M110
Messier 110 - Click here for full resolution
Messier 110 (M110), also known as NGC 205, is a dwarf elliptical galaxy that is a satellite of the Andromeda Galaxy in the Local Group, a group of galaxies where the Milky Way is a part of. Charles Messier never included the galaxy in his list, but it was depicted by him, together with M32, on his drawing of "Nébuleuse D'Andromède", later known as the Andromeda Galaxy. A label of the drawing indicates that Messier first saw the object in 1773. M110 was independently discovered by Caroline Herschel on August 27, 1783; her brother William Herschel described her discovery in 1785. The suggestion to assign the galaxy a Messier number was made by Kenneth Glyn Jones in 1967, making it the last member of the Messier List. This galaxy has a morphological classification of pec dE5, indicating a dwarf elliptical galaxy with a flattening of 50%. It is designated peculiar (pec) due to patches of dust and young blue stars near its center. This is unusual for dwarf elliptical galaxies in general, and the reason is unclear. Unlike M32, M110 lacks evidence for a supermassive black hole at its center.
source: Wikipedia
NGC/IC:
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NGC205
n.a.
Galaxy
Andromeda
00h 40m 22s
+41° 41.1′
01 November
86º N
Conditions
M110 can be very well observed in Autumn, with maximum altitudes reaching 86° in the North. M110 was photographed over 6 nights during early October 2024 from the remote observatory at IC Astronomy in Oria, Spain.
Equipment
The default rig at the observatory was used. The core of this rig is a Planewave CDK-14 telescope on a 10Micron GM2000 mount, coupled to a Moravian C3-61000 Pro full-frame camera. The RoboTarget module in Voyager Advanced automated the process to find optimal time-slots during astronomical night.
Telescope
Mount
Camera
Filters
Guiding
Accessoires
Software
Planewave CDK14, Optec Gemini Rotating focuser
10Micron GM2000HPS, custom pier
Moravian C3-61000 Pro, cooled to -10 ºC
Chroma 50mm Luminance, Red, Green and Blue unmounted, Moravian filterwheel L, 7-position
Unguided
Compulab Tensor I-22, Windows 11, Dragonfly, Pegasus Ultimate Powerbox v2
Voyager Advanced, Viking, Mountwizzard4, Astroplanner, PixInsight 1.8.9-3
Imaging
M110 is seldomly photographed on its own. It stands very close to M31, the Andromeda Galaxy, and can be seen on all Andromeda images. The field of view of the setup used is way too narrow for an image of M31 without using a large mosaic. But for M110, the field of view is just right. So this was a great opportunity to look up close into this object, and add to the growing body of photographed Messier objects in my portfolio. The image was made as a broadband image, using standard LRGB filters. A total of about 20h of exposure was captured.
Resolution (original)
Focal length
Pixel size
Resolution
Field of View (original)
Image center
6251 × 4167 px (26.0 MP)
2585 mm @ f/7.3
3.8 µm
0.30 arcsec/px
31' x 20'
RA: 0h 40m 21.815s
Dec: +41° 41’ 05.28”
Processing
All images were calibrated using Darks (50), Flats (50) and Flat-Darks (50), registered and integrated using the WeightedBatchPreProcessing (WBPP) script in PixInsight. All further processing was done in PixInsight, including the use of scripts and tools developed by RC-Astro, SetiAstro, GraXpert, and others. For a step-by-step description of the processing techniques applied, see the below schedule. The object is so close to M31, that part of that galaxy was visible in the corner of the captured image. Therefore as a last step in the process, the image was rotated 90° and cropped to eliminate as much as possible from the M31 signal.
The very coarse ‘noise’ structure was not evenly spread among colour channels. The Red channel (and luminance) showed the effect most clearly. In the Blue channel the effect was barely seen and the Green channel was somewhere in the middle.
When the original masters came out of WBPP, the images seemed a bit of a disappointment. It looked like there was a lot of noise left in the image. But not normal noise, some very large-scale noise. A total of 198 sub-frames were integrated for the luminance master alone, so it was unlikely an integration issue. Still all sorts of aspects were checked, such as quality of darks and flats, integration parameters, relative signal levels, etc. Even a full re-run of the data was made using Fast Batch Preprocessing, but with the exact same result. In the processing this ‘noise’ also behaved very differently. NXT did not remove it, BXT non-stellar adjustments caused small worm-like shapes, and SXT extracted a lot of this ‘noise’ out into the stars-only image. A close-up of the individual colour channels shows that the effect is most visible in the red (and luminance), slightly less so in Green and only very vague in the Blue channel (see above).
Based on this information I came to the conclusion that this must be actual signal. Perhaps a mixture of hydrogen gas and dim stars? I tried to find confirmation in photos from others on Astrobin, but that was not very easy. M110 is seldomly imaged on its own, and all M31 images have a much higher pixel scale and a resolution where this small-scale structure becomes almost invisible. But looking close into some higher resolution images, they do show hints of this kind of coarse noise, or small-scale structure.
Originally this was a target I wanted to image just to complete the catalogue. The somewhat boring nature of this type of galaxy did not seem to make it a very interesting object. But the ability to pick up some of this much smaller detail made it actually quite a fun project to complete.
Processing workflow (click to enlarge)
This image has been published on Astrobin.
