This file contains both: GRB 061222A and GRB 061222B //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5954 SUBJECT: GRB 061222: Swift detection of a burst DATE: 06/12/22 03:56:00 GMT FROM: David Palmer at LANL D. Grupe (PSU), L. M. Barbier (NASA/GSFC), P. J. Brown (PSU), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/GSFC/USRA), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), K. M. McLean (LANL/UTD), D. M. Palmer (LANL), J. L. Racusin (PSU) and M. Stamatikos (NASA/ORAU) report on behalf of the Swift Team: At 03:28:52 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 061222 (trigger=252588). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 358.243, +46.526 which is RA(J2000) = 23h 52m 58s Dec(J2000) = +46d 31' 34" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed three peaks of increasing size from about 0 to 10, 25 to 35 and 70 to 110 seconds after the trigger. The peak count rate was ~13000 counts/sec (15-350 keV), at ~86 sec after the trigger. The XRT began observing the field at 03:30:33 UT, 101 seconds after the BAT trigger. XRT found a bright, fading, uncatalogued X-ray source located at RA(J2000) = 23h 53m 03.45s, Dec(J2000) = +46d 32' 00.4", with an estimated uncertainty of 3.7 arcseconds (90% confidence radius). This location is 59 arcseconds from the BAT on-board position, within the BAT error circle. The initial flux in the 0.1s image was 1.5e-08 erg/cm2/s (0.2-10 keV). UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 110 seconds after the BAT trigger, and a finding chart exposure of 400 seconds with the V filter starting 215 seconds after the BAT trigger. No afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The 3-sigma upper limit in the White image is 19.7 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.10. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5955 SUBJECT: GRB 061222A: Prompt ROTSE-III Optical Limits DATE: 06/12/22 04:01:17 GMT FROM: Eli Rykoff at U of Michigan/ROTSE E.S. Rykoff (U Mich), F. Yuan (U Mich), B. E. Schaefer (Louisiana State), report on behalf of the ROTSE collaboration: ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 061222A (Swift trigger 252588, GCN 5954, Gruppe, et al), producing images beginning 7.3 s after the GCN notice time. An automated response took the first image at 03:29:39.3 UT, 47.1 s after the burst, under excellent conditions. We took 10 5-sec, 10 20-sec and 10+ 60-sec exposures. These unfiltered images are calibrated relative to USNO A2.0 (R). We note that several of our images, with limiting magnitudes ~17.0, overlap the main peak in the BAT emission. Imaging is ongoing. Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma BAT error circle or the XRT error circle, for both single images and coadding into sets of 10; however, we are limited as the field is somewhat crowded. Individual images have limiting magnitudes ranging from 16.5-18.0; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 03:29:39.4 03:29:44.4 5 16.5 47.2 N 03:30:14.4 03:30:19.4 5 17.0 82.2 N 03:30:21.4 03:30:26.4 5 17.0 89.2 N 03:29:39.4 03:30:47.4 68 18.1 47.2 Y 03:30:55.4 03:35:50.8 295 18.5 123.2 Y //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5956 SUBJECT: GRB 061222b: optical afterglow DATE: 06/12/22 04:33:34 GMT FROM: Edo Berger at Carnegie Obs E. Berger (Carnegie) reports: "We imaged the location of GRB 061222b with LDSS3 on Magellan. Within the XRT error circle we find a bright optical afterglow at: RA = 07:01:24.6 DEC = -25:51:36 with an uncertainty of about 1". Spectroscopic observations are in progress." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5957 SUBJECT: GRB 061222B: Swift detection of a burst DATE: 06/12/22 04:50:44 GMT FROM: David Palmer at LANL J. L. Racusin (PSU), L. M. Barbier (NASA/GSFC), S. D. Barthelmy (GSFC), P. J. Brown (PSU), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC), D. Grupe (PSU), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), K. M. McLean (LANL/UTD), D. M. Palmer (LANL) and M. Stamatikos (NASA/ORAU) report on behalf of the Swift Team: At 04:11:02 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 061222B (trigger=252593). