|481. COMET IKEYA-MURAKAMI P/2010 V1 Perihelion: 2010 October 13.12, q = 1.578 AU
During the 1960s and 1970s, when a majority of comets were being discovered by amateur astronomers who carried out visual searches, this endeavor was dominated by a number of amateur astronomers in Japan, who to some extent were inspired by the exploits of their countryman Minoru Honda, who discovered twelve comets between 1940 and 1968. One of the most successful of these Japanese comet-hunters was Kaoru Ikeya, who discovered his first comet (1963a) in early 1963 at the age of 19, and who would go on to discover four additional comets over the course of the next five years (one of these being the great Kreutz sungrazer Comet Ikeya-Seki 1965f, the brightest comet of the entire 20th Century). After a hiatus of over 3 1/2 decades Ikeya discovered his sixth comet in early 2002, this being Comet Ikeya-Zhang P/2002 C1 (no. 301), which became a nice naked-eye object during the spring months of that year, and which moreover was found to be identical to a comet that had been observed in 1661 by (among others) the active Polish astronomer Johannes Hevelius, making it the longest-period comet that has been definitely seen on two returns (and receiving the designation 153P in the process).
Visual comet discoveries are, of course, very rare nowadays thanks to the comprehensive all-sky surveys that are currently operating, but despite this Ikeya discovered his seventh comet on the morning of November 2, 2010. On the following morning the same comet was independently discovered -- again, visually -- by another Japanese amateur astronomer, Shigeki Murakami; this is his second named comet discovery, the first one being Comet Snyder-Murakami C/2002 E2 (no. 305) which, curiously, he found less than six weeks after Ikeya's last discovery. Both of them reported the comet as being between magnitudes 8 1/2 and 9, and when I first observed it on the morning of November 4 I saw it at about this same brightness. It was located in western Virgo 1 1/2 degrees southwest of the bright double star Gamma Virginis and 2 1/2 degrees (i.e., in the same binocular field) west of the planet Saturn; at an elongation of only 32 degrees and deep in the zodiacal light it was difficult to see in binoculars but very easy in the 41-cm telescope.
According to the most recently calculated orbit at this writing, Comet Ikeya-Murakami has just recently passed through perihelion, and is just now emerging into the morning sky following conjunction with the sun back in mid-July. Earlier this year it was theoretically accessible in the evening sky, having been at opposition in November 2009 and not disappearing into evening twilight until around this past April; based upon its discovery brightness it should have been easily discovered by the ongoing surveys and quite possibly detectable visually. The fact that the comet wasn't discovered back then suggests that it might have undergone an outburst not too long before its discovery, and in fact Ikeya has reported that he covered the same region of sky on November 1 but didn't pick it up, thus adding some additional evidence to this suggestion. Furthermore, CCD images that have been taken since the comet's discovery show that it is becoming increasingly diffuse, and when I obtained my second observation on the morning of the 8th it had clearly faded some (by perhaps half a magnitude) and was distinctly less condensed than it had been on the 4th. The comet's orbital inclination of only 9 degrees suggests, incidentally, that it might be of short period, and within another week or two there should be enough positional information available to confirm (or refute) this suggestion; if it does turn out to be periodic it is conceivable that it might be found to be identical to some comet observed in the past.
In any event, the comet is currently located just over a degree south of Saturn, and according to the most recent orbit its elongation will slowly increase over the coming weeks as it travels towards the east-southeast through Virgo, passing some two degrees northeast of the bright star Spica towards the latter part of November. It crosses into Libra shortly after mid-December and then into northern Scorpius during the latter part of January 2011, where it remains for the next several months, passing 1 1/2 degrees southwest of the bright star Antares during the latter part of February, reaching its stationary point in early April, and being at opposition shortly before the end of May. A "normal" brightness behavior would suggest only a half-magnitude or so of fading from its present brightness by the end of 2010 and a still relatively bright 11th magnitude when the comet is near opposition, however the outburst scenario that is starting to look increasingly likely suggests a fairly rapid fading during the coming weeks, and it may well be beyond the range of visual detectability by the end of this year.
Here on the home front, life continues on. Among other things, this past weekend I was involved in another Murder Mystery production that was staged by our local acting troupe, and in addition to me the cast also featured my younger son Tyler (home for the weekend from college) and my girlfriend Susanne. None of us were among those "whodunit," however . . .
UPDATE: Within a fairly brief period of time it became clear that Comet Ikeya-Murakami had indeed undergone an outburst shortly before its discovery. CCD images over the subsequent days (such as this one) showed that a distinct hood-shaped structure was expanding out from the central condensation, and over the next few weeks the entire comet clearly faded; by shortly after mid-November I was seeing it as a rather diffuse object between 10th and 11th magnitude, and by early December it had faded still further to magnitude 13.
Furthermore, my suggestion above that the comet might be of short-period has turned out to be correct. As of early December the orbital period is still somewhat uncertain, but appears to be in the neighborhood of a rather short 5.0 years. There isn't too much change from the trajectory described above; the passage south of Antares will now be in mid-February 2011, and opposition takes place in early June. I expect the comet will have faded from visibility long before then, of course.
UPDATE: Comet Ikeya-Murakami's orbital period now seems to be fairly well established as being 5.3 years. According to this orbit, the geometrical circumstances at the comet's next return, in 2016 (perihelion latter part of January) are quite favorable, with its passing 0.69 AU from Earth during the latter part of March and being at opposition in early April. Since we now know that the comet's discovery brightness was due to an outburst, there is no reason to believe that it will be bright enough to detect visually in 2016, but it will be interesting to see just how bright it does get at that return (assuming it still even exists then).
Meanwhile, the geometry at the previous return, in 2005 (perihelion late June), was pretty unfavorable. The return before that, however -- perihelion in mid-March 2000 -- was even better than that in 2016 will be, and the comet would have passed 0.64 AU from Earth around the time of opposition in mid-February. It obviously wasn't discovered, of course, despite the fact that the LINEAR program was fully operational at the time, and this adds further weight to the idea that this comet is normally a very faint object.
UPDATE: More definitive orbital calculations have now rather firmly fixed the orbital period as being 5.38 years. The geometical conditions at the comet's next return, in 2016, are excellent, with perihelion passage taking place in late February, and opposition and closest approach to Earth (0.59 AU) taking place in early March. The previous return, in 2005 (perihelion early June) was still relatively unfavorable, while the return before that, in 2000, was a moderately favorable one, with perihelion passage in mid-January, closest approach to Earth (0.76 AU) in late March, and opposition in mid-April.
