Instrument

12.5" RCOS @  ~f/9 (2880 mm fl) at 0.64 arcsec/pixel. Shown at 1.31 and 3.15 arcsec/pixel.

Mount

Paramount ME

Camera

SBIG STL-11000 w/ FW8 filter wheel, AstroDon Gen-2 Filters

Acquisition Data

3/23/2014 to 4/24/2014 Chino Valley, AZ... with CCDAutoPilot, CCD Commander & CCDSoft, AOL guided.

Exposure

Lum  600 min. (20 x 30 min. bin 1x1)

Lum  180 min. (12 x 15 min. bin 1x1)

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

Software & Processing Notes

• CCDSoft, CCDStack, PixInsight, Photoshop CS6 and Noel Carboni's actions.

• eXcalibrator v4.25 for (g:r) color balancing, using 55 stars from the SDSS-DR9 database.

• CCDBand-Aid to repair KAI-11000M vertical bars.

• CCDStack to calibrate, register, normalize, data reject, combine the sub exposures and create the RGB image.

• PixInsight processing includes gradient removal, initial non-linear stretching with HistogramTransformation and MaskedStretching and selective use of HDRMultiscaleTrans to enhance the detail in the center of the galaxy.

• PhotoShop for the LRGB combine & final touch-up.

• Noiseware 5, a PhotoShop plug-in.

Comment

North is to the right.

NGC 3521 is located in the constellation Leo. On the scale of cosmology, the galaxy is practically in our backyard at a distance of only 52 million light years. NGC 3521 is commonly known as the Bubble Galaxy. This is because of the galaxy's large shell, likely caused by a series of mergers with smaller satellite galaxies. Deep exposures reveal the tidal tail extending to the right. The shape of this tale could also prompt a common name of the Goldfish Galaxy.