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
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| Picture obtained from observatory J87 La Cañada, this is a stack of 50 images with 1 minute of exposure time each following on the movement predicted by the Minor Planet Center ephemeris Service MPES based on just three observations by F51 Pan-STARRS the night before. |
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: 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 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
My personal NOTE, shame on the central bureau for astronomical telegrams:
Hello Daniel,
It's not correct the observations by J. Lacruz were done after the object was posted on the PCCP as CBET 4100 states.
To be fair, the remarks on the cometary nature of this object by J. Lacruz should appear rigth after the discovery observations, and before those by Wainscoat and Micheli because the cometary appearance of this body by J. Lacruz was noted and communicated to cbat before others did..
The observations from La Cañada and remarks noting the cometary appereance were done before the object was posted on the PCCP. At that time the object was posted on the NEOCP and only three observations by the discovery site were available. In summary it was moved to the PCCP because of the remarks sent by J87 when it was in the NEOCP.
The object was moved to the PCCP right after I sent the remarks on its cometary nature and it appeared there with just the discovery observations together with mine. After that observations by others were added including those taken by the Canada-France-Hawaii Telescope.
It is not the same to note the cometary nature of such a faint object when it mey just be a NEO that once you know it may most likely be a comet
Please correct
Best regards
