As I have been discussing in numerous previous entries, and as I wrote in the text of my new "Comet Page," at the end of 2024 I "retired" from systematic visual comet observing, after 55 years at this endeavor and with my lifetime comet tally standing at 760. But as I also wrote in the new page, for at least the near-term future I am not walking away from visual comet observing altogether, but will continue to make efforts to observe bright and/or interesting comets that might comet along, although this will be on an occasional rather than a systematic basis. (I also expect to continue my imaging activities via the Las Cumbres Observatory network and my collaboration with its Global Sky Partners educators' forum.) As I have done for the past several years, I will continue to write up descriptions of any additional comets I add to my tally, and post them to these pages.

My first "post-retirement" tally addition certainly qualifies as a "bright and/or interesting" comet. It was discovered on April 5, 2024 by the ATLAS program's Chile telescope, a 19th magnitude object in southern circumpolar skies near a declination of -74.5 degrees. I obtained my first set of images of it via the LCO network five days later, and the astrometrical measurements from this set and another set of images I obtained on the 16th were included in the comet's discovery announcement. Even as early as that second set of images I could detect a short tail extending towards the north-northwest.

As soon as the first orbital calculations were published, Comet ATLAS' extremely small perihelion distance called almost immediate attention to it. A comet approaching that close to the sun might very well not survive perihelion passage, however as additional observations and calculations began to show that Comet ATLAS is apparently not a first-time visitor from the Oort Cloud -- the previous return having taken place approximately 190,000 years ago -- these seemed to suggest that there was at least some chance it might survive perihelion and, conceivably, put on a respectable show. The comet is traveling in a steeply-inclined retrograde orbit (inclination 117 degrees) and, unfortunately for those of us in the northern hemisphere, the orbit is oriented such that the comet both approaches and recedes from the sun from almost directly south of it, and would only be north of the sun, and accordingly accessible from the northern hemisphere, for a very brief interval around perihelion, when, of course, it would be located very close to the sun.

I continued to image Comet ATLAS via LCO on a semi-regular basis up through the end of August (after which its elongation became too small for the LCO telescopes to access); by my last set of images it had brightened to about 17th magnitude and was displaying a distinct tail several arcminutes long. The earliest visual observations of which I'm aware were made by observers in the southern hemisphere in late October, which indicated a brightness near 12th magnitude -- as much as two magnitudes brighter than expected, which in turn suggested a higher probability of surviving perihelion passage. The southern hemisphere observers continued to make additional observations into early November, which indicated a slight brightening, but shortly thereafter the comet went into conjunction with the sun (roughly 28 degrees south of it) and, for a time at least, observations were no longer possible.

Comet ATLAS began emerging into the southern hemisphere's morning sky around the beginning of December, although it remained at a small elongation -- initially around 20 degrees, decreasing to 18 degrees by month's end. Observations continued to show it running about two magnitudes brighter than originally expected, and by the end of 2024 observers in the southern hemisphere were reporting brightnesses around 6th magnitude. A few days later, however, the comet underwent a distinct outburst, to about 2nd magnitude, and despite an elongation of only 16 degrees several observers reported naked-eye sightings. Comet ATLAS continued to brighten from that point as it approached the sun, being about 1st magnitude when it began disappearing into morning twilight around January 11. By this time the comet had traveled far enough north such that observers in the northern hemisphere also began reporting observations and images.

      LEFT: The final image I took of Comet ATLAS via the Las Cumbres Observatory network, obtained August 29, 2024 from the LCO facility at Cerro Tololo Inter-American Observatory in Chile. RIGHT: Comet ATLAS as photographed by astronaut Donald Pettit aboard the International Space Station on January 11, 2025. Courtesy NASA.

