NGC2403 (Caldwell 7) NGC2403 is a mixed spiral galaxy, 23.8’ by 12.8’ in size with a surface brightness of mag 7.3 located near the nose of the Great Bear, Muscida. NGC2403 is 14 million light-years away from Earth. It is a member of the Coma-Sculptor Cloud of galaxies. Historically, this was first discovered in 1788 by William Herschel. Another contribution to the science of astronomy is that NGC2403 is the first system beyond our local group where Cepheids (variables whose periodicity has been an important tool for measuring extragalactic distances) were identified. It was the large number of H II star-forming regions that captured my interest. I used Hydrogen-alpha to amplify these regions. North on this image is located to the right and somewhat down. Details: Began: Dec. 5th - Concluded: Dec. 19, 2006 Object: NGC2403 Location: Kimberton, PA Telescope: Tak BRC-250 Camera: SBIG ST-10XME & CFW-10 Filter Wheel Other Equip: Finger Lakes Instruments DF2 Focuser, Astrodon Filters, & MI-250 Software: Maxim DL version 4.56, FocusMax, MiraPro, CCDStack, & Photoshop CS2 Exposures: H-alpha, Lum, RGB 420:264:60:60:60 minutes Total: 14.4 hours Color combine ratios were based upon G2V calibration on the night of color capture. Special thanks to Stephen Roffo who provided invaluable assistance with the processing of this image! Chris Abissi 19 December 2006