So after getting some suggestions from a few users over at the Cloudy Nights forums, I reworked the same data set with greatly improved results. Practice!
I’ve never attempted to photograph this gas giant… our largest planet. It had been so long since I tried to take a picture of a planet that I really wasn’t sure I’d remember the steps. The planet was set to transit around 10:45pm at around 37° altitude, so the seeing was challenging despite being a beautiful night. You can see (left to right) Io, Europa, and Ganymede visible in orbit… these are 3 of the more well known siblings of Jupiter’s 79 moons. Fun fact: Ganymede is the largest moon in our solar system. I’m looking forward to trying this again when Jupiter and Saturn are higher in the sky, but I’m pretty ok with this first attempt!
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.”
“The Christmas Comet” is in Taurus and likely as close as it’ll be to Earth for at least another 20 years. The best night to view the comet was Saturday (12/16) where it achieved the closest point of it’s pass at about 7.1 million miles over Tranquility Base. We were at a neighborhood Christmas parade and party that night and it’s been overcast since. Last night looked to be the next available window, so I blew the dust off my brain and set up to hopefully take a photo. Well, if there is one consistency in this hobby, it is that challenges arise. There was tremendous (albeit beautiful) spotty cloud coverage for the first several hours after sunset… but that wasn’t the rub. The moon was SO bright that polar alignment was tricky and imaging in full band was going to be a problem. My goal from the start was to try to get the comet and M45 in the same frame, so I pressed on with what I’d already set up and crossed my fingers. It was quickly clear to me that I wasn’t going to pull off anything close to my attempt at C/2011 W3 (Lovejoy) in 2015, so I decided to try something completely new to me… an animated image. So yes, there is not much to speak of in terms of capturing a magnificent coma or nebulosity around Pleiades, but you do get three hours of the comet’s journey through our solar system… from 9pm to midnight last night. Cheers!
Comet 46P/Wirtanen is a small short-period comet with a current orbital period of 5.4 years… meaning it swings on by us every five and a half years. It belongs to the Jupiter family of comets, all of which have aphelia between 5 and 6 AU. Short period means it’s orbit is less than 20 years and “Jupiter family” is just saying that it’s orbit is dictated/controlled by Jupiter’s gravitational field (aphelia is the maximum distance it gets from it’s controlling body). Its diameter is estimated at 1.2 kilometers, so almost three-quarters of a mile at it’s widest bits. 46P/Wirtanen was discovered photographically on January 17, 1948, by the American astronomer Carl A. Wirtanen. The plate was exposed on January 15 during a stellar proper motion survey for the Lick Observatory. Due to a limited number of initial observations, it took more than a year to recognize this object as a short-period comet. You can still see it if you have any interest as it is quite bright at the moment. If you are near any form of light pollution, you’ll probably need some binoculars to find the feint fuzzy traveling 83,000 mph overhead.
I had a lot of trouble with processing this in PixInsight and having it turn out looking like the SHO renditions I’ve seen floating around the Net. I ended up using Don Goldman’s tutorial on using Hue/Sat adjustment layers and clipping masks in Photoshop, but I really would like to find some native PI techniques and reprocess it without having to fiddle with it in PS CC. This is 90 minutes per narrowband channel – so not a lot of data, but it was all I could get before the nebula hit the pine tree tops lining the imaging location. Practice is a good thing, though…
It is hard to believe I haven’t imaged since the first week of August and we are about to start November in a couple of days. I love the winter target selection and I probably would have selected something besides the Triangulum Galaxy if I weren’t boxed in by pine trees at my imaging location such that near-horizon targets just can’t be reached. I picked Messier 33 for last night because it was high in the sky all night and provided plenty of imaging time for a multi-channel attempt. This represents about 6.2 hours of total data… 20x180s each R, G, B… 34x180s Lum… 9x600s Ha. I tried Silvercup’s HaRGBCombination Script for PixInsight, but it kept locking up my client, so I ended up using the Vicent Peris method that Harry has in his tutorial. The post-processing is trickier already with multiple channels and trying to blend in narrowband, but I kinda made it more difficult for myself by binning the color channels 2×2. I figured out the hard way that I needed to go back and shoot dark subframes that were also binned 2×2 in order to register and calibrate the color channels. It was a beautiful night out and a great learning experience. Let’s hope the next one isn’t another 3 months out!
NGC 7380 (Sh2-142), more commonly called The Wizard Nebula due to it vaguely resembling Professor Albus Percival Wulfric Brian Dumbledore and his ilk, was first discovered by Caroline Herschel, sister of German-born British astronomer Sir William Herschel, in 1787. William included it in his famous catalog as H VIII.77. The Wizard is about 7,200 light years from Earth within our own Milky Way Galaxy, is one of the larger nebulae in Cepheus, and is moving toward us at 34.13 kilometers per second. The gas and dust within the cluster span about 110 light years across. This kind of nebulae are the birthplace of stars. They are formed when very diffuse molecular clouds begin to collapse under their own gravity, often due to the influence of a nearby supernova explosion. The cloud collapses and fragments, sometimes forming hundreds of new stars. The newly-formed stars ionize the surrounding gas to produce an emission nebula. In this case, the stars of NGC 7380 have emerged from its natal cloud some 5 million years or so ago, making it a relatively young cluster.
ps. William Herschel discovered infrared light in 1800. He was a stud.