Beginning on January 11, Comet ATLAS entered the field-of-view of the LASCO C3 coronagraph aboard SOHO, where it would remain for the next four days. Its high brightness in the LASCO images rather strongly suggested that it might be visible during daytime, and, indeed, several observers soon successfully took daytime images and/or reported successful daytime observations. Eighteen years ago I had used a 20-cm SCT and altitude/azimuth offsets from the sun to make successful daytime observations of Comet McNaught C/2006 P1 (no. 395), and I decided I would use the same instrument and procedure to attempt daytime observations of Comet ATLAS. Bad weather and clouds precluded any realistic attempts for a couple of days, but, finally, on January 14 I had clear skies, and shortly after 11:20 A.M. I managed to spot the comet -- then at an elongation of just under 7 degrees -- although I lost it in the bright sky after about a minute. A little less than an hour and a half later I spotted it again, and successfully followed it for the next half-hour. It appeared as a bright central condensation with a faint trace of coma and the beginnings of a slightly curved tail. Under the circumstances the making of a formal brightness measurement would be somewhat problematical, but the comet definitely appeared fainter than I remember for Comet McNaught, and I accordingly "guesstimated" the brightness as being near magnitude -2.

    LEFT: Comet ATLAS in the LASCO C3 coronagraph aboard SOHO on January 14, 2025, at roughly the same time as my initial sighting. Courtesy NASA/ESA. RIGHT: Daytime image of Comet ATLAS taken by Monika Landy-Gyebnar in Hungary on January 14, 2025, roughly 10 hours before my initial sighting. The comet's appearance in this image approximates what I saw through the 20-cm SCT. Image used with permission.

Shortly thereafter Comet ATLAS began emerging into bright twilight in the evening sky, and several observers took images and reported successful observations. I do not have a good horizon in that direction from my home location, so I made arrangements to view the comet on the evening of the 15th from the parking lot of the New Mexico Museum of Space History in Alamogordo (which is located on a mountainside above the city and which has a good view of the far western horizon). Unfortunately, some thick cirrus clouds began moving into the southwestern sky during the hours immediately preceding my observing session, although I nevertheless did set up my 10-cm SCT in case there was some clearing. As things turned out, I did successfully see the comet for about 30 seconds when it passed through a brief gap in the clouds just over 20 minutes after sunset when, at an elongation of just under 10 degrees, it was located some 4 degrees above the horizon. Once it disappeared behind a thick cloud at the bottom of that gap, that was the end of its visibility. The comet exhibited a bright central condensation and the beginnings of a curved tail a few arcminutes long; I would "guesstimate" its brightness as being somewhere near magnitude -1.

For me, Comet ATLAS is already gone. Theoretically it has remained accessible in the evening sky and may continue to be so for a couple of more nights, although it is only marginally higher above the horizon than it was on the 15th, and with less-than-ideal weather prospects (and my reluctance to embark on another two-hour roundtrip drive to Alamogordo for what might very well end up being the proverbial "wild goose chase") I have made no plans for further observation attempts. Furthermore, the comet is plunging southward fairly rapidly -- thus quickly becoming inaccessible again from the northern hemisphere -- and since it is now receding from the sun and Earth it is also fading.

For observers in the southern hemisphere, meanwhile, the conditions for visibility are rapidly improving, and it is entirely possible that they may witness a pretty good show over the next two to three weeks -- indeed, initial reports at this writing do suggest a relatively decent display could be in the works. The comet remains somewhat low in the evening sky, however, with the elongation not going above 30 degrees until almost mid-February and not above 40 degrees until mid-March. It is in conjunction with the sun (48 degrees south of it) at the beginning of April, at which time it will probably be close to fading beyond visual detectability.

The current view of Comet ATLAS from the southern hemisphere. This image was taken by Rob Kaufman from near Bright, Victoria, Australia on the evening of January 17, 2025. Used with permission.

This sort-of "extra" comet to my tally is unique and at or near record-breaking in several respects. It has the 4th-smallest perihelion distance of any comet on my tally, and at the time of my first sighting on January 14 its heliocentric distance was 0.119 AU, the smallest heliocentric distance at which I've ever observed a comet. Comet ATLAS becomes only the third comet that I have observed during daytime, a total that includes Comet Hale-Bopp C/1995 O1 (no. 199) which I sucessfully followed for one minute after sunrise one morning before losing it in the bright sky; it is the only comet I have ever added to my tally during daytime. At magnitude -2 it is the 3rd-brightest comet I have ever seen, and it is the brightest comet I have ever observed on my initial observation. Since I never observed Comet ATLAS with my naked eye (or even with binoculars) I don't consider it a "Great Comet" (at least, from my perspective), but the fact I could observe it during daytime does warrant consideration as being among my "best" comets; I accordingly rank it as the 8th-best comet I have ever observed.

