An asteroidal object reported in the constellation of Libra by the LINEAR team on May 17, 2001, revealed its cometary nature on further observations. Comet C/2001 K5 (LINEAR) presented itself as a 14.5m bright object with a 12" small, strongly condensed coma and a 13" short tail at p.a.=210°. This comet will reach perihelion in autumn 2002 at a distance of 5.2 AU (IAUC 7634). If it behaves as an average comet it should remain brighter than 14.5m until the end of 2003, with a maximum brightness of 13.0m in mid-2002, then in the constellation Ophiuchus.
Visual observers gave a brightness of 13.5m in May 2002, the apparent coma diameter was reported as about 1'. With a maximum brightness of 13.0m at the beginning of summer it confirmed the predictions as well as the assumption, that it is a relatively large or active comet. The coma diameter was estimated at 1.0'. The published estimates during September/October 2002 gave a brightness of about 13.5m and a coma of 0.7' diameter. Analysing 90 estimates made by international observers between April 2002 and September 2003 yield a wide range of possible brightness parameter. Only by using the few observations of 2001 the parameters can be better defined (most plausible values: m0=2.5m / n=4). Thus the comet has reached its maximum brightness of 13.0m in early summer 2002. The coma diameter was 1.0' (240.000 km) at first, 1.3' (270.000 km) in 2002, measuring 1.0' (240.000 km) during spring 2003. During the whole apparition the coma was only moderately condensed (DC 3).
Total Brightness and Coma diameter --------------------
On Dec. 5, 2002 an 18m object reported as asteroidal by LINEAR was discovered in the constellation Leo. Detailed observations on Dec. 7 found the object to be cometary on CCD images: about 20" coma, m_1 = 15.5m, hint of tail at p.a. about 300° (IAUC 8028). Comet C/2002 X1 (LINEAR) will pass perihelion in July 2003 and may be observable (at about magnitude 14.5) through amateur instruments during spring in Gemini/Taurus. After conjunction with the sun it should become visible again as an object of magnitude 13.5 in Taurus/Eridanus. In February/March 2003 the comet presented itself 1m brighter than expected with the coma diameter estimated as slightly larger than 0.5'. If this positive evolution continues the comet could be a 12.5m bright object in autumn 2003, moving through the constellations of Taurus, Eridanus and Cetus.
According to the observations published during summer 2003 the brightness peaked at about 13.5m, as predicted shortly after discovery. The coma of diameter 0.7' was only weakly condensed.
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On Jan. 10, 2003 Arianna Gleason discovered a comet of magnitude 20 with the Spacewatch II - telescope in the constellation Cancer. It showed a 20" coma and a broad tail (p.a. ranging from 20° to 200°). Observations at Klet observatory showed a false nucleus of magnitude 21. Comet C/2003 A2 (Gleason) will pass perihelion in November 2003 at the greatest distance (11.4 AU) of all known comets (IAUC 8049/67, MPEC 2003-C72). --------------------
An asteroidal object of magnitude 15.5m, discovered by the LINEAR-Team on Apr. 23, 2003 in the constellation Hercules, showed a strongly condensed 20" coma and a faint fan-shaped 5" tail pointing towards south. Comet C/2003 H1 (LINEAR) will reach perihelion in February 2004 (IAUC 8122). If it should show an average evolution it should reach magnitude 11.0 in spring 2004. It should be brighter than magnitude 12.0 from February to April 2004. However, during this period it will move through Libra and Hydra, south of declination -15° (with the turning point at -28°).
Until the end of 2003 only CCD-observations were published. During summer/fall 2003 the brightness was estimated as 14.5m - about 0.5m fainter than expected. The coma diameter was in the order of 0.5'. During 2004 the number of visual estimates kept small - mainly due to the rather discouraging observing circumstances. Thus this analysis is based on only 31 estimates, which yield the formula m = 7.3m + 5×log D + 11×log r for the brightness evolution, meaning a maximum brightness of 11.9 mag in mid-March 2004. The apparent coma diameter increased from 1.1' at the beginning of the apparition to 1.6' at the beginning of March, therefter decreasing to 1.2' until mid-April. The absolute coma diameter decreased during the apparition from 100.000 km to 85.000 km. The degree of condensation was about DC 3.
