NGC 4725, Ring Galaxy in Coma Berenices

After having fun with lunar/planetary imaging for a while, last night I returned to what I like best, deep sky imaging (maybe I like it best because deep sky is what my equipment works best for).  Conditions were reasonably good ahead of a storm (and it is cloudy now as I write this).  Because I had changed everything (principally the telescope, with the Telrad and guider) for imaging the eclipse last week, I had a terrible time getting the Telrad and guide scope lined up tonight; I never did get the guider where it needed to be, but just decided to go ahead.  I could not find the Coma Berenices stars in the Telrad, though I could see them (too dim tonight for my sky conditions and lack of patience with dark adaptation), so I used Cor Caroli instead as my starting point, and that worked fine.  Once again, the PicGoto came through beautifully.  I imaged up past the meridian, then manually did a meridian flip and reacquired the target from Cor Caroli with no problems.  I used 2 markers in Nebulosity to realign after the flip, and that seemed to work very well.  Unfortunately, my guiding after the flip left a lot to be desired.  Still, I think this is better than last year’s image.  Seeing the diffuse outer arms of NGC 4725, I wonder if there has been some tidal interaction with NGC 4712, the galaxy in the right of the image, but I don't know if these two are really close to each other or if this is one of those chance alignment optical illusions.

Date: 23 Apr 2014

Subject: NGC 4725, Ring Galaxy in Coma Berenices

Scope: AT8IN + HPS Coma Corrector

Filter: None

Mount: CG-5 (Synta motors+PicGoto Simplificado)

Guiding: 9x50 Finder/Guider + DSI Ic + PHD 2.2.1 (Win7 ASCOM VMWare)

Camera: DSI IIc (no chiller T = 6-8 °C)

Acquisition: Nebulosity 3.2.1, no dither

Exposure: 19x480 s

Stacking: Neb 3, bad pixel map, bias included, normalize first, trans+rot align, 1.5 SD stack.

Processing: StarTools 1.3.5.279 Crop; Wipe:Color & Brightness 77%; Rotate 180°; Develop 87.49%; HDR:Optimize; Contrast; Color:Scientific, Sat. 250%; Sharpen; Deconvolute: 2.0 pix; Life:Moderate; Track, RNC 48.28%; Magic:Shrink 1.  CS6+Astronomy Tools deep space noise reduction; less crunchy more fuzzy; increase star color; Gaussian blurred layer mask to enhance outer arms; AstroFrame.