Spiral Galaxy in Pisces

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M74 is a striking 10th magnitude galaxy in Pisces, approximately thirty-two million light years from Earth. It is a prominent grand design spiral galaxy, with about 100 billion stars (slightly fewer than our Milky Way is thought to have). It has a diameter of approximately 80,000 light years (also a bit less than our Milky Way). The uncropped field is about the angular size of a full moon.

Many galaxies have a super-massive black hole in their center; unusually, scientists believe that they have found a medium-sized black hole out in one of the arms of M74, perhaps from a collapsed star cluster. You can read about it here.

As with most images, this one has dozens of background galaxies (the oblong or large, dim--compared to the brightest stars--objects in the background; there's even a recognizable barred-spiral galaxy near the bottom of the image close to the center). We live in a universe consisting of hundreds of billions of galaxies; they really are all over!

This is a very dim galaxy, appearing only as a tiny blob though a moderate-sized telescope. Its low surface brightness makes it a challenging object to image. I had imaged M74 thirteen years earlier from my yard; impressed by how poor my results were then, I put a huge amount of exposure time into this image. If you want to compare that image to this one, click here.


Technical Information:

HaLRGB: 540:1250:330:225:300 (That's 44 hours of keepers included in this image); luminance layer consists of data from 23 thirty-minute images, 27 fifteen-minute images and 31 five-minute images; R, and G consist of fifteen-minute images; B consists of 15 twenty-minute images; Ha data consists of 18 thirty-minute images. I gathered Ha data to enhance the pink HII (star-forming) regions. All images were unbinned.)

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, deconvolution and noise reduction) done in Pixinsight; some cleanup finish work was done in Photoshop CC.

Location: Data acquired remotely from Deep Sky West Remote Observatory, Rowe, New Mexico, USA.

Date: Images taken on many nights in September, October and November 2019. Image posted November 29, 2019.

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

Seeing: Variable over that time period, with individual calibrated luminance frames varying from 1.5 to 2.7 arcsecond FWHM; the integrated luminance image had a FWHM of 2.8 arcseconds, deconvolved to 2.4 arcseconds.

CCD Chip temperature: -25C

Copyright 2019 Mark de Regt

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