Electronic Telegram No. 2187 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION CBAT Director: Daniel W. E. Green; Room 209; Dept. of Earth and Planetary Sciences; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A. e-mail: cbat@iau.org; cbatiau@eps.harvard.edu URL http://www.cfa.harvard.edu/iau/cbat.html APPARENT NOVAE IN M31: M31N 2010-01a AND M31N 2010-01d EDITOR'S NOTE: This text replaces that on CBET 2181. W. Pietsch and M. Henze, Max-Planck-Institut fuer Extraterrestrische Physik; and the XMM-Newton/Chandra M31 nova-monitoring collaboration, report the discovery of an apparent nova close to the center of M31 in 2360-s UVW1-filter (240-360 nm) images. Designated M31N 2010-01d, the object was first detected in observations starting on Jan. 15.52 UT with an instrumental magnitude of 15.75; located at R.A. = 0h42m42s.81, Decl. = +41d16'14".7 (equinox 2000.0; uncertainty 0".3), which is 17" west and 5" north of the core of M31, the presumed nova was also detected in the two following XMM- Newton observations of the monitoring campaign. M31N 2010-01d and M31N 2010-01a (cf. CBETs 2124, 2127, 2136) were also detected in observations with the Ultraviolet/Optical Telescope (UVOT) on board the Swift satellite starting on Jan. 27.05 in the uvw1 (range 181-321 nm; 1486 s exposure time), uvm2 (166-268 nm, 525 s), and uvw2 (112-264 nm, 1550 s) bandpasses, performed to monitor x-ray emission from the nova M31N 2009-10b. Additional UVW1 magnitudes for M31N 2010-01d: Jan. 25.10, 15.80; Feb. 2.10, 15.49 (uncertainty +/- -.01 mag). Additional uvw1 magnitude for M31N 2010-01d: Jan. 27.05, 16.60 +/- 0.05. The XMM-Newton UVW1 magnitudes are instrumental (Vega); the SWIFT magnitudes are on the UVOT photometric system (Poole et al. 2008, MNRAS 383, 627). The magnitudes have not been corrected for extinction. K. Hornoch, Ondrejov Observatory, measures position end figures 42s.79, 14".3 (offset 17".3 west, 5".8 north) for M31N 2010-01d and provides the following magnitudes from co-added R-band CCD frames: Jan. 2.799, [19.9 (CCD frame taken during software tests by P. Kubanek, J. Gorosabel, P. Martorell, and M. Jelinek with the 1.23-m telescope at Calar Alto); 16.795, 16.7 +/- 0.3 (K. Hornoch, 0.65-m telescope at Ondrejov); 30.845, 19.5: (Kubanek, N. Morales, J. L. Ortiz, Gorosabel, and Jelinek, 1.23-m telescope at Calar Alto); 31.838, 18.9 +/- 0.3 (Kubanek, Morales, Ortiz, Gorosabel, and Jelinek). NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2010 CBAT 2010 February 23 (CBET 2187) Daniel W. E. Green