For reporting and commenting upon new observations of astronomical transients by the professional astrophysics community.

• ATel 2480: ROTSE3 J133033.0-313427 is a Type Ia Supernova

  A spectrum (340-760 nm) of ROTSE3 J133033.0-313427 (Zheng et al., ATel #2468) obtained on Mar 14.58 UT with the 10-m Keck I (+ Low Resolution Imaging Spectrometer) shows it to be a normal Type Ia supernova. ...

• ATel 2479: WSRT Radio Observations of PTF10bzf

  We observed the position of the broad-line Type Ic supernova PTF10bzf (ATel 2470) with the Westerbork Synthesis Radio Telescope at 4.8 GHz, at March 13 17.89 UT to March 14 1.45 UT. ...

• ATel 2478: Swift XRT Detection of Supernova 2008M in X-Rays

  Using 10.1 ks of Swift X-Ray Telescope (XRT) observations of the Type II SN 2008M in ESO 121-026 (CBET #1214), obtained between 2008-01-28 and 2008-01-30, an X-ray point-source is detected at the position of the SN with a 3-sigma significance of source detection. ...

• ATel 2477: Recurrent Nova U Sco Has Sharp Decline in X-ray/UV/Optical/IR

  U Sco is a recurrent nova with a fast decline leveling off to a plateau in the optical light curve (IAUC #9111, ATEL #2452), and it has become visible as a super-soft source (SSS) at the start of the plateau phase (ATEL #2430, ATEL #2442). ...

• ATel 2476: X-ray Transient detected by MAXI/GSC

  MAXI/GSC detected an X-ray transient at the scan transit centered at UT 2010-03-11T02:42:38. The averaged source flux during the scan is about 180 mCrab in the 4-10 keV band. ...

• ATel 2475: Near-IR observations of the Supergiant Fast X-ray Transient (SFXT) IGR J17544-2619

  The Supergiant Fast X-ray Transient (SFXT) IGR J17544-2619 which went to outburst on 2010 March 04 (ATel #2463) was observed in the near-infrared J-band on March 6 and in J, H, and K-band on March 7 with the 1.2m telescope (+ NICS with HAWAII-1 infrared array) at Gurushikhar, Mt Abu, operated by Physical Research Laboratory, Ahmedabad, India. ...

• ATel 2474: Optical ID of CXOM31 J004253.1+411422, a bright Black Hole X-ray Nova in M31

  We report the likely optical ID of the bright transient recently discovered in M31, CXOM31 J004253.1+411422 (Henze et al, ATEL #2356). With a peak X-ray luminosity of nearly 5e39 erg/sec, this is the brightest X-ray transient yet found in M31. ...