Update on Arp 1 (NGC2857)  and Neighboring Galaxies in Ursa Major

Dick Steinberg

 February 29, 2012

We now have 310 minutes exposure available on Arp 1 (NGC2857) and its neighbors.

The tidal tails of the galaxies NGC2856 and NGC2854 are now well delineated as shown in our stretched and inverted image: http://www.physics.drexel.edu/~steinberg/astro2/ngc%20galaxies/ngc2857-L310-neg.jpg . Comparison with SDSS-III Digital Sky Survey data shows that this 5.2-hour exposure reaches slightly beyond magnitude 22.

What we earlier thought were "clouds" now appear to be very faint nebular wisps, probably of the type known as "galactic cirrus", thin clouds of gas distributed through the Milky Way, but most easily seen at high galactic latitude, where the best contrast is available.  See R. Jay Gabany's article http://www.cosmotography.com/images/galactic_cirrus.html for a discussion.

These wisps are not readily visible in the Mt Palomar DSS2 All Sky Survey, nor in the SDSS-III Sloan Digital Sky Survey data set. It would be interesting to see whether our observation of galactic cirrus near NGC2857 is substantiated by other images.

-------------------------------------------------------------------
Starizona Hyperion 317mm f/8 corrected Cassegrain - Paramount ME - Apogee U16M - 4096x4096 nine-micron pixels binned 2x2 - 0.73 arc-sec/unbinned pixel - field-of-view 50 arc-min square - image acquisition and processing with MaxIm DL 5.14 - calibration (dusk-flat/dark/bias) - system automation: CCD Commander 1.6.67 - piggy-back guider Takahashi FSQ106 + Orion StarShoot Pro V1 camera - 5-minute subexposures - Blue Mountain Vista Observatory.

Astrophoto webpage:
http://www.physics.drexel.edu/~steinberg/Astro Welcome.html