A Charming Comet

There was the standard hype and hope surrounding Comet C\2023 A3 (a.k.a. Comet Tsuchinshan-ATLAS) as it closed in on perihelion last month. Discovered some 18 months earlier, it had seemed to stutter on its brightening curve over the summer, leading some to wonder if it'd be only a 3rd-4th magnitude object. Others fretted that the comet was not even going to survive buzzing the Sun and would go the route of Comet ISON in 2013 and disintegrate.

However, by early October it became apparent that the comet had survived and was poised to put on a nice show in northern skies around the 2nd week of October. The window of opportunity would not be very long as the Oort visitor would be quickly heading outbound and fading with each passing day. Would it be something I could see with my naked eye? And would nature cooperate with some clear skies?

Comet C/2023 A3 on Oct 15th

The evening of October 15th had beautifully clear skies so I grabbed the camera and walked up the street a little to get the best possible western sky view. I started around 7:20 pm and continued looking for the comet for about 25 minutes. I had no luck with either naked eye or using my 7x50 binoculars, which I attributed in part to being quite literally 20 yards from a street light. I kept snapping bracketed images of the sky in hopes that maybe I would pick up something.

Once inside with the images downloaded to the laptop it was quite apparent that I had been scouring the area a little south of the comet's position, because it was there quite clearly in the 4-second exposure. Sigh - a missed opportunity yet again due to Towson's light pollution!

Fortunately the weather was in one of those fabulous fall runs of clear, dry skies. So the next day I used Google Maps to identify a location in Hereford that appeared to have some parking as well as a nice western horizon. Shortly after dinner I set off with camera and binoculars to the Gunpowder State Park Trails off of Mt Carmel Rd. Twilight was fading when I got there and I was a little surprised at the number of people who were already there in the tiny parking lot. I grabbed the camera and walked across the road to keep the overhead power lines out of any picture.

It took only seconds to sweep up the comet in the binoculars sporting a beautiful coma of about 2nd magnitude with a tail fanning out behind it for several degrees. Lowering the binoculars and using averted vision I could definitely make out a streak in the western sky. There'd be no way to discern that from home, but out here, even with the automobile lights on this heavily traveled road, it was clearly naked-eye visible. I did a quick look in the glove compartment for my distance glasses but alas they were missing.

I started clicking off shots of Tsuchinshan-ATLAS as quickly as I could as some malingering clouds threatened to get in the way. I bracket exposures as well as focal length to hopefully get a wide angle and then a closer shot of the beautiful visitor. The rising full Moon over my shoulder served as a good test of focus to ensure I did not mess that up. I kept taking occasional breaks to admire the comet in the binoculars, admiring the gossamer tail trailing the star-like coma. 

While Tsuchinshan-ATLAS was certainly a pretty sight, it made me appreciate just how amazing the late 90's had been with Hyakutake and then Hale-Bopp. Those were truly spectacular comets that graced our skies back then, setting the benchmark against which all other icy interlopers are measured in my mind.

19 stacked 2.5 second frames at ISO 800

All too soon the comet lost altitude as it parachuted towards the horizon. Venus had set and Boötes with his lucida of Arcturus was struggling to stay above the horizon, signaling it was time to wrap things up. I grabbed the camera & tripod and carefully crossed the road to the parking lot (as one gets older it's critical to move carefully in the dark to avoid a fall!)

As I reached the car I chatted with a couple of folks who were also enjoying the spectacle. One of them had brought a Seestar and was getting some very impressive shots with that. And as it turned out one the guys was John Rose, a high school friend who had been in the Boys' Latin Astronomy club with me some 50 years earlier. I couldn't help but think how very cool it was that here we were a half century later, still being lured out under the night sky to witness its wonders! 

C/2022 E3 (ZTF)

Last March the folks at the Zwicky Transient Facility picked up an object using their wide field survey. It was soon determined that this was a comet heading inbound for a rendezvous with the Sun after a 50,000 year absence. The orbital calculations along with the comet's brightness led astronomers to predict that C/2022 E3 (ZTF) might become a naked-eye object soon after its perihelion on January 12th, peaking as it makes its closest approach to Earth on February 1st. Given it's the brightest comet to grace our skies since Neowise in the summer of 2020 I thought it was worth trying to observe it and possibly get an image or two last Friday.

---

Jan 27, 2023 21:45 ET from Towson, MD
Clear skies, 35°F with light wind
Seeing 3/10 Transparency 9/10

First up is a quick scan of the area just a little NW of β Ursae Minoris (Kochab) using the 15x70 Oberwerk binoculars. At 2nd magnitude and a deep orange color it is easy to pick out Kochab from even my Bortle 8 skies to start the brief star hop. A little pan to the right and up and I can quickly see what appears to be a tiny, weak nebulosity. Working to hold the binoculars steady enough to get a good look I confirm that we have a comet that should be an easy target.

Rolling the 10" Cyrus Newtonian out I ditch getting 2-star alignment in favor of just using the finder scope to target the fuzzy visitor. It's readily visible in the spotting scope so it doesn't take long to sweep it up in the 40mm eyepiece. It's set in a nice star field and there is a star-like nucleus along with a diffuse, weak haze representing its coma. No real color can be discerned. Bumping up to the 25mm Plossl to darken the background a bit the coma is a little easier to see but in all honesty I cannot make out any shape to it that would let me guess as to the presence of a tail and its direction. It certainly seems to be at about 5th magnitude as predicted.