UPDATE: The first formal predictions for the comet's next return in 2016 have now been published. Perihelion passage is predicted for the second week of March, with opposition and closest approach to Earth (0.61 AU) taking place shortly after mid-February.
One morning after adding the previous comet to my tally I added yet another one, a comet that I have been somewhat expecting. This one was discovered on January 19, 2010 by Rob Cardinal with the Rothney Astrophysical Observatory at the University of Calgary in Alberta; this is his second comet discovery, his first one being an earlier "Countdown" comet that I added to my tally two years ago. Like that earlier object, this newer Comet Cardinal was also in northern circumpolar skies (declination +74 degrees) when found, and it is traveling in a steeply-inclined retrograde orbit (inclination 102 degrees). After begin in conjunction with the sun in early July it began emerging into the morning sky, and I began searching for it in early September; while from time to time I occasionally saw some very faint "suspects" I never saw anything that I could confirm. Finally, on the morning of November 5 I clearly saw an extremely faint, small and condensed comet of magnitude 14 1/2, and verified it by tracking its motion against the background stars over an interval of three hours.
For the most part, this is another one of those faint, distant, nondescript long-period comets that appear on my tally with some frequency. It is currently located in southeastern Gemini five degrees southeast of the star Lambda Geminorum and, having passed through its stationary point in early October, is traveling in a generally southwesterly direction, crossing into northwestern Canis Minor shortly before mid-November and then into northern Monoceros by the end of that month. The comet then crosses into southeastern Orion at the very end of 2010, into northern Lepus in mid-January 2011, and then into Eridanus at the end of that month, where it remains for several weeks therafter, being in conjunction with the sun (48 degrees south of it) in early June. It is at opposition, and is nearest Earth, during the latter part of December, when it should be near its brightest -- about a half-magnitude or so brighter than it is now -- and it should remain visually detectable until perhaps sometime in February.
The date that I added this comet to my tally is, to those who follow such things, "Guy Fawkes Day," as celebrated recently in the 2006 motion picture "V for Vendetta" -- one of my younger son Tyler's favorite movies. It is also the birthday of my late older brother Wayne, who was killed in an automobile accident many years ago; he would have been 62.
Among the many, many small and faint short-period comets that have been discovered over the past decade or so during which the comprehensive sky surveys have been operating was an 18th-magnitude comet found in December 2002 by the NEAT program, utilizing the 1.2-meter Schmidt telescope at Palomar Observatory in California. It was found to be traveling in an orbit with a period of 8.1 years and a perihelion distance of 2.53 AU; although it was still 3 1/2 months away from perihelion passage it had already gone through opposition and was receding from Earth, and thus it never got any brighter.
Meanwhile, after its subsequent aphelion a close approach to Jupiter (0.25 AU) in July 2007 shortened its orbital period to 7.59 years and decreased its perihelion distance to the present 2.12 AU. On its next return the comet was initially recovered on August 9, 2010 by H. Taylor in Georgia (US), and then over the next two mornings by several observers (including Hidetaka Sato, Leonid Elenin, and T. Yusa) utilizing various remote-controlled telescopes in New Mexico. The decreased distances from the sun and Earth, and the fact that the various observers who recovered it called it a relatively bright 17th magnitude at the time of its recovery, suggested that it might be worthwhile to attempt the comet visually, and I began doing so in early September; all my attempts up through the end of November were unsuccessful. However, soon thereafter I read of a successful visual observation by the experienced Japanese observer Seiichi Yoshida, who utilizes a telescope about the same size as my 41-cm reflector, and when I was able to attempt the comet again on the morning of December 8 I was clearly able to see it as a small and extremely faint object of magnitude 14 1/2. It was located only 15 arcminutes northeast of the 4th-magnitude star Theta Geminorum, and exhibited distinct motion during the hour and a quarter that I followed it.
The geometry of the current return is relatively favorable; although perihelion was a little over two months ago, the comet will be closest to Earth (1.25 AU) shortly after mid-December, and at opposition right before the end of the year. Unless there is a distinct asymmetry in its brightness, however, it is currently as bright as it is going to get, and I will likely only obtain another two or three observations of it at best. It is currently located in northern Gemini (still just over a degree northwest of Theta Geminorum) and, traveling towards the north-northwest, crosses into eastern Auriga within the next couple of days; it reaches its stationary point just over a degree southeast of the star Beta Aurigae in early February 2011 but will almost certainly be too faint for visual observations by then. Curiously, during the total lunar eclipse on December 21 the comet will be located just 17 degrees northeast of the eclipsed moon.
There are no close approaches to Jupiter, or any other planet, for several more decades, so Comet 240P will remain in its present orbit for the foreseeable future. The next return, in 2018 (perihelion mid-May) is pretty unfavorable, however the following return, in 2025 (perihelion shortly after mid-December) is somewhat more favorable than the current one, with opposition and closest approach to Earth taking place less than a month before perihelion passage. Thus, if I'm still observing faint comets then, I might be able to grab a handful more observations of this small and dim member of our solar system.
Over the many years that I've been observing comets there have been times when the comet activity has been very busy, with numerous comets to observe; indeed, it seems like this has been the situation throughout much of "Countdown" (for example, the occasion in March 2009 when I visually observed 15 comets in a single night). On the other hand, there are the occasional "dry spells," when there are few if any comets visible -- at least, bright enough for me to detect visually; although such periods are somewhat rare in this era of the comprehensive sky surveys, they do come by from time to time.
We've been in one of these "dry spells" during recent weeks; the various comets that I was observing during the latter months of 2010 have either all faded away or are currently in conjunction with the sun. About the only comet that I've been able to follow during the very recent past has been 29P/Schwassmann-Wachmann 1 (no. 226), which has undergone a couple of weak outbursts (although not getting above 14th magnitude on either occasion). There is, on the other hand, the apparent main-belt asteroid (596) Scheila, which underwent a dramatic comet-like outburst in early December, and which I've been following ever since; the "coma"-like structure that it was exhibiting shortly afterwards has dissipated by now, but Scheila itself reached 13th magnitude when it was at opposition around mid-February (although it has now started to fade). There are a handful of "dual-designation" objects (i.e., they have received both cometary and asteroidal designations), and an argument could conceivably be made that Scheila should be included among these; however, observations so far are suggesting that Scheila's outburst might have been due to an impact by a small (and unknown) asteroid, as opposed to an episode of cometary outgassing. If that is indeed the case then it would not be appropriate to assign Scheila a "cometary" designation, and so far at least the International Astronomical Union has not done so. Investigations are continuing, meanwhile, and if at some future date Scheila is accorded a "dual designation" status then I will add it to my tally retroactively.
