//////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5491 SUBJECT: GRB 060901: a long GRB detected by INTEGRAL DATE: 06/09/01 19:53:34 GMT FROM: Sandro Mereghetti at IASF/CNR S. Mereghetti, A. Paizis (IASF, Milano), D.Gotz (CEA, Saclay), S.Shaw, M.Beck (ISDC, Versoix), and J. Borkowski (CAMK, Torun) on behalf of the IBAS Localization Team report: A GRB lasting about 20 s has been detected by IBAS in IBIS/ISGRI data at 18:44:00 UT on September 1 2006. The refined coordinates (J2000) derived from the off-line analysis are: RA: 287.15758 [degrees], DEC: -6.63957 [degrees] with an uncertainty of 2.5 arcmin. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5492 SUBJECT: GRB 060901: Watcher observations DATE: 06/09/01 20:56:33 GMT FROM: Petr Kubanek at AIO J. French (UCD Dublin) and P.Kubanek (AsU AV CR Ondrejov & ISDC Versoix) on behalf of the Watcher collaboration reports: We observed GRB 060901, detected by INTEGRAL, with 40cm Watcher telescope, located at Boyden Observatory, South Africa, starting at 20:06:00 UT, 82 min after ISGRI/IBAS detection. At location mention in GCN Circ. 5491 we do see few sources not present in USNO, which are all visible on ESO archive plates. We place conservative limit R 18 mag for any OT from this GRB. Futher observations and analysis are in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5493 SUBJECT: GRB 060901: further INTEGRAL results DATE: 06/09/01 21:23:59 GMT FROM: Sandro Mereghetti at IASF/CNR S. Mereghetti (IASF, Milano), D.Gotz (CEA, Saclay) on behalf of the IBAS Localization Team report: GRB 060901 was relatively bright and saturated the ISGRI telemetry. Preliminary estimates of the peak flux and fluence in the 20-200 keV energy range are 6.6 ph (7x10e-7 erg)/cmq/s and 3.5x10e-6 erg/cmq. Due to the telemetry gaps these should be considered as lower limits //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5494 SUBJECT: GRB 060901: Swift/XRT Position DATE: 06/09/02 02:21:14 GMT FROM: Judith Racusin at PSU J. Racusin (PSU), D. Grupe (PSU), S. Hunsberger (PSU), and N. Gehrels (NASA/GSFC) report on behalf of the Swift XRT team: Swift/XRT began a target of opportunity observation of the INTEGRAL detected GRB 060901 (Mereghetti et al., GCN Circ. 5491) at 22:30 UT September 1 2006 (~3.8 hours after the burst). We have analyzed the first 3 orbits of XRT data and we find a previously uncatalogued source at the following coordinates: RA(J2000): 19:08:37.98 Dec(J2000): -6:38:07.84 with an estimated uncertainty of 4.9 arcseconds radius (90% containment). This position is 14.8 arcseconds from the INTEGRAL position given in GCN Circ. 5491. Further observations and analysis are in progress. This is an official product of the Swift XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5495 SUBJECT: GRB 060901: SMARTS optical/IR observations DATE: 06/09/02 03:50:43 GMT FROM: Bethany Cobb at Yale U B. E. Cobb (Yale), part of the larger SMARTS consortium, reports: Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 060901 (GCN 5491, Mereghetti et al.) with a mid-exposure time of 2006-09-02 00:24:54 UT, which is ~5.7 hours post-burst. Total summed exposure times amounted to 15 minutes in I and V and 12 minutes in J and K. Within the error region of the X-ray afterglow detection (GCN 5494, Racusin et al.), we detect a stellar object in all wavebands that is apparent in both USNO and 2MASS. Additionally, in the J-band observation there is a very marginal detection of a source inside the X-ray error region at: RA = 19:08:38.2 Dec = -06:38:06.14 The nature of this source is unclear, however, because of the low significance of the detection and the fact that the object is too dim to have previously been detected in 2MASS. We also do not know if the object is fading. The approximate limiting magnitudes of our images are: J > 18.5 K > 17.4 I > 21.2 These values are calibrated against several USNO-B1.0 stars in the I-band, and 2MASS stars in J and K. