(for comets 1 through 400)

as of March 1, 2007*

*NOTE ADDED MAY 1, 2007: With the exception of the two comets described below (and the very unlikely possibility that one of the outbound comets might experience a major outburst), I am finished with the first 400 comets. I have thus recomputed the relevant statistics for these comets and have modified this page accordingly to reflect this. These modifications do not include any observations of comets no. 401 and higher (my total at this writing being 405).

The two comets that are still "ongoing" as of this writing are:

29P/Schwassmann-Wachmann 1 (no. 226). At this writing this comet is entering solar conjunction and thus is "done" for this particular opposition. It does not reach aphelion until November 2011, and -- especially based upon its activity during recent years -- there is good reason to suspect it will continue to undergo outburst activity during the oppositions between now and then.

174P/Echeclus (no. 384). This Centaur comet underwent a significant outburst in late 2005 when located over 13 AU from the sun, and in early 2006 I succeeded in observing it as an extremely faint object. This outburst has since subsided and the comet is no longer visually detectable. The comet does not pass perihelion until April 2015, at a much closer but still relatively distant 5.8 AU, and it is conceivable that it might undergo additional outburst activity between now and then (and/or, for that matter, afterwards).

I do not plan any further updates to this page until after Comet 29P goes through aphelion.

General Comments

It took me over 17 years to get from my first comet to comet no. 100. This was due in significant part to the fact that, like everyone, I began as an inexperienced observer, and it took some time for me to gain experience in tracking down and detecting the dimmer and more obscure comets. For the first three years my sole source of information about observable comets was the magazine Sky & Telescope, and because there is a necessary time lag in a monthly publication like this, some comets were already gone by the time I learned of them. I began subscribing to the IAU Circulars in 1973, and this obviously helped significantly in increasing my comet total. During those years the rate of comet discoveries was significantly less than it is today, and the number of known periodic comets was also quite a bit less. Finally, I did not have access to much in the way of large telescopes then; for the first five years all I had was that first 4.5 inch (11.4 cm) reflector, and during my last two years of high school I had access to the 12.5 inch (32 cm) reflector owned by the local school district. During my years at the U.S. Naval Academy (1976-1980) I did have access to a 16 inch (41 cm) reflector, but this was not an especially good instrument for comet observing; I sometimes had better success with its 4 inch (10 cm) guide scope. During the early- to mid-1980s my main instrument was an 8 inch (20 cm) reflector I had purchased from Meade as a graduation present to myself; I still have this telescope, and use it occasionally.

I acquired the Meade 16 inch (41 cm) reflector I use most often nowadays in mid-1987, by which time I had just recently reached comet no. 100. With this larger instrument that helps me observe fainter comets, together with the experience I had gained over the years, the ever-faster means by which I learned of new comets, and the ever-increasing comet discovery rate, my rate of adding comets increased dramatically. I reached comet no. 200 in mid/late 1995, slightly less than 8 1/2 years after no. 100, and no. 300 in early 2002, less than 6 1/2 years later. By this time the first of the comprehensive sky surveys (LINEAR) was on-line, and I was using CCD imaging to, among other things, help me identify some of the extremely faint comets. It took me slightly over five years to get from comet no. 300 to no. 400.

Overall, my average wait time between adding new comets to the tally is 34 days, although this includes the long times typical of the early years (in one case a full year elapsed between successive comets). Since I acquired the 41 cm scope in 1987 my average wait time is 24 days. The median wait time for all the comets is 22 days, and since I acquired the 41 cm scope the median wait time is 19 days. There have been several occasions when I've added two comets in one night, and on one occasion I added three in one night.

General statistics

For the below analyses, it's worthwhile to keep in mind that the first 100 comets are, generally, brighter on the average than the last 300, due to reasons I discussed above. Also, a small handful of the comets are still under observation at this writing, so there may be some final "tweaking" of the results once I'm finally finished with them. (NOTE ADDED MAY 1, 2007: This has now been done -- see note at top of this page.)

The average perihelion distance for my observed comets is 1.486 AU, and the median is 1.366 AU. (For the first 100 comets, the average was 1.268 AU and the median 1.206 AU). The perihelion distances have ranged from 0.099 AU for Comet NEAT C/2002 V1 (no. 323) to 8.454 AU for Comet 95P/Chiron (no. 196). I've observed 16 comets with a perihelion distance of 0.20 AU or less, and 10 comets with a perihelion distance of 5.0 AU or greater.

My average tracking interval is 123 days, and the median tracking interval is 67 days. (The wide difference is due to some extremely long tracking intervals for a handful of comets.) For the first 100 comets, the average interval was 92 days and the median interval 49 days. There are several comets that I've only seen once (hence a tracking interval of zero), and the longest interval is for the 2004 return of Comet 29P/Schwassmann-Wachmann 1 (no. 226), which I picked up shortly after aphelion in early 1997 and which has now gone over 10 years (with another potential 4 1/2 years to go). I've followed 24 of the comets for over one year, 10 of these for over 18 months, and 4 of these for over two years (two of these being returns of 29P/Schwassmann-Wachmann 1).

