A comet of magnitude 17 was discovered with the 0.5m-Uppsala telescope by G.J. Garradd on Aug. 13, 2008 in the constellation Phoenix. Comet C/2008 P1 (Garradd) showed a condensed 10" coma and a 15" tail pointing westward. The comet will pass perihelion in July 2009 and could reach 15.5 mag, positioned near the borders of the constellations Pisces/Andromeda/Pegasus (IAUC 8965 / MPEC 2008-U16). According to the very small number of published observations the comet peaked at about 15 mag in fall 2009.
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On Dec. 8, 2008 A. Watson found a 10 mag comet in the constellation Sagittarius on STEREO-B images, which showed a short faint tail. Maik Mayer first pointed to the similarity of the calculated orbit with the one of comet P/2003 K2 (Christensen). The difference in the perihelion date of comet P/2008 X4 (Christensen) was dt=-22d as compared to the predictions. It passed perihelion on its 5.66 orbit in mid-December, peaking at 9.0 mag, then positioned quite close to the Sun (IAUC 9005). In mid-December J.N. Marcus suggested that the comet would be a good candidate for enhanced brightness due to significant forward-scattering geometry on Dec. 23, when the solar elongation would reach a minimum of only 0.4°. Indeed it was clearly seen on SOHO images of those days with an estimated brightness of 6-6.5 mag. K. Kadota estimated the brightness of the comet on Dec. 14 (in bright twilight) as 11 mag and on Dec. 30 as 10.5 mag. From mid-Europe the comet started to be observable in the second week of January in the morning sky. The few reported observations indicate a brightness evolution which may roughly be described by the parameters m0=13.5m/n=4. The apparent coma diameter was estimated at 2.5' at the beginning of January. In the meantime the comet received the permanent designation 210P/Christensen (IAUC 9007/08/10, Comet's Mailing List).
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On images taken by the satellite STEREO on Apr. 3, 2009 a 10-11 mag comet was discovered near the border of the constellations Pegasus/Aquarius. Comet C/2009 G1 (STEREO) was tailless and passed perihelion in mid-April. The first terrestrial observation was achieved on Apr. 9 by K. Kadota with the position of the comet 4' off: the 4.5' coma with a pronounced central condensation was of magntiude 10.6 mag (IAUC 9036/37). The comet was not be visible from mid-European latitudes. Based on 55 international observations the comet showed a very smooth brightness evolution according to the formula m = 7.9 mag + 5×log D + 7.1×log r, yielding a maximum brightness of 8.8 mag around May 20. The coma diameter measured about 4' at the beginning of the apparition, increasing to 6' until the end of May. Thereafter it shrunk, measuring less than 1' at the end of July. The coma was medium-condensed (DC 4) at first, but became more and more diffuse with passing time. At the end of the apparition it was estimated as DC 2.
Total Brightness and Coma Diameter
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On June 15, 2009 Riu Yang and Xing Gao discovered a comet near the border of the constellations Serpens / Sagittarius while performing their search program. Comet P/2009 L2 (Yang-Gao) showed a 40" coma with a total magnitude of 13.5 and a rather broad 1.5' tail in p.a. 240°. It exhibits an extremely faint absolute magnitude and has a period of 6.3 years. The comet was close to Earth when it was discovered (minimum distance: 0.303 AU), already receding, and therefore fading (IAUC 9052 / MPEC 2009-P14). Successful visual observations were obtained between mid-June and the beginning of July, when the comet appeared about one magnitude brighter than expected (maximum brightness about 12.8 mag). The 1' coma was considerably condensed (DC 6).
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On Catalina images of Aug. 26, 2009 A. Boattini discovered an 18.5 mag comet in the constellation Taurus. Comet P/2009 Q4 (Boattini) showed a strongly condensed 8" coma with central condensation and a narrow 10-15" tail in p.a. 290°. It will pass perihelion of its orbit with a period of 5.0 years in November 2009 and could peak at 15 mag near Year's end, the positioned in Leo (IAUC 9069 / MPEC 2009-R30). Observers reported a maximum brightness of about 13.0 mag in November/December 2009. The condensed coma measured 0.8'.
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During winter 2009/10 comet 30P/Reinmuth (P=7.34a) could be observed with large amateur instruments as a 15 mag object in the constellations Orion/Taurus, being visible during the whole night. International observations show a large scatter, but it seems that the comet reached about 14.5 mag in December/January. The coma diameter was measured to be about 0.4'.
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Between Jan. 11 and 30, 2009 comet 33P/Daniel brightened about 3 mag (from 18 mag to 15 mag), according to CCD-observations. Between Feb. 7 and 20 it brightened 1 mag further. This comet passed perihelion (r = 2.17 AU) already on July 20, 2008. According to the standard formula the comet was not expected to show more than slight brightness variations during the mentioned period (IAUC 9022 / MPEC 2009-D52).
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No visual observations were published of comet 59P/Kearns-Kwee. The few CCD-observations showed the comet at magnitude 15.0-15.5 at the beginning of 2009.
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The ICQ predicted a maximum brightness of 15 mag for comet 74P/Smirnova-Chernykh (P=8.53a) during winter 2008/09. During this time it moved near the border of Cancer/Leo, thus was a comfortably placed object. The comet peaked at 14.5m at the end of 2008 - half a magnitude brighter than expected.
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Two magnitudes brighter than expected became comet 77P/Longmore. In March 2009 it was estimated at magnitude 13.5 mag, showing a medium condensed coma of 0.6' diameter.
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Comet 94P/Russell (P=6.60a) peaked at about 14.5 mag during the apparition in winter/spring 2009/10.
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Comet 116P/Wild (P=6.48a) was expected to be observable in medium-sized telescopes during winter and spring 2009. Positioned in the western part of Leo, it was an object of the whole night. The comet was not well-observed, only 35 observations could be used for a crude analysis. According to these the comet reached magnitude 11.5 at the start of June. The evolution can be represented by the formula m = 8.5 mag + 5×log D + 0.02×(t-T), yielding a (not observable) maximum brightness of 10.5 mag in mid-July. The coma diameter increased only from 1.7' to 2.3', with the coma moderately condensed (DC 3-4).
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Comet 118P/Shoemaker-Levy (P=6.60a) passed perihelion at the beginning of January 2010. The number of published observations is too small for a definite analysis. However, the brightness evolution can be described rather well with the parameters m0=10.0 mag / n=4, resulting in a brightness of 13.0 mag at the time of perihelion. At the end of Februar / start of March the brightness peaked at 12.5 mag. The diameter of the very diffuse coma measured about 1'.
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On June 29, 2009 the 18.5 mag object 2009 MB9 was discovered during the Siding Spring Sky Survey near the border of the constellations Lupus/Centaur. R.H. McNaught found the object of cometary nature on Aug. 2. H. Sato pointed out, that it was Comet P/2004 X1 (LINEAR) (CBET 1893). Komet P/2009 MB9 (LINEAR) passed perihelion in September 2009 (dT = -2.2d), supposed to reach 16 mag, but remaining close to the Sun. At the beginning of August it passed Earth at the distance of only 0.174 Au. In the meantime it received the final designation 222P/LINEAR (IAUC 9062). Visual observations showed the comet to be 5 mag brighter than expected in September. At the beginning of September it was estimated to be of magnitude 12.3, showing a medium-condensed coma short of 1'. Due to the rapidly increasing distance to earth at the end of September it was of magnitude 13.6, showing a similar coma than four weeks before.
Andreas Kammerer
