Bubble nebula - NGC7635, Winter 2011-12

Setup: AstroTech 8" f/8 RC telescope , DF-2 focusser, AO8 guider with MOAG and remote guide head, CFW8, ST10XE (0.86"/pixel), Takahashi EM-200 mount (image)

Acquisition: guiding at 9Hz, 33 hours total exposure time through narrowband H-alpha, SII, OIII filters and broadband R,G,B filters

This is my first serious imaging attempt with the new 8" RC scope. I needed to learn basic use of this imaging setup - setting up, calibrating, navigating, etc. I had not yet tweaked the collimation so it's like it came out of the box. Not perfect, but still impressively good considering the journey from China to USA to Denmark. Inspired by an APOD in October 2011 I chose this object since it was high in the night sky during fall and winter.

Imaging was done from a light polluted suburb of Copenhagen sometimes with moon light interfering as well. The integration time for the narrowband subexposures was 1800sec and the stellar FWHM ranged from 2.7-3.3 arcsec. I am very satisfied with the setup - mechanical stability was excellent, not once did I loose tracking and focus position never changed during a run. I attribute the latter to the RC carbon tube and the fact that I replaced the Crayford focusser with a sturdy metal tube - my only focussing capability comes from the DF-2.

I spent one and a half month on image calibration, filtering and processing. It took me so long because I wanted to learn new tricks in Photoshop and because I just can't stop optimizing and exploring different paths. The final image is a Hubble pallette narrowband image with RGB data for the stars. The brightest portions of nebula have been sharpened with Lucy-Richardson deconvolution (example). A synthetic luminance layer is constructed as the sum of all narrowband images. Click here for an outline of my processing steps (more notes here). Note how the original batch of images quickly fragments into parallel tracks and later on start to merge into a single image which finally undergoes a sequence of steps. Click here for an early version of this image with minimal processing beyond basic calibration.

Here's my main page where you can see more of the pictures I have taken so far.

Comments greatly appreciated! (mikael@leif.org)