NGC 4565 is a very large spiral galaxy, presenting to us almost edge-on. NGC 4565 is estimated to be about 40 million light years away from us (relatively close, as cosmic distances go, for galaxies I image). At that distance, NGC 4565 is about 186,000 light years in diameter (significantly larger than our Milky Way, itself a large galaxy). NGC 4565 is estimated to have about one trillion (one thousand billion) stars.

It is thought that the shape of the central bulge indicates that this galaxy is a barred-spiral galaxy, but there still is debate on that point. You may note a bit of distortion toward both ends of the galaxy; these result from past gravitational interactions with galaxies in the neighborhood of NGC 4565.

Lots of galaxies, including our galaxy, have many globular clusters associated with them. NGC 4565 is no exception. And this perspective allows us to see them--There are a lot of faint, slightly fuzzy, star-looking points of light near the galaxy, which are (mostly, at least), globular clusters. As a point of reference, this is a globular cluster in our galaxy.

As usual in a deep-sky image, there are a lot of small (meaning more distant) galaxies in the image (look for the oblong and/or fuzzy "stars"). In particular, there are a few background galaxies large enough to see structure, some of which probably are interacting with NGC 4565 (easier to see in the, uncropped higher-resolution versions linked above).

Technical Information:

L:R:G:B: 420:255:180:240 (a total of a bit over 18 hours of light-frame exposure time); luminance consisted of 15-minute images; red and green exposures were all 15-minute exposures; blue all 20-minute exposures.

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 and combined in Pixinsight. Color combine in Pixinsight. Some finish work (background neutralization, color calibration, BlurXTerminator, NoiseXTerminator, HDR multiscale transform) done in Pixinsight; some cleanup finish work was done in Photoshop CC.

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

Date: Images taken on many nights in May, June and July of 2023. Image posted November 12, 2023.

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

Seeing: Generally good; luminance images varied in FWHM from 1.5 to 2.1 arcseconds.

CCD Chip temperature: -25C

Copyright 2023 Mark de Regt

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