Location of photoLos Alamitos, CA
Date/Time of photo8/27-28/08, 9/27-30/08
Equipment8" LX200R scope, G11 Mount, SX AO .2 sec exposures, IDAS LPR filter, Ha CS 10 nm filter, Oiii baader 8.5 nm filter, SX H9 Camera. Luminance 28x2 min, Ha and Oiii 17x5 min each
DescriptionGlobular cluster M 15 augmented with narrow band filters to enhance planetary nebula Pease 1 (red object lower right of core). Pease 1 was the first planetary nebula found in a globular cluster. It was initially noted to appear very bright on a photographic plate using a Pulkovo ultra-violet filter compared to neighboring stars (otherwise of about equal magnitude). Subsequent spectrographic study revealed green lines of oxygen characteristic of planetary nebulae as well as red lines of hydrogen.
A larger version is available here:
Here's a nice article on the topic by Leos Ondra: