Bode’s and Cigar Galaxies
About 12 million light-years away in the constellation Ursa Major, you’ll find Bode’s Galaxy (M81), a large spiral galaxy, and is it’s nearby neighbor, the famous Cigar Galaxy. You’ll also see NGC 3077 and NGC 2976, two smaller galaxies that are also in the same area and are thought to be gravitationally linked to M81 and M82.
January 29, 2025
This is the combined image of M81 and M82 using both RGB data from the Antlia Triband filter, and narrowband data from the Antlia ALP-T Dual Band Ha and Oiii filter. Overall, I’m pretty happy with how this turned out, especially given the amount of integration time required for a two panel mosaic. Essentially, I needed to do two, two-panel mosaics: one for the RGB data and one for the narrowband data. Rather than attempting pure continuum subtraction, I opted to blend the narrowband (processed in a Foraxx palette) and RGB data 50/50. The RGB data alone creates a very nice image, but the narrowband data really helps the nebulosity in each galaxy pop (especially the hydrogen alpha signal in the cigar galaxy.)
I’m a little disappointed that I wasn’t able to capture much of the IFN around this area that I know is there… but this target is toward a very light polluted portion of the sky for me, so I would probably need at least 5x he integration time to see any of it. Ultimately, the focus for me on this project was to highlight the nebulosity, keep the galaxies looking reasonably natural, and I think I accomplished that well enough this time around. Perhaps on some future rainy day I may revisit processing this one!
Now that I’ve wrapped up this project, I’m looking forward to diving into the next one!
Technical Details
Imaging Telescope: Orion Optics UK Ideal 8
Imaging Camera: ZWO ASI533MC Pro
Mount: Sky-Watcher EQ6-R Pro
Filter: Antlia Tri-band RGB Ultra Filter - 2” Mounted; Antlia ALP-T Dual Band 5nm 2”
Accessories: ZWO ASIAIR Plus, ZWO EAF, ZWO Filter Drawer (Gen 2), Antlia OAG with Filter Drawer
Software: PixInsight, Starnet, BlurXterminator, GraXpert, SetiAstro Automatic DBE, SetiAstro Statistical Stretch, SetiAstro Continuum Subtraction Utility
Guiding Telescope: SVBony SV106 60mm Guide Scope
Guiding Camera: ZWO ASI174MM
Imaging Dates: January 13-14 and 27-28, 2025
Frames (gain 101.0) f/4.9 -10c: 310x180” (15.5h) Dual Band; 340x180” (17h) Triband
Integration Time: 32.5h
Darks/Flats/Dark Flats: 60/60/60
Bortle Dark-Sky Scale: 6.00
January 29, 2025
Once again, continuum subtraction was somewhat difficult for this image, so I opted to create a Foraxx Palette with with the dual band data and simply combine it with the RGB data. I think it came out pretty nicely. The Antlia OAG performed excellently as well. I set the guide camera to Bin2, so guide stars were much more prominent in the guiding FoV. As a reference, for M81 RGB data, I was guiding between .6”-.7” RMS most of the night, but last night I was between .4” and .7” RMS most of the night, and it even dipped into the .2-.3”RMS range on a few occasions. Of course, numbers aren’t everything, the results are what’s important. And the result here is that I have overall better subs and I can be even more selective with the subs I use for integration, which of course results in a better final image.
Now that I’ve had a test run on processing M81 and M82 individually, I’m going to get to work on the mosaic that includes both.
