731. COMET PANSTARRS C/2019 U5          Perihelion: 2023 March 29.84, q = 3.624 AU

As I write these words, the calendar year of 2022 is drawing to its close. For me personally, 2022 was a relatively quiet and uneventful year -- perhaps not a bad thing at my present age -- with the biggest happenings being my older son Zachary's moving back to Australia in August (although he and his girlfriend Karina paid a visit back here earlier this month) and an unpleasant physical ailment I had to deal with, also in August. On the wider national and international scene many things remain quite unsettled, although there were some occasional hopeful signs here and there. From the perspective of astronomy and space 2022 could be considered a positive and productive year, which included the successful DART mission (which I discuss in my tally entry for (65803) Didymos (no. 725)), the recently-completed unmanned Artemis 1 mission (which, despite my lifelong interest in and advocacy for human spaceflight, I am actually somewhat ambivalent about, since I have come to feel that there are a host of serious issues here on Earth that we as humans need to confront and deal with before we can seriously consider expanding into space, and in any event I believe any decisions to such effect should be left to the generations that follow mine), and the successful deployment of the James Webb Space Telescope, which among many, many other wondrous accomplishments managed to image Comet Hale-Bopp (no. 199) -- at the enormous heliocentric distance of 46.2 AU -- in early July.

Before the year ends, I have managed to add one additional comet to my tally, giving me my 19th tally addition and, overall, my 26th comet, for the year, something that strikes me as at least somewhat remarkable since I now consider myself "semi-retired" from visual astronomical activities. The comet in question was discovered by the Pan-STARRS survey in Hawaii as far back as October 22, 2019, at which time it was located at a heliocentric distance of 10.4 AU and almost 3 1/2 years away from perihelion passage. At the time of its discovery it appeared as a stellar object near 21st magnitude and didn't exhibit any cometary activity, and was accordingly announced under the designation A/2019 U5. About a year later large telescopes began to detect weak activity, and in April 2021 it was formally re-designated as a comet.

Comet PANSTARRS is traveling in a steeply-inclined retrograde orbit with an inclination of 113.5 degrees. It was at opposition in early May 2022, and according to various reports I've read and images I've seen it was apparently close to 14th magnitude around that time, i.e., bright enough for visual observations, and had I been operating at my previous level of activity I almost certainly would have looked for it and, more than likely, would have successfully detected it. As it was, I waited until after it went through conjunction with the sun (23 degrees north of it) in mid-October and subsequently re-emerged into the morning sky; again, various reports and images (including a set of images I obtained via the Las Cumbres Observatory network on December 20) indicated it was bright enough to detect visually. On the morning of December 22 I successfully did so; it appeared as a small, moderately condensed object slightly brighter than 14th magnitude.

At present the comet is located in central Virgo some four degrees northwest of the star Tau Virginis and, having just passed through a stationary point, is traveling almost due southward at a relatively slow 6 arcminutes per day. Over the coming weeks it accelerates and curves toward a more directly westward motion, and will pass through opposition (and be at its closest to Earth, 2.63 AU) during the latter part of March, when it will be located three degrees west-southwest of the star Eta Virginis and traveling at half a degree per day. (At that time it will also be close to perihelion passage, making the viewing geometry about as favorable as it can be.) The comet crosses into southeastern Leo in early April and into Sextans a month later, but not too long thereafter it starts curving more directly southward as it goes through its other stationary point at the beginning of July. By that time it is becoming inaccessible from my latitude, although observers in the southern hemisphere will still be able to follow it; meanwhile, it enters Hydra in early August and is in conjunction with the sun (25 degrees south of it) shortly before the end of that month. It begins emerging into the southern hemisphere's morning sky by November and is at opposition again in early February 2024, when it will be located at a declination of -46 degrees about three degrees southwest of the star Lambda Velorum.

Since it is faint and distant and otherwise relatively nondescript, I will probably only be observing Comet PANSTARRS on an occasional basis over the next few months. It may brighten by perhaps a half-magnitude or so by the time of perihelion passage, and I may follow it for perhaps a month or so thereafter, but once it starts fading and getting low in my southwestern sky I will probably be done with it. Observers in the southern hemisphere may still be able to detect it visually as it approaches its opposition in early 2024, but it will likely soon fade from view for them as well.

