SILVER NEEDLE GALAXY

[dpaul]

Another good week last week (3 clear nights, no aeroplanes!!!!!!!!!!!!).

Attached is one of 4 objects imaged, here are the details:

30'' Dobsonian
Unguided Equatorial Platform
Horizon Mono Camera
3x3 binned frames, 5 sec capture each (high gain)
Frames captured:
  120 Luminance
  79 Red
  94 Green
  104 Blue
Overall capture = 33 minutes
All processing done with Pixinsight

Regards

David

[CraigG]

Nice David!

Curious about your decision to bin 3x3? Never tried that level before.

Glad the aeroplanes left you alone. I seem to be dealing with more sat trails here recently...Starlink onslaught maybe? I'm using Sigma Clipping stacking option in SharpCap to limit the damage. I'm still experimenting with the settings but it does help.

Best wishes,
Craig

[dpaul]

Hi Craig,

I've got a 2667mm focal length scope and also a Paracorr Coma corrector which adds another 15% so that's 3067mm. Its an F3.5 focal ratio so I can't use a focal reducer because of Coma. That means 2x2 gives considerable under-sampling so lots of pixels in bloated stars. They weren't too bad but 3x3 binning means less oversampling and exposures can be much shorter which is important for my unguided equatorial platform. I've even done 4x4 once with a narrow band image of a planetary nebula.
So in summary I can get away with larger binning without under-sampled/pixelated stars.
Regards
David

[CraigG]

Interesting! Thanks for the explanation David...you certainly have it dialed in for your setup.

Here's a recent composite of the Sombrero Galaxy taken with my Horizon OSC with some pretty heavy influence from the moon. One hour of 30sec subs with low gain, 1x1 binning, and guided. It was difficult to stretch the image too much given the sky glow but I had the best result when I reprocessed the stack in the RGB color synthesis routine in Nebulosity. Getting close to switching my rig over to the 70mm scope with the filter wheel as the galaxy season wanes.

Cheers!
Craig

[dpaul]

Hi Craig,

Well done!

I'm off outside now with narrow band filters and Horizon Mono to try ring nebula then crescent nebula hopefully.
I also have the OSC Horizon but needs to be 1x1 binning to maintain the colour filter array of the sensor. That means longer exposures for my unguided platform. I can just do 20 second frames!

David