Once the object was confirmed by J87 at the predicted position and movement, the astrometry and photometry report was sent to the Minor Planet Center MPC together with remarks on the diffuse aspect of the object. A coma about 8 arc seconds elongated in PA 320 degrees was measured.
Soon after that, the MPC moved the body from the NEOCP to the Possible Comet Confirmation Page PCCP, the only observations available from the PCCP then were the discovery observations and those of the confirmation by J87.
The calculations updated May 18.63 UT based on 35 observations spanning 2.89 days showed a nearly parabolic orbit with a semi axis about 100 AU passing the perihelion around 2015 Oct. 17.8
Electronic Telegram No. 4100
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION CBAT
Director: Daniel W. E. Green; Hoffman Lab 209; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A. e-mail: email@example.com (alternate firstname.lastname@example.org) URL http://www.cbat.eps.harvard.edu/index.html Prepared using the Tamkin Foundation Computer Network
COMET C/2015 J2 (PANSTARRS) E. Lilly and R. Weryk, Institute for Astronomy, University of Hawaii, report the discovery of another apparent comet in three w-band exposures taken with the 1.8-m Pan-STARRS1 telescope at Haleakala on May 15.5 UT (discovery observations tabulated below); the object shows a prominent tail with approximately 8" long extending towards p.a. approximately 300 degrees.
2015 May UT R.A. (2000) Decl. Mag.
15.48694 16 10 05.44 -23 22 05.6 19.6
15.49789 16 10 05.12 -23 22 07.0 19.7
15.50882 16 10 04.80 -23 22 08.7 19.6
Wainscoat and M. Micheli add that three 60-s r-band follow-up exposures were taken of the object with the 3.6-m Canada-France-Hawaii Telescope on May 16.5 UT (queue observer D. Woodworth), which show the object clearly cometary in appearance, with a broad, low-surface-brightness tail that extends from the nuclear condensation for at least 10" toward p.a. approximately 300 degrees.
After the comet was posted on the Minor Planet Center's PCCP webpage, other CCD astrometrists have also noted the object's cometary appearance. J. Lacruz, Madrid, Spain, reports that sixty stacked 60-s exposures taken with a 0.40-m Ritchey-Chretien reflector on May 17.0 UT show the comet to be diffuse with a fan-shaped coma 9" across with an apparent tail in p.a. 320 deg. A. Maury and J.-F. Soulier finds that images taken on May 17.1 with a 0.4-m f/8 Ritchey-Chretien reflector at San Pedro de Atacama show a 11" x 13" coma and a tail 15" long in p.a. 310 deg; they measured the comet's brightness in a 6".2 radius to be 18.8. W. H. Ryan communicates that his R-band images taken on May 18.33-18.36 with the Magdalena Ridge Observatory 2.4-m f/8.9 reflector show a distinct tail at p.a. about 300 deg, and he finds the comet's magnitude to be 18.6-18.9. H. Sato, Tokyo, Japan, writes that four stacked 60-s exposures taken with an iTelescope 0.51-m f/6.8 astrograph (+ luminance filter) at Siding Spring on May 18.6 UT show the comet to be strongly condensed with a coma 10" in diameter and no tail; the w-band magnitude was 20.2 as measured within a circular aperture of radius 6".6. The available astrometry, the following preliminary parabolic orbital elements by G. V. Williams, and an ephemeris appear on
MPEC 2015-K18. T = 2015 Oct. 17.8168 TT Peri. = 208.0670 Node = 57.2873 2000.0 q = 4.448423 AU Incl. = 18.7941
NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2015 CBAT 2015 May 19 (CBET 4100) Daniel W. E. Green