{
  "bibcode": "2005GCN..3499....1S",
  "body": "M.Sasaki, N.Manago, Y.Aita, T.Aoki, Y.Asaoka, M.Jobashi, K.Noda,\nA.Okumura (ICRR, Univ.Tokyo), S.Ogawa (Toho Univ.), T.Chonan, Y.Watanabe\n(Titech) report on behalf of the Ashra collaboration:\n\nWe have observed the field of GRB050504 (08:00:59 UT) covering the\nIntegral error circle (Mereghetti et al, GCN 3348) by Ashra-P2/3\n(Prototype of 2/3 scale) and Ashra-AFT at the Haleakala observatory in\nHawaii (latitude = 20d 42' 37\" N, longitude = 156d 15' 31\" W, altitude =\n3020m) in conditions of variable clouds across the field. \n\nThe Ashra-P2/3 continuously monitored the Integral field with 5sec-repeat\nof unfiltered 4sec exposures from 1 second before the burst. The\nAshra-AFT automatically responded to the Integral trigger and took the\nfirst image of 4sec-exposure at 08:01:57 UT (58 seconds after the burst\nand 37 seconds after the alert socket). We also took following 10\nunfiltered images of 4sec-exposure every 9 to 10 seconds (08:01:57 UT -\n08:03:29 UT). \n\nNo new source was found within the Integral position by the two telescopes.\nWe compared the co-added 10 images (10 x 4sec) from Ashra-P2/3 with BT\nin the Tycho catalog and the earliest 3 images and the co-added images\n(10 x 4sec) from Ashra-AFT with the USNO-B1.0 respectively. We preliminarily\nobtained 4-sigma limiting magnitudes as follows:\n\nAshra-P2/3 limiting magnitude\n -----------------------------------------------------\n   start    end      exposure     limit mag.\n   after GRB (s)          (s)     BT\n -----------------------------------------------------\n      -1      49    40.0           8.0\n -----------------------------------------------------\n\nAshra-AFT limiting magnitude\n -----------------------------------------------------\n   start    end      exposure     limit mag.\n   after GRB (s)          (s)     B1          R1\n -----------------------------------------------------\n      58      62     4.0          16.7        15.0\n      68      72     4.0          16.9        15.1\n      77      81     4.0          16.8        15.1\n -----------------------------------------------------\n      58     150    40.0          17.7        16.0\n ----------------------------------------------------- \n\nURL: http://www.icrr.u-tokyo.ac.jp/~ashra/\n\nThis message can be cited.",
  "circularId": 3499,
  "createdOn": 1117291137000,
  "email": "nodak@icrr.u-tokyo.ac.jp",
  "subject": "GRB050504: Ashra-P2/3 monitor and Ashra-AFT response",
  "submitter": "Koji Noda at ICRR,U of Tokyo  <nodak@icrr.u-tokyo.ac.jp>",
  "eventId": "GRB 050504"
}