//////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3166 SUBJECT: Swift Trigger 113225: P60 Observations DATE: 05/04/02 07:32:42 GMT FROM: S. Bradley Cenko at Caltech S. Bradley Cenko and Derek B. Fox report on behalf of the Caltech-NRAO- Carnegie GRB Collaboration: We have observed the field of Swift Trigger #113225 with the Palomar 60- inch telescope. Automated observations began approximately three minutes after receiving the alert. We have obtained 3 x 120 second images in the Kron R band. Visual comparison with the Digitized Sky Survey yields no new sources in the field. We estimate our (3 sigma) limiting magnitude to be R ~ 20 (calculated with reference 4 objects in the Guide Star Catalog). Further observations are planned. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3167 SUBJECT: GRB 050402: Early observations with Swift-UVOT DATE: 05/04/02 08:02:08 GMT FROM: Patricia Schady at MSSL/Swift S. T. Holland, M. Still (GSFC/USRA), W. Landsman (GSFC), Adam Morgan, S. Hunsberger (PSU), A. Breeveld (MSSL), P. Roming (PSU), K. Mason, P. Schady (MSSL), M. Ivanushkina (PSU), T. Poole (MSSL), C. Gronwall (PSU), A. Blustin (MSSL), P. Brown (PSU), S. Rosen, K. McGowan, M. De Pasquale (MSSL), P.Boyd, S. T. Holland (GRFC/UMBC), H. Huckle (MSSL), P. Broos (PSU), T. Kennedy, P. Smith, B. Hancock (MSSL), H. Krimm (GSFC/USRA), S. Kock (PSU), M. Carter (MSSL), K. Gendreau (GSFC), M.Chester (PSU), D. Hinshaw (GSFC/SPSYS), J. Nousek (PSU), N. Gehrels (GSFC), on behalf of the Swift UVOT team. The Swift Ultra-Violet/Optical Telescope (UVOT) began observing the field of GRB 050402 at 06:12:01.6 UT, approximately 125 seconds after the BAT trigger. The first image was sent down via the TDRSS link approximately 300 seconds after the trigger. This image was a 100 second exposure taken with the V filter. It was centred on the BAT position, and had a size of 5 x 5 arcminutes, which covered 88% of the BAT error circle. The image was binned 8 x 8 to reduce the bandwidth required for transmission. A comparison against the DSS showed no new sources down to a 5-sigma limiting magnitude of approximately V = 18.84 +/- 0.09 , based on preliminary in-orbit zero points. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3168 SUBJECT: GRB 050402A: IR Observations DATE: 05/04/02 08:19:12 GMT FROM: Josh Bloom at Harvard/CFA H. W. Chen (MIT), J. S. Bloom (UCB), J. X. Prochaska (UCSC) & C. Blake reports on behalf of a larger collaboration: "We began imaging the position of Swift Burst #113225 at 2005-04-02 06:27:42.5 UTC with PAIRITEL on Mt Hopkins. There appears to be be no object brighter than the 2MASS catalogue in J, H, and K. In comparing two epochs, there appears to be a fading source at: 09:05:55.42, 16:37:25.5 (J2000) Further analysis is in progress." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3169 SUBJECT: GRB050402: XDSS counterpart DATE: 05/04/02 09:02:51 GMT FROM: Derek Fox at CIT Derek B. Fox and S. Bradley Cenko (Caltech) reports on behalf of a larger collaboration: "We note that the IR afterglow candidate of Chen et al. (GCN 3168) has a point-like counterpart in second-generation Digitized Sky Survey (XDSS) i-band (n-emulsion) images. The source is also detected close to threshold in R-, I-, and z-band imaging from P60. Analysis as to source variability is ongoing." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3170 SUBJECT: GRB 050402A: IR Analysis DATE: 05/04/02 10:01:42 GMT FROM: Josh Bloom at Harvard/CFA H. W. Chen (MIT), J. S. Bloom (UCB), J. X. Prochaska (UCSC) & C. Blake reports on behalf of a larger collaboration: "Upon more detailed analysis following GCN #3168 we cannot confirm our earlier claim of significant variability as suggested. We thus find no variable or new source to the 2MASS detection levels in J, H, and K starting ~18 min after the GRB." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3172 SUBJECT: Very questionable identity of Swift-BAT GRB050402 (Trig=113225) DATE: 05/04/02 15:45:36 GMT FROM: Scott Barthelmy at NASA/GSFC S. Barthelmy, L. Barbier (GSFC), J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), M. Suzuki (Saitama), J. Tueller (GSFC) on behalf of the Swift-BAT team: At 06:09:55 2-April-2005, UT Swift-BAT triggered on a marginal event (trigger=113225) which has been reported as GRB 050402 (GCNs 3167, 3168, 3169, 3170). The BAT team believes that the automated notice sent out earlier is likely consistent with a noise fluctuation, but we can not absolutely rule out that it was due to a very soft, weak GRB. The reasons which make this a questionable detection are: (a) detected only in the 15-25 keV band, (b) the image significance is very marginal, and (c) the noise in the detector array is slightly elevated during this interval (thus increasing the chance coincidence of a rate fluctuation and an image-domain fluctuation).