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ATEL # 1857; Eamonn Kerins (University of Manchester)
on 30 Nov 2008; 20:16 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: Eamonn Kerins (Eamonn.Kerins@manchester.ac.uk)
Subjects: Optical, Microlensing Events, Nova
We report the discovery of two new optical transients in M31 by the Angstrom Project M31 bulge microlensing survey using the Liverpool Telescope (La Palma). These transients were discovered using difference imaging techniques by the Angstrom Project Alert System (APAS) in a series of Sloan i'-band images of the bulge of M31.
ANG-08B-M31-04 is located at RA=00:42:57.3 Dec=+41:15:41.1 (J2000), 148.''05 East and 33.''52 South of the core of M31. Periodic light-curve behaviour is seen throughout the previous four Angstrom observing seasons, consistent with a long-period variable at or close to the position of this event. However a stronger and sharper peak in the i' band was observed to reach a maximum of mi=20.2±0.1 (provisional) on November 24.885 2008. The light-curve of this object suggests that it is likely to be an ongoing nova or possibly an exotic microlensing system.
ANG-08B-M31-05 is located at RA=00:42:59.0 Dec=+41:17:15.5 (J2000), 164.''06 East and 72.''06 North of the core of M31. Periodic variation has been observed at this position through the past four Angstrom observing seasons. However the current rise is substantially stronger than previous variations. This event was observed with a magnitude of mi=20.4±0.1 (provisional) as of November 24.885. The current behaviour is consistent with microlensing with a full-width half-maximum time-scale of 30.43±1.89 days and a predicted peak occurring at MJD=54793.28±0.92 days. Follow-up observations of this event are encouraged.
More information, including light-curves and imaging data, is available from the Angstrom Project Alert page.
The Angstrom Project Website