NGC 6946 - Fireworks Galaxy (Torben van Hees)

NGC 6946 - Fireworks Galaxy

This was the first rather clear night in the last weeks, so I set up the equipment. Still, numerous clouds interrupted the session. I am quite fond now of Voyager which kept going even through all the interruptions with a custom script and also took automatic sky flats during dusk and dawn. I could sleep all night. There was a problem though with the Lum flats, which you can barely make out in the lower right part: An overcorrected dust spot. I tried reaquiring the flats with a flat panel and switching to flat darks instead of bias, but that did not help. I am thinking the shadow of the dust may be too dark to be fully corrected. But now to the interesting parts:

The Fireworks Galaxy is a member of the Virgo Cluster - that much is sure. Much else is little understood even though it is among the most-studied galaxies. Its study is made difficult because we observe it through gas and dust of our own Galaxy. The latest distance study I could find is from 2019 and estimates distance at about 21 million lightyears. Other studies had it between 13 and 32 million lightyears. In the southeastern part (upper left) one can make out the Hodge complex which seems a small, white ellipse. It was long thought to be a hydrogen cloud and supergiant cluster. Newer studies, however, suggest it is an interacting dwarf galaxy moving through the halo at high speed. Furthermore, there are numerous large holes in the hydrogen clouds of this galaxy whose origin is not well understood. Theories range from supernovae to passing black matter objects to just occurring because of the fractal nature of gas accretion in a galaxy. M81 has similar holes, but they are much smaller.

Original
Final
B

B

Description: reprocessed with new workflow

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Cloudy Nights
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Status	Advanced success
Started	...
Astrometry.net job	6917096
PixInsight job	5FSHR4FFB6B4LT5OSFSR9ZDW28CUBHMX
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	20h34m50s.723
RA (top/left)	20h32m29s.449
RA (top/right)	20h36m04s.484
RA (bottom/right)	20h37m12s.884
RA (bottom/left)	20h33m35s.657

Dec (center)	+60°09′11″.61
Dec (top/left)	+60°04′01″.17
Dec (top/right)	+59°53′19″.90
Dec (bottom/right)	+60°14′11″.57
Dec (bottom/left)	+60°24′58″.88

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