Decided to attempt the Coma Cluster for the first time, despite quite a lot of moonlight. These are the most distant objects I have ever attempted, 333 million light years away according to Wikipedia. Synched on Cor Caroli and the PicGoto put
NGC4874 close to dead center. There is a 3-star asterism that helps ensure you are looking in the right place. Tried a 600 s subframe and it was completely washed out, so cut back to 300 s (i.e. I may want to try this again when the sky is darker). Imaged up to the meridian, did the meridian flip, and resynched with Astrotortilla. Guiding was not great this session. CCD uncooled, about 14 °C. It is hard to distinguish background stars from galaxies in this image! Gradients (presumably mostly from the nearby Moon) were difficult to remove from this image.
In the B revision, stacked with Nebulosity 4’s 80/20%tile method, and some additional Curves stretching at the end in Photoshop CC 2014 with some layer masking to try to remove a bit more gradient. I think this one is a little better.
Date: 28 Apr 2015
Subject:
NGC4874 and many others, Coma Cluster
Scope: Astrotech AT8IN+Antares 0.5x focal reducer
Filter: Baader Fringe Killer
Mount: CG-5 (Synta motors, PicGoto Simplificado)
Guiding: 9x50 Finder/Guider + DSI Ic + PHD 2.5.0 (Win 7 ASCOM)
Camera: DSI IIc no cooling (about 15 °C)
Acquisition: Nebulosity 3.3.3, no dither
Exposure: 60x300 s
Stacking: Neb 3.3.3, bad pixel map, bias included, 33 flats, histogram match, deBayer & square. 40-60% stack.
Processing: StarTools 1.3.5.289 Crop; Wipe: 88%; Develop: 69.89%; HDR
ptimize; Color:Scientific 300%; Deconvolute 3.0 pix; Life:less=more; Track 4.5 pix, smoothness 81%. Photoshop CC 2014 + Carboni Astronomy Tools Deep space nr; Increase star color; Levels; Astroframe.
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