128P/Shoemaker-Holt (0128P)

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Type: Periodic Perihelion date: 9 January 2017 Perihelion distance (q): 3.1 Aphelion distance (Q) : 5.9 Period (years): 9.5 Eccentricity (e): 0.32 Inclination (i): 4.4 JPL orbit diagram COBS lightcurve The comet, also known as Shoemaker-Holt 1, was discovered by Carolyn S. Shoemaker, Eugene M. Shoemaker, and Henry E. Holt on plates obtained on 1987 October 18 and 19 with the 0.46-m Schmidt telescope at Palomar Observatory. It was described as "strongly condensed, with a slight coma asymmetric toward the southwest." Its photographic magnitude was estimated as 14.5. J. V. Scotti (University of Arizona, USA) recovered this comet with the Spacewatch telescope at Kitt Peak on 1996 September 19.19. His precise positions indicated the perihelion date to be 1997 November 20.25 (3.0470 AU). Scotti described the comet as between magnitude 20.7 and 21.1 at discovery. Scotti's images obtained on September 20 revealed a diffuse secondary companion situated about 4 arc seconds north-northeast of the main nucleus. The comet passed closest to Earth (2.06 AU) on November 27. The maximum magnitude was not expected to be much brighter than 15. Observations during 1997 December and 1998 January indicated the comet had reached magnitude 14.9. The coma diameter was about 0.8 arc minute. Observations (VEMag = visual equivalent magnitude) Date 10x10 mag Error VEmag Coma ' 09-Sep-16 18.97 0.07 17.2 0.2 28-Sep-16 18.93 0.13 18.1 0.2 29-Oct-16 17.91 0.03 17.0 0.2 24-Nov-16 17.62 0.02 16.1 0.3 19-Dec-16 17.84 0.02 16.3 0.3 26-Dec-16 18.02 0.09 16.7 0.2 17-Jan-17 18.15 0.01 15.8 0.3 24-Jan-17 18.50 0.08 17.7 0.3 15-Feb-17 18.60 0.07 18.0 0.2 25-Feb-17 18.49 0.25 16.4 0.2