This image of the huge supernova remnant known as G65.3+5.7 in southern Cygnus, just north of Albireo, is the hardest imaging project I’ve undertaken. This image is an eight-panel mosaic of over 32 megapixels representing over 92 hours of exposure time. The field of view shown is over 5° across. G65.3 is very dim and emits mostly in OIII. As crazy as it sounds after 92 hours of imaging, I wish I’d gone deeper, since that’s only about 11 hours per panel.
I used OIII, Ha, and green filters. The green exposures were only three hours of the total, but they helped to capture star color and preserve the violets where the OIII and Ha areas overlap.
The star field in this part of the Milky Way is insanely dense, and the background also has a thin soup of H-alpha emission everywhere. Both of these, in addition to bringing together eight panels in three channels, made processing a real challenge. I processed it four separate times before I got a result I was pleased with.
The Sharpless catalog lists three of the brightest (relatively speaking) areas in the Ha channel: Sh2-91 in the lower left, Sh2-94 at center right, and the faint Sh2-96 above it. The OIII filaments connect these, but to my knowledge they are not individually cataloged.
- Exposures: 8 panel mosaic (cropped here) consisting of 42 hours H-alpha, 47 hours of OIII, and 3 hours of green exposures, all binned 2×2. Total exposure time: 92 hours 4 minutes
- Telescope: Two William Optics Star71s (360mm f/5)
- Cameras: SBIG ST-8300M and QSI583
- Mount: Takahashi EM200
- Guiding: QHY 5L-II mono, guided using PHD2
- Processing: PixInsight and Photoshop
Clicking the image below will open the full-resolution 32-megapixel version (15 MB):