Monday, 11 February 2019

Pixinsight Progress, The Flaming Star and Orion

The Flaming Star Nebula - IC 405

I've had somewhat of a hiatus from astronomy and astrophotography for a while.  So, when a weekend at the start of February presented itself with good weather (a rarity in these parts this Winter) and a new moon, I was determined to get outside with all the kit.  Setting up out the back garden highlighted how rusty I was, when it come to getting everything right.  The slick operation that had been refined over the many months previous had turned into one of head scratching and re-tracing steps to get things all done and dusted.  Eventually, I had everything ready (ish) and so I threw myself into my first night of imaging for quite a while.
I wanted to try for a new target, something that I had not imaged before.  Not knowing if it was even possible to pick up this nebula, I selected IC 405, The Flaming Star Nebula.  I had seen many images of this by people using mono CCD cameras, but nothing from the Hypercam range of OSC cameras.  I decided to give it a crack, and collected 30 light frames, followed by 29 dark frames.  The next morning, I collected 30 flat frames.
IC 405 is in the constellation of Auriga, and is around 1500 light year away.  This image is made up of 30 x 3 minute exposures, 90 minutes overall.
As a first attempt at the target, and the first time back in the astronomy seat for a while, I'm quite pleased with it.  It's a bit noisy, which is something I could sort out with better processing, and different camera settings, but overall, I'm happy.

The Orion Nebula - M45

That night, I decided to image a second target.  M45 is the 'go to' target for many imagers at this time of year.  After all, it's well positioned, bright, and colourful in OSC and DSLR cameras.  Surprisingly though, this is only the second time I had imaged this target with the Altair 183c Hypercam.
Because of it's brightness, I needed to be careful not to blow out the core of the image too much.  In a way, restricting the amount of data I was collecting.  It's very hard to do this, and the final image relies on some processing to bring out the detail in the central, brighter core of the nebula.
I was able to use the same dark and flat frames when creating this image, but this time, I only used 22 light frames.
The Orion Nebula is in the constellation of Orion.  On a clear evening with good quality skies, it is visible naked eye and is a mark of how much, or how little light pollution you have.  This image is made up of just over an hour of exposure time.

PixInsight and Progress with Calibrating

So to the crux of this post.  It was great to get out under the stars again.  To have everything set up, working away without too much hassle was a timely reminder to me of how much I had missed sitting outside in sub zero temperatures, getting annoyed with neighbours lights, and not being able to feel my fingers.  Good times!  But, the big development I made this time around, and the thing that I had learnt came at the calibration stage of processing.  Last September, I thought I made a huge break through in the calibration stages of my images.  In truth, I probably did, but could I repeat it?  No.  I refer to the thing that is common with the highly sensitive Hypercam 183c series, and that is the amp glow and sensor/star burst that appears in the right side frames.  Particularly in the dark and light frames.
A single dark frame, stretched in PixInsight shows up the anomaly.

Here's the theory if you're not familiar with the process.  The light frames capture all the detail from the target you are imaging.  But, they also contain lots of other anomalies.  These could be sensor anomalies as is the case with the Altair Hypercam, but also pixel noise etc.  Taking dark frames (exposures with the cap on) gives you a series of frames that contain nothing other than whatever is produced purely by the camera and the imaging train.  During the calibration process, in principle, you stack up all your dark frames to produce one single 'master dark' frame.  All the noise and anomalies in this master dark is then compared to each of the light frames.  The software (in this case PixInsight for me) looks at the master dark frame and subtracts whatever the anomalies are in there from your light frames.  Theoretically, you are then left with a much cleaner set of light frames which can then be further calibrated before finally being stacked to produce your single image, ready for processing.  Hope that makes sense.
In my case though, I couldn't get this to work reliably.  I would go through the whole calibration process, and still be left with a final image containing all the noise and anomalies which should of been removed.  Then, along come the eureka moment.
Over the last 18 months, I have been following the 'Astro Dude' YouTube channel, run by Mitch.  He has produced an excellent series of 12 tutorials for calibrating and processing data in PixInsight.  I was having a browse through the channel, and noticed a video that he produced around 6 months ago.  It was this video that held the hidden gem.  The awesome thing is that Mitch is also a Sharpcap Pro user, a Altair Hypercam user and a PixInsight user.  Rather conveniently, the exact set of tools that I use!  I set about watching the video, then watching it again making some notes.  And then finally again to make sure that there was nothing that I had missed.  I followed my notes, using the exact same settings as Mitch did in his video, and like magic, no sensor noise or no amp glow in my final image stack!  I was made up!  If you want to see this video, well, here it is...


I don't know about you, but seeing things in video, as someone else is doing them is all well and good.  But when it comes to doing it myself, I find it easier to have everything in notes with some screenshots etc.  So, I set about typing up my notes which I can now carry with me, and refer to whenever I need to.  I've made those notes available for download if you want them.  A huge thank you to Mitch for putting up this tutorial, and a massive plug for his YouTube Channel  Definitely subscribe to it, if only to pick out little gems in some of the videos.
So, that about wraps up this post.  Thanks for reading!

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