INITIAL OBSERVATION: 2022 December 22.46 UT, m1 = 13.7, 0.6' coma, DC = 4-5 (41 cm reflector, 229x)


732. COMET 118P/SHOEMAKER-LEVY 4          Perihelion: 2022 November 24.33, q = 1.829 AU

My first tally addition of 2023 is a long-time acquaintance. After its discovery by the team of Carolyn and Eugene "Gene" Shoemaker and David Levy in 1991, I observed it during its subsequent return in 1996-97 (no. 222), during which it reached a peak brightness near 12th magnitude and for a time shared the sky with Comet Hale-Bopp C/1995 O1 (no. 199). Following an unfavorable return in 2003 I observed it again during its return in 2009-10 (no. 464) as a part of "Countdown," and I give a more detailed discussion of its history in its "Countdown" entry. The comet was somewhat fainter than I expected during that return, reaching a peak brightness near 13th magnitude.

As I indicated in its "Countdown" entry, Comet 118P returned under unfavorable geometry in 2016 (although it was duly recovered and, according to the astrometric measurements that were reported, reached a peak brightness perhaps near 16th magnitude), and then in 2020 made a moderately close approach to Jupiter which shortened its orbital period and its perihelion distance. On the present return it was recovered on May 25, 2021 by a team of French astronomers utilizing a remotely-controlled telescope in Chile, although there apparently were no further observations until August of that year, and meanwhile following its conjunction with the sun in late March 2022 it has been followed somewhat extensively since emerging into the morning sky three months later. Although -- again, as I indicated in its "Countdown" entry -- the reduced perihelion distance and the favorable viewing geometry this time around suggested it might become at least somewhat bright, the comet instead seems to have continued the overall fading trend it has exhibited during previous returns, as the reports and images I saw, including some occasional images I took via the Las Cumbres Observatory (LCO) network, indicated it was remaining too faint to be worth attempting visually. However, some of the most recent reports I've seen have suggested it might have brightened some during the recent past, and some additional LCO images I took in mid-January 2023 seemed to support this, so after having to wait out a series of "mini"-snowstorms that were moving through the area I made my first visual attempt on the evening of January 18, and successfully detected it as a diffuse, slightly condensed object of 13th magnitude.

Although Comet 118P passed through perihelion almost two months ago, it is right now as its closest approach to Earth (0.92 AU) and will be at opposition just before the end of January, and accordingly is probably as bright as it is going to get. It is currently located in southern Cancer some 3 1/2 degrees west of the open star cluster M67 and is traveling towards the north-northwest at approximately 15 arcminutes per day; after passing through its stationary point (about 7 degrees north-northwest of its present location, and 4 1/2 degrees southwest of the Praesepe, or "Beehive," star cluster M44) shortly before the end of February it begins traveling just northward of due east and passes a little over one degree north of the center of M44 at the end of March. Since the comet is now pulling away from both the sun and Earth it will likely start fading pretty quickly, and at most I will probably only see it another one or two times.

While I wasn't at all sure I would even be looking for, let alone seeing, Comet 118P this time around, as I wind down my visual observational activities I am actually quite glad that I was in fact able to observe it and add it once again to my tally. Via their many discoveries both the Shoemakers and David Levy made frequent appearances on my tally during much of my earlier years, but during more recent years their only appearances have been due to returns of some of the periodic comets they found; indeed, this is the first time that either of their names appear since this comet's previous return. The Shoemakers terminated their survey program at Palomar in the mid-1990s, and Gene tragically died in a car accident in Australia in 1997, while Carolyn passed away just a year and a half ago. David Levy, meanwhile, remains active in astronomical educational and promotional activities, although in the teeth of all the current survey programs he has not made any comet discoveries since his most recent one in 2006 (Comet 255P/Levy P/2006 T1, no. 397); I last saw him at the 50th Anniversary (and penultimate) Riverside Telescope Makers Conference in 2018. This return of Comet 118P gives the Shoemakers their 21st entry on my lifetime tally and David Levy his 18th, which currently puts them in 4th and 6th place, respectively, for most appearances. I don't expect any more appearances for either of them.

