Tracking and Stacking - part 2

In the previous entry it was mentioned that there is software that allows us to combine a series of images into one image to enhance the dimmer features of a sky object. There are some challenges to this process, however. The software has to see a certain number of stars in each image in order to align them precisely. In effect, the software uses stars as registration marks much as an old fashioned printer would use fine criss-cross lines to align printing plates in a multi-color process. The software that we have likes to use at least 10 or so stars in order to correctly align each image. Unfortunately, many interesting objects out there are not particularly near any sufficiently bright stars. This makes it impossible to stack certain galaxies and nebulae. The narrow field of view of our long focal length Cassegrain telescope often excludes what few brightish stars are nearby. Nevertheless, we get some results.

M64

The lack of nearby stars made this galaxy in Coma Berenices a challenge to stack. The software was only identifying 6 stars and that was just enough to make it work. This image is a stack of 15 images of 20.22 seconds each for a total of 303 seconds.

M5

This globular cluster in Serpens was easy to stack. Lots of stars for the software to detect. This image is a composite of 20 frames with an exposure of 15.22 seconds each for a total of 304 seconds.