Electronic Telegram No. 2823 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 2011 CR42 A. Waszczak, California Institute of Technology; and E. O. Ofek and D. Polishook, Weizmann Institute of Science, report that CCD images (1".01/pixel) of 2011 CR42, taken by the "Palomar Transient Factory" (PTF; cf. Law et al. 2009, PASP 121, 1395; Rau et al. 2009, PASP 121, 1334) on Mar. 5 and 6 with the 1.2-m f/2.44 Oschin Schmidt telescope, suggest that this minor-planet- designated object may have episodic cometary activity. The object consistently had a FWHM nearly twice that of all similar-magnitude SDSS- referenced stars (York et al. 2000, A.J. 120, 1579), thus suggestive of a cometary coma. This could not be caused by trailing, as the object's motion was < 1"/min. No sign of a cometary tail was visible before or after stacking the images. Six g-band 60-s astrometric observations are tabulated below in MPC format. K11C42R C2011 03 5.47755 11 25 21.43 +17 05 13.2 17.8 g I41 K11C42R C2011 03 6.14243 11 24 51.10 +17 08 12.8 17.9 g I41 K11C42R C2011 03 6.19523 11 24 48.60 +17 08 27.1 17.8 g I41 K11C42R C2011 03 6.23933 11 24 46.50 +17 08 39.1 18.0 g I41 K11C42R C2011 03 6.43924 11 24 36.90 +17 09 32.7 17.6 g I41 K11C42R C2011 03 6.48991 11 24 34.48 +17 09 46.0 17.7 g I41 The object was 2.92 AU from the sun and approaching perihelion (q = 2.53 AU on 2011 Nov. 30.0 TT). The object is currently on the earth's day side and will not be observable until after perihelion. Based on its current 86-day orbital solution (MPO 198577) and photometric parameters (H = 13.0, G = 0.15), the PTF survey should have acquired pre-discovery observations of 2011 CR42 in 2010 Feb. and Dec., at predicted magnitudes 19.2 and 18.8, when the object was at 3.8 and 3.1 AU from the sun, respectively. Upon inspection of these earlier images, no source was found within 200" of the predicted position brighter than mag 20.5. These null detections may be indicative of recent and relatively abrupt cometary activity. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2011 CBAT 2011 September 23 (CBET 2823) Daniel W. E. Green