INITIAL OBSERVATION: 2023 January 19.16 UT, m1 = 13.2, 1.4' coma, DC = 2-3 (41 cm reflector, 70x)


733. COMET 96P/MACHHOLZ 1          Perihelion: 2023 January 31.09, q = 0.116 AU

In the entry for Comet 141P/Machholz 2 on its 2020 return (no. 690) I discuss the accomplishments of its discoverer, amateur astronomer Don Machholz, who during a "career" that started in 1975 visually discovered 12 comets, the last three of these coming in the teeth of the comprehensive sky survey programs that have come on-line within the past two decades. He found two of the three comets visually discovered during the decade of the 2010s, with the last of these -- Comet Machholz-Fujikawa-Iwamoto C/2018 V1 (no. 655) -- being the most recent visually-discovered comet as of this writing; I consider it distinctly possible, if not probable, that this may well be the last visually-discovered comet, ever.

I first met Don in early 1981 when I was in the U.S. Navy, and the ship I was stationed on made a liberty port call in San Francisco; I rented a car, drove to San Jose where he was living at the time, called him up, and ended up having dinner with him and his then-wife Laura. We have remained good friends ever since, and I have had the distinct pleasure of confirming or co-confirming four of his subsequent comet discoveries. I last saw him at the penultimate Riverside Telescope Makers Conference in May 2018, where he informed me that he was still hunting for comets on a fairly regular basis; he found his last comet just a little over five months later, and not too long thereafter relocated from California to rural northwestern Arizona. He continued to hunt for comets from there, but, very sadly, he will never find another one, for just a little over six months ago, on August 9, 2022, Don passed away from COVID-19 at the age of 69.

Due to the two short-period comets Don discovered it is theoretically possible that his name can continue to show up on my tally from time to time. He discovered the first of these -- his third overall discovery -- in May 1986, and together with Charles Morris I officially co-confirmed Don's discovery the following morning. Prior to this year I have observed it on four subsequent returns, including in 2007 (no. 405) as a part of "Countdown" and again in 2012 (no. 507). The comet has turned out to be of enormous interest from a scientific perspective, and I discuss some of the reasons for that in its "Countdown" entry.

The comet was badly placed for observation -- especially for the northern hemisphere -- during its 2017 return, and I did not attempt it. Since Comet 96P has been observed near aphelion in the past it can be considered an "annual" comet and thus is not "recovered" in the traditional sense; the first observation of the current return was obtained on May 6, 2022 by Japanese amateur astronomer Hidetaka Sato utilizing a remotely-controlled telescope at Siding Spring Observatory in New South Wales. It continued to be imaged on an occasional basis up through the beginning of December, but -- at least on the images I've seen -- it remained a faint and essentially inactive object.

As the comet was passing through perihelion at the end of January 2023 it spent roughly four days traversing the field-of-view of the LASCO 3 coronagraph aboard the SOHO spacecraft, wherein it put on a spectacular show. As it was doing so researchers Karl Battams and Qicheng Zhang carried out a research program utilizing a special narrow-band filter, and during the course of this they detected several small fragment accompanying the comet -- some of which may be the same as those that have been detected in LASCO images taken during previous returns -- as well as what appears to be a thin trail of smaller debris. These objects are all quite probably related to some of the other items of scientific interest associated with Comet 96P, and at this writing a detailed analysis of the LASCO data is being carried out.

      LEFT: Comet discoverers at the 50th Anniversary Riverside Telescope Makers Conference, May 26, 2018. Left to right: David Levy, Jean Mueller, Don Machholz, and me. This would be the last time I saw Don while he was still alive. Photograph by Vickie Moseley. RIGHT: Comet 96P in the LASCO C3 coronagraph aboard SOHO roughly 10 minutes before its perihelion passage on January 31, 2023. Courtesy NASA/ESA.