---

To round out my ZTF session I grab my Canon camera and put the kit 70-300mm lens on. This time I try to avoid focus issues by targeting the almost 1st quarter moon and dialing it in to be as sharp as possible. At 200mm focal length I should get a reasonable size for the comet, and the rule of 500 suggests an exposure of 2½ seconds. But a quick test exposure shows unacceptable trailing at 2 seconds, so I drop it back to 1 second and begin firing off pictures, accumulating about 100 of them. From there I drop the focal length down to 70mm and run a series of 6 second exposures before calling it a night.

A few months ago Sky & Telescope ran a nice spread on nightscape photography. Among the tools that they mentioned was Sequator, a free program that I had not heard of before that stacks your images and can "freeze" the foreground. Sounded like a perfect tool to use for my ZTF images, so I downloaded and did a quick YouTube video to get me oriented to its use. I have to say it was much easier and faster than my standard go-to in this scenario (Deep Sky Stacker), although it could not keep my foreground tree from blurring, likely because of the breeze shifting its branches. But the resulting TIF yielded a very nice result after having some tweaking in Photoshop, especially given the minimal effort I put into the capture.

While the comet is outbound to the Kuiper belt deep freeze, we do have a couple of opportunities to get some interesting shots of it as it photo-bombs a few celestial luminaries as it leaves the stage:

Feb 6: The comet swings close by Capella

Feb 11: ZTF buzzes Mars

Feb 15: The green ghost will contrast nicely with nearby Aldebaran

While comet C/2022 E3 ZTF is likely to fall short of the media hype, it still is an interesting and readily accessible example of what most comets look like - star-like nucleus encased by a puffy, tenuous cloud. 

NEOWISE Breaks the Drought

“Comets are like cats: they have tails, and they do precisely what they want.” ― David H. Levy

While they are not as infrequent as Venus transits, a showy comet is pretty rare based on my experience. And hands down they are the biggest tease that the solar system has to offer. From Kohoutek (1974) to this year's PANSTARRS (C/2020 K1) comets often show promise of putting on a show only to either massively under perform or occasionally just crumble into pieces. Even the most famous of comets, Halley, was a bit of a dud for northern hemisphere observers on its last visit in 1986.

In my half century of sky gazing I've seen 3 comets that fit the archetype of a comet: Bennett (1970), Hyakutake (1996), and the grand Hale-Bopp (1997). There are likely some I missed when I was less active but most comets that I've viewed are small fuzzies that need a scope or binoculars to see well and resemble a Manx rather than a Persian feline. They make you appreciate why Messier, fooled by the faux comets of nebulae and galaxies, started his catalog.

I had adopted a "I'll believe it when I see it" attitude towards NEOWISE C/2020 F3 when the initial assessments were that it could be a winner. No Lucy, this Charlie Brown wants to know that football isn't going to be pulled away at the last moment! And by the way - I know we need these robotic scopes to efficiently catch incoming asteroids and comets for our safety, but their comet names are so sterile. And it takes away one of the best lotteries in amateur astronomy - the glory of finding a great comet and having your name slapped on it. If I were in charge I'd say that the robots have to keep quiet - report their finding to a secret database but then wait for some lucky amateur to stumble upon it and get the naming honor. Bring back awesome comet names like Ikeya-Seki! Sigh - but I digress...

Once NEOWISE had completed its rendezvous with the Sun the reports - and images - started coming in with good news. There appeared to be a naked-eye visible tail, even from suburban venues. Excited with the prospect of ending the long drought of a fine comet I waited for a break in the normal Baltimore July weather pattern - hazy, warm, humid. Finally the weather sites agreed that Sunday morning was likely to be a good opportunity. While many HAL members were planning to assemble at Carrs Mills I opted for a closer spot with good horizons at Dulaney Springs park. 

I pulled into the parking lot with camera, binoculars, and face mask (just in case) at about 4:15. A last quarter Moon hung high above, and Venus gleamed adjacent to Aldebaran. To the left was Capella, and farther to the left should be roughly where NEOWISE ought to be hanging out. I thought with averted vision I could catch a shaft of light extending above the tree line, and the binoculars confirmed it. Moving out onto the field to shift the comet's apparent position into a break in the trees revealed a glowing nucleus and nearly 2° tail.

NEOWISE's Tail Above Treeline

Setting up the camera I worked on getting some shots of NEOWISE as it ascended above the treeline. As I'm taking one of the shots I notice a bright object moving nearby. First impression was that it was the ISS starting a pass but then it winked out, pretty suddenly. Odd - did it just enter the Earth's shadow that quickly? Something didn't seem quite right so I noted the time in order to check later as to what was in the area. As it turned out Jim Johnson captured it and properly identified it as a meteor. It was likely quite distant given the appearance in both our shots is pretty similar while separated by some 25 miles.

NEOWISE Crests Treeline and Greets Meteor

As NEOWISE gained altitude it became a fine sight! To the naked eye it had perhaps a 1^st magnitude coma gradually fading into a delicate gossamer tail. In the 7x50 binoculars the head was a compact, bright white with the tail streaming upward like a jet contrail. The tail had more yellowish-gold tones compared to the whiter coma, making a beautiful impression. The tail also seemed to be a bit stronger on its edges, as though the coma had active jets on each side. I drank in the experience of this celestial visitor to our neighborhood, knowing that the creeping dawn would soon overwhelm its presence. By 5 a.m. I headed back home, eager to see my digital images on a laptop screen.

A Sight to Behold

So now NEOWISE heads back out to the icy depths of the solar system and we'll get to see it in a more convenient evening sky. Hopefully it will continue to delight as it gradually recedes from view over the summer months.