...continued from page 1 of Astroimaging Log

Our targets are objects in the Milky Way and the Local Group of galaxies and other objects within a radius of about 40 million ly. The Milky Way is roughly 100,000 light years in diameter and it has a spherical halo of about the same diameter, so anything within the distance of 100,000 ly is in the galaxy. Most of the distinct stars are in the Milky Way.

Outside the Milky Way, Andromeda Galaxy (53 and elsewhere) is a good point of reference at 2.54 million ly distant, still within the Local Group. Another is Bode's Galaxy (12, 58), which is ~11.8 million ly distant and belongs to a neighboring group. Bode's is near enough to have a slightly negative redshift, indicating that it is moving toward us rather than away from us.

All images up to number 51 were taken with small scope (80 mm diameter, 560 mm focal length) and 15 megapixel digital single lens reflex (DSLR) camera. With it we could reach out as far as 37 million ly to see a large object such as M63, the Sunflower galaxy (27). In September, 2013, we acquired a 110 mm refractor. Though it still has a short focal length (770 mm), it gathers 80 percent more light, so it should enable imaging deeper and dimmer objects, at least out to 50 mly and apparent magnitude 10 or 11.

So far we have managed to keep our cumulative expenses down around $4000, about what one might pay for an used economy car with 90,000 miles on it. This is a modest sum in a hobby where it would be no trouble at all to begin with a $20K down payment. Most of our statistics are from Wikipedia, because it is the easiest source to use. A dedicated astronomy database such as those of NASA or SIMBAD would be more reliable and precise.

Notes on deep sky objects and on imaging methods and problems accompany the images. Since our main interest in imaging is in learning more about deep sky objects, we process mainly to reveal object structures rather than to create the most aesthetic images. Up to October 28, 2013 we had used Photoshop on only three images (7, 52, and 53). In January, 2014 we acquired PixInsight, so a few of the recent images have been reprocessed. Image 58 of M81/82 was the first to use PixInsight for integration (stacking) as well as processing.