Circular No. 5621

Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION

Postal Address: Central Bureau for Astronomical Telegrams Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. Telephone 617-495-7244/7440/7444 (for emergency use only) TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505 MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)

PERIODIC COMET SWIFT-TUTTLE (1737 II = 1862 III = 1992t)

Total visual magnitude estimates: Sept. 27.41 UT, 9.1 (D. Machholz, Colfax, CA, 29 × 127 binoculars; 4′ coma); 27.47, 9.1 (C. S. Morris, Pine Mountain Club, CA, 0.26-m reflector; diffuse and uncondensed, coma 5′.2); 27.48, 10.2 (A. Hale, Las Cruces, NM, 0.20-m reflector; coma 4′).

Ephemeris from the orbital elements on IAUC 5620:

1992TT α_{2000} δ_{2000} Δ r ϵ β m_{1}
Sept. 25 11^{h}37.^{m}16 +58^{o}52.^{′}3 1.837 1.595 60.^{o}1 33.^{o}0 9.3
27 11 49.18 +59 03.5 1.791 1.571 61.0 33.9 9.2
29 12 01.95 +59 12.2 1.744 1.548 61.8 34.8 9.1
Oct. 1 12 15.47 +59 17.8 1.699 1.524 62.6 35.7 9.0
3 12 29.78 +59 19.6 1.654 1.501 63.4 36.6 8.9
5 12 44.86 +59 16.7 1.610 1.478 64.1 37.5 8.7
7 13 00.69 +59 08.2 1.567 1.455 64.7 38.4 8.6
9 13 17.22 +58 53.0 1.525 1.432 65.3 39.3 8.5
11 13 34.37 +58 30.2 1.484 1.409 65.8 40.3 8.3
13 13 52.05 +57 58.7 1.445 1.386 66.3 41.2 8.2
15 14 10.11 +57 17.5 1.407 1.364 66.6 42.1 8.1
17 14 28.39 +56 25.5 1.372 1.342 66.9 43.1 8.0
19 14 46.72 +55 22.1 1.338 1.320 67.0 44.0 7.8
21 15 04.94 +54 06.5 1.307 1.299 67.1 44.9 7.7
23 15 22.86 +52 38.6 1.278 1.277 67.0 45.8 7.6
25 15 40.35 +50 58.2 1.253 1.256 66.9 46.7 7.5
27 15 57.26 +49 05.6 1.230 1.236 66.6 47.5 7.4
29 16 13.49 +47 01.3 1.210 1.216 66.1 48.3 7.3
31 16 28.98 +44 46.2 1.194 1.196 65.6 49.1 7.2
Nov. 2 16 43.69 +42 21.4 1.182 1.177 64.9 49.7 7.1
4 16 57.59 +39 48.3 1.173 1.158 64.1 50.3 7.0

Further reports, mainly from P. Brown and J. Rendtel of the International Meteor Organization and referring to visual Perseid observations this year in Okinawa, China and eastern Europe, as well as to radio monitoring in Japan and Europe, confirm the peak as having occurred around 1992 Aug. 11.81 UT (cf. IAUC 5586). Although this may indicate the next peak as occurring on 1993 Aug. 12.05 UT, observers are cautioned that the behavior of the peaks in 1991 and 1992 with respect to the comet’s nodal longitude and now the recovery of the comet suggest that the 1993 peak may be up to 0.1 day earlier than this.

1992 September 27 Brian G. Marsden