Comet 96P was unfavorably placed for viewing after perihelion, and although I had successfully obtained a couple of observations at the similarly unfavorable return in 2002 (no. 300) in my present reduced rate of activity I wasn't sure if I would even attempt it this time around. However, in tribute to Don's recent passing I decided I would make a special attempt to see it at least once. The comet actually did become accessible from the ground a little over a week after perihelion, albeit at a very small elongation, and a few of the images taken then that I've seen show it as a relatively nice object near 8th magnitude with a distinct tail. Per its normal behavior it faded pretty rapidly, and since it is receding on the far side of the sun from Earth its elongation increased only gradually and remained fairly small. I had to contend with moonlight and a continuing series of storms and cloudy weather that passed through New Mexico during February, plus the fact that from my normal observing site I have trees in that particular direction, and I knew things would be pretty much touch-and-go as far as seeing the comet was concerned. Finally, on the morning of February 24 I had relatively decent sky conditions, and although dawn was well underway by the time the comet cleared the trees, I successfully detected it -- and was able to see it for all of two to three minutes before the dawn began to overwhelm it. It appeared as a dim, small, and slightly condensed object roughly between magnitude 11 1/2 to 12, although it's fair to say that in the bright sky I was probably only seeing the inner coma.

While my brief observation under far-from-ideal conditions is not what I would consider an especially satisfying observation, I am nevertheless thrilled to have been able to see one of Don's comets again. (Incidentally, this gives him his 21st entry on my lifetime tally, which puts him tied for 4th place with the Shoemakers (discussed in the previous entry). This is also the 7th-smallest perihelion distance of all the comets on my tally; curiously, Don's second discovery, Comet Machholz 1985e (no. 83), which had a perihelion distance of only 0.106 AU, is in 5th place on that same list.). This will quite probably be my only observation of this comet this time around; while the elongation -- 34 degrees at the time of my observation -- does continue to increase gradually over the coming weeks, it still remains relatively small for quite a while yet, and meanwhile the comet should continue to fade rapidly.

It so happens that Comet 96P's next return, in 2028 (perihelion mid-May), is an especially favorable one, with an approach to Earth of 0.32 AU and a traverse through northern circumpolar skies -- maximum declination +87.5 degrees -- the following month. I have stated in numerous previous entries, however, that I have been looking seriously at "retiring" from visual observing in 2024, ostensibly after the apparitions of Comets 12P/Pons-Brooks and 13P/Olbers are over -- although I may extend that, since a just-discovered apparent (and not yet officially announced) comet found by the ATLAS program -- for which I have already submitted several astrometric measurements from images I've obtained via the Las Cumbres Observatory network -- has the potential to become a spectacular object later that year. (Although, to borrow a cliche, "a lot of stars would have to align" properly for it to do so, if this object does indeed become bright it is accordingly conceivable that I could "go out with a 'bang!'" In any event, I will presumably have more to say about this as the time approaches.) I have always retained the caveat, meanwhile, that I reserve the right to "come out of retirement" if something bright or otherwise interesting comes along. While a lot will depend upon what my personal life circumstances are five years from now -- which I am not going to speculate about at this time -- this appearance by Don's comet might well warrant such a special occasion. Perhaps it would be a fitting tribute to this champion comet discoverer and my long-time friend.

INITIAL OBSERVATION: 2023 February 24.52 UT, m1 = 11.5:, 0.7' coma, DC = 2-3 (41 cm reflector, 229x; low altitude, twilight)

UPDATE (February 28, 2023): I stated above that I probably would not be seeing this comet again, however it turns out that on the last morning of February I had good sky conditions, and although I was concentrating on some of the other morning-sky comets I decided to make another attempt for this one, since its elongation had increased to 37 degrees and it was accordingly rising somewhat earlier. I successfully detected it, and although it had faded some since my initial observation, the fact that I was able to view it in a darker sky (albeit still in twilight) and could follow it for a somewhat longer period of time made this a distinctly more satisfying observation.

At this time I plan no further observations of Comet 96P -- until, conceivably, 2028.

