Objects: M81, M82, and NGC3077 Galaxies
Date: 3/14/04
Location: Casa Dockery - Las Cruces, NM (my backyard)
Telescope: TeleVue 85mm refractor (f/5.6) piggyback on a Meade 10" LX200
Guiding: 208XT
Camera: Canon Digital Rebel (300D) with an IDAS LPS filter @ Prime Focus
Exposure: 16x5min, 6x5min darks, ISO-800, 55-60 degrees
Processing: Raw images converted to 16bit TIFF, darkframe calibration, alignment and stacking (adaptive addition) performed in ImagesPlus. There was a fine pattern of noise evident as diagonal bands that I could not track down and struggled to remove. I finally used one of Mike Unsold's IP background masking techniques and image subtraction to remove most of it and some residual background glow. SGBNR was then used for additional smoothing. Levels and curves (final color balance) were adjusted in Photoshop.
Comments: This beautiful trio of galaxies lie in the constellation of Ursa Major and are part of a nearby (11 million light-years distant) galaxy group called the M81 group. A few tens of millions of years ago, a close encounter occurred between the galaxies M81 and M82. During this event, the larger M81 dramatically deformed M82 by gravitational interaction. This encounter also left traces in the spiral pattern of M81. Their centers are still only separated by a linear distance of about 150,000 light years. NGC 3077 is a smaller member of the M81 group, located 45' ESE of M81. It looks like an elliptical galaxy but is peculiar because it shows wispy edges and scattered dust clouds similar to M82. This is probably a result of gravitational interaction with its larger neighbors. (Information courtesy of the SEDS website.)
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© Dave Dockery 2004
