It’s been 498 days since I pointed a camera at the sky… that’s over 16 months! This was a great reminder that astrophotography is a proficiency-oriented hobby… and I’m really out of practice. Last week, I decided I would try and get back on the horse and barely missed getting pummeled by a surprise hailstorm after all data pointed toward what should have been a clear night with great viewing. Yesterday was windy, but the forecast looked good again… and although the moon was more prevalent in phase, it was scheduled to set fairly early. I didn’t have as much issue with setting the rig up since I’d been through that evolution last week and worked through the process. I didn’t have too much trouble with polar alignment and calibration, but did stumble a bit during the star alignment of the equatorial mount. Focusing the imaging and guide scope took longer than it should have and I neglected to refocus the imaging scope between each filter change, so that resulted in out-of-focus subs. I really, really don’t like out of focus stuff. Perhaps a bit aggressive for being so out of practice, I decided to run 600 second subframes for each channel. I actually took an hour of Hydrogen Alpha subs, but ironically have completely forgotten how to integrate them into my red channel, so I need to go read up on that again. I also did not have any 600 second calibration data, so I had to set up the camera and run darks this morning while I worked. I didn’t grab enough subframes per channel for the usual Windsorized Sigma Clipping integration I use, so I had to use Percentile Clipping and felt like I was winging it. After managing to get the light frames calibrated and registered to each other, I fumbled through RGB integration, then added the Lum channel with a smaller set of the images I’d taken because I tossed over an hour of out-of-focus luminance subs. Overall, this image of M101 is littered with technical problems… focus, noise, insufficient color data, color calibration of starfield, and the list goes on, but I’m pretty happy to get at least something pulled together after nearly a year and a half out of practice. This image as shown is comprised of 24 subs split fairly evenly over red, green, blue, and luminance channels… so about 4 hours of data (sans Ha). The night was nice and other than being a little chilly (I layered up), it was relaxing to sit under the stars and listen to the wildlife. There seemed to be less air traffic due to the pandemic in effect, so that was a little silver lining that helps when you are leaving the shutter open for 10 minutes at a whack. At any rate, it’s clear some more practice is in order. Hopefully, I can make that happen sooner rather than later.
“The Pinwheel Galaxy (also known as Messier 101, M101 or NGC 5457) is a face-on spiral galaxy distanced 21 million light-years (six megaparsecs) away from Earth in the constellation Ursa Major. Discovered by Pierre Méchain on March 27, 1781, it was communicated to Charles Messier who verified its position for inclusion in the Messier Catalogue as one of its final entries. M101 is a large galaxy, with a diameter of 170,000 light-years. By comparison, the Milky Way has a diameter of 100,000 light years. It has around a trillion stars, twice the number in the Milky Way. It has a disk mass on the order of 100 billion solar masses, along with a small central bulge of about 3 billion solar masses. M101 is asymmetrical due to the tidal forces from interactions with its companion galaxies. These gravitational interactions compress interstellar hydrogen gas, which then triggers strong star formation activity in M101’s spiral arms that can be detected in ultraviolet images. It is estimated that M101 has about 150 globular clusters, the same number as number of Milky Way’s globular clusters.”