Comet C/2015 GX (Panstarrs)
Abstract
An apparently asteroidal object discovered with the 1.8-m Pan-STARRS1 telescope at Haleakala on Apr. 8.6 UT (discovery observations tabulated below), and announced with the minor-planet designation 2015 GX on MPS 598613, has been found to show cometary appearance by CCD astrometrists elsewhere. 2015 UT R.A. (2000) Decl. Mag. Apr. 8.58495 18 07 24.39 +40 07 38.4 20.0 8.59564 18 07 24.73 +40 08 05.1 19.9 8.60629 18 07 25.04 +40 08 31.8 19.8 8.61698 18 07 25.37 +40 08 58.3 20.0 R. Haver, Frasso Sabino, Italy, reported that twenty stacked 90-s unfiltered images taken on May 9.94-9.95 with a 37-cm Cassegrain reflector show a possible faint coma elongated slightly southward; the comet was very faint (mag 19.2 with a limiting mag of about 21). Haver's follow-up images taken on May 18.0 continued to show a faint cometary appearance, with an apparent elongation toward the south; he adds that additional images taken on May 25.0 again appear to show a faint coma of diameter about 7", elongated southward, noting that the coma was now more obvious than previously. L. Buzzi reports that thirty stacked 30-s images obtained with a 1.0-m f/8 Ritchey-Chretien telescope at McDonald Observatory on May 25.4 show a central condensation surrounded by a coma at least 6" wide, with a hint of a tail suspected toward the south; thirty stacked 30-s follow-up images on May 27.4 show a compact coma 5" across with a short, faint, fan-shaped tail in p.a. around 190 deg. H. Sato, Tokyo, Japan, writes that twelve stacked 60-s exposures taken on May 26.3 with an iTelescope 0.51-m f/6.8 astrograph (+ luminance filter) near Mayhill, NM, USA, show the object to be strongly condensed with a coma 10" in diameter and no tail; the w-band magnitude was 19.0 as measured within a circular aperture of radius 6".5.
- Publication:
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Central Bureau Electronic Telegrams
- Pub Date:
- June 2015
- Bibcode:
- 2015CBET.4109....1H