page 24 Ha-LRGB NGC 4490

                       Astrophotography by Keith B. Quattrocchi

                                NGC 4490 (and NGC 4485)                 
                The "Cocoon Galaxy" in Canes Venatici
                H-alpha/LRGB Image


                                      Image Acquisition Information                      
                               Telescope:   16" RCOS Richey Chretien Telescope (ion milled at 6/9) 
                               Camera:       SBIG STL-6303 M
                               Guiding:       SBIG AOL,  Astrodon  MOAG AOG (SBIG 237 with FLR)
                               Filters:        Astrodon Ha, SII, OIII
                               Mount:        Software Bisque Paramount ME
                               Acquisition Programs:   The Sky,CCDAutopliot III, CCD Soft. 
                               Processing ProgramsCCDStack, Maxim DL, Photoshop
                               Date: May 31-June 11, 2008                              
                               Time: 18x20 min ( 6 hours) each for each of L, R, G, B and H-alpha:
                               Total of 24 hours of imaging time      .                           
                               Processing:  CCD Stack and PhotoShop CS/3
Image Infornmation:  NGC 4490, also called the "Cocoon Galaxy" is made up of two galaxies (the larger, NGC 4490 and the smaller, NGC 4485), with the smaller (upper left) intereacting with the larger galaxy.  The larger galaxy has lost it's spiral structure (assuming it was ever present) whereas the smaller one has faint spiral outlines.  These galaxies are about 46 million light years away.  A supernova was found in 2008 (the white star 3/4 of the way down the larger galaxy,  see the UCB Site  ).  While I was processing this image I noticed the star was NOT on other images I had seen and will admit my heart skipped a beat.  Then I ran a search and found it was first noticed in March of 2008.  At least I noticed  !! :)  
Additional Comments:  Image processing with CCDStack, producing an RGB.  The RGB and Luminance images were combined in Photoshop CS/3 (twice, first using soft light option with differently processed luminance images).   The H-alpha data ws pseudocolorized and combined (soft light) with the LRGB image.  Further data stretching, high pass filtering and background smoothing (Kodac Gem) performed with Adobe Photoshop CS/3.

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