MOST RECENT OBSERVATION: 2023 February 28.52 UT, m1 = 12.2:, 1.6' coma, DC = 2 (41 cm reflector, 229x; twilight)


734. COMET 364P/PANSTARRS          Perihelion: 2023 May 14.02, q = 0.801 AU

With this addition to my comet tally this particular comet, with a current orbital period of 4.89 years, becomes the comet with the 5th-shortest orbital period that I have seen on two or more returns. It was originally discovered by the Pan-STARRS survey in Hawaii in February 2013 and I searched unsuccessfully for it during that return, and then I successfully observed it during its subsequent return in 2018 (no. 643); I give a more complete account of its history in that entry. It was during the course of that return -- shortly after its closest approach to Earth, and during the period of time when it was inaccessible from my latitude -- that I underwent the period of hospitalization associated with some of the health issues that are causing me to give serious consideration to the thought of "retiring" from visual comet observing in about a year and a half's time.


On the present return Comet 364P was recovered on December 25, 2022 by the Mt. Lemmon Survey in Arizona. Initially it was very faint and appeared entirely asteroidal, but as it approached the sun and Earth various images, including a set I obtained via the Las Cumbres Observatory (LCO) network on March 17, showed it as having brightened and exhibiting a distinct tail. I took another set of LCO images on the night of March 26-27 which suggested it was bright enough to detect visually, and shortly after midnight I successfully did so. It appeared as a small and condensed object of 13th magnitude, with a slight suggestion of the tail that shows so well on images. I followed it for half an hour and it exhibited distinct motion during that time.

At the time of my observation the comet was located 0.18 AU from Earth, and on April 7 it passes 0.121 AU from our planet -- the 15th closest approach to Earth of all the comets on my tally. It is a morning-sky object, presently located in western Hercules and traveling east-ward at three degrees per day. Over the next few weeks it turns gradually towards the east-southeast and accelerates, crossing southern

Comet 364P/PANSTARRS on the night of March 26-27, 2023 -- five hours before my first visual observation -- as imaged by the Las Cumbres Observatory facility at Teide Observatory in the Canary Islands.

Hercules and southern Lyra, and at the time of its closest approach to Earth will be located in western Vulpecula some four degrees south-southeast of the star Albireo (Beta Cygni) and traveling at 5 1/2 degrees per day. On the following day the comet passes 20 arcminutes south of the planetary nebula M27, and eight days later (after crossing Delphinus and entering Pegasus) it passes one degree south of the globular star cluster M15. At the beginning of May it will be located in eastern Aquarius and will have slowed down to one degree per day; at an elongation of 46 degrees and south of the sun it will by then primarily be a southern hemisphere object. During the weeks after that the comet tracks in a generally eastward direction across Cetus, where it remains until the end of 2023; meanwhile, by the latter part of June it again becomes accessible from mid-northern latitudes.

Comet 364P may reach a peak brightness near 12th magnitude, possibly 11th, around the time of its closest approach to Earth, although unfortunately moonlight -- full moon taking place on April 6 -- will interfere with observations during this interesting period of time. I expect it to fade as it pulls away from Earth, and it will probably no brighter than 13th or 14th magnitude around the time of perihelion passage. By the time the comet becomes accessible again from my latitude in June I suspect it will have faded beyond the range of visual observations. It appears, then, that my period of viewing this comet will be fairly brief, and at best I will likely only obtain a handful of observations of it.

As I indicated in the entry for the 2018 return, at this comet's next return in 2028 (perihelion late April) it passes 0.50 AU from Earth in mid-March and, theoretically at least, may again become bright enough for visual observations, although I doubt if it gets any brighter than 13th or 14th magnitude. That, together with the fact that it will be crossing dense Milky Way star fields in Sagittarius during the time of its closest approach, along with the fact that this is well after my probable "retirement" date, suggests that whatever additional observations I am able to obtain this time around will be the final ones I ever obtain of this small and frequent visitor to the inner solar system.

INITIAL OBSERVATION: 2023 March 27.27 UT, m1 = 13.1, 0.5' coma, DC = 6-7 (41 cm reflector, 70x)


735. COMET ATLAS C/2023 E1          Perihelion: 2023 July 1.11, q = 1.027 AU

After a high level of cometary activity in early 2023 -- highlighted by the relatively brief naked-eye appearance of Comet ZTF C/2022 E3 (no. 722) -- that activity has dropped dramatically during recent weeks; by early May I was only following a couple of faint, distant long-period comets. I expect the comet activity to pick up again later this year, and in the meantime I've been able to add this new comet to help bridge the gap.