The first comet that I've been able to add to my tally in almost three months was discovered on February 10, 2011, by Rob McNaught during the course of the Siding Spring survey in New South Wales. (We've encountered Rob's name numerous times already in "Countdown;" overall, this is his 58th comet discovery, and the 18th of his that I have seen, putting him all alone in 3rd place in names most frequently encountered in my tally.) At the time of its discovery this latest Comet McNaught was located in Libra, near the "head" of the constellation Scorpius, and was about 16th magnitude. It has traveled rapidly eastward since then, and after a couple of unsuccessful attempts I observed a fairly strong suspect on the morning of March 5 that I was able to confirm three mornings later (when it was located just one degree east of the star cluster (and Eagle Nebula) M16); on both occasions the comet appeared as a very faint, vague, and diffuse object of 14th magnitude. (During that three-day interim, incidentally, I "celebrated" my 53rd birthday (ugh!))
Comet McNaught is traveling in a relatively shallowly-inclined orbit (inclination 17 degrees), and is currently heading towards the east-northeast at a moderately fast 1 1/2 degrees per day (being closest to the earth -- 0.91 AU -- on March 20). Right now it is located in southern Scutum and is traveling through some very rich Milky Way star fields (making observations even more difficult than they otherwise would be); at mid-month it crosses into Aquila (gradually leaving the Milky Way fields) and near the end of this month will be located in the far eastern region of that constellation (passing just 45 arcminutes north of Comet LONEOS C/2006 S3 on the 28th). During April the comet continues its eastward trek through Aquarius and Pegasus, and after spending a couple of weeks traveling a few degrees south of and roughly parallel to the southern "edge" of the "Great Square" it enters Pisces during the second week of May, remaining there until the third week of June (and passing just over 10 arcminutes north of the spiral galaxy M74 on June 15). By an interesting coincidence, on June 14 it will be located just three degrees from the spot where Comet Levy 1991q (no. 159) was discovered exactly twenty years earlier, to the day.
Ostensibly, the comet should brighten by perhaps a magnitude or so by around the time it passes perihelion in mid-April, although I wouldn't be too surprised if it develops somewhat faster than that and reaches a peak brightness near 11th or 12th magnitude around then. Unless it becomes unusually bright, though, I expect it will probably fade beyond visual range by sometime in June. Between mid-April and the end of May the comet's elongation from the sun will be less than 50 degrees (being at a minimum value of just over 46 1/2 degrees during the second week of May); because it will be located south of the sun the viewing geometry is somewhat better from the southern hemisphere, although it should still be accessible for those of us located north of the Equator.
Meanwhile, there are some interesting comets on their way in to perihelion, and I suspect that the activity level will begin picking up by the time this comet is done . . .
UPDATE: Comet McNaught brightened unexpectedly rapidly during March, and by the beginning of April had become as bright as 10th magnitude. It is difficult to predict what to expect during the weeks to come, but theoretically the comet could brighten further to perhaps 9th magnitude around perihelion passage, and then remain visually detectable until perhaps as late as July.
The cometary "dry spell" that we've been in since early this year has continued. Comet McNaught C/2011 C1 reached 10th magnitude in April and early May, and Comet 29P/Schwassmann-Wachmann 1 (no. 226) has undergone a series of several outbursts (becoming slightly brighter than 13th magnitude on one occasion), but otherwise, there hasn't been much to observe. I finally got a second addition to my tally in 2011, but to illustrate just how slow things have been, this is only the fourth time in the past thirty years -- and only the second time since I began using the 41-cm telescope in 1987 -- that I entered the month of May with only one tally addition.
The comet in question was discovered in September 2005 by Mike Van Ness, during the course of the LONEOS program based in Arizona (a program which has produced a handful of earlier "Countdown" comets but which ceased operating in 2008). It was found to have passed perihelion seven months earlier and to be traveling in a short-period orbit with a period of 6.34 years. The comet was bright enough to be detected visually, and I obtained a handful of observations (no. 381) between late September and early November, as a dim object of 14th magnitude.
Comet Van Ness could have theoretically been discovered some time earlier than it was (the LINEAR program in New Mexico did in fact record several pre-discovery images taken in August), and there was speculation that it might have undergone an outburst at some point before its discovery. However it faded slowly, and large telescopes followed in until January 2007 (almost two years past perihelion). Then, at its next return it was recovered surprisingly early: on January 31, 2009 (almost 2 1/2 years prior to perihelion passage) by Gary Hug at his private Sandlot Observatory in Scranton, Kansas. The viewing geometry in 2011 is significantly better than it was in 2005, and if the post-discovery brightness in 2005 is indicative of its "true" brightness than it should be somewhat brighter this time around; on the other hand, if the post-discovery brightness in 2005 was due to an outburst then it could still be quite faint.
The comet was in conjunction with the sun in late November 2010 and has been slowly emerging into the morning sky ever since. CCD observations began to be reported from the southern hemisphere during April 2011, and these indicated that the comet was indeed fairly bright (14th magnitude or so). Because of its location south of the sun I wasn't able to attempt it until the morning of May 4, and I indeed did see a faint suspect then. Because of travel, and some poor star fields it was located in, I wasn't able to confirm this observation until four mornings later. It has appeared as a faint and relatively diffuse object slightly brighter than magnitude 14.
Comet Van Ness is currently located in central Aquarius, and over the next several weeks tracks east-northeastward across that constellation, finally crossing into western Pisces at the end of June and being at its stationary point a month later just to the west of the "circlet" asterism in that constellation. Afterwards it travels almost directly westward, being at opposition in early September and then crossing into southern Pegasus at mid-month, where it remains for the next several weeks; it will be at its other stationary point in mid-October. The comet's present brightness suggests it should peak near 13th magnitude during July and August, and remain visually detectable until perhaps October.
