NGC 3628 is a large spiral galaxy, presenting to us edge-on, located near two other large galaxies; the tidal forces from the gravitational interactions among those three massive galaxies has resulted in NGC 3628 being distorted. The three galaxies can be seen together in this photo I took years ago of the so-called Leo Trio. NGC 3628 is estimated to be about 35 million light years away from us; at that distance, it is well over 100,000 light years in diameter (similar in size to our Milky Way, itself a large galaxy).

Two distinctive features of NGC 3628 (in addition to its odd shape) are the huge tidal tail (the faint stream of stars that tapers off toward the lower left of this image), and its satellite galaxy (the faint smudge just below and to the right of the middle of the galaxy). The tidal tail likely is the telltale (see what I did there? I crack me up) of a collision (or very close encounter) between NGC 3628 and another galaxy in the past; it extends about 300,000 light years from NGC 3628 (most of it doesn't show up in my photo). Also, because we see this beautiful galaxy exactly edge-on, the dust lanes are particularly prominent (the structure one sees in our Milky Way when viewed in very dark skies is the dust lanes in our galaxy. NGC 891 is a well-known, undistorted large spiral galaxy that we see edge on; contrast the shape of NGC 891 to that of NGC 3628 to see the effects of the tidal interactions to which NGC 3628 has been subjected.

It is sometimes difficult to understand the nickname given to celestial objects; it's not hard to understand why this galaxy is called "Hamburger Galaxy."

As usual in a deep-sky image, there are a lot of small (meaning distant) galaxies in the uncropped versions of the image (look for the oblong and/or fuzzy "stars").

Technical Information:

L:R:G:B: 820:330:180:240 (a total of more than 26 hours of light-frame exposure time); luminance was a blend of 30-minute images and 10-minute images; red and green exposures were all 15-minute exposures; blue all 20-minute exposures. After discovering that my mirror looked like it had been on the wrong end of a mudslide, I cleaned it and re-took the luminance images (and did not use any of the earlier luminance data).

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, deconvolution, multiscale linear transform, HDR multiscale transform, and noise reduction) 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 April and May of 2022. Image posted June 20, 2022.

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

Seeing: Generally good; luminance images varied in FWHM from 1.7 to 2.8 arcseconds; luminance master was deconvolved to 2.0 arcsecond FWHM.

CCD Chip temperature: -25C

Copyright 2022 Mark de Regt

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