NGC 6058

Object: NGC 6058, planetary nebula in Hercules, 12.9 mag, 0.7' diameter.

Subimages: 24 frames x 600s (4 hrs) SigmaClip combined after full calibration. Actually 32 frames were acquired but changes in focus and lousy tracking conspired against me. The lousy tracking in this case I believe was caused by improper DEC balance.
Scope: C11XLT, EFL=2936mm (f/10.5 effective)
Mount: Losmandy G11 with Gemini L4
Camera: ST7EI with Lumicon OIII filter (0.63"/pixel) set to -15C
Guiding: SX716 camera on a Taurus Tracker III OAG
Acquisition and Processing: MaxIm DL/CCD v4.5

Planetary nebula imaged with OIII filter over two nights, 2006/06/23 and 06/24. The stars in the final image have a FWHM~2.1" as reported by MaxIm v4.54, some of the individual frames had stars as small as 1.8" FWHM, fantastic for this region. I had to shoot new flat field frames with an OIII filter since my standard unfiltered set was ineffective. Even with the filtered flats the nebula and background showed noisy pixels (click here to download FITS of cropped area). Applying a 3x3 median filter improved things a lot at the cost of a slight reduction in resolution. A DDP filter was then applied due to the very large difference in brightness between the outer wisps and the inner arcs.

Cropped 4x view.