Comet C/2011 L1 (McNaught)
Abstract
Robert H. McNaught reports his discovery of a comet (discovery observation tabulated below) on CCD images taken with the 0.5-m Uppsala Schmidt telescope at Siding Spring; on the discovery images, the object appears nearly asteroidal with a 10" coma and a 1'.4-long narrow tail in p.a. 225 deg. McNaught's images from June 3.4-3.6 show a tail 0'.7 long in p.a. 220-225 deg; he adds that the comet's head merges into the tail, making a small aperture essential to define the center of light for astrometry. On June 6.4, McNaught found total mag 16.2 and a 0'.6 tail in p.a. 218 deg, again noting the difficulty in determining the astrometric center of light, suggesting that most measures will be biased down the tail to some extent. After posting on the Minor Planet Center's 'NEOCP' webpage, other CCD astrometrists have commented on the object's cometary appearance. Three images taken by J. D. Armstrong, A. N. Martin, M. Micheli, M. E. Schindler, and S. H. Spear with the 'Faulkes Telescope South' 2.0-m f/10 reflector on June 3.52-3.56 show a 7" elliptical coma elongated toward the tail, which itself was 1'.5 long in p.a. 213 deg. Thirty stacked 60-s images taken by R. Holmes (Ashmore, IL, USA, 0.61-m f/4 astrograph, June 4.2) show an 8" round coma and a 25" tail in p.a. 230 deg (measured by S. Foglia and T. Vorobjov). Foglia adds that stacked images taken remotely on June 4.64-4.67 by S. Baroni, L. Buzzi, P. Concari, G. Galli, M. Tombelli, and himself with a 0.18-m f/2.8 reflector at the Tzec Maun Observatory near Moorook, Australia, show a 10" round coma (total red mag 16.2-16.6) and a 120" tail in p.a. 215 deg. 2011 UT R.A. (2000) Decl. Mag. Observer June 2.63479 16 08 14.08 -34 30 36.5 16.9 McNaught The available astrometry, the following preliminary parabolic orbital elements by G. V. Williams, and an ephemeris appear on MPEC 2011-L26. T = 2011 Jan. 1.129 TT Peri. = 301.300 Node = 251.426 2000.0 q = 2.41987 AU Incl. = 70.862
- Publication:
-
International Astronomical Union Circular
- Pub Date:
- June 2011
- Bibcode:
- 2011IAUC.9212....1M