INITIAL OBSERVATION: 2025 January 14.84 UT, m1 = -2:, 0.5' coma, DC = 8, 2' tail in p.a. 050 (20 cm SCT, 80x; daytime)

UPDATE (February 5, 2025): Pretty much as expected, Comet ATLAS put on a good show for observers in the southern hemisphere during the latter half of January, pretty much approaching "Great Comet" status. Various reports placed it between 1st and 3rd magnitude, and it exhibited a bright, somewhat curved dust tail at least 15 degrees long. (The extremities of this tail were even detectable from the northern hemisphere, although I never looked for this.) By around January 20, however, it was starting to become clear that the comet's nucleus had disintegrated, and from that point on the comet has appeared more-or-less as a "headless wonder," i.e., still a bright tail but with no real coma.

  IMAGES OF COMET ATLAS FROM THE SOUTHERN HEMISPHERE. LEFT: January 22, 2025 as photographed by Michael Mattiazzo in Swan Hill, Victoria. RIGHT: The comet's inner regions on January 26, 2025, imaged remotely from Namibia by Gerald Rhemann. There is no actual coma, just tail streamers extending from the comet's front. Both images used with permission.

By late January the comet's overall brightness had faded to about 4th magnitude, although it was still readily visible to the naked eye, with the tail's appearance being likened to that of a "searchlight beam." Now that the moon is in the evening sky the show is essentially over; by the time the moon leaves the evening sky later this month there may not be very much of the comet left to see.

762. COMET SWAN C/2025 F2          Perihelion: 2025 May 1.16, q = 0.333 AU

Thus far, this current year of 2025 has been "interesting," often in the sense of the ancient Chinese curse, and at times it almost seems surreal. While I have usually avoided commenting on political issues in these tally entries, I feel compelled to say that I am ashamed of and disgusted at the havoc wreaked on this country and the world at large by the current Presidential administration -- which I foresaw in the aftermath of the election last November (and commented on at the end of a previous entry). Although I have not -- yet, at least -- been personally affected much in any direct sense, many, many others are not so fortunate, and it is difficult for me to maintain any kind of optimism in the current climate. Hopefully we will find a way to get through this, but any thoughts I have previously had about a positive future for humanity have been all but shattered, at least for now. I would love to be proven wrong, but . . . In any event, I continue to take things one day at a time, and am continuing my collaboration with the Las Cumbres Observatory Global Sky Partners, since that, at least, seems to offer me some hope for the future.

As any readers who have been with me for any significant time may recall, I "retired" from systematic visual observing, including visual comet observing, at the end of 2024. I have nevertheless continued to make observations on an occasional basis, which included my observations of the previous tally entry in January, and one observation of Comet 29P/Schwassmann-Wachmannn 1 (no. 498) -- which had just undergone a new outburst -- on the evening of February 2 in order to mark the 55th anniversary of my first comet observation. (I also observed the total lunar eclipse on the night of March 13-14, although the sky conditions were less than ideal.) I did not make any visual comet observations at all during the month of March, the first calendar month I have failed to observe any comets since September 1981 -- over 43 years ago. Part of the reason for this is that the overall cometary activity in the sky has been quite low lately -- although 29P has certainly been observable -- but in keeping with my "retirement" I have not made the effort I would have made in previous years.