This particular comet was discovered on March 1, 2023 by the ATLAS program's telescope located in South Africa -- one of two ATLAS telescopes in the southern hemisphere that became operational in early 2022 (the other being based in Chile). Orbital calculations have shown this Comet ATLAS to be a Halley-type object with an orbital period of 85 years and to be traveling in a moderately-inclined direct orbit (inclination 38 degrees). At the time of its discovery the comet appeared as a faint and only slightly non-stellar object of 18th to 19th magnitude, however within the fairly recent past various images I've seen have shown the presence of a faint and diffuse extensive outer coma; a set of images I obtained via the Las Cumbres Observatory network a few nights ago also showed this. When I attempted the comet visually on the evening of May 9 I was able to detect it as a vague and diffuse object of 12th magnitude.

Comet ATLAS has now entered northern circumpolar skies, and is presently located three degrees north of the star Delta Ursae Majoris ("Megrez" -- the star where the Big Dipper's "handle" connects to the "bowl") and traveling almost due northward at half a degree per day. Over the coming few weeks it gradually begins curving eastward -- in the process passing 20 arcminutes east of the bright spiral galaxy NGC 4236 on June 2 -- and reaches a peak declination of +80.6 degrees on July 8, at which time it will be located roughly half-way between the stars Zeta and Epsilon Ursae Minoris in the "handle" of the "Little Dipper." Afterwards the comet's motion turns more southerly as it travels through eastern Draco, Cepheus -- passing 1 1/2 degrees southwest of the future North Pole Star Alpha Cephei on August 4 -- and then Cygnus, where it crosses the open star cluster M39 on August 12. On August 18 Comet ATLAS passes 0.37 AU from Earth, at which time it will be close to opposition and located in eastern Cygnus 1 1/2 degrees south of the star 72 Cygni and traveling just eastward of due south at slightly over two degrees per day. After that it gradually slows down as it pulls away from Earth, traveling southward through eastern Pegasus and then Aquarius -- passing less than 10 arcminutes west of the star Alpha Aquarii on September 6 -- where it remains until finally crossing into northeastern Piscis Austrinus in late October.

The large outer coma that Comet ATLAS has developed and its recent rapid brightening are not unusual phenomena in Halley-type comets. Although brightness predictions in a case like this are always a bit problemetical, I consider it a reasonable possibility that the comet could reach a peak brightness of at least 10th magnitude as it passes through perihelion and then makes its passage by Earth, and subsequently should remain visually detectable until perhaps sometime in October.

The most recent orbital calculations for Comet ATLAS suggest it should have previously returned to perihelion in early September 1937. Taking that at face value, the viewing geometry then was distinctly less favorable than it is this time around, with the comet's closest approach to Earth being a relatively distant 1.2 AU, and with its being located in the evening sky near an elongation of 50 degrees around the time of perihelion. Most of the photographic patrol programs of that era tended to concentrate on areas of the sky near opposition, and with a brightness of perhaps 12th magnitude it was probably a little too faint for the visual hunters then; thus, it is unlikely -- although certainly not impossible -- that records of the comet's appearance then might someday be identified.

INITIAL OBSERVATION: 2023 May 10.20 UT, m1 = 11.9, 2.5' coma, DC = 1 (41 cm reflector, 70x)


736. COMET 237P/LINEAR          Perihelion: 2023 May 14.68, q = 1.987 AU

In many respects, this comet's story starts in June 2010, when the Wide-field Infrared Survey Explorer (WISE) spacecraft -- now retooled under the mission name NEOWISE -- discovered a faint comet in infrared images, which was soon found to be about 20th magnitude when observed by ground-based telescopes. Shortly after it was discovered it was found to be identical to an apparent asteroid, designated as 2002 LN13, that had been discovered in June 2002 by the LINEAR program in New Mexico, and followed for the next two months. Despite its stellar appearance at the time 2002 LN13 was found to be traveling in a distinctly cometary orbit with an orbital period of 7.2 years, and at the time of its re-discovery by WISE in 2010 it was located very close to its expected location.