Technical Details
Imaging Telescope: Orion Optics UK Ideal 8
Imaging Camera: ZWO ASI533MC Pro
Mount: Sky-Watcher EQ6-R Pro
Filter: Antlia Tri-band RGB Ultra Filter - 2” Mounted; Antlia ALP-T Dual Band 5nm 2”
Accessories: ZWO ASIAIR Plus, ZWO EAF, ZWO Filter Drawer (Gen 2), Antlia OAG with Filter Drawer
Software: PixInsight, Starnet, BlurXterminator, GraXpert, SetiAstro Automatic DBE, SetiAstro Statistical Stretch, SetiAstro Continuum Subtraction Utility
Guiding Telescope: SVBony SV106 60mm Guide Scope
Guiding Camera: ZWO ASI174MM
Imaging Dates: January 14 and 28, 2025
Frames (gain 101.0) f/4.9 -10c: 160x180” (8h) Dual Band; 170x180” (8.5h) Triband
Integration Time: 16.5h
Darks/Flats/Dark Flats: 60/60/60
Bortle Dark-Sky Scale: 6.00
January 28, 2025
As I noted in my post on my most recent M33 image, I’ve long admired many of the starburst galaxy images I’ve seen with continuum subtracted nebulosity data. M33 was my first go at it, and I thought I might give it a try on M81 and M82 as a mosaic. To remind myself how to accomplish the processing, I went ahead and tried my hand at processing M81 on its own since I will be collecting the RGB data for M82 tonight. I collected the narrowband data a few weeks ago (under a full moon… but it was the first time we had clear skies in a month!), and finally had the chance to collect the RGB data last night since the skies were clear and the moon is mostly done for this phase. M81 and M82 are toward Denver’s light dome, so even though I crossed my fingers and hoped for it, I didn’t really capture any of the faint IFN in the region. As with before, I still found continuum subtraction to be challenging, especially so with this target since all of the nebulosity is small (about the size of a star, which StarNet typically will remove, making the subtraction processing a bit more challenging).
Also of note, for the RGB data in this image, I finally made the switch to an Off-Axis Guiding solution: the Antlia OAG with Filter Drawer. I chose it because of the larger prism for my 174mm guide camera, built in filter drawer, and it’s plug and play ability to fit into the standard 55mm back focus dimension (it’s 37.5mm thick, so It works with cameras that have a 17.5 or 6.5mm + 11mm spacer amount of back focus to the sensor, like all ASI cameras). It took a little bit of fiddling but I was able to quickly find some stars and get it working. I must say, it was quite an improvement over the separate guide scope solution! Stars were much more round all night, and there was less (non-dither related) target drift throughout the night.
Overall, I think the image turned out great. Keep an eye out for an individual version of M82 and then a combined mosaic of M81 and M82. The mosaic may look a little bit different since I will probably reprocess both M81 and M82 from scratch for the mosaic.
Technical Details
Imaging Telescope: Orion Optics UK Ideal 8
Imaging Camera: ZWO ASI533MC Pro
Mount: Sky-Watcher EQ6-R Pro
Filter: Antlia Tri-band RGB Ultra Filter - 2” Mounted; Antlia ALP-T Dual Band 5nm 2”
Accessories: ZWO ASIAIR Plus, ZWO EAF, ZWO Filter Drawer (Gen 2), Antlia OAG with Filter Drawer
Software: PixInsight, Starnet, BlurXterminator, GraXpert, SetiAstro Automatic DBE, SetiAstro Statistical Stretch, SetiAstro Continuum Subtraction Utility
Guiding Telescope: SVBony SV106 60mm Guide Scope
Guiding Camera: ZWO ASI174MM
Imaging Dates: January 13 and 27, 2025
Frames (gain 101.0) f/4.9 -10c: 150x180” (7.5h) Dual Band; 170x180” (8.5h) Triband
Integration Time: 16h
Darks/Flats/Dark Flats: 60/60/60
Bortle Dark-Sky Scale: 6.00
March 2, 2024
Last night I was able to spend some time imaging the region of interacting galaxies in Ursa Major, predominantly defined by Bode’s and Cigar Galaxies. As you can see, the wide field of view from my current telescope limits the amount of detail I can capture, on these objects, but some day I do plan to add a longer focal length telescope to my arsenal so I can better capture these objects in more detail.
Technical Details
Imaging Telescope: William Optics RedCat 51 II
Imaging Camera: ZWO ASI533MC Pro
Mount: Sky-Watcher EQ6-R Pro
Filter: Antlia Tri-band RGB Ultra Filter - 2” Mounted
Accessories: ZWO ASIAIR Plus, ZWO EAF, ZWO Filter Drawer (Gen 2)
Software: Siril, Starnet, Photoshop, NoiseXterminator
Guiding Telescope: William Optics UniGuide 32
Guiding Camera: ZWO ASI174MM
Imaging Dates: Mar. 1, 2024
Frames (gain 101.0) f/4.9 -10c: 60x120” (2h)
Integration Time: 2h
Darks/Flats/Dark Flats: 30/30/30
Bortle Dark-Sky Scale: 6.00