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5496 SUBJECT: GRB 060901: Swift/XRT Refined Analysis DATE: 06/09/02 13:30:23 GMT FROM: Judith Racusin at PSU GRB 060901: Swift/XRT Refined Analysis J. Racusin (PSU) reports on behalf of the Swift XRT team: We have analyzed the first 4 orbits of Swift XRT observations of GRB 060901 (Mereghetti et al., GCN Circ. 5491), with a total exposure of 3 ks. The refined position is: RA(J2000): 19:08:37.93 Dec(J2000): -6:38:08.1 with an estimated uncertainty of 4.3 arcseconds (90% containment). This position is 0.7 arcseconds from the preliminary XRT position given in GCN Circ. 5494 (Racusin et al.) and 14.5 arcseconds from the INTEGRAL position given in GCN Circ. 5491 (Mereghetti et al.). The 0.2-10 keV light curve in Photon Counting (PC) mode starts ~14 ks after the burst. The X-ray afterglow is faint, initially 0.05 counts/s, decaying with a slope of -1.7 +/- 0.7. The preliminary spectral fit to the PC data gives a spectral power law photon index of 2.1 +/- 0.6 in the [0.3-10] keV band, assuming Galactic absorption (2.34e21cm^-2). The average (in the time range 14 - 30 ks from trigger) estimated unabsorbed 0.3-10 keV flux was ~2.6e-12 erg cm^-2 s^-1. The XRT count rate extrapolated to T+24 hr is estimated to be ~0.003 counts/s, corresponding to an unabsorbed 0.3-10 keV flux of about 4.4e-13 erg cm^-2 s^-1. This circular is an official product of the Swift XRT Team. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5497 SUBJECT: GRB 060901: SMARTS optical/IR observations update DATE: 06/09/02 22:14:15 GMT FROM: Bethany Cobb at Yale U B. E. Cobb (Yale), part of the larger SMARTS consortium, reports: Additional analysis of the data described in GCN 5495 indicates that the possible J-band source was a spurious detection and, therefore, not associated with GRB 060901. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5498 SUBJECT: Konus-Wind observation of GRB 060901 DATE: 06/09/03 14:15:14 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and T. Cline on behalf of the Konus-Wind team report: The long GRB 060901 (Mereghetti et al., GCN 5491, 5493) triggered Konus-Wind at T0=67439.385 s UT (18:43:59.385). The Konus-Wind light curve shows a single pulse with a duration of ~8 sec, followed by a weak tail seen up to T-T0 ~15 sec. The spectrum of the pulse (accumulated from T-T0=0 to T-T0=7.936 sec) is well fitted (in the 20 keV - 2 MeV range) by GRBM (Band) model for which: the low-energy photon index is alpha = -0.77(-0.23, +0.26), the high energy photon index beta = -2.31(-0.36, +0.18), the break energy E0 = 156(-46, +71) keV (chi2 = 48/61 dof). The peak energy Ep = 191(-30, +40) keV. The burst total fluence is 1.51(-0.19,+0.14)x10^-5 erg/cm2 and peak flux on 256-ms time scale measured from T-T0=2.496 sec 3.06(-0.61, +0.54)x10^-6 erg/cm2/sec (both in the 20 keV - 2 MeV energy range). All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5499 SUBJECT: GRB 060901: pseudo-z from spectral parameters of the prompt DATE: 06/09/03 14:57:54 GMT FROM: Jean-Luc Atteia at Lab d Astrophys.,OMP,Toulouse A. Pelangeon & J-L. Atteia (LATT-OMP) report: We have used the spectral parameters of GRB 060901 provided by Golenetskii et al. (GCNC 5498) to compute the spectral pseudo-redshift** of this burst detected by INTEGRAL (Mereghetti et al., GCNC 5491). We find a pseudo-redshift pz= 2.0 +/- 0.5 ** cf. http://www.ast.obs-mip.fr/grb/pz //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5500 SUBJECT: 060901: Swift UVOT followup observations DATE: 06/09/03 15:48:50 GMT FROM: Alice Breeveld at MSSL-UCL A. Breeveld (MSSL/UCL) and