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Comet 65P/GUNN - (= 1954 P1 = 1970 U2)

65P on Kronck’s cometography

Photometric data obtained by use of FOCAS-II software

                                   10x10  20x20  30x30  40x40  50x50  60x60   SNR   SB   COD

OBJECT        DATE       TIME        +/-    +/-    +/-    +/-    +/-    +/-     N  FWHM  CAT

------------  ---------- --------  -----  -----  -----  -----  -----  -----  ----  ----  ---

65P           18/01/2016 04:19:23  17.28  17.01  16.90                       11.5  17.8  B96

65P           18/01/2016 04:19:23*  0.06   0.10   0.13                          5   3.5  USN

65P           25/04/2023 20:59:42  18.95  18.52  18.51                        6.6  18.3  B96

65P           25/04/2023 20:59:42*  0.13   0.09   0.02                          2   3.5  Gai

                                                                     AFRHO         LOG

COMET         UTC                   DELTA    r    BOX "   MAG   RSR    CM    +/-  AFRHO  OBS

------------  -------------------   -----  -----  -----  -----  ---  -----  ----  -----  ---

65P           18/01/2016 04:19:23    3.42   3.99   8.06  17.35   12    206    18  2.314  B96

65P           25/04/2023 20:59:42    3.97   4.28   6.94  19.07    7     65    10  1.816  B96

Discovery

James E. Gunn (Palomar Observatory, California, USA) discovered this comet on a plate of the galaxy cluster Abell 194. The plate had been exposed on October 27, 1970 with the 122-cm Schmidt telescope. The comet appeared as a 16th-magnitude, diffuse, trailed image, which exhibited a central condensation and a small tail. The motion was slow and southwestward. Gunn made a request for confirmation to J. W. Young (Table Mountain Observatory, California, USA), but the 61-cm reflector only showed faint, threshold images near magnitude 15. A more definite confirmation had to wait until November 22 and 23, at which time J. N. Bahcall (Palomar Observatory, California, USA) used the 122-cm Schmidt to detect the comet at magnitude 16.

     In november 1980, prediscovery images were found on plates exposed during the Palomar Observatory Sky Survey (POSS). J. Dengel and R. Weinberger (Institut fur Astronomie, Innsbruck, Austria) discovered images of an "unidentified comet" on prints 1172. The 12-minute O exposure revealed a "small, slightly diffuse, elongated, weak spot of mean diameter ~5" and magnitude 19," while the 50-minute E exposure revealed a diffuse trail about 0.2' long, which exhibited an "extremely faint, narrow tail" extending about 1' toward PA 250°. This announcement was made on IAU Circular No. 3540 (1980 November 17). On IAU Circular No. 3588 (1981 March 31), T. Nomura (Waseda University, Tokyo, Japan) noted that this comet was "a prediscovery record of P/Gunn."

[Source: Kronk’s Cometography]