A New Target and an Old Friend

24 Mar 2014.  I took advantage of the nice conjunction between beautifully clear skies and a Saturday when I could stay up late this past weekend to image a new, difficult target and to return to my all-time favorite astroimaging subject.  

I found the Medusa Nebula from Beta Canis Minoris using the PicGoto.  This is one of the dimmest targets I have ever attempted; in fact, it is one of those you are not supposed to try with a one-shot color camera from the suburbs, so I was happy to get anything.  I think images with a lot of detail in the nebula would need to be LRGB or narrowband.  Conditions were excellent: cold, clear, and little wind (some came up later in the session).  Guiding performance was very good, but not so great that I didn’t apply some corrections in post-processing (StarTools’ Repair:Warp tool works well).  The technique of using HDR twice in StarTools seems to really help in bringing up faint stuff. 

Conditions were exceptionally clear, so even though I was sleepy I couldn't pass up the chance to image my favorite target, M51 (the Whirlpool Galaxy), once again (and this time without the filter; see my last post to see what a big difference the filter makes)).  There was a bit of gusty wind so I threw out about 1/3 to 1/2 of my subframes.  I imaged up to the meridian, then used the PicGoto again to reacquire the target after the meridian flip.  This is so much easier than doing it "by hand!"  After the meridian flip, I went to bed and let the camera run until daylight.  I think this is my best image of M51 so far (I’m including one of my earliest images for comparison; it’s fun to see how far I have come).  I like the way the tidal streams show up in the new image.  I’d like to understand better the physics of galactic collisions like the one happening in this picture; as the tidal streams show, the collision has flung stars all over.  So here's what I can do with M51 with my current skill set:

Date: 22 Mar 2014

Subject: M51, Whirlpool Galaxy

Scope: AT8IN + HPS Coma Corrector

Filter: None

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

Guiding: 9x50 Finder/Guider + DSI Ic + PHD 2.2.2 (Win ASCOM)

Camera: DSI IIc (no chiller, T = 3 °C)

Acquisition: Nebulosity 3.2.0, no dither

Exposure: 23x480 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 80%; Develop 87.49%; Contrast; HDR:optimize; Sharpen; Deconvolute 3.0; Color:Scientific 301%; Life:Isolate; HDR:Equalize; Track:Read Noise 7.6%; Magic:shrink 1 pix. CS6 Astronomy Tools increase star color; space noise reduction; AstroFrame

And here's what it was like 3 years ago (and I remember I was thrilled to get this picture!):

One of my earliest (11 Feb 2011) M51 images.  Stack of 33 JPEGs (Keith’s Image Stacker; DSS would not stack these).  Afocal, PowerShot A560 at f/2.6 on camera, 800 ISO, 32 s exposures, U19 eyepiece (system f/2.4).  Processing with GimpShop Curves & Levels.  The spiral arm structure is visible all the way out to the interacting NGC 5195 satellite.