2010CBET.2187....2P

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. = 0:42:42.81, Decl. = +41:16:14.7 (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.