//////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4938 SUBJECT: H4043, an unusual high-energy transient observed by HETE DATE: 06/03/31 16:00:17 GMT FROM: Jean-Luc Atteia at Lab d Astrophys.,OMP,Toulouse E. Fenimore, G. Ricker, J-L. Atteia, N. Kawai, D. Lamb, and S. Woosley, on behalf of the HETE Science Team; M. Arimoto, T. Donaghy, M. Galassi, C. Graziani, N. Ishikawa, A. Kobayashi, J. Kotoku, M. Maetou, M. Matsuoka, Y. Nakagawa, T. Sakamoto, R. Sato, T. Shimokawabe, Y. Shirasaki, S. Sugita, M. Suzuki, T. Tamagawa, K. Tanaka, and A. Yoshida, on behalf of the HETE WXM Team; N. Butler, G. Crew, J. Doty, G. Prigozhin, R. Vanderspek, J. Villasenor, J. G. Jernigan, A. Levine, G. Azzibrouck, J. Braga, R. Manchanda, G. Pizzichini, and S. Gunasekera, on behalf of the HETE Operations and HETE Optical-SXC Teams; M. Boer, J-F Olive, A. Pelangeon, J-P Dezalay, and K. Hurley, on behalf of the HETE FREGATE Team; report: At 06:41:42 UTC on March 31, 2006 HETE-2 detected a long, bright and soft event at the extreme edge of the WXM field of view. Ground analysis yields an error box centered at (J2000): (RA,DEC) (deg) = 233.444d -15.235d (15h 33m 47s -15d 14' 04") with the following corners (J2000): (RA,DEC) (deg) = 233.792 -15.396 (RA,DEC) (deg) = 233.081 -15.456 (RA,DEC) (deg) = 233.096 -15.072 (RA,DEC) (deg) = 233.806 -15.015 The error box area is 944 square arc minutes. The time profile shows a rise time of ~10 seconds and a fall time of >100s, with little obvious spectral evolution. Neither a power-law nor a blackbody yields an acceptable spectral fit. This event is unusual. It resembles an X-ray burst from a galactic binary, yet its location at high galactic latitude, its long duration without the expected spectral evolution from photospheric expansion, and the failure of a blackbody spectral fit all argue against this interpretation. On the other hand, it is unusually bright for an X-ray flash, and the failure of a power law fit argues against this interpretation. There is a known x-ray source (1RXS J153521.7-150420) in the error box, but this is not unlikely for a box this large. A light-curve of the event is given at http://space.mit.edu/HETE/Bursts/GRB060331/ We urge further observations of this unusual event at all wavelengths. [GCN OPS NOTE(31mar06): Per author's request, the URL was corected; see GCN Circ 4939.] //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4939 SUBJECT: Correction to Circular 4938, =H4043, an unusual high energy transient observed by HETE DATE: 06/03/31 18:57:21 GMT FROM: Joel Villasenor at MIT The web site showing the light curve for this unusual transient was incorrectly reported; the correct link can be found at: http://space.mit.edu/HETE/Bursts/GRB060331 The HETE Ops team apologizes for any confusion caused by this error. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4940 SUBJECT: HETE Trigger 4043: ROTSE-III Optical Limits DATE: 06/03/31 19:02:10 GMT FROM: Eli Rykoff at U of Michigan/ROTSE E.S. Rykoff (U Mich), S.A. Yost (U Mich), H. Swan (U Mich), report on behalf of the ROTSE collaboration: ROTSE-IIIa, located at Siding Spring Observatory, Australia, responded to HETE Trigger #6063 (Fenimore, et al, GCN 4938), producing images beginning 7.2 s after the GCN notice time. An automated response took the first image at 15:32:47.2 UT, 31864 s after the burst, under fair conditions. We took 10 5-sec, 10 20-sec and 80+ 60-sec eposures. These unfiltered images are calibrated relative to USNO A2.0 (R). Comparison to the DSS (second epoch) reveals no new sources within the WXM error box described in GCN 4938. Individual images have limiting magnitudes ranging from 15.8-17.2; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 