Friday, 10 January 2020

SharpCap and the Bubble

SharpCap and the Bubble

Happy New Year!  Other than a couple of quick test and alignment opportunities since setting up the observatory, I managed to get in my first full imaging session of 2020.  I wasn't planning on a full blown session, but the weather played good, so off came the obsy roof, and on with the imaging!
The Bubble Nebula is high in the sky this time of year, making a good and slightly challenging target to image.  
This is my second attempt at the Bubble Nebula in recent years.  Now I have the observatory, I have so much more time to play with SharpCap and learn more about some of its functionality.  Time which otherwise would be spent hauling kit outside and setting up.  I’ve used SharpCap ever since I got my Altair Hypercam, and every time I use it for imaging, I learn something new!
This time out, I decided to try out the Smart Histogram’s Brain function, setting maximum exposure times of 5 minutes, and a total exposure of 3 hours.  SharpCap then started to determine the best combination of settings for my location and conditions.  I will certainly be doing this every time I get ready for an imaging run from now on.  It takes all the pain out of the guesswork!

The Smart Histogram Brain function analyses your sky conditions, takes into consideration how much time you want to spend on an imaging run, and then gives you all the optimum settings to use for exposure, to gain, to black level etc.  Very easy!
This was also the first time I used plate solving.  Following the instructions from the SharpCap website, and checking out some posts on the SharpCap forum, I installed AstroTortilla and got it working with SharpCap.  There's something reassuring about now being able to image a target, knowing that it will be central to the frame, and not having to guess if I have framed the target, or if I am indeed miles off!  Guiding was run by PHD2, and to be honest, it behaved brilliantly!  With good polar alignment (using the PA function in SharpCap) and the ability to leave everything set up in between sessions, PHD2 just seems to work really reliably.

My PHD2 graph during the imaging run.
After capturing all the lights and darks, the second thing I used in SharpCap was the Logarithmic Histogram, to help achieve a good exposure for my master flat frames. 
So, here’s the tech specs:
Altair Hypercam 183c (v1) with AA Quadband filter
Altair Starwave 80 ED-R
SkyWatcher EQ6-R Pro mount
Guiding with PHD2
Captured with SharpCap Pro
Processed in PixInsight
34 frames of 300 second exposures (2 frames were trashed because of focus and satellites).
1232 Analogue Gain
120 Auto Exp Target
24 Black Level

I had to drop this frame because of the satellite trails running either side of the main part of the nebula.  One other frame was also dropped because it was wildly out of focus, possibly to some high level cloud running through the sky that evening.
Finally, after running all the data through my PixInsight routines for calibrating, stacking and processing, I have managed to produce the image below.  During the processing stages, it was very evident that there was much less noise to start off with.  I can only assume that as I was using the SharpCap suggested optimal settings during the data capture, it made a huge difference to the end result.  See what you think.


Clear skies everyone, and thanks for reading!

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