Total Brightness and Coma diameter
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On Oct. 13, 2003 an apparently asteroidal object of magnitude 18 was discovered by the LINEAR-team in the constellation Draco. Closer inspections revealed its cometary nature. Comet C/2003 T2 (LINEAR) showed a 15" coma of total magnitude 15.0 and a broad 20" tail towards p.a. 30-35°. (IAUC 8222). CCD-observations of Jäger/Rhemann on Oct. 17 showed a 14 mag comet with a 1' inner coma and an outer coma of diameter 2.5'. This comet peaked at magnitude 14.0 at the beginning of November 2003. The very diffuse coma reached an apparent diameter of 1.0' and showed a small central condensation. --------------------
Due to not more than 35 estimates only very preliminary results can be given for the evolution of comet 30P/Reinmuth concerning the current perihelion passage. The brightness evolution can be best represented by the parameters m0=10.3m/n=4. However, the published estimates still allow a rather great interval for the activity parameter n. The apparent coma diameter was in the order of 1.0' at the start and end of the apparition, reaching a maximum of 1.4' in March 2003. These changes, however, simply mimic the changing distance comet-earth, because the absolute coma diameter constantly measured 60.000 km. Equally constant was the degree of condensation: except for February/March (DC 3) constant at DC 2.
Total Brightness and Coma diameter --------------------
According to the published observations comet 53P/Van Biesbroeck evolved as predicted during spring and summer 2003, getting a bit brighter than 14.0m, thereby displaying a 0.5' coma. Michael Jäger observed the comet with a 1000mm/f3.3 Hypergraph via CCD on May 23/24 as an object of magnitude 13-14m with a 40", rather condensed coma and a tail of 3.5' length. --------------------
Surprisingly many observations (perhaps due to the comfortable position in Leo) of comet 65P/Gunn were published in April/May 2002, although this comet exhibited a brightness of only 14.5m and a coma diameter of about 0.6'. After conjunction with the sun this comet reappeared in January 2003. Additional estimates point to a maximum brightness of about 11-12m during summer 2003. However, due to its southerly positions (south of declination -30°) observations from mid-Europe will be difficult and of very limited value.
For a first analysis 40 international observations could be used. These indicate a rather different brightness evolution according to the formula m=9.2m+5×log D +5×log r, which yield a maximum brightness of 12.0m at the end of June. The absolute coma diameter constantly measured 75.000 km, resulting in an increase of the apparent coma diameter from 0.7' at the beginning of the apparition to 1.0' in August 2003. The degree of condensation was estimated as DC 4-5.
Total Brightness and Coma Diameter --------------------
J.V. Scotti recovered comet 66P/du Toit, so far only seen in 1944 and 1974, on Mar. 10, 2003 as a 20.5m object in Virgo (IAUC 8093) - 4m fainter than expected. Thus it is very uncertain whether this comet should become accessible to amateur equipment. It was expected to reach magnitude 13 in August. Michael Jäger succeeded in observing this comet via CCD: whereas it was only of magnitude 16 (with a 2' coma) on May 3/4, it had brightened to magnitude 14-15 (with a 3x2' coma) on May 30/31. Extrapolating this trend the comet could reach magnitude 13 around perihelion, although it will be invisible from mid-Europe during those weeks. Michael Jäger assumes that it is a gas-rich comet, hence it should be a difficult object visually.
The observations published until the beginning of September 2003 indicate a very rapid brightening, according to the parameters m0=10.0m / n=8. It was brightest during July/August, reaching magnitude 12.0-12.5. At this time the weakly condensed coma (DC 2) showed a diameter of 2'.
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An increasing number of observations of comet 81P/Wild 2 were published in February/March 2003. These show the comet to be of magnitude 13.5m, thus confirming the brightness parameters m0=6.0m / n=6. The diameter of the coma was estimated as short of 1'. According to CCD-observations by Jäger/Rhemann the comet displayed a 25' long dust tail at the end of May. If the comet should follow this evolution it should be of magnitude 13-14 at the time it will reappear in the mid-European morning sky in spring 2004. --------------------
On Sep. 28, 2003 comet 104P/Kowal was rediscoverd with the Spacewatch-telescope at magnitude 21.5 in the constellation Delphinus (MPEC 2003-S96). The comet will pass perihelion in May 2004, but will be situated very near the sun around this date. Until it disappears in March it is not expected to get brighter than 15 mag.
