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Monday, November 2, 2020

A supernova remnant G65.3+5.7 SNR in visual spectrum

 I have published this image in mapped colors yesterday. This time the color channels from narrowband channels H-alpha, O-III and S-II are combined so, that result is very close what human eye might see, if it could be sensitive enough.

G65.3+5.7 SNR in constellation Cygnus has about the same angular dimensions, than brighter and more famous remnant in Cygnus, the Veil Nebula The angular dimensions are about 3x4 degrees. This is a very difficult target it has a large angular dimensions, very low surface brightness and the starfield is extremely dense in this part of the Milky Way.

NOTE, the "noise" in the photos is not a noise at all, it's glow from countless stars,
it can be seen in full size photo!

G65.3+5.7 SNR in visual colors

Please, click for a large image, it's worth it!

Image is in Natural color palette from the emission of ionized elements, R=Hydrogen + Sulphur, G=Oxygen and B=Oxygen + 10% Hydrogen to compensate the missing H-beta emission

A closeup, lots of stars out there!
click for a large image

This is a closeup from the full resolution photo to show, how dense the star field really is!

H-alpha and O-III channels separated

click for a large image

Ha & S-II
click for a large image

A separated photos of the light from an ionized hydrogen and sulfur (H-alpha & S-II) and the light from an ionized oxygen (O-III). There is a big difference between elements. Note, the bright star just up from the center is almost invisible at O-III light. it's there but very dim at light of an ionized oxygen.


SNR G65.3+5.7 was discovered by Gull et al. (1977) during an OIII survey of the Milky Way. Some parts of this SNR were already catalogued by Stewart Sharpless in his SH2 catalog as SH2-91, SH2-94 and SH2-96, but they were not recognized as being part of a bigger structure at that time. The idea that they could be part of a larger SNR was postulated by Sidney van den Bergh in 1960, but it took until 1977 for this to be confirmed.

This is one of the larger SNR in the sky spanning a region of roughly 4.0×3.3 degrees. Mavromatakis et al. (2002) determined the age of the SNR to be 20.000-25.000 years and the distance about 2.600 – 3.200 light years. The shell has a diameter of roughly 230 lightyears! This SNR is a predominantly OIII shell with also some H-alpha signal.

Orientation in Cygnus

Technical details

Processing workflow

Image acquisition, MaxiDL v5.07.
Stacked and calibrated in CCDStack2.
Deconvolution with a CCDStack2 Positive Constraint, 33 iterations, added at 50% weight
Color combine in PS CS3
Levels and curves in PS CS3.

Imaging optics
Tokina AT-x f2.8 camera lens

10-micron 1000

Cameras and filters
Imaging camera Apogee Alta U16 and Apogee seven slot filter wheel
Guider camera, Lodestar x 2 and an old spotting scope of Meade LX200

Astrodon filters,
5nm H-alpha 3nm S-II and 3nm O-III

Total exposure time

H-alpha, 12 x 1200 s, binned 1x1 = 4 h
O-III, 12 x 1200 s, binned 1x1 = 4 h
S-II, 6 x 1200 s, binned 2x2 = 2 h

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