The WISE discovery took place some six months after the comet's perihelion passage, and it remained a very faint object for the rest of that apparition. On the way back in to its next return it passed 0.41 AU from Jupiter in March 2013, which shortened its orbital period to 6.6 years and decreased its perihelion distance from 2.4 AU to its present value; after that it was duly recovered in early 2015 en route to its perihelion passage the following year. Since all the previously-reported observations suggested this was a faint and nondescript short-period comet I never considered it as something I might see visually, however in mid-2016 -- about two months after it had gone through opposition -- I started to read reports that suggested it might be worth attempting, and in late June I successfully detected it (no. 599) near 14th magnitude. I subsequently followed it on an occasional basis for the next four months, and when I last saw it in late October -- two weeks after perihelion passage -- when it was getting low in my southwestern evening sky it had brightened to slightly brighter than 13th magnitude.

On its current return Comet 237P was recovered on February 4, 2022 by the Pan-STARRS survey based in Hawaii. Reports and images I've seen over the past several weeks -- including a set of Las Cumbres Observatory (LCO) images I took in mid-April -- have suggested that it might be bright enough to detect visually, although when I attempted to do so during the latter part of April I couldn't convince myself I was seeing it. (The rich Milky Way star fields in Sagittarius that the comet was traveling through at the time didn't help in that effort.) Just within the past couple of weeks more recent images, including another set of LCO images I took, have suggested that it is even brighter now, and when -- after having to wait out a week of rainstorm activity that passed through New Mexico -- I attempted the comet again on the morning of May 22 I successfully detected it as a small and moderately condensed object of 13th magnitude.

Comet 237P just passed through perihelion a week and a half ago, and will be closest to Earth (1.06 AU) on July 8 and at opposition a few days later. It is presently located in far southern Aquila some two degrees northeast of the star 51 Aquilae and traveling towards the north-northeast at roughly 15 arcminutes per day; it remains in southern Aquila for the next five months, curving northward and then westward as it passes through its stationary point on June 8 and reaches a peak northerly declination of +0.9 degrees on August 2, after which it curves southward and then eastward as it passes through its other stationary point on August 22 and passes 10 arcminutes southwest of the star Iota Aquilae on September 15. There isn't much to go on as far as predicting its post-perihelion brightness behavior, but it might brighten by perhaps a half-magnitude or so by the time it passes closest to Earth and then might remain visually detectable for perhaps another month.

This becomes, incidentally, the third Periodic Comet LINEAR that I have seen on two or more returns, the other two being 209P/LINEAR which I observed in 2009 (no. 455) and in 2014 (no. 543), when it passed 0.055 AU from Earth; and 217P/LINEAR, which I observed on its discovery return in 2001 (no. 297), in 2009 (no. 459), and in 2017 (no. 620). Overall, I have visually observed 71 LINEAR-discovered comets, and including these multiple-return objects LINEAR now accounts for 75 comets on my tally, 10.2% of the grand total.

Although I have primarily focused on observing comets, throughout most of my visual observing "career" I have also observed numerous other phenomena, including novae and supernovae when reasonably bright ones have appeared, but as I have been winding down my visual activities during recent years I have significantly diminished that facet of my observing, with rare exceptions. One of these exceptions has now taken place, as on the same morning I added Comet LINEAR to my tally I also observed, for the first time, the recently discovered Supernova 2023 ifx in the nearby galaxy M101 at a relatively bright magnitude 11.2. (This supernova was discovered on May 19, 2023, by Japanese amateur astronomer Koichi Itagaki, who among his many other discoveries over the years re-discovered the long-lost periodic comet now known as 205P/Giacobini in 2008 (no. 438), which I also observed at the subsequent return in 2015 (no. 583), and discovered Comet Itagaki C/2009 E1 (no. 452).) Supernova 2023ifx is the 48th supernova I have visually observed, albeit the first one in almost 4 1/2 years, and is the brightest one I have seen since Supernova 2011fe (which also appeared in M101) in September 2011. As of right now Supernova 2023ifx is tied for the third-brightest supernova I have ever seen, although theoretically it may continue to brighten some more over the coming days.

INITIAL OBSERVATION: 2023 May 22.36 UT, m1 = 12.9, 1.2' coma, DC = 4-5 (41 cm reflector, 70x)


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