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NGC 5921
NGC 5921
Barred Spiral Galaxy in Serpens Caput

Click here for uncropped versions: 100% (3966x4036)  65% (2662x2662)   40% (1638x1638)

 

NGC 5921 is a barred spiral galaxy, visually located in the constellation Serpens Caput. It presents to us almost face-on, giving us a nice view of the prominent bar at its core. It is thought to be about 65 million light years away from us, which would give it a diameter of approximately 100,000 light years, making it a relatively large galaxy (our Milky Way now is thought to be of similar size, or perhaps a bit larger). Being so far away, it is only about 5 arcminutes across in our sky. The entire field of the uncropped versions is about the angular size of a full moon.

This image is a heavily-cropped piece of the entire field I photographed; if you click through where indicated, there are three different resolution versions of the entire (uncropped) version. As is often the case with large-field deep-sky photographs, there are a lot of tiny (meaning, of course, very far away) galaxies in the background of this photo (including and especially a number that show significant structure).

 

Technical Information:

Ha:L:R:G:B: 420:772:180:270:240 (a total of over 31 hours of light-frame exposure time); there are thirty-five 20-minute exposures and 24 3-minute exposures through the luminance filter; red and green exposures were all 15-minute exposures; blue were all 20-minute exposures, while Ha were all 30-minute exosures. The luminance layer consisted of an HDR blend of the 20-minute and 3-minute exposures, with the Ha data blended in; the red channel is a combination of twelve 15-minute images thorugh a red filter and the Ha data. The green channel is a combination of fifteen 15-minute images through the green filter. The blue channel is a combination of thorteen 20-minute images through a blue filter.

Equipment: RC Optical Systems 14.5 inch Ritchey-Chretien carbon fiber truss telescope, with ion-milled optics and RCOS field flattener, at about f/9, and an SBIG STX-16803 camera with internal filter wheel (SBIG filter set), guided by an SBIG AO-X, 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, combined and cropped in Pixinsight. Color combine in Pixinsight. Some finish work (background neutralization, color calibration, NB blend, Noise XTerminator and Blur XTerminator) done in Pixinsight; some cleanup finish work was done in Photoshop 2024.

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

Date: Images taken on many nights in May and June of 2024. Image posted December 29, 2024.

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

Seeing: Generally good.

CCD Chip temperature: -25C

Copyright 2024 Mark de Regt

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