Great image, Paul!
Looks like a Hubble.
Christopher
Paul LeFevre wrote:
> Saturday night was very clear and dry down here near San Diego, but
> quite windy...
> I gave up trying to image at long focal lengths because of the wind,
> and instead started a wide-field image appropriate to Galaxy season.
>
> The image is of the portion of Markarian's Chain in Virgo, just poking
> into Coma a bit (with NGC 4473).
> I used my little Takahashi FS60C with a focal reducer for a 264mm
> focal length, a StarlightXpress HX916 camera, and 38 minutes of
> exposure unfiltered (I shot 60 minutes, but had to throw away a few
> 'cause of windblown trailed stars!), piggybacked on a C8 SCT, all
> carried on an AP900GTO mount unguided.
>
> (the images are 1300x1030 in size, and about 175k)
> http://www.lefevre.darkhorizons.org/ccdimaging/mkchn1.jpg straight image
> http://www.lefevre.darkhorizons.org/ccdimaging/mkchn1lb.jpg labeled
> version
> (North is down in the images)
>
> I'm amazed at how deep the image goes for just 38 minutes exposure.
> The faintest galaxies I can easily pick out are mag 16.4, and the
> faintest star I can positively identify is mag 21.3. If I hadn't been
> shooting into my southern light-pollution gradient from my backyard,
> and had to throw away 22 minutes, it would probably be much deeper.
> It's quite fun to shoot an image like this, then track down all the
> visible objects. Incidentally, in making the labelled version, I had
> to check multiple references because of some conflicting positions --
> in the process, I verified that the Coma/Virgo cluster charts in the
> Spring "Night Sky Observer's Guide" (specifically page 94, Volume 2)
> have a number of mis-named NGC and IC galaxies. The labels on the
> image are as correct as I can be sure of, verified through The Sky and
> SkyMap Pro along with some Palomar Sky Survey images from the web.
> The NSOG were generated with a version of MegaStar (it doesn't say
> which one), which leads me to believe that MegaStar must also have
> some mis-named galaxies in the region.
>
> I'm going to make the image negative (makes it easier to discern
> really faint stuff) and try to chase down some of the really faint
> galaxies in the image. I'll post up that version later if anyone's
> interested.
>
> Paul
>
