These data have maybe the most tricky so far. They are over 4 years on the hard drive, and in the meantime I changed the computer, the version of TheSkyX (32 bit ->64 bit) and many other details of my setup. So recovering the best calibration frames was a challenge and I did have to regenerate some of them.
These were separate high-gain and low-gain data acquired with the Kepler 4040 -- later I realised that using the so-called merged image, where the driver combines these, leads to a much easier workflow. Even later I discovered this forum post (
https://www.astrobin.com/forum/c/equipment-forums/gpixel-gsense4040-mono/about-the-calibration-and-usage-of-cameras-with-the-gsense-4040-sensor/ ) which explains exactly how it should be done for this sensor. However, I didn't have appropriate cal data to make use of this and the camera is currently in storage.
The image shows two galaxies from the Messier catalogue: M81 and M82.
M81 is the lower one in the image. Although appearing in Messier's catalogue, it was not discovered by him, but by Johann Bode on New Year's Eve, 1774. He also discovered M82 (the upper galaxy in the image) at the same time. Both are about 12 million light-years away. Like most galaxies (including our own), it harbours a super-massive black hole at its centre, and in this case it is estimated to be the equivalent of 70 million times the mass of our sun, all compressed into a single, infinitesimally small point.
M82 is a so-called starburst galaxy: the high rate of star production, about 10 times that of other galaxies, has apparently been triggered by gravitational (tidal) interactions with M81. At least one of these events is thought to have caused a flood of gas into the galaxy's core, resulting in many "super star clusters", of which almost 200 have been observed with the Hubble Space Telescope. There are many supernovae amongst these new stars (about 1 every 10 years) and these are causing the "superwind" of energised hydrogen which is flowing out from each side (red in the image).
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