Tonight, receeding Comet Lovejoy made a close conjunction with the 11th magnitude Sc spiral NGC 6015. This sounded like a good photo opportunity, and I and Chris Angelos converged at the observatory to use the ST2000XCM on the 8" f/4 LXD75 on the GM8 mount to get a series of photographs. The comet is still moving rapidly and I have recently learned of a technique for getting un-trailed stacked images showing both the full stack of comet images and the full stack of star images. Skies were clear, but damp after dark. We had some trouble, since the comet was 70 degrees declination and so the RA motion was much smaller than the Dec motion. There may be a way for the GM8 to track accurately in this situation, but I hadn't looked carefully into it as this was a first - shooting this far north. After much effort, I got a calibration which looked fairly reasonable. However, tracking was still pretty poor, and several images were lost when the mount completely lost track of the guide star. Many others were ruined by wild oscillations which will require a lot of photoshop'ing to remove the errors. For now, I'm posting one of the few single 3 minute self-guided photographs which tracked reasonably well. A final image should be significantly better, but it'll take a lot of work and it won't happen any time soon.
10:29pm PDT (5:29UT May 18) Comet Lovejoy (left) has a weak dust tail pointing up, and a strong greenish CN glow around a stellar nucleus. The galaxy is at right. 3 minutes, cropped, PS CS2 + AstroTools; 'make stars smaller', 'deep space noise reduction', 'space noise reduction', curves, saturation, median filter, cropped. |
