NGC 2523 and NGC 2523B are a pair of galaxies (NGC 2523 is the barred spiral galaxy in the center of the image; NGC 2523B is the spiral galaxy, seen edge-on, above and to the left of NGC 2523). Although close in this photo, they are not gravitationally interacting, and they are quite far apart. NGC 2523 (the face-on barred spiral) is thought to be about 168 million light years from us, while NGC 2523B is thought to be about 186 million light years from us. At those distances, NGC 2523 is about 120,000 light years across (similar in size to our Milky Way, a large galaxy), while NGC 2523B is about 100,000 light years across. There is relatively little star formation in NGC 2523.

As usual, there are MANY other galaxies in this photo (galaxies in the same line of sight, but much farther away that the principal target(s)). In particular, the one near the bottom of the image is UGC 4279, a spiral galaxy about 190 million light years from us; the one above and to the right of NGC 2523 is Mailyan 026, thought to be a dwarf galaxy about 160 million light years from us; the blob below and to the left of NGC 2523B appears, oddly enough, not to be catalogued. And there are MANY more smaller background galaxies in the uncropped image.

When those photons my camera captured started their journey, Earth had only one continent, which was starting to break apart, and the land was dominated by dinosaurs.

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

Technical Information:

LRGB: 1140:180:180:300 (a total of 30 hours of light-frame exposure time); here's a chart showing the various subexposures I used in the image:

Luminance: 54 twenty-minute and 20 three-minute
Red: 12 fifteen-minute
Green: 12 fifteen-minute
Blue: 15 twenty-minute

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 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, NoiseXTerminater, BlurXTerminator) 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 nights during February and March of 2026. Image posted September 19, 2026.

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

Seeing: Variable, but generally mediocre.

CCD Chip temperature: -25C

Copyright 2026 Mark de Regt

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