I commented in an earlier "Countdown" entry that the month of January had managed to produce, via discovery and/or recovery, at least one comet for my tally in every year going back to 1986 and extending through 2008. With the addition of this comet to my tally that string extends into 2009, and I have already observed two comets that were discovered in January 2010. Unfortunately, while there were three comets discovered and two more recovered during January 2011, none of these are objects I expect to observe. This particular string thus comes to an end, but having nevertheless extended for 25 years it is still the longest of any such string that my comet observing days have entailed.
UPDATE: Early in August several observers began to report the existence of a separate fragment of Comet Van Ness, approximately five arcminutes from the main comet. This fragment is about 19th or 20th magnitude, and once its discovery was reported it has since been noted on images of the comet taken back to mid-July. At this time it is unclear if this has separated from the main comet rather recently, or instead some time ago, i.e., around the time of the previous return in 2005. If it did in fact separate during the previous return, this could conceivably explain the possible outburst in brightness that the comet might have undergone some time before its discovery.
UPDATE: Calculations by Zdenek Sekanina at the Jet Propulsion Laboratory conclude that the fragment did indeed separate from the primary during the previous return in 2005, in fact, probably not too long before the comet was discovered. It thus seems rather likely that this fragmenting event created a surge in brightness which in turn led to the comet's discovery.
While I had to wait a long time to get my first two tally additions in 2011, the wait for my third one was pretty brief. It's a comet I've been expecting, but it has the rather dubious distinction of having one of the longest periods of unsuccessful attempts before I finally picked it up. It's not quite the longest; the record-holder in this department is the Centaur comet 95P/Chiron (no. 196), which I began attempting almost six years before I finally first observed it in early 1995.
The comet was discovered as far back as April 10, 2010, by Rik Hill during the course of the Catalina Sky Survey in Arizona. It was a very faint object of 19th magnitude at that time, and since it was still almost a year and a half away from perihelion passage it brightened only very slowly over the following months. However, at the end of August it underwent a distinct outburst, and I made a handful of unsuccessful attempts for it over the subsequent couple of weeks; according to the CCD images I saw it appeared as a very condensed, almost stellar object of 16th magnitude, and apparently was just a little too faint for me to detect. Afterwards it began to enter conjunction with the sun, and I began to attempt it again in mid-December after it started emerging into the morning sky. Despite regular attempts (two to three times per month) over the next several weeks I never convincingly saw the comet, until finally on the morning of May 8 (the same morning I confirmed the above comet) I clearly saw a very faint (slightly brighter than magnitude 14 1/2), small, and relatively condensed object that exhibited distinct motion over the course of half an hour.
Comet Hill is traveling in a steeply-inclined retrograde orbit (inclination 104 degrees) and currently is in far northern circumpolar skies, passing slightly less than 1 1/2 degrees from the north celestial pole on May 15 before passing 45 arcminutes south of the Pole Star Polaris a day later. Afterwards it begins plunging southward, entering Camelopardalis in late May where it remains for the next 2 1/2 months. It is in conjunction with the sun (44 degrees north of it, at a declination of +65 degrees) in mid-July (and, curiously, will then be passing only 15 arcminutes east of the bright spiral galaxy NGC 2403), thereafter becoming better viewed in the morning sky.
In early August the comet -- perhaps 13th magnitude -- enters Lynx, and spends 2 1/2 months traveling southward, then southwestward, across that constellation before entering northeastern Auriga during the latter part of October, by which time it may be near its peak brightness around magnitude 12. After crossing centrally across that constellation it enters northern Taurus in late November shortly before it reaches opposition near the end of that month, and it then enters northeastern Cetus during the latter part of December. At that time Comet Hill's motion again turns almost directly southward and it enters northern Eridanus shortly after mid-January, and will likely fade beyond the range of visual detectability within about another month or so.
As I've indicated in a couple of the previous entries, the current cometary "dry spell" shouldn't be lasting much longer, and there are several noteworthy comets that I have reasonable expectation of adding to my tally within the next few months. My personal life has, meanwhile, continued to remain active, and I'll share some of the recent activities and developments in one or more of those forthcoming entries.
UPDATE: Following its perihelion passage Comet Hill's brightness remained steady near 11th magnitude for the next three months as it approached Earth and opposition in late November, however after that it faded rapidly and grew quite diffuse; by late December it appeared as a pale, vague, and only slightly condensed object near 12th magnitude, and I suspected that I was about done with it. However, just after the start of the new year Alfons Diepvens in Belgium reported that it was in outburst, and despite bright moonlight I easily saw it a couple of nights later as a condensed 11th-magnitude object slightly less than an arcminute in diameter. This will likely extend the period of visual detectability for perhaps another month or so.
From an examination of various CCD images this outburst appears similar to the one that took place in August 2010. This would suggest that Comet Hill is prone to outburst activity, and thus even after I am formally finished with it, it might conceivably outburst again and allow for a handful of additional observations.
This has, undoubtedly, been one of the most eagerly-awaited comets in recent years. It was discovered back on December 10, 2010 by Leonid Elenin, an astronomer in Lyubertsy, Russia (affiliated with the Keldysh Institute of Applied Mathematics in Moscow), who is an accomplished observer of comets and who has in fact made several recoveries of expected periodic comets within the fairly recent past; this is his first comet discovery. Leonid was observing remotely with a 45-cm (18-inch) telescope (equipped with a CCD) at the International Scientific Optical Network observatory in New Mexico (not too far from where I live, incidentally), and at the time of his discovery the comet was a rather faint object between 19th and 20th magnitudes and was located 4.2 AU from the sun.
The first calculated orbits for Comet Elenin suggested it would remain a distant object, however it soon became clear that it was traveling on a remarkably low-inclination orbit (1.8 degrees) that would carry it quite close to both the sun and the earth. Furthermore, the geometry for forward scattering of sunlight -- and thus an accompanying brightness enhancement -- is quite favorable around that time. All this has led to a realization that Comet Elenin possesses at least the potential to become a relatively bright object -- conceivably even a "Great Comet" -- for a brief period of time around perihelion passage and its closest approach to Earth.
