Hunting the Phantom Galaxy

As I saw the forecast for last night was for clear skies, I began thinking about an astrophotography target. My first criterion is almost always favorable placement of the object in my sky, which generally means it should be in the east or southeast. I have light pollution to my north and west, so I avoid those parts of the sky. I usually want something I can image all night if possible. So to choose targets I use my Astroplanner observing list (which began as the list of objects from Ruben Kier's The 100 Best Targets for Astrophotography (Springer: New York, 2009)) but which has expanded from there as I've added objects I've seen others image (mostly on Astrobin.com). I sort the list by time of meridian transit, then look for things I haven't yet imaged or prior targets I think I can improve on. I then use Astroplanner to check the field of view with the combination of telescope, optical aids, and imaging chip at my disposal, with the goal of making sure I can frame things properly.

Via this process, last night I decided to image M74, the "Phantom Galaxy." M74 is in the dim constellation of Pisces, but is not far from some brighter, easily recognized stars in Aries. This galaxy has fairly low surface brightness, which probably accounts for its mysterious-sounding nickname; it is relatively difficult to find, see, or image. It is also a beautiful, perhaps prototypical example of a "grand design" spiral galaxy, with two spiral arms emerging from a nucleus with two bright concentrations of stars. I've imaged M74 before (the last time 2 years ago), but the results were fairly noisy so I thought I could probably improve on them. Also, M74 is the right size to frame pretty nicely at 800 mm focal length with my AT8IN scope.

So I hauled all my gear out and got set up. At first I had a hard time even seeing Polaris in my polar scope; my 20-month-old grandson loves to twiddle any knobs he can reach, including the elevation knobs on my CG-5 telescope mount, so he had "adjusted" things a bit for me at the start. After getting polar aligned once via the polar scope, I had to stop and move the mount and redo the alignment once I realized M74 would be behind a tree an inordinate amount of time from the place I had set up the mount initially. (It turned out that even after moving the mount I still got M74 behind the tree--oh well!) I synched my scope using the PicGoto on β Ari and did the goto, only to see...nothing! Checking the position of the scope I discovered the aforementioned occultation by the tree. So I waited until M74 got high enough to clear the leaves, and to my delight it was right in the center of my field of view so I started the imaging session. After about an hour and a half, something went wrong (I suspect a USB cable came loose) and Windows 7 crashed, but I got it restarted and continued imaging. M74 reached my local meridian last night about 3:30 AM (more useful information from Astroplanner), and I expected the telescope mount to bump shortly after that time, but decided I'd go to bed and just let that happen. Happily, when I got up to shut everything down this morning I discovered the end of the scope had cleared the tripod, so there was no bump and imaging continued until dawn.

The stacked image is not as sharp as I would like, but considering that I was battling wind gusts and all my usual cheap gear issues, it turned out OK and certainly a lot better than the 2-years-ago image.

Some gusty wind early (probably canyon breeze). Had to wait for Brown's tree to get out of the way before I could start. USB connections dropped and Windows crashed after the first hour and a half, but restarted and went to bed, expecting the mount to bump around 3:30 AM. However, it missed and imaging continued all the way until dawn. I still got quite a lot of differential flexure in this set of subs. This object must get the name “Phantom Galaxy” because its surface brightness is so low, but it was easy to find with the PicGoto from β Ari; the goto was dead center.

Date: 23 Sep 2014

Subject: M74, “Phantom Galaxy”

Scope: AT8IN

Filter: Baader Fringe Killer

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

Guiding: 9x50 Finder/Guider + DSI Ic + PHD 2.3.1 (Win 7 ASCOM)

Camera: DSI IIc chiller at 2.50 A, 15-9 °C

Acquisition: Nebulosity 3.2.1, no dither

Exposure: 69x300 s

Stacking: Neb 3, bad pixel map, bias included, no flats, normalize first, trans+rot align, 1.5 SD stack.

Processing: StarTools 1.3.5.289 Crop; Wipe:Color & brightness 75%; AutoDev with ROI; HDR:Optimize; Color:Scientific, 300%; Life:Moderate; Deconvolute auto mask 2.3 pix; Track Grain size 5.2 pix; Magic:Shrink 1 pix. Photoshop CC 2014 + Carboni Astronomy Tools Healing brush; Deep space noise reduction; Space noise reduction; Layer masked levels; Increase star color; Astro Frame.