My second post-"retirement" tally addition is a comet that was initially detected in images taken by the SWAN ultraviolet telescope aboard the SOHO spacecraft beginning on March 22, 2025, independently by three champion SWAN comet-hunters: Vladimir Bezugly in Ukraine, Rob Matson in California, and Michael Mattiazzo in Victoria. Because of the poor positional and time resolution of the SWAN images, as well as to a relatively small elongation from the sun, it took a while before ground-based observers were able to locate the comet, but once it was found shortly after the beginning of April numerous observations began to be reported, most of these indicating it was around 10th magnitude. After an orbit was computed it was found as a very faint object in images taken by the Pan-STARRS survey (as well as in one DECam image) to as far back as early September 2024. Meanwhile, several ground-based observers noted that the comet apparently underwent a distinct increase in brightness, to about 8th magnitude, around April 6.

From my own perspective, although I was aware of the discovery quite early on, the comet's low elongation (28 to 29 degrees) rendered it inaccessible from my main home observing site (since I have trees in that direction), and this, combined with my "retirement" and the initial large uncertainty as to its actual location, made me reluctant to expend any effort to travel to another location for any observation attempts. Furthermore, a series of several consecutive cloudy nights, which included a non-trivial snowstorm on the night of April 4-5, precluded any such attempts anyway. I finally had clear skies on the morning of the 7th -- although in the wake of the earlier storm the temperature was well below freezing, which is unusually cold for early April -- and in light of the reports of the comet's recent brightening I took the 4-inch SCT to a nearby location, and successfully detected the comet shortly after it rose above the trees, however I encountered some problems with my overall setup that prematurely ended my observation after only about one minute. I tried again on the following morning and had a pretty good observation; the comet appeared as a rather condensed object of magnitude 7 1/2, and I could faintly detect the beginning of the ion tail that is quite prominent on various CCD images I have seen.

Comet SWAN is traveling in a steeply-inclined orbit with an inclination of almost exactly 90 degrees, and appears not to be a first-time visitor from the Oort Cloud, the previous return having taken place 70,000 to 100,000 years ago. It is on the far side of the sun from Earth, and was at its maximum elongation -- just under 29 degrees -- around April 5. It is presently located in the northeastern part of the "Great Square" of Pegasus, some five degrees west-southwest of the star Alpheratz (Alpha Andromedae, the star at the northeastern corner of the "Great Square") and is traveling towards the east-northeast at 1 1/2 degrees per day, passing 40 arcminutes northwest of Alpheratz on April 12. The elongation slowly decreases over the coming days, and the comet is in conjunction with the sun -- 25 degrees north of it -- on April 20, thereafter becoming primarily an evening-sky object, and reaching a maximum northerly declination just north of +35 degrees on April 23 before turning towards the southeast. At the time of perihelion passage the comet is closest to Earth (0.96 AU) and will be located in northwestern Taurus five degrees northwest of the Pleiades star cluster (M45), when it will be traveling towards the southeast at three degrees per day and passing one degree northeast of the Pleiades the following day; it will then be near its minimum elongation of just over 19 degrees. After that it turns more towards the south-southeast and slows down as it recedes from the sun and Earth, and the elongation slowly increases, although it very quickly becomes accessible only from the southern hemisphere, traveling south of the celestial Equator just after mid-May.

At this writing the moon is approaching its Full phase and is washing out the morning sky. Whether or not I observe Comet SWAN again depends largely on how it brightens during the next few weeks. If it brightens "normally" from the brightness I observed on the 8th this would suggest a possible maximum brightness near magnitude 3.5 around the time of perihelion passage, which would make travel to an observing site that could access something at the small elongation at perihelion worthwhile (especially on the evening of May 2, when it will lie quite close to the Pleiades, making it easily locatable). The fact that it is apparently not a first-time visitor from the Oort Cloud would seem to be a good sign, but on the other hand I have read very recent reports that suggest the comet may be fading, which in turn might suggest that the recent brightening was due to an outburst, from which it is now starting to subside. If that is the case, the comet may well be fainter when it passes through perihelion, and conceivably could even disintegrate as it approaches that point. We will just have to wait and see what the comet does . . . just as we will have to wait and see if this country, and the world, can pull itself out of the mess it is currently in.

SECOND OBSERVATION: 2025 April 8.47 UT, m1 = 7.5, 2.5' coma, DC = 7, 12' tail in p.a. 315 (10 cm SCT, 40x)

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