My average number of observations per comet (rounded to the nearest whole number) is 11, and the median number of observations per comet is 8. (For the first 100 comets, the average was 10 and the median was 8.) As mentioned above, there are several comets that I've only seen once; my most-observed comet is Comet Hale-Bopp C/1995 O1 (no. 199), with 182 observations. There are 5 comets for which I have over 50 observations, and 3 for which I have 100 observations or more. My total number of observations at this writing is 4331. (NOTE ADDED MAY 1, 2007: This observation total is only for comets 1-400, and is current as of this writing.)

The average peak brightness that I have observed for the comets is magnitude 10.2, and the median peak brightness is magnitude 11.0. (For the first 100 comets, the average peak brightness was magnitude 9.0 and the median peak brightness was magnitude 9.5.) The brightest comet I've observed is Comet McNaught C/2006 P1 (no. 395), for which I measured a peak brightness of magnitude -4; the faintest comets are 95P/Chiron (no. 196) and LINEAR C/2002 CE10 (no. 340), which never were brighter than magnitude 15.0. I've observed 46 comets which reached a peak brightness of magnitude 6.0 or brighter; of these, I've observed 32 with my unaided eye.

Other miscellaneous comments

The smallest heliocentric distance at which I've observed a comet is 0.171 AU, for Comet McNaught C/2006 P1 (no. 395), which I was observing (in daylight!) at the moment of perihelion. The largest heliocentric distance at which I've observed a comet is 13.049 AU, for Comet 174P/Echeclus (no. 384) during its outburst in early 2006. The smallest geocentric distance at which I've observed a comet is 0.031 AU, for Comet IRAS-Araki-Alcock 1983d (no. 56) during its flyby of Earth in May 1983, and the largest geocentric distance at which I've observed a comet is 13.022 AU, again for Comet 174P/Echeclus (no. 384).

The longest tail I have ever observed on a comet is 70 degrees, for Comet Hyakutake C/1996 B2 (no. 212), shortly after its close approach to Earth in March 1996.

My record for most comets observed in one night is 11, which took place on the night of February 22-23, 1996. My record for most comets observed in one year is 34, in 2002. My record for most comet observations in one year is 274, in 1996 (helped enormously by Comets Hyakutake C/1996 B2 (no. 212) and Hale-Bopp C/1995 O1 (no. 199)).

There have been two occasions when I've observed two comets simultaneously in the same telescope field, one occasion when I've observed two comets simultaneously in the same binocular field, and one occasion when I've observed two comets simultaneously with my unaided eye.

The most productive month for comet discoveries (and recoveries) for the comets on my list is January, with 41; the least productive is February, with 16. The most productive month for comets passing perihelion is December, with 57; the least productive is June, with 16. The most productive month for adding comets to my list is August, with 51; the least productive is June, with 17.

I've observed 94 numbered periodic comets (of the 186 periodic comets that have been numbered as of this writing). I have a goal to reach 100 numbered comets, which I will almost certainly reach even if I never observe another comet in my life, thanks to the several periodic comets which I've observed on their discovery apparitions and which have yet to return. Of these 94, I have observed 45 on one return, 20 on two returns, 18 on three returns, 8 on four returns, two (41P/Tuttle-Giacobini-Kresak and 81P/Wild 2) on 5 returns, and one (2P/Encke) on 9 returns, for a total of 96 "repeat" comets (and thus a total of 304 separate comets out of the 400). (NOTE ADDED MAY 1, 2007: At this writing there are now 187 numbered periodic comets, but my "observed" total of these remains at 94.)

A total of 195 different names (of which 181 are of actual people) are represented in the tally of 400 comets. 99 of these names (including Hale) appear only once. The name that appears most often in the tally is LINEAR, with 46 appearances, followed by Shoemaker (with 17), Levy (15), Machholz (14), Bradfield (13), and Hartley (12).

I have observed comets from 10 states within the U.S. (Arizona, California, Colorado, Maryland, New Mexico, Oklahoma, Tennessee, Texas, Utah, and Washington) plus the District of Columbia, and from six countries outside the U.S. (Australia, Indonesia, Iran, Mexico, New Zealand, and Zimbabwe) as well as from international waters in the Pacific Ocean (during my Navy years) and the Caribbean Sea (during an eclipse cruise).

For the record, in addition to the 400 comets I have observed, I have made unsuccessful visual attempts for 162 other comets. (Some of these are ones I have attempted very recently, and which I may successfully observe within the near future.) Of these comets, I've successfully imaged 11 of them with CCD. (NOTE ADDED MAY 1, 2007: I have now observed two of these "non-successes" among comets 401-405, but in the meantime I have unsuccesfully attempted two additional comets, so my total of "non-successes" at this writing remains at 162. It is possible that I'll visually observe one or both of these new additions, as well as one of the older ones, at some point in the future. I have also successfully imaged two more of these "non-successes" with CCD, so this total now stands at 13.)

From an entirely subjective standpoint, the "best" comet I have observed is Comet West 1975n (no. 20) during its appearance in the morning sky in early March 1976.


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