Following its discovery Comet Elenin slowly brightened as it approached the sun and Earth, and it went through opposition in mid-March of this year. Towards the end of that month I broke out the Earthrise telescope/CCD system (that has been dormant for a few years amongst all the transitions both Earthrise and I are undergoing) and managed to obtain some images of the comet as a faint object near magnitude 15 1/2 or 16. I also began visual searches for it around that time, however it remained elusive for quite some time thereafter. Finally, on the evening of May 23 I suspected it as a very faint, diffuse and "soft" object a little fainter than 14th magnitude, and was able to verify this as being the comet by observations on several additional nights over the subsequent week. (This confirmation process was hindered some by the fact that the comet was at its stationary point, and thus hardly moved at all from night to night.)
The comet is currently an evening-sky object, located in western Leo some six degrees southeast of the bright star Regulus and two degrees southwest of the star Rho Leonis. Over the coming several weeks it tracks to the east-southeast across Leo roughly parallel to the ecliptic, until finally it enters western Virgo in early August. Its elongation from the sun at that time will have shrunk to 40 degrees, and since it will be south of the sun observations may be difficult from the northern hemisphere but should still be fairly easy from the southern. Even though the elongation continues to decrease after that, since the sun is moving southward we northern hemisphere observers may be able to keep following it for a while, perhaps even up until the time of perihelion passage when the elongation will be 26 degrees. After that its motion on the sky reverses as it crosses almost directly between the earth and the sun, passing less than two degrees north of the sun on September 26.
By the end of the first week of October Comet Elenin will emerge into the morning sky, traveling rapidly west-northwestward through Leo and passing six degrees north of Regulus on October 11. It makes its closest approach to Earth (0.23 AU) on October 16 and travels rapidly through Cancer and Gemini around this time (passing just one degree north of the bright star Pollux on October 22), then enters Auriga shortly before the end of October and then northern Taurus at the end of the first week of November. The comet is at opposition shortly after the middle of that month, and then passes through the northern regions of the Pleiades star cluster on November 23. At the end of that month it crosses into eastern Aries, where it remains up through the end of January 2012.
Brightness predictions for any potentially bright comet like this one are always problematical. Unfortunately, the news thus far for Comet Elenin is not especially good; it is already running somewhat behind the original expectations, and the distinctly diffuse and uncondensed appearance it is currently exhibiting visually is also not a good sign. Furthermore, calculations now clearly show that Comet Elenin is making its first visit to the inner solar system from the Oort Cloud, and such comets quite often tend to appear relatively bright when far from the sun but under-perform as they approach and pass through perihelion. (The most famous, or infamous, example is Comet Kohoutek 1973f (no. 10), but compared to some Oort Cloud comets even it did not perform all that poorly.)
With all this in mind, a cautiously optimistic scenario would suggest that Comet Elenin might reach 10th magnitude by early August when it becomes a somewhat difficult object from the northern hemisphere, and may brighten further to around 6th magnitude by the time it passes through perihelion. It may still be near this brightness when it reappears in the morning sky in early October, and then might fade slowly by perhaps half a magnitude by the time it is nearest Earth. Fading may be more rapid thereafter, with the comet's being perhaps 10th or 11th magnitude when near opposition in November, and no brighter than perhaps 13th magnitude by the end of the year. As I mentioned above, there is a potential for a forward scattering enhancement of brightness (perhaps by as much as a couple of magnitudes) in late September when the comet passes almost directly between the Earth and the sun, however this will probably be fairly short-lived and, more importantly, this will occur when the comet is at a very small elongation from the sun. (The LASCO coronagraphs aboard the SOHO spacecraft should nevertheless be able to provide a spectacular view.)
This is only a guide, of course; the comet could easily be one, or two, or more, magnitudes brighter, or fainter, than this. Conceivably, it could fragment as it passes through perihelion and come out distinctly brighter that it was earlier; on the other hand, it could break apart completely and disintegrate as it passes through perihelion. There is precedent for both scenarios, as well as precedent for "normal" behavior. We'll just have to wait and see what the comet actually does.
Unfortunately, some elements in our society have latched onto the news about Comet Elenin and have been promulgating various apocalyptic scenarios regarding it. (I will not link to any of those, or give them any more publicity than they deserve.) Some of these have gone so far as to question Leonid Elenin's existence as an actual person. (I can assure "Countdown" participants that he is a real person; while I have not met him, I correspond with him on a fairly regular basis.) Many of these scenarios are almost identical to the nonsense that I remember combatting when Comet Hale-Bopp (no. 199) was around 14 years ago -- with some of these being put out by the same people! -- and, needless to say, we're all still here. There is, in fact, nothing all that unusual about Comet Elenin; it does have the potential to become somewhat bright, and it does come somewhat close to Earth (although several comets, including at least four earlier "Countdown" comets, have come closer to Earth during recent years), but there is nothing of any kind to fear. Let's enjoy whatever show it gives us.
My personal life has been very busy of late. I'm currently tripled up on the classes I'm teaching as part of my day job (including a course in Planetary Science that I'm teaching for the first time), and once again I'll be teaching classes as part of the Summer Science Camps at the New Mexico Museum of Space History in Alamogordo. I've recently joined the team of Project Icarus, and am also exploring several additional potentially exciting opportunities for Earthrise-related endeavors that I'll hopefully be able to report positively upon within the not-too-distant future. Our local acting troupe has just completed its first play of the current summer season, and, once again, I played the part of the villain. (Am I being typecast?) And, as if I need reminding that I've been hanging around this planet for a good long while, my High School graduating class is celebrating its 35th reunion this coming weekend. Finally, my relationship with my girlfriend Susanne continues to develop, and it's conceivable I may have something positive to report about that within the not-too-very-distant future. Life continues, then, to be very fulfilling, as I continue my quest for the comets . . .
UPDATE: For the first month and a half or so after I picked it up, Comet Elenin remained a faint and elusive object, however it began to brighten noticeably during July, and by the beginning of August had reached 10th magnitude, consistent with the nominal scenario described above. However, it is now very low in my western sky during dusk, and I probably won't be able to follow it any longer, although observers in the southern hemisphere should still be able to do so. Unless the comet becomes unexpectedly bright, I probably won't be seeing it again until it emerges into the morning sky in early October.
At this point I am not especially optimistic as to any bright display we might conceivably get from Comet Elenin. It may still reach 6th magnitude, but I'm beginning to doubt rather strongly that it will get any brighter than that. I could be wrong, of course, but we'll just have to wait and see how it performs as it arrives at and passes through perihelion.
