CONTINUING WITH COMETS
|LATEST UPDATE: NOVEMBER 22, 2017|
|CURRENT TALLY: 633|
|In my July 6, 2017 personal statement I discuss where I am in my life right now, and where I am with Earthrise. As I stated there, the one effort that I am definitely continuing with is my visual observations of comets, and while I wouldn't call "Continuing With Comets" an actual "program," this is where I will discuss the comets that I am observing and adding to my lifelong tally.
Back when I still had substantial plans for Earthrise, I had more formal programs that involved the observation of comets. I inaugurated "Countdown to 500 Comets" in early 2007 for the purpose of (as the name implies) encouraging students to observe comets along with me as I strove to observe my 500th comet. I finally achieved that goal in January 2012, and after a brief hiatus inaugurated a newer, lower-key program, "Counting Comets." I continued with this for another year and a half, but as I recount in my personal statement, by the end of 2013 the state of my emotional health had reached the point where I was unable to continue with any semblance of a "program," and I completely stopped all updates, descriptions of tally additions, and so on.
However, I did not stop the visual comet observing; indeed, that played a significant role in sustaining myself emotionally throughout this entire time. As I have slowly recovered to the point where I can start "sharing" my comets again, I have continued to observe comets on a regular basis and to add them to my tally, and although I am not quite the same person that I was when I was working through "Countdown," I can at least once more share my quest for comets with the world.
I should stress that "Continuing With Comets" is strictly a personal effort on my part. As I've said, I am not specifically encouraging anyone to observe any of these comets -- although obviously anyone who wishes to observe them should make the efforts to do so; rather, this is simply just sharing the comets that I observe and add to my tally. As I did with "Countdown" and with "Counting Comets," when I do add a comet to my tally I will include in its writeup the various pieces of worthwhile information, including historical information, about it, and discuss its observational prospects. In lieu of regular updates (that included all the comets I was observing), however, when appropriate I will include updates to the specific writeups of the comet(s) in question. And as I also did with "Countdown" (and to a lesser extent in "Counting Comets"), when appropriate I will include in the writeups some of the goings-on in my personal life; after all, life continues on, and my observing of comets, along with everything else, takes place against the overall backdrop of life in general.
The CCD imaging system I was using a decade and more ago is no longer operational, and while it is conceivable I may upgrade it in the future and reinstate it, that would require a significant financial investment on my part that I am not ready or willing to make at this time. However, in 2014 I acquired a Digital SLR camera that allows me to take decent images of some of the brighter comets, and I will likely include these with some of the tally entries. Some of the entries may also include public domain images of the comets in question, and, possibly, images obtained by other observers who will have given me permission to display them.
On the right side of this page I am including links to "Countdown" and to "Counting Comets" as well as to various sites and services that should be of interest and use to potential comet observers. Among these are regularly updated image galleries of currently detectable comets. With rare exceptions the comets discovered by SOHO and STEREO do not usually become visible from the ground, however these links are still provided for those who might be interested in these objects. The link to the Digitized Sky Survey is provided for those comet observers who might be interested in observing or imaging the dimmer comets.
If all goes reasonably well, I should still be regularly observing comets in February 2020 -- now less than three years away -- which will mark the 50th anniversary of my first comet observation. I will obviously address this at the appropriate time.
Although the thought would almost have been heretical for most of my life, within the relatively recent past I have started to consider "retiring" from the visual comet observing. Health issues, and general life happenings, will obviously play a non-trivial role in how my observing progresses over the coming years, but as I see things right now, I would like to continue on my current heavy basis at least until I reach my 500th separate comet. (The 622 comets that are on my present tally comprise a total of 447 separate comets). At my present rate of adding comets, I should reach that milestone sometime around 2021 or 2022. I may start to slow down a little bit at that point, but two of the brighter, "classical" Halley-type comets, 12P/Pons-Brooks and 13P/Olbers, are both returning to perihelion during the first half of 2024, and I certainly want to follow those closely when they return; the recently-discovered long-period Comet PANSTARR S C/2017 K2 which doesn't pass perihelion until late 2022 should also be a most interesting comet, although its rather large perihelion distance of 1.8 AU will probably keep it from becoming "Great." I expect to continue my quest to observe a comet during a total solar eclipse; at the very least, this will include the eclipse that takes place next month (on August 21) as well as the eclipse on April 8, 2024, which crosses the central U.S. Whether or not I travel to any of the other total solar eclipses during this time frame is, at best, debatable, although I won't say anything definitive one way or the other at this time.
I do hope that I get to observe at least one more "Great Comet" before all is said and done. The last "Great Comet" that was easily visible from here was the one that bears my name, i.e., Comet Hale-Bopp C/1995 O1 (no. 199), that is now over two decades in the past. While there have been two "Great Comets" since then -- Comet McNaught C/2006 P1 (no. 395) and Comet Lovejoy C/2011 W3 (no. 500) -- these were only "Great" from the southern hemisphere; they were almost total washouts from my latitude (although I was able to observe Comet McNaught during the daytime, which was quite a treat). A recent paper suggests that Comet Lovejoy is the first of an incoming "cluster" of Kreutz sungrazers, and if that is true -- and I sure hope it is -- then hopefully I will get to see at least one of them in something approaching its full splendor. Perhaps Comet PANSTARRS C/2017 K2 may become "Great" despite its large perihelion distance (although it, too, will be visible only from the southern hemisphere when it is at its best) -- or perhaps an entirely as-yet unknown comet may reach "Great" status sometime within these next few years. In any event, as long as something "Great" comes this way, I would be content.