This comet has been identified with an object observed by L. Boethin in the Philippines between Jan. 11 and 14, 1973 - about 6 years before the official discovery of this comet. On Jan. 11 Boethin estimated the brightness of this comet, then in the constellation Crater, as 9.5m (with a 8' large, diffuse coma and a noticeable false nucleus). On Jan. 14, however, he reported a sudden decrease to 12-13m. A search initiated by CBAT, based on these observations, was not successful although covering a large area. The positions reported by Boethin are consistent within 2' with comet Kowal. According to the official brightness parameters this comet should then have not been brighter than 17m (more than five months after perihelion). Since the comet shows some large non-gravitational terms a short-lived outburst seems likely (IAUC 8255).
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Analyzing 45 observations of comet 116P/Wild 4 yield brightness parameters of m0=9.5m/n=5, indicating a maximum of 12.0m at the beginning of May 2003. However, due to the rather small variance in r all values between 10.2m/1.5 and 7.7m/4 can not be excluded. The coma showed a diameter of 1.3' (90.000 km) and a degree of condensation of DC 3 (with a maximum of DC 4 in June).
Total Brightness and Coma Diameter --------------------
On Aug. 26, 2002 comet P/2002 Q4 (Brewington) = 1992p = 1992 XIV - now designated as 154P/Brewington - was recovered as an object of magnitude 15.5 in the constellation Sagittarius at Observatorio Astronomico Los Molinos, Montevideo. It displayed a diffuse coma of diameter 20" with a central condensation; the correction to the prediction was dT = +0.52 day (IAUC 7961). This comet passed perihelion in February 2003 and was expected to get as bright as 10.5m by then.
Only a small number of observations were published. These clearly demonstrate that this comet was about 2m fainter than predicted. The maximum brightness of about 12.5m was reached at the start of February (crude brightness parameters: m0=7.0m / n=7). The coma was only weakly condensed and showed a diameter of about 1'. Michael Jäger photographed the comet on the evening of Nov. 11, 2002 with his 8"-Schmidtcamera at magnitude 14.0m. On Dec. 1 he derived magnitude 13.5-14.0m and a coma of diameter 1.5'.
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T. Oribe and A. Nakamura independently recovered comet P/2002 R2 (Shoemaker) = 1986a = 1985 XVIII - now designated as 155P/Shoemaker - on Sep. 9 and 12 near the border of Orion/Gemini. It was an object of magnitude 18.0 with a 12" coma (IAUC 7969). During December 2002 the CCD-magnitudes of this comet were clearly fainter than predicted, However, during January 2003 it gained in brightness with the magnitudes only 0.5m fainter then the predictions (which themselves have been modified, according to the ICQ handbook). Maximum brightness of about 13.0m was reached in January 2003 (crude brightness parameters: m0=10.0m / n=5). The 1.5' coma was only weakly condensed. --------------------
On Oct. 6, 2003 the american amateur C. Juels discovered a fast-moving 12.5m object in the constellation Cancer. P. Holvorcem detected a 2' coma and a 1.5' tail in p.a. 257° during his CCD-observation, which was confirmed by further observers. On the basis of orbital calculations by Maik Meyer, Sebastian Hönignoticed the possible identity with comet Tritton, which was confirmed by Brian Marsden. Comet 157P/Tritton = P/2003 T1 (Tritton) = 1978d was observed for only one month in 1978. The derived period of 6.34 years predicted the perihelion passage during spring 2003. Because this comet was not detected during its perihelion passages between 1978 and 2003 it is plausible that it was rediscovered during a rare outburst (IAUC 8215-17).
CCD-observations showed a very elliptical coma (nearly a streak) with only a weak central condensation at the top - very reminiscent of the appearances comets 1999 S4 and Hönig showed shortly before they fizzled out. Observations of this comet span only the period October to November 2003. At magnitude 13 it showed a 1.5' coma, which became more and more elongated.
Andreas Kammerer