J. Racusin (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began taking data on 2006-09-01 at 22:33:37 on the field of the INTEGRAL burst 060901 about 4 hours after the burst (Mereghetti et al., GCN 5491) . At the position of the XRT error circle (Racusin et al., GCN 5494) there are no new sources, although there is a catalogued source. There is no source seen either at the position of the new source in J band reported by Cobb et al. (GCN 5495). In the summed UVOT images we obtain the following 3 sigma upper limits: Filter T_range(s) Exp(s) 3sig_UL(mag) V 19306-19729 413.2 19.4 B 22900-23805 885.1 20.6 U 29566-29619 51.4 19.2 UVW1 28660-29560 885.6 20.6 UVW2 13777-17580 657.5 20.9 White (160-650nm) 23812-23821 8.7 18.7 //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5501 SUBJECT: GRB060901: Optical observations DATE: 06/09/03 19:51:06 GMT FROM: Klaas Wiersema at GRACE/U of Amsterdam K. Wiersema (University of Amsterdam) and C.C. Thoene (DARK Cosmology Centre) report: Using DFOSC on the Danish 1.5m telescope at La Silla we obtained R band imaging of the error circle of Integral burst GRB060901. Observations consisted of a series of 5 min exposures, starting at 1 Sep 23:46 UT and lasted until 2 Sep 02:19 UT. A second epoch was taken from 03:59 UT to 04:25 UT. We performed PSF matched image subtraction (Alard 2000) on the dataset as the field is very crowded. We find no significantly varying source in or near the XRT error circle (Racusin, GCN5496). Our full stacked dataset reaches a limiting magnitude of R~23.9. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6188 SUBJECT: GRB060901: Candidate optical afterglow DATE: 07/03/10 16:22:10 GMT FROM: Klaas Wiersema at GRACE/U of Amsterdam K. Wiersema (University of Amsterdam), E. Rol (University of Leicester) and C. C. Thoene (DARK Cosmology Centre) report: We re-analysed the data we took of INTEGRAL GRB 060901, as reported earlier in GCN 5501, supplemented with late time observations. We obtained three epochs of imaging in R band using DFOSC on the Danish 1.5m telescope at La Silla. The first two epochs were reported in GCN5501, and we re-observed the GRB position on September 8, midpoint 6.3 days after the burst. The first two epochs are close together in time, and suffered from bad seeing (~1.6 arcsec) and proximity to the bright Moon. The third epoch, while much shorter in exposure time and at full Moon, reaches a deeper magnitude limit than epoch 2 due to good seeing (~1 arcsec). The field is very crowded and the XRT error circle (Racusin, GCN 5496) partly overlaps with a bright star (present in the USNO-B catalogue with number 0833-0546379, possibly a blend of multiple stars), so we performed PSF matched image subtraction (Alard 2000) on the three epochs. A subtraction of the first two epochs does not yield a candidate afterglow (Wiersema & Thoene, GCN5501), but a subtraction of the first and third epoch reveals a clear, fading, residual located in the XRT error circle, at position: RA: 19:08:37.9 DEC: -06:38:07.4 With conservative astrometric errors of 0.4 arcsec. There are no other variable sources in the XRT error circle, but the source is located in the wing of the much brighter USNO star. We tentatively identify the variable object as the optical afterglow of GRB 060901. Using artificial stars with the subtractions, we find the OT candidate to be already below the (3-sigma) limiting magnitude of the second epoch image, and are able to derive a magnitude for the first epoch (midpoint 0.26 days after burst). of R ~ 22.6 +/- 0.5. We note that the Galactic extinction in this direction is considerable, at A_R ~1.8 mag. An image of the three epochs, the subtraction and the XRT error circle can be found on: http://staff.science.uva.nl/~kwrsema/grb060901/