Another LINEAR-object was announced in the constellation Scutum on July 11, 2001. Subsequent observations permitted identification with the object 2001 MD7 (magnitude 17.5m), observed on June 21 and 24 by LINEAR and showed the comet P/2001 MD7 (LINEAR) to round the sun on an elliptical orbit with a period of 7.5 years. On an image taken on July 11 the diffuse comet is of magnitude 15.5m (IAUC 7660). It passed perihelion in November 2001 when a brightness of about 13.5m was predicted.
The use of 40 international observations gives the following results: the brightness evolution is best described by the parameters m0=12.1m/n=1, leading to a maximum brightness of 12.4m in mid-November. The coma diameter remained at 1.3' (65.000 km) for many weeks, but decreased rapidly to 0.6' (40.000 km) during February. The DC-value was constant at 3.
Total brightness and coma diameter --------------------
On the same day, Aug. 28, 2001, the NEAT team announced just another discovery. Comet P/2001 Q6 (NEAT) presented itself as a 16.5m object with a 10" coma and a 15" long, broad tail towards WSW in the constellation Taurus. This comet, too, is periodic and rounds the sun in 23.0 years. It will pass perihelion at the beginning of November 2001, prior passing Earth at an distance of 0.67 A.U., thereby reaching perhaps magnitude 14 (IAUC 7698).
In October 2001 the few observations clearly indicated that this comet was about 2.5m brighter than expected. Six observations of members of the German comet section and 60 international observations show great scatter during most of the apparition, which is the reason for the only approximate result of the brightness evolution, yielding parameters m0=8.5m/n=8 (a suspected minor outburst on Oct. 14 could not be verified). These indicate a maximum brightness of 10.7m around October 25 (with estimates remaining constant until November 20). This may indicate that the comet showed an increase in intrinsic activity well after discovery (with maximum around mid-November). This is supported by the fact that the coma diameter increased rapidly from 2.5' (80.000 km) at discovery to 3' (125.000 km) in mid-November. It decreased rapidly afterwards and was only 1.2' (70.000 km) at the end of the year 2001. The coma was only slightly condensed with a maximum of DC 3 at the beginning of November. At the end of the year the DC value was only 1-2.
Total brightness and coma diameter --------------------
An object independently discovered and reported as nebulous with a 3" coma by NEAT on Nov. 16, 2001, has been identified by G. V. Williams with an apparently asteroidal object reported on Oct. 13 and 17 by LINEAR (m2 = 19.8) and on Oct. 19 by NEAT, from which an apparently routine minor-planet orbit was computed. Observations of comet P/2001 TU80 (LINEAR-NEAT), situated in Cancer, by P. Kusnirak at Ondrejov showed a moderately condensed coma of diameter 0'.3. The comet, circling the sun every 7.0 years and passing perihelion in December 2001, was not expected to get brighter than 17m (IAUC 7753). However, during January 2002 CCD- and visual observers reported the comet to be around 14.0m with a 0.4' coma. This comet was observed visually during January and February, reaching a maximum of 14.0m. The observed brightness evolution can be rather well described by the parameters m0=9.5m / n=6. --------------------
CCD-observations by P. Manteca with a 31cm-SC on Dec. 6.1 UT showed comet 51P/Harrington to have split, the two components being separated by some 10" on an east-west line. Each is around mag 17.0-17.4m, the western component was perhaps up to 0.4m brighter than the eastern one, which is evidently the one that was under observation during July-November 2001. On Dec. 7.0 and 7.9 Manteca gave 16.4m for the eastern component and 16.6m for the western. The eastern component is also clearly the object defined as component A at the comet's 1994 apparition, when two much fainter components, B and C, were also recorded with an effective perihelion time almost 0.3 day later. The current western component is therefore denoted as component D, and its effective perhelion time on 2001 June 5 is only about 0.006 day later than that of component A (IAUC 7769). According to Z. Sekanina companion D separated from primary A on Sept. 5.6 +/- 3.6 TT, or 3 months after perihelion. Predicted separation distances and position angles (0h TT): 2001 Dec. 17, 12", 268°; 2002 Jan. 6, 10", 263°; Jan. 26, 9", 255°; Feb. 15, 9", 249°; Mar. 7, 11", 248°; Mar. 27, 15", 251°; Apr. 16, 19", 255°; May 6, 24", 259°. K. Kadota reported CCD observations that indicated an intrinsic brightening of more than two magnitudes between Aug. 22 and Sept. 23, an outburst confirmed by other observers (IAUC 7773).
Andreas Kammerer
