Sh2-224 is a very, very faint supernova remnant; this photo shows only a piece of the remnant (another large piece if to the right of this; you can see the faint red of the nebula trailing off the frame to the right). The red wispy stuff is ionized hydrogen, while the fainter blue wispy stuff is ionized oxygen; these two elements often dominate the visible light emitted by supernova remnants (see, e.g., the Veil Nebula supernova remnant).

Sh2-224 is estimated generally to be about 14,700 light years away from us; at that distance, this piece is about 146 light years in diameter.

The supernova explosion is thought to have occurred between 13,000 years ago and 24,000 years ago.

The entire field of the photo is about the same width as a full moon.

This object reminds me a lot of NGC6888, except that this object is even dimmer.

Technical Information:

(HaL)(HaR)(OIIIG))(OIIIB): Ha:1590; OIII:1260; L:1170; R:240; G:180; B:240 (a total of 78 hours of exposures); the luminance layer consists of blend of 28 fifteen-minute images using a luminance filter, 25 thirty-minute images using a luminance filter, 33 thirty-minute images using an Ha filter, 10 sixty-minute images using an Ha filter, 20 thirty-minute images using an OIII filter, and 11 sixty-minute images using an OIII filter; the R channel is a blend of 16 fifteen-minute images taken through a red filter and the Ha data; G is a blend of 12 fifteen-minute images taken through a green filter and the OIII data, while B is a blend of 12 twenty-minute images taken through a blue filter and the OIII data (with a bit of the Ha data included).

Equipment: RC Optical Systems 14.5 inch Ritchey-Chrétien carbon fiber truss telescope, with ion-milled optics and RCOS field flattener, at about f/9, and an SBIG STX-16803 with internal filter wheel (SBIG filter set), guided by an SBIG AO-X/STX Guider, all riding on a Bisque Paramount ME German Equatorial Mount.

Image Acquisition/Camera Control: Maxim DL, controlled with ACP Expert/Scheduler, working in concert with TheSky X.

Processing: All images calibrated (darks, bias and sky flats), aligned, and combined in Pixinsight. Color combine in Pixinsight. Some finish work (background neutralization, color calibration, deconvolution, gradient removal, Multiscale Linear Transform for noise reduction and sharpening, and blending the Ha data with the broadband data) done in Pixinsight; some finish work (LRGB combination, contrast and saturation adjustment) was done in Photoshop CC.

Location: Data acquired remotely from Sierra Remote Observatories, Auberry, California, USA.

Date: Images taken on many (and I mean MANY) nights during November and December of 2021, and January of 2022. Image posted January 12, 2022.

Date: Image scale of full-resolution image: 0.56 arcseconds per pixel.

Seeing: Quite variable with individual luminance images having FWHM varying from 1.7 to 3.0 arcseconds; the luminance master was deconvolved to 1.6 arcsecond FWHM.

CCD Chip temperature: -25C

Copyright 2021, 2022 Mark de Regt

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