I’m a sucker for faint emission nebulae, and for this one in particular, I’m apparently a glutton for punishment. Back in the summer of 2017, I imaged the supernova remnant G65.3+5.7, taking over 90 hours of exposures across an eight-panel mosaic. It was great to even reveal this object, but I wanted a sharper and deeper image. So this summer I made it my project again, this time with a faster, sharper scope (FSQ-106ED at f/3.6) and a larger, lower-noise camera (ZWO ASI2600MM). I’m much more pleased with the result, but this remains a very challenging target!
It lies at the head of Cygnus the swan, on the border of Vulpecula. Here, I’ve mapped H-alpha to red and [OIII] to blue. The whole object is extremely dim in both channels—this image took 41 hours of exposure. It’s also extremely large, spanning 5.5° in RA and 3.3° in declination, so it took a four-panel mosaic to cover it. The size of the full moon is shown at upper right for a sense of scale.
G65.3+5.7 was discovered by Gull, Kirshner, and Parker in 1977, though Sharpless cataloged the fragments brightest in H-alpha as Sh2-91, Sh2-94, and Sh2-96. Gull et al estimated it to be about 230 light years in diameter and 4000 light years away. In 2002, it’s age was estimated to be about 27,500 years old.
The bright star at bottom left is magnitude 4.7 Phi Cygni. The deep red star near the center is the planetary nebula PK064+05.1.
This is reduced-size version, at about 15 megapixels. The full resolution image is just over 60 megapixels.
- Exposures (-10ºC, gain=100):
- H-alpha 264×300s (spanning four panels)
- OIII: 226×300s (spanning four panels)
- Total exposure time: 40 hours 50 minutes
- Taken from Doylestown, PA on the nights of Aug 4, 5, 6; Sep 3, 6, 7, 26, 27
- Telescope: Takahashi FSQ106ED w/0.72x reducer (f/3.6)
- Camera: ZWO ASI2600MM-Pro with Astrodon filters (5 nm)
- Mount: Takahashi EM-200
- Guiding: ZWO ASI120MM on 50 mm finder scope
- Processing: AstroPixelProcessor, PixInsight
Below is an annotated version of the image showing the coordinate grid and the locations of the Sharpless objects.