THE ASTRONOMER Electronic Circular No 557 1991 August 31 17.55UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise, Basingstoke,
Hants, RG22 4PP, England. Telephone: (0256)471074 Int:+44256471074
Telex: 9312111261 Answerback: TA G JANET BOXES:
GMH at UK.AC.CAM.ASTRONOMY.STARLINK or GUYH at UK.AC.SUSSEX.CLUSTER
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PERSEID METEORS AND PERIODIC COMET SWIFT-TUTTLE
D. Levy and P. Jedicke report that their observations from
Springfield, VT, through clouds, showed what was obviously a rather
intense display of Perseids on Aug. 12.3 UT, with 15 meteors, one
as bright as mag -8, being noticed in an interval of 40 min.
Yamamoto Circ. 2170 quotes a report from Y. Taguchi, Osaka, to the
effect that observations by a group at an altitude of 1720 m near
the Kiso Observatory gave the following individual hourly rates for
the midtimes specified: Aug. 12.62 UT, 64; 12.66, 352; 12.70, 62;
the corrected ZHR for the middle hour (Lsun = 138.86, equinox
1950.0) was more than 400. P. Aneca, B. de Pontieu, J. Deweerdt
and J. Vanwassenhove, Vereniging voor Steerenkunde, Brussels,
observing in very good conditions (limiting mag 6.2-6.5) at Haute
Provence, individually recorded between 280 and 320 meteors during
two hours surrounding Aug. 13.08 UT; correction only for the
radiant height yields a ZHR of up to 200. Observations by Levy and
Jedicke on Aug. 13.3 UT, this time under clear skies south of
Montreal, showed far fewer meteors than the night before.
Although it is generally presumed that the associated comet,
P/Swift-Tuttle (1862 III), passed perihelion unobserved around 1981
+/- 2, the possibility that P/Swift-Tuttle was identical with comet
1737 II (Kegler) and that it may therefore return in late 1992 is
perhaps enhanced by this year's very strong Perseid display. The
nominal prediction (Marsden 1973, A.J. 78, 662) is T = 1992 Nov.
25.85 ET, Peri = 153.05, Node = 138.74, i = 113.45 (1950),q= 0.9582
AU, e = 0.9633. Because of nongravitational effects, the
uncertainty in T could be as much as +/- 2 months, and this affects
the ephemeris (below) through mid-October by +/- 2 degrees, mainly
in declination. The predicted mag is little more than a guess.
1991 ET R.A. (1950) Decl. Delta r m2
Sept.11 9 36.73 +31 22.6
21 9 43.10 +31 32.2 6.022 5.324 21.2
Oct. 1 9 49.23 +31 48.5
11 9 55.01 +32 13.2 5.589 5.143 20.8
21 10 00.26 +32 47.7
31 10 04.83 +33 33.9 5.101 4.960 20.5
Nov. 10 10 08.51 +34 33.7
20 10 11.03 +35 48.8 4.591 4.774 20.1
30 10 12.10 +37 20.9
Dec. 10 10 11.33 +39 11.0 4.097 4.584 19.7
IAUC 5330
OW GEMINORUM
This eclipsing variable (=NSV 3005) has an orbital period of
3.4458 years with mid-eclipse predicted for 1991 Sept 2 (Sky and
Telescope Sept 1991 p285-286).
Patrick Schmeer, Germany, e-mails that the eclipse has started:
Aug 22.128UT, 8.6; 26.122, 8.6; 27.144, 8.6; 29.145, 8.7;
30.115, 8.8.
Guy M Hurst