Meanwhile, at the beginning of August Comet Elenin is passing only 0.05 AU from the STEREO B spacecraft (which is lagging behind Earth). The spacecraft was deliberately rolled in order to image the comet in the outer Heliospheric Imager instrument, and it should remain detectable with one or more of the cameras aboard STEREO for the next few weeks.
UPDATE: According to observers in the southen hemisphere, Comet Elenin continued to brighten during the first part of August, reaching about 8th magnitude by around mid-month. Not too long thereafter, however, it began fading, and remainded near 9th magnitude thoughout the latter part of the month; perhaps more importantly, the central condensed region of the coma began to smear out, suggesting that it might be starting to disintegrate. This process continued during early September, with the comet fading further to 10th magnitude, and by the time of perihelion passage it was little more than a vague, uncondensed patch of light. The last image I've seen, which was taken on September 14 (four days after perihelion) when the elongation had shrunk to 22 degrees, shows nothing more than a fuzzy patch of diffuseness.
It would appear, then, that Comet Elenin has all but completely disintegrated, and there will obviously be no kind of bright display when it emerges into the morning sky during the second week of October. It will be interesting to see if anything is visible with the LASCO coronagraphs aboard SOHO when the comet goes through inferior conjunction on September 26 and passes two degrees north of the sun. Regardless of what is or isn't seen I will still probably make an attempt or two once it enters the morning sky, but it's fair to say that I'm not holding my breath as to seeing anything . . .
UPDATE: No trace of Comet Elenin was visible in any of the images taken with the LASCO coronagraphs aboard SOHO when it went through inferior conjunction on September 26. It thus appears that the comet has indeed completely disintegrated, and it is quite doubtful that anything will be visible when it emerges into the morning sky in early October.
UPDATE: At the end of the first week of October Comet Elenin emerged into the morning sky. As the earlier observations (or lack thereof) suggested, however, there doesn't seem to be anything left of the comet to observe; I couldn't see anything when I attempted it visually on the morning of the 7th, and several attempts by other observers to recover the comet with CCDs were also unsuccessful. It is conceivable that, once the elongation becomes high enough (and when the moon clears from the morning sky), some cloud of debris might still be detected, but I am not going to hold my breath on this, and at this point it seems rather likely that the comet indeed completely disintegrated as it approached and passed through perihelion.
UPDATE: Sometimes . . . we are surprised. Shortly after mid-October, after the moon had cleared from the morning sky, CCD images began to show a long faint cloud, over half a degree in length, extending to the west-northwest from Comet Elenin's ephemeris position. (One of the best images I've seen was taken on October 22 by Italian amateur astronomer Rolando Ligustri.) While certainly nothing remains of the comet's nucleus or coma, it is clear that we are seeing what is left of its dust tail.
It turns out that this stream of dust is detectable visually, although it is extremely faint. I suspected it on the morning of the 24th, with an appearance as nothing more than a faint brightening of the background sky that shifted position with the comet's expected motion, and saw similar appearances on the mornings of the 26th and 28th, although I wasn't able to convince myself that I was actually seeing something real until I was able to examine CCD images taken around the same time that were consistent with what I was detecting. These are, by far, among the most difficult cometary observations I have ever made, and as far as cometary phenomena go they are also among the most unique I have seen.
It is difficult to predict just how much longer this dust stream will remain detectable, at least visually. It should continue to spread out as time goes by, although as the comet approaches opposition shortly after mid-November it will also become more foreshortened from our viewing perspective, and thus may appear "thicker." In any event, it will certainly remain extremely difficult to observe visually, and I don't know how many more times I will bother to attempt it. Astronomers equipped with good CCDs will undoubtedly be following it for as long as they can, and when all is said and done we will likely have learned quite a bit how the disintegration process works in comets.
Rob McNaught strikes again . . . three times, in fact. On the nights of June 2 and June 3, during the course of his work with the Siding Spring survey in New South Wales, Rob discovered three (completely unrelated) comets (C/2011 L1 through C/2011 L3), raising his already record-breaking personal discovery total to 62. The third of these three comets, which he found on the second night, was a morning-sky object located in southern Aquarius about three degrees west of the star Delta Aquarii, and traveling towards the north-northwest, with reports indicating it was between 15th and 16th magnitudes. I attempted it visually a couple of times in early June prior to the mid-month full moon, then started attempting it again near the end of the month after the moon had cleared from the morning sky. On the morning of July 1, when it was located just over a degree northwest of the star Alpha Aquarii, I successfully observed it as a diffuse object of magnitude 13 1/2 that exhibited distinct motion during the half-hour that I watched it.
This newest Comet McNaught is traveling in an orbit almost exactly perpendicular to Earth's (inclination 87.1 degrees) and continues its rapid northwestern motion over the coming few weeks, being nearest to Earth (1.04 AU) on July 24 and at opposition three days later. During this time it travels through Pegasus, Delphinus, and Vulpecula, with its motion gradually turning more due westerly; it passes two degrees northeast of the Dumbbell Nebula M27 at the end of July and half a degree northeast of the bright double star Albireo (Beta Cygni) at the end of the first week of August. At the time of perihelion passage it will be in southwestern Lyra, and it passes just 15 arcminutes southwest of the globular star cluster M56 the following day before passing 1 1/2 degrees south of the Ring Nebula M57 a week later. By the end of August it enters Hercules, where it remains for the next several months, and will be at its stationary point in early October. The comet should brighten by perhaps a a half- to a full magnitude by the latter part of July and remain there for the first one to two weeks of August before beginning to fade, and then remain visually detectable until sometime in September.
Neither of the two other comets that Rob found during this trio will likely become visually detectable; C/2011 L1 is traveling in a Halley-type orbit (period approximately 37 years) and had already passed perihelion last December, while C/2011 L2, although it doesn't pass perihelion until the beginning of November, is a somewhat more distant and fainter object that, moreover, remains in southern circumpolar skies for several more months. But as long as Rob keeps working with the Siding Spring survey he will almost certainly discover additional comets during the months and years to come, and thus it is quite likely that his name will continue to make appearances in my tally from time to time.
