Irregular Starburst Galaxy in Cassiopeia

Click here for other versions: full resolution cropped (2006x2006)  50% uncropped (2018x2023)  100% uncropped (4036x4046)
Click on image to toggle between the version as the light comes to us, and a version of what it might look like were there not a huge amount of dust between us and the galaxy


IC10 is a very dim, irregular galaxy, visible in late summer, fall and early winter. IC10 is often classified as a dwarf galaxy; it is a starburst galaxy.

IC10 is about 2.5 million light years from us (give or take a half million light years); it may be orbiting the huge spiral galaxy M31, our nearest large spiral galaxy neighbor. An unusual amount of star formation is taking place in IC10 (the most vigorous star-forming regions are the red areas within the galaxy); it is thought that this starburst is a result of a collision between IC10 and another dwarf galaxy. It has a diameter of about 5,000 light years.

IC10 has a black hole at its center, and it contains far more Wolf-Rayet stars than would be expected.

As you can see from the dense star field in the photo (Pixinsight counts 18,262 stars in the uncropped image), IC 10 lies in the plane of our Milky Way galaxy, so we are looking at it through a large amount of interstellar dust (in addition to the stars). A result of this (aside from all the stars in the photo) is that the galaxy looks far redder than it probably is, since blue light is more easily extinguished by dust than red light. By clicking on any version of the image, you can see how I imagine the galaxy would look if it weren't on the other side of all that dust.


Technical Information:

(HaL)(HaR)GB: 420:930:240:270:4400 (a total of a bit over 38 hours of exposures); luminance layer consists of blend of 62 fifteen-minute images using a luminance filter and 14 thirty-minute images using an Ha filter; R channel is a blend of 16 fifteen-minute images taken through a red filter and the Ha data; G consists of 18 fifteen-minute images taken through a green filter, while B is the combination of 22 twenty-minute images taken through a blue filter.

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 AO-X/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, deconvolution, gradient removal, Multiscale Linear Transform for noise reduction and sharpening, and blending the Ha data with the broadband data) 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 December 2021 and January 2022. Image posted February 4, 2022.

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

Seeing: Highly variable, with individual luminance images having FWHM varying from 1.7 to 3.3 arcseconds.

CCD Chip temperature: -25C

Copyright 2021, 2022 Mark de Regt

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