If all goes as I plan, then in this space I will be sharing all the various comets I observe up until "the end" -- whatever "the end" turns out to be. This is a glimpse into comets, and a glimpse into my life as well, and I hope that any readers of this page will come to appreciate the former, and, perhaps, even the latter.
Over the past several decades it has become clear that there is a significant "grey area" between what constitutes an "asteroid" vs. what constitutes a "comet," and there appears to be significant overlap between these two types of objects, without any sharp dividing line between them. The International Astronomical Union has in fact accorded "dual designation" status to a handful of objects that exhibit characteristics of both types of objects. For purposes of my comet tally, I consider any dual-designated objects I observe to be "comets," and I have observed two such objects (both of which are Centaurs): 95P/Chiron P/1977 UB = (2060) Chiron (no. 196) and 174P/Echeclus P/2000 EC98 = (60558) Echeclus (no. 384).
Throughout the years I have been observing comets I have also observed, whenever possible, "asteroids" that are, conceivably, "dead" or extinct, or, possibly, "dormant" comets (usually considered as such based on their traveling in cometary orbits, and/or some other kind of physical phenomena). When I observe these I do not add them to my tally as bona fide comets, however I have reserved to myself the discretion to add them retroactively if future observations warranted such (even if the International Astronomical Union does not accord them "dual designation" status). At the end of 2014 I did this with two such objects: a) the asteroid (3200) Phaethon, the apparent parent of the Geminid meteors, which by then had, on two separate returns (and now a third return) exhibited a coma, tail, and non-asteroidal brightness behavior when near the sun in images obtained by the STEREO spacecraft. The tally entries are nos. 559, 560, and 561 for the three returns of Phaethon I had observed until then, and no. 607 (in sequence) for the return I have observed since that point. I hope to add it again during the close approach it makes to Earth near the end of 2017. b) the asteroid (3552) Don Quixote, which travels in a distinctly cometary orbit, and which I observed on two occasions during its 2009 return. A report that came out in 2013 describes infrared images taken in 2009 by the Spitzer spacecraft that clearly show a coma and a tail, and strongly suggest sublimation of carbon dioxide; the press releases that came out with this report described Don Quixote as "a comet hiding in plain sight." The tally entry for the 2009 return is no. 562.
Within just the past few years there have been reports (examples here and here) of possible weak cometary activity associated with "asteroids" in the main asteroid belt; some of these "asteroids" were discovered as long as a century or more ago and are in fact rather large objects. The entire arena of so-called "main-belt comets" (sometimes alternately described as "active asteroids") is an active area of research at present, and a handful of relatively small such objects have been accorded "dual designation" status by the International Astronomical Union. The larger objects that have been the subject of recent reports have not (as of yet) been observed to exhibit phenomena of the scale exhibited by the "dual designation" objects, and even if a reasonable level of activity were to be exhibited by these objects at some point, it is difficult to determine just what might warrant classification as a "comet," even for purposes of my tally.
I have begun observing some of the "asteroids" that are the subject of these recent reports, but for now I am not listing them as comets on my tally. If at some point in the future they are observed to exhibit activity at a level that warrants their listing as a "comet" on my tally -- although, again, I'm not sure just what that would be -- I will retroactively add them as I did with the previous objects.
Finally, there is the main-belt "asteroid" (596) Scheila, which underwent a distinct outburst in brightness, and even exhibited cometary phenomena such as a coma, in December 2010. All of the available evidence indicates that Scheila's outburst was caused by an impact by a smaller asteroid, as opposed to any kind of sun-driven intrinsic activity such as sublimation of volatiles, and thus at face value its inclusion as a "comet" on my tally would not seem to be justified. (I have maintained a semi-regular watch on Scheila ever since, during which time it has behaved entirely normally for an asteroid.) However, the object originally designated as "Comet" P/2010 A2, which, like Scheila, was subsequently found to be the result of an asteroidal impact, has recently been "recovered," and if the IAU assigns it a short-period comet number, that would suggest that any object that exhibits observable cometary activity, regardlesss of the mechanism that produced that activity, can be classified as a "comet," and thus a rather strong argument can be made that Scheila can be considered a comet, at least for tally purposes, and I will likely add it to my tally retroactively. A similar argument can be made for the main-belt "asteroid" (493) Griseldis, which underwent a similar type of activity in March 2015 and which I hope to observe around the time of its perihelic opposition in October 2018.
|"Continuing With Comets" links
Statistical analysis (comets 1-600)
Basic information on observing comets (from "Countdown")
Minor Planet Center
International Comet Quarterly
Comet Base (observations repository)
Erik Bryssinck (Belgium)
Peter Carson (UK)
Jose Chambo (Spain)
Pieter-Jan Dekelver (Belgium)
Alfons Diepvens (Belgium)
Michael Mattiazzo (Australia)
Gerald Rhemann (Austria)
Chris Schur (Arizona)
SOHO comet web site