stacked in Deep Sky Stacker and processed further in GIMP2.
This is the final result of the first collection of data.
M51 The Whirlpool Galaxy
In the final image, although the galaxy is visible quite clearly, when you zoom into the image, there is evidence of star trailing going on.  It was evident that something was amiss with the positioning of my mount.  This could be down to poor polar alignment, poor balancing of the scope and counterweights, or even the mount being uneven on the ground.  Nevertheless, for a first effort, it was acceptable for me.
The second set of data I collected was of M103, an open cluster in Cassiopeia.  Knowing what the conditions were like in terms of seeing, I wasn't sure how well the second set of data was gong to turn out.  For this image, I collected the following exposures:
10 x 30 sec iso 800 light frames.
10 x 30 sec iso 400 light frames.
3 x 30 sec iso 400 dark frames.
3 x 1/14000 sec iso 400 bias frames.
Again, the frames were stacked and processed giving the following result.
M103 in Cassiopeia

The bright star in the top left of the image is Ruchbah.  The size and fuzziness of it are a result of the atmosphere, not any degree of post processing.  The cluster can be see clearly though.  Again, zooming in on the raw frames after I had packed away showed plenty of trailing going on.

Session 2 - 29th August 2016

I was trying to cram these sessions in whilst getting up early for work the next day.  For this session, I was already tired, but wanted to do something.  Setting up the SBT is much quicker than setting up the AVX mount and imaging kit.  So, it was time for some observing.
I turned straight to my notebook and to the page on which I have a list of Messier objects I have still to see.  I chose two targets to go for that evening.
First up, in the constellation of Ophiuchus on the South Western horizon.  Before the constellation sunk below next doors fence line, I waned to find M14, which is a globular cluster.  It took quite a while to find it, even though it it supposedly rather bright at magnitude 7.6.  Nevertheless, using the 32mm panaview eyepiece I could make out a rather disappointing, although distinct grey smudge.  I was unable to resolve any individual stars though.
I had several attempts at some other targets, but the constellation was dropping lower and lower, so I decided to move onto the second new target of the evening, M76.  This is a planetary nebula in the constellation of Andromeda.  This nebula is also know as the Little Dumbbell nebula,  this was another very tricky target to pick out at first.  Sticking with the 32mm eyepiece, I scoured the area of the constellation where the nebula should be found and eventually honed in on it.  As the name suggests, it looks like a smaller version of the Dumbbell Nebula.  However, it's also dimmer with less colour too.  The SBT proved its worth once again though, gathering enough photons to allow me to see it.  I also attached the UHC filter which allowed the nebula to stick out a little more against the darkened background of the rest of space.  Not amazing to look at, but really pleasing to have found such a small and tricky object.

Session 3 - 30th August 2016

The final session of this little run, and I was greeted by the smell of burning plastic.  Not from any of my equipment I must add, but from the chavs 'over there' who decided that burning their rubbish was the right thing to do instead of leaving it for the binmen.  I digress.  Fortunatly, there wasn't much wind around, but what was around carried the smoke along the street instead of straight towards us, So, we missed the worst of it.
I wanted to go back and revisit the Whirlpool Galaxy again, determined that I could get a better result with better data.  Armed with a plan that looked like this, I started collecting data,
30 x 120 sec iso 400 light frames.
5 x 120 sec iso 400 dark frames.
5 x 1/14000 sec iso 400 bias frames.
Once everything had been collected, I did notice that some of the frames showed evidence of significant trailing, though some frames were near perfect.  I noted that perhaps 2 minutes of unguided exposure was perhaps a little too much to expect of the current set up.  This time however, I had taken much greater care preparing the mount and its alignment before I started collecting the data.  Post stacking and processing, the final image I feel was better than my first attempt.
M51 - The Whirlpool Galaxy
Sessions over, and what have I learnt?
  • 2 minute exposures are perhaps a little too long.
  • It really is worth taking the time to get the mount level and aligned correctly first time.
  • Greater different seems to be achieved by changing the iso settings that exposure time.
  • Sometimes, hours of post processing isn't always required.  The last image was produced in 30 minutes after the stacking process!
Notes for the future...
  • Investigate the use of VNC viewer to monitor the imaging run remotely from another computer.
  • Following a quick test shot of M81 and M82, this should be my next target.  They can both be captured in the same field of view and are both well positioned at this time of year.
Until next time, clear skies!

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