Instrument

12.5" RCOS @  ~f/9 (2880 mm fl) 0.64 arcsec / pixel.  The Zoomify image scale is 1.28 to 3.42 arcsec / pixel.

Mount

Paramount ME

Camera

SBIG STL-11000 w/ internal filter wheel, AstroDon Gen I Filters

Acquisition Data

10/9/2010 to 10/29/2010 Chino Valley, AZ... with CCDAutoPilot3 & CCDSoft.  AOL guided

Exposure

Lum (no filter) 180 min (12 x 15 min, bin 1x1)

RGB               360 min ( 8 x 15 min each, bin 2x2)

Software

• CCDSoft, CCDStack, Photoshop CS w/ the Fits Liberator plugin, Noel Carboni's actions and Russell Croman's GradientXTerminator.

• eXcalibrator for (b-v), (v-r) color calibration, using 18 stars from the NOMAD1 database. 

• PixFix32 (pre-beta) to repair column defects.

• CCDStack to calibrate, register, normalize, data reject, combine the sub exposures and LRGB color.

• PhotoShop for non-linear stretching, LLRGB combine.

NGC 7788 and 7790 are two small open clusters in the constellation Cassiopeia, at distances of about 8,000 and 10,000 light-years respectively. NGC 7790 is at the top center and NGC 7788 is to the lower right. The beautiful bright copper colored star, to the left center, at magnitude 6.63 is SAO 20954.

NGC 7790 is astronomically important because it contains three Cepheid variable stars. These three Cepheids are useful for determining a zero point distance for this special type of star. Cepheid variables are used to determine galactic distances.