A rather spotty and unusual observational history accompanies this Halley-type periodic comet. It was first seen in February 1818 by the great French comet hunter Jean Louis Pons, however he was the only person to see it, and even then he only followed it for four days. It was then seen again in November 1873, being discovered by Jerome Coggia in France and independently by Friedrich Winnecke in Germany, but as before was only followed for a very brief period of time (six days in this case). Finally, it was re-discovered by Alexander Forbes in South Africa in November 1928, and shortly thereafter the British astronomer Andrew Crommelin (the top calculator of cometary orbits of that time) determined that Forbes' comet was identical to the two earlier ones, and was traveling in an orbit with a period of 28 years. (Crommelin also suggested that a comet seen from China, Japan, and Italy in 1457, and another one seen from Germany in 1625, were earlier returns of this comet, but these possible identities are now known to be incorrect.) For some time after Crommelin's determination the comet was known by the rather cumbersome name of P/Pons-Coggia-Winnecke-Forbes, but in 1948 the International Astronomical Union voted to rename it in honor of Crommelin.
The comet returned again in 1956, reaching 7th magnitude around the time of perihelion passage in late October, and then again in 1984, when it reached 8th magnitude around the time of perihelion passage in late February. At this latter return it was selected to be the "trial run" comet for the International Halley Watch (IHW), which was then gearing up for the expected return of that object two years later, and it remained an unexpectedly bright 9th magnitude during the IHW's "trial run" period in late March. Meanwhile, I followed the comet fairly extensively during that return (no. 64), with my observations spanning the interval from late January through early April.
At its present return P/Crommelin was first recovered on May 12, 2011, by Tsutomu Seki in Japan (discoverer of several comets during the 1960s and 1970s, including the great Kreutz sungrazer Comet Ikeya-Seki 1965f, and who still remains active in comet observing), and then independently by several other astronomers toward the end of May. After an earlier unsuccessful visual attempt I successfully viewed it on the morning of July 1 (less than an hour after picking up the above comet, thus making this the 21st occasion on which I have added two or more comets to my tally on the same night); at that time it was located three degrees east of the star Zeta Persei, low in the northeastern sky at the beginning of dawn (the elongation from the sun being only 33 1/2 degrees). At that time it appeared as a vague, diffuse object between magnitudes 12 1/2 and 13, and I was able to follow it for about half an hour before it disappeared into the brightening dawn sky.
The viewing geometry of P/Crommelin's current return is distinctly less favorable than it was in 1984. After being in conjunction with the sun in early February it emerged into the morning sky, but its elongation never reached higher than 41 degrees, which occurred during late May (when most of the independent recoveries were taking place). The elongation is now shrinking fairly rapidly, dropping below 30 degrees during the second week of July, below 25 degrees a week after mid-month, and below 20 degrees just after the beginning of August; meanwhile, the comet remains fairly far from Earth, the closest approach (still at a relatively distant 1.59 AU) taking place on July 19. Meanwhile, during this time it travels rapidly eastward (turning more southeasterly) through Perseus, Auriga, Taurus, and Gemini, passing two degrees north of the star cluster M35 on July 20. Historically, one hallmark of P/Crommelin has been that it tends to brighten quite rapidly as it approaches perihelion, and it should reach a peak brightness near 11th magnitude during the latter half of July, although the small elongation (and also moonlight, following full moon on July 15) will continue to make observations difficult. After perihelion, the comet passes over to the opposide side of the sun from Earth and disappears into sunlight for the next several months, and by the time it emerges back into the morning sky near the end of this year it will likely be too faint to be detectable with just about any telescope. Thus, unlike in 1984 I will at most only obtain a handful of observations of P/Crommelin this time around.
With its current orbital period of 27.9 years, P/Crommelin now becomes the longest-period periodic comet that I have seen on two returns, a status that it will hold for at least seven years. A lot has happened in my life since those days when I was observing it in early 1984; at that time I had gotten out of the Navy a few months earlier and had just started working at the Jet Propulsion Laboratory in California, and I would work there for another 2 1/2 years (being heavily involved in the Voyager 2 Uranus encounter in 1986) before leaving and returning home to New Mexico to enter graduate school at New Mexico State University, where I would earn my Ph.D. six years later. My career has taken a number of twists and turns since then, but it has included the discovery of the comet that made my name a household word for a while during the late 1990s, as well as a number of interesting adventures that are discussed elsewhere on this web site. In early 1984 I had a girlfriend, Eva, whom I would marry the following year, although that marriage ended in divorce last year; during the course of that marriage, meanwhile, two sons were born, Zachary and Tyler, both of whom have now reached adulthood. (Zachary, in fact, is now only a year younger than I was at the time I was following P/Crommelin.) As "Countdown" readers and participants know, I now have a new girlfriend, Susanne, and I would like to think I still have several adventures and career accomplishments ahead of me.
It would be nice to think that P/Crommelin and I will be able to check in on each other again at its next return, but unfortunately that won't happen. As unfavorable as this year's return is, the remaining three returns in the 21st Century are all even more unfavorable, and it is very doubtful that visual observations will be possible at any of them. Thus, whatever observations of P/Crommelin I am able to obtain over the course of this next month will constitute the last times that I will ever see it.
A long-time friend stops by for another visit. It has a rather cumbersome name -- and thus is usually referred to as "P/H-M-P" or, more formally, as "Comet 45P" -- due to its discovery in early December 1948 by three of the world's top visual comet hunters of that time, all independently of each other. Minoru Honda was a Japanese amateur astronomer who discovered twelve comets between 1940 and 1968 and then a dozen novae between 1970 and 1987 (one of these being Nova Cygni 1975, the brightest nova of the entire second half of the 20th Century and the first -- and brightest -- nova that I have seen; Honda was not the first person to see it, but was the first to report its existence). Many of the Japanese comet hunters who would dominate the field of comet discoveries during the 1960s and 1970s were inspired by Honda's achievements. Meanwhile, Antonin Mrkos and L'udmilla Padjusakova were members of a team that made visual comet searches from Skalnate Pleso Observatory in then-Czechoslovakia (now Slovakia) during the 1940s and 1950s. Mrkos made eleven visual comet discoveries between 1948 and 1959 (the brightest of these being the conspicuous naked-eye Comet Mrkos 1957d) and then later in his career was director of the Klet' Observatory in southern Bohemia in the Czech Republic, where he photographically discovered two additional comets, both short-period objects; I managed to obtain a single observation of the second of these, 124P/Mrkos, at its discovery return in 1991 (no. 155). Pajdusakova discovered five comets, all from Skalnate Pleso, between 1946 and 1953, and later specialized in solar research and was director of Skalnate Pleso for two decades. For a period of time during the 1950s she and Mrkos were married to each other.
