Electronic Telegram No. 4281 Central Bureau for Astronomical Telegrams Mailing address: Hoffman Lab 209; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A. e-mail: cbatiau@eps.harvard.edu (alternate cbat@iau.org) URL http://www.cbat.eps.harvard.edu/index.html Prepared using the Tamkin Foundation Computer Network COMET P/2016 J3 (STEREO) K. Battams, Naval Research Laboratory, reports that Scott Ferguson has found a slightly diffuse comet with a short tail on HI-1 images taken with the STEREO-A spacecraft, with the object apparently fading from mag about 10 to mag about 13 over two days. Astrometry from COR-2 images was measured by Man-To Hui, and the positions tabulated below are geocentric positions computed from the first and last STEREO-A astrometry. Battams adds that only COR-2 observations were measured asstrmetrically, as the HI-1 data are of such poor quality that it is doubtful that they would give any additional benefit; he also relates that the SOHO spacecraft did not observe this comet. 2016 UT R.A. (2000) Decl. May 11.57932 3 41.95 +20 53.2 13.47515 3 55.65 +20 34.7 Battams further notes that forward scattering may have played a major role in the comet's apparent brightness, as it was around mag 8 in the STEREO COR-2 images when nearer to the sun. The reduced astrometry and the following uncertain elliptical orbital elements by G. V. Williams appear on MPEC 2016-K41. T = 2016 May 21.4476 TT Peri. = 210.7379 e = 0.880351 Node = 259.0085 2000.0 q = 0.466936 AU Incl. = 25.3299 a = 3.902562 AU n = 0.1278437 P = 7.71 years The following is provided as a geocentric search ephemeris for potential ground-based observations, from the above orbital elements; the brightness is highly uncertain. Date TT R. A. (2000) Decl. Delta r Elong. Phase 2016 05 12 03 45.02 +20 49.5 1.503 0.517 7.3 14.4 2016 05 13 03 52.23 +20 39.8 1.489 0.507 7.9 15.9 2016 05 14 03 59.51 +20 28.6 1.475 0.499 8.5 17.5 2016 05 15 04 06.86 +20 16.0 1.461 0.491 9.2 19.3 2016 05 16 04 14.27 +20 01.8 1.447 0.484 10.0 21.3 2016 05 17 04 21.72 +19 46.0 1.433 0.479 10.8 23.3 2016 05 18 04 29.23 +19 28.8 1.419 0.474 11.6 25.4 2016 05 19 04 36.76 +19 10.1 1.405 0.471 12.5 27.7 2016 05 20 04 44.33 +18 50.0 1.390 0.468 13.3 29.9 2016 05 21 04 51.92 +18 28.5 1.376 0.467 14.3 32.2 2016 05 22 04 59.51 +18 05.7 1.362 0.467 15.2 34.6 2016 05 23 05 07.12 +17 41.6 1.347 0.468 16.1 36.9 2016 05 24 05 14.72 +17 16.3 1.333 0.471 17.1 39.2 2016 05 25 05 22.32 +16 49.8 1.319 0.474 18.0 41.4 2016 05 26 05 29.90 +16 22.3 1.305 0.479 19.0 43.6 2016 05 27 05 37.48 +15 53.9 1.291 0.485 20.0 45.6 2016 05 28 05 45.03 +15 24.5 1.278 0.492 21.0 47.6 2016 05 29 05 52.58 +14 54.2 1.264 0.499 22.0 49.5 2016 05 30 06 00.10 +14 23.2 1.251 0.508 23.0 51.2 2016 05 31 06 07.60 +13 51.5 1.239 0.518 24.0 52.8 2016 06 01 06 15.09 +13 19.0 1.227 0.528 25.0 54.3 2016 06 02 06 22.56 +12 46.0 1.215 0.539 26.0 55.7 2016 06 03 06 30.00 +12 12.4 1.204 0.550 27.0 56.9 2016 06 04 06 37.43 +11 38.3 1.193 0.563 28.1 58.0 2016 06 05 06 44.85 +11 03.7 1.183 0.575 29.1 59.0 2016 06 06 06 52.24 +10 28.7 1.174 0.588 30.1 59.8 2016 06 07 06 59.62 +09 53.3 1.165 0.602 31.1 60.6 2016 06 08 07 06.98 +09 17.6 1.157 0.616 32.1 61.2 2016 06 09 07 14.32 +08 41.6 1.149 0.630 33.1 61.7 2016 06 10 07 21.64 +08 05.3 1.142 0.645 34.1 62.1 2016 06 11 07 28.94 +07 28.8 1.136 0.660 35.1 62.4 2016 06 12 07 36.22 +06 52.2 1.131 0.675 36.1 62.6 2016 06 13 07 43.47 +06 15.5 1.126 0.690 37.1 62.7 2016 06 14 07 50.70 +05 38.6 1.122 0.706 38.1 62.7 2016 06 15 07 57.89 +05 01.8 1.119 0.721 39.1 62.7 2016 06 16 08 05.05 +04 25.0 1.116 0.737 40.1 62.6 2016 06 17 08 12.17 +03 48.3 1.115 0.753 41.1 62.4 2016 06 18 08 19.25 +03 11.7 1.113 0.769 42.0 62.2 2016 06 19 08 26.29 +02 35.3 1.113 0.785 42.9 61.9 2016 06 20 08 33.28 +01 59.2 1.114 0.801 43.9 61.6 2016 06 21 08 40.22 +01 23.3 1.115 0.817 44.8 61.2 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2016 CBAT 2016 May 31 (CBET 4281) Daniel W. E. Green