15:32:47.2 15:36:3.1 50 17.2 31864 Y 15:42:14.3 15:53:53.9 600 18.0 33131 Y //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4941 SUBJECT: Swift XRT observations of the HETE transient H4043 DATE: 06/04/02 07:27:01 GMT FROM: Vanessa Mangano at INAF-IASFPA V. Mangano, T. Mineo (INAF-IASFPA), J. Kennea, D. Burrows (PSU) and V. La Parola (INAF-IASFPA) on behalf of the Swift XRT Team Swift observed the field of the HETE II transient H4043 (Fenimore et al. 2006, GCN 4938) on 2006 March 31 for three consecutive orbits starting at 16:53 UT. About 65% of the HETE error box was covered in two different pointings with 1500 and 500 s exposure, respectively. No point source was detected up to limiting fluxes of about 5.e-13 and 1.3.e-12 erg cm^-2 s^-1, respectively. This circular is an official product of the Swift XRT Team. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4942 SUBJECT: H4044, a Repeat Outburst From The Source of H4043 (="GRB060331") DATE: 06/04/02 18:58:54 GMT FROM: Carlo Graziani at U.Chicago R. Vanderspek, G. Ricker, J-L. Atteia, N. Kawai, D. Lamb, and S. Woosley, on behalf of the HETE Science Team; M. Arimoto, T. Donaghy, E. Fenimore, M. Galassi, C. Graziani, N. Ishikawa, A. Kobayashi, J. Kotoku, M. Maetou, M. Matsuoka, Y. Nakagawa, T. Sakamoto, R. Sato, T. Shimokawabe, Y. Shirasaki, S. Sugita, M. Suzuki, T. Tamagawa, K. Tanaka, and A. Yoshida, on behalf of the HETE WXM Team; N. Butler, G. Crew, J. Doty, G. Prigozhin, J. Villasenor, J. G. Jernigan, A. Levine, G. Azzibrouck, J. Braga, R. Manchanda, G. Pizzichini, and S. Gunasekera, on behalf of the HETE Operations and HETE Optical-SXC Teams; M. Boer, J-F Olive, A. Pelangeon, J-P Dezalay, and K. Hurley, on behalf of the HETE FREGATE Team; report: At 13:11:23 UTC on April 2, 2006 HETE-2 detected another long, bright and soft event coming from the same position as H4043(="GRB060331"). Ground analysis yields an error box with the following corners: R.A. = 233.7856 deg. ; Dec. = -15.4384 deg. = 15h35m09s ; = -15o26'18" R.A. = 233.3906 deg. ; Dec. = -15.5543 deg. = 15h33m34s ; = -15o33'15" R.A. = 233.3972 deg. ; Dec. = -15.6477 deg. = 15h33m36s ; = -15o38'51" R.A. = 233.7922 deg. ; Dec. = -15.5313 deg. = 15h35m10s ; = -15o31'52" This position is consistent with the position of event H4043 (Fenimore et al., GCN 4938). It is therefore unlikely that either H4043 or H4044 were due to cosmic gamma ray bursts. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4950 SUBJECT: HETE Triggers H4043 and H4044 Not Due to New Cosmic Source DATE: 06/04/04 03:19:32 GMT FROM: Carlo Graziani at U.Chicago C. Graziani, G. Ricker, J-L. Atteia, N. Kawai, D. Lamb, and S. Woosley, on behalf of the HETE Science Team; M. Arimoto, T. Donaghy, E. Fenimore, M. Galassi, N. Ishikawa, A. Kobayashi, J. Kotoku, M. Maetou, M. Matsuoka, Y. Nakagawa, T. Sakamoto, R. Sato, T. Shimokawabe, Y. Shirasaki, S. Sugita, M. Suzuki, T. Tamagawa, K. Tanaka, and A. Yoshida, on behalf of the HETE WXM Team; N. Butler, G. Crew, J. Doty, G. Prigozhin, R. Vanderspek, J. Villasenor, J. G. Jernigan, A. Levine, G. Azzibrouck, J. Braga, R. Manchanda, G. Pizzichini, and S. Gunasekera, on behalf of the HETE Operations and HETE Optical-SXC Teams; M. Boer, J-F Olive, A. Pelangeon, J-P Dezalay, and K. Hurley, on behalf of the HETE FREGATE Team; report: We have performed further analyses of HETE triggers H4043 and H4044, in conjunction with a similar event (H4047). We have concluded that these events are not in fact due to a previously unknown cosmic source. They are instead due to SCO-X1, in conjunction with episodes of loss of spacecraft attitude control that can occur sporadically near the daytime terminator. We regret the confusion created by this error.