Last updated: February 5, 2012

Ephemerides for all of these comets (and many others) can be calculated at the IAU Minor Planet Center's web site. Recent reports of their brightness can be found at the ICQ's magnitude page, the Comet Observation Home Page [currently inactive] and the Yahoo! comet observations group. Discussions of these and other comets are carried out at the Yahoo! comets mailing list group, and links to images are at the Yahoo! comet images group. For basic comet observing information see the appropriate page at this web site.

NOTE ADDED NOVEMBER 21, 2007: There are numerous objects that are apparent asteroids but that travel in distinctly cometary orbits or are otherwise associated with cometary phenomena in some way, and it is entirely possible that these are extinct or dormant comets. When any of these come by I do attempt to observe them, but they are not eligible for adding to my comet tally unless observations show that they are indeed comets, in which case I'll add them to my list retroactively (as has happened once so far). This page will now include any such objects that I'm currently following at the time of any updates.

NOTE ADDED JULY 3, 2008: This page will now highlight in red print those comets that are 9th magnitude or brighter (and that are also easily accessible for observation) at the time of the update in question. Such comets should be detectable from suburban areas with small telescopes, and thus are those that are specifically recommended for "Countdown" participating students.

NOTE ADDED JANUARY 28, 2012: With the addition of comet no. 500 to my tally, "Countdown" now comes to a close. Earthrise will be transitioning to a new program within the fairly near future, probably in about two to three months; during the interim, we will continue to update this page on a fairly regular basis just as we have throughout "Countdown." New additions to my tally will be included as they are added, however this will normally happen without announcement or fanfare.

Comet LINEAR C/2010 S1 (no. 494)

This very distant comet, which is now a little less than 15 1/2 months away from perihelion passage, has remained a small and very faint object between magnitudes 14 and 14 1/2 ever since I first picked it up a little over five months ago, and I expect little, if any, change in brightness over the coming weeks, although it is now starting to get a little bit low in the northwestern evening sky and I may briefly lose it around the time it is in conjunction with the sun (53 degrees north of it) in early March. It continues to travel through rich star fields in the northern Milky Way, being currently located in northwestern Andromeda 45 arcminutes southwest of the star 3 Andromedae, and it is traveling at a relatively slow five arcminutes a day presently towards the southeast but gradually curving more directly eastward.

Comet 78P/Gehrels 2 (no. 492)

After receding from Earth for several months, this comet passed through perihelion a little over three weeks ago and is now receding from the sun as well. It was still visible without difficulty when I last saw it a week and a half ago, when it appeared as a small and somewhat condensed 12th-magnitude object, but I expect a distinct fading over the coming weeks and I doubt if I will be able to follow it for much longer. The comet is currently located in eastern Pisces two degrees southwest of the star Omicron Piscium and is traveling towards the east-northeast at half a degree per day, passing 45 arcminutes south of that star on February 9, then crossing into northern Cetus ten days later and into southern Aries three days after that.

Comet Hill C/2010 G2 (no. 486)

The outburst that this comet underwent near the beginning of January had almost completely subsided by the time I obtained my most recent observation a week and a half ago, when it appeared as a rather vague and diffuse object slightly brighter than 12th magnitude; unless there is some additional outburst activity in the near future I am probably done with it. The comet is located in northwestern Eridanus 2 1/2 degrees southwest of the star 5 Eridani and, having gone through its stationary point late last month, is now traveling towards the southeast at a relatively slow eight arcminutes per day.

Comet 29P/Schwassmann-Wachmann 1 (no. 498)

The weak outburst that this comet underwent shortly before the end of December has by now subsided, and I was unable to detect the comet when I last attempted it a week ago. It is currently located in northeastern Corvus two degrees south of the "Sombrero Galaxy" M104 and three degrees north-northeast of the star Eta Corvi and, having just gone through its stationary point two weeks ago, it is now heading very slowly towards the southwest. As is always the case with this comet, a fresh outburst can take place at any time.

Comet LINEAR C/2011 F1 (no. 499)

This relatively recent addition to my tally, still eleven months away from perihelion passage, is currently located in northeastern Bootes 4 1/2 degrees east of the star 44 Bootis, and is traveling towards the northeast at ten arcminutes per day. Thus far the comet has remained a small and relatively condensed object slightly fainter than 14th magnitude, although it did perhaps appear marginally brighter when I last observed it about a week ago; at most I expect a slow and gradual brightening over the coming several weeks.

Comet Garradd C/2009 P1 (no. 478)

This comet continues to climb higher into the morning sky as it approaches its opposition in mid-March. Its brightness had remained fairly steady near magnitude 7 1/2 for the past several weeks, however since it is drawing somewhat closer to Earth (although now receding from the sun) it may exhibit a slight brightening trend, and in fact it did appear marginally brighter to me when I most recently observed it a few mornings ago. Meanwhile, telescopically the comet is exhibiting a fairly bright and broad "anti-tail" towards the east (about half a degree long visually) and a main tail a similar distance towards the north-northwest (with the ion tail lying coincident with this); this appearance is well demonstrated in this recent image. Comet Garradd is located in northern Hercules two degrees northwest of the globular star cluster M92 and is traveling towards the north-northwest (currently at 50 arcminutes per day, increasing to 75 arcminutes per day by late this month); it crosses into southeastern Draco on February 13 and enters northern circumpolar skies by the end of February.

Comet McNaught C/2009 F4 [not observed]

Now a little over a month past perihelion passage (at a distant 5.45 AU from the sun), this distant comet remains deep in southern circumpolar skies, currently at a declination of -76.6 degrees and located in southern Hydrus two degrees north-northwest of the star Sigma Hydri (and five degrees southeast of the Small Magellanic Cloud); it is traveling towards the north-northeast at slightly over 15 arcminutes per day. The most recent reports I've read from the southern hemisphere suggest that the comet's brightness continues to remain steady between 13th and 14th magnitude (where it has been for the past several months), and there should be little, if any, change in brightness over the coming months.