Comet 45P was found to have a short orbital period (currently, 5.25 years), and has only been missed on one return since its discovery. It became only the third periodic comet I ever saw when I observed it on its 1974 return (no. 13) while I was still in high school; it briefly reached 8th magnitude then. After unfavorable returns in 1980 and 1985 I observed it again during its favorable returns in 1990 (no. 144) and 1995 (no. 207), with it reaching a peak brightness between 7th and 8th magnitudes both times; during the latter return it passed 0.17 AU from Earth and also for a time was visible in the LASCO C3 coronagraph aboard the SOHO spacecraft, becoming the first previously-known comet to be detected with that instrument. I managed to obtain a handful of observations of it during its rather mediocre return in 2001 (no. 291) but failed to see it during its unfavorable return in 2006, although I did search for it on a couple of occasions.
On it present return Comet 45P was recovered on June 5, 2011, by Carl Hergenrother utilizing the 1.5-meter (61-inch) Kuiper Telescope on Mount Bigelow in Arizona; at that time it was reported as being an extremely faint object of 21st magnitude. One of the characteristics of this comet it that it begins to brighten almost explosively when it approaches to within 1.2 to 1.3 AU of the sun, and -- pretty much right on schedule -- that seems to be what occurred this time. I couldn't see anything convincing when I attempted it on the morning of July 25 (when it was 1.31 AU from the sun), but when I tried it again four mornings later (when it was 1.26 AU from the sun) I saw it rather easily as a diffuse and somewhat condensed object of magnitude 12 1/2.
The comet has a rather unusual treat in store for Earthbound comet-watchers this time around, although unfortunately for me this treat is exclusively for comet observers in the southern hemisphere. It was already at a declination of -27 degrees (and located in northwestern Piscis Austrinus) when I first saw it, and it is traveling almost due southward quite rapidly; by the middle of the second week of August, by which time it should have brightened to 9th or 10th magnitude, it will be traveling over four degrees per day and will drop below my southern horizon. Within a couple of days afterward it will be in southern circumpolar skies as it travels southward through Grus and Tucana, and on August 13 it passes within three degrees northeast of the Small Magellanic Cloud. The following day it reaches its farthest south point, declination -73.4 degrees.
On August 15 Comet 45P passes only 0.060 AU from Earth, the second-closest approach to Earth of any comet on my tally (only Comet IRAS-Araki-Alcock 1983d (no. 56), which passed 0.031 AU from Earth in May 1983, has come closer) and, indeed, about the 15th closest cometary approach to Earth in recorded history. On that date it will be traveling east-northeastward at a rate in excess of 13 degrees per day, and during the first few hours it will be transiting across the southern regions of the Large Magellanic Cloud, passing within one degree south of the "Tarantula Nebula" NGC 2070 and the location of Supernova 1987A. The total brightness could be close to 6th magnitude, although this will likely be spread out in a coma over a degree in diameter, and it may or not be visible to the naked eye at that time.
After its approach the comet begins heading rapidly back northward, although the rate of motion rapidly decelerates as it pulls away from Earth. The comet will likely fade some, although since it is continuing to approach perihelion it will likely not drop below 8th magnitude. Over the coming days it travels through Carina, Pyxis, and Hydra, but the conditions of visibility deteriorate as it enters the dawn sky, with the elongation dropping below 30 degrees on August 22, below 25 degrees on the 24th, and below 20 degrees on the 28th. The comet reaches a mimimum elongation of 19 degrees at the very end of August, at the same time that it is crossing the Celestial Equator.
The comet passes 22 degrees west of the sun on September 8, and sometime within a week or two after that point it should again be accessible to those of us in the northern hemisphere, although the elongation remains rather small. At the time of perihelion passage it will be located in central Leo four degrees southeast of the star Regulus (and at an elongation of 31 degrees), and probably close to 8th magnitude. Over the subsequent few weeks it tracks to the east-southeast across Leo before crossing into western Virgo during the latter part of October; during this time it should fade fairly rapidly, and during late October it will likely be no brighter than 11th or 12th magnitude. Since its elongation even then will still only be about 36 degrees I will likely lose it sometime around that point.
All in all, then, I probably won't be getting too many observations of Comet 45P this time around, despite the unusually close approach to Earth. But I can take heart that things will be quite a bit better at the subsequent return, in 2016 (perihelion late December); the comet makes another very close approach to Earth (0.085 AU) the following February, and since that takes place on the outbound leg from perihelion, those of us in the northern hemisphere will have the better view of it. The subsequent return, in 2022, is quite unfavorable (perihelion late April) and any observations will be difficult, but the return after that, in 2027 (perihelion late August) is moderately good and the comet should reach 8th or 9th magnitude. The comet makes a close approach to Jupiter (0.17 AU) in 2030, which increases its perihelion distance to 0.63 AU and its orbital period to 5.5 years; at the subsequent return in 2032 (perihelion early November) it passes 0.37 AU from Earth (and goes through inferior conjunction) at the time of perihelion but is observable beforehand (southern hemisphere) and afterwards (northern hemisphere). The returns after that alternate between favorable and unfavorable, and thus I should continue to have this long-time friend to observe from time to time for as long as I remain active in comet observing.
Meanwhile, though, I am now set to enter the "home stretch" of "Countdown." Based upon the known comets that are inbound, I estimate that I will reach comet no. 500 by sometime next March or April, although it's conceivable that, should there be a lot of new discoveries in the near future, I could get there by the end of this year. We'll see what happens . . .
UPDATE: Somewhat surprisingly, there were very few reports of this comet from the southern hemisphere around the time of its closest approach to Earth in mid-August, although to be fair this occurred right around the time of full moon, and I understand there was widespread poor weather throughout much of the southern hemisphere at that time. The few reports I did read indicated that the comet reached around 8th magnitude when it was nearest Earth. There were no observations that I'm aware of that were made as the comet receded from Earth and entered morning twilight.
Meanwhile, shortly after mid-September I successfully picked up the comet in the morning sky, appearing (pretty much as expected) as a relatively condensed object of 8th magnitude. The remainder of the period of detectability should proceed more or less as I've described above.