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 105.357, -25.855 which is RA(J2000) = 07h 01m 26s Dec(J2000) = -25d 51' 19" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single rounded peak with a duration of about 50 sec. The peak count rate was ~800 counts/sec (15-350 keV), at ~48 sec after the trigger. The XRT began observing the field at 04:13:27 UT, 145 seconds after the BAT trigger. XRT found a bright, fading, uncatalogued X-ray source located at RA, Dec 105.35372, -25.8592 which is RA(J2000) = 07h 01m 24.89s Dec(J2000) = -25d 51' 33.1" with an estimated uncertainty of 4.1 arcseconds (90% confidence radius). This location is 18.5 arcseconds from the BAT on-board position, within the BAT error circle. The initial flux in the 2.5s image was 1.3e-09 erg/cm2/s (0.2-10 keV). UVOT took a finding chart exposure of 400 seconds with the V filter starting 146 seconds after the BAT trigger. No afterglow candidate has been found in the initial data products. We note that there is no detected source flux in the UVOT V image at the position of the afterglow candidate reported in GCN 5956. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The 3-sigma upper limit is 19.0 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The limiting magnitude is expected to be about 17.8. No correction has been made for the expected extinction of about 1.3 magnitudes. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5958 SUBJECT: GRB 061222b: Magellan redshift DATE: 06/12/22 04:55:36 GMT FROM: Edo Berger at Carnegie Obs E. Berger (Carnegie) reports: "Spectroscopic observations of the afterglow (GCN 5956) of GRB 061222b (GCN 5957) with LDSS3 on Magellan reveal a strong continuum break at about 5340A corresponding to Ly-alpha at z~3.4." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5959 SUBJECT: GRB 061222B: TAROT La Silla observatory optical observations DATE: 06/12/22 05:00:20 GMT FROM: Alain Klotz at CESR-CNRS Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report: We imaged the field of GRB 061222B detected by SWIFT (trigger 252593) with the TAROT robotic telescope (D=25cm) located at the European Southern Observatory, La Silla observatory, Chile. The observations started 149.8s after the GRB trigger (70.0s after the notice). The elevation of the field increased from from 70 degrees above horizon and weather conditions were excellents. The date of trigger : t0 = 2006-12-22T04:11:02.112 The first image is 30.0s exposure in tracking mode. We do not detect any OT in the XRT error box (Racusin et al. 2006 CNC circ. 5957) with a limiting magnitude of: t0+149.8s to t0+179.8s : R > 17.9 It must be noticed that the XRT position is near the star USNO-B1.0 0641-0103283 (R=9.3) that can masks a faint afterglow on TAROT images. The second image is 30.0s exposure in tracking mode: t0+185.4s to t0+215.4s : R > 17.9 We co-added a series of exposures: t0+149.8s to t0+534.5s : R > 19.9 Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction. N.B. Galactic coordinates are lon=237.2359 lat= -9.4366 and the galactic extinction in R band is 0.6 magnitudes estimated from D. Schlegel et al. 1998ApJ...500..525S. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5960 SUBJECT: GRB 061222B: TAROT La Silla observatory afterglow observation DATE: 06/12/22 05:21:30 GMT FROM: Alain Klotz at CESR-CNRS Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report: We analyzed carefully the afterglow position provided by Berger GNC Circ. 5956 on TAROT la Silla images. A very faint source is detected only on the first 30s image obtained from 150 to 180 seconds after the trigger. We estimate a magnitude R=18.2 +/- 0.5 (S/N=2). N.B. As we mentioned in the GCN Circ. 5959, the GRB position is near the star USNO-B1.0 0641-0103283 (R=9.3). The afterglow lies at the end of a "arm spider" of the star. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5961 SUBJECT: GRB 061222b, SMARTS optical/IR afterglow observations DATE: 06/12/22 05:31:57 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 061222b (GCN 5957, Racusin et al.), with a mid-exposure time of 2006-12-22 04:42:11 UT, which is ~0.5 hours post-burst. Several dithered images were obtained in each filter, with total summed exposure times of 180s in each of BRIYJK and 120s in each of H and V. In the I-band a dim object is detected with a preliminary magnitude of I=20.7+/-0.4 at the position of the afterglow reported by Berger (GCN 5956). This source is not significantly detected in the J-band to a limiting magnitude of J<18. Photometry is calibrated with USNO-B1.0 stars in the optical and 2MASS stars in the IR. Photometry is effect by high background due to the nearby bright star. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5962 SUBJECT: GRB 061222b: Refined redshift DATE: 06/12/22 05:33:56 GMT FROM: Edo Berger at Carnegie Obs E. Berger (Carnegie) reports: "Using several metal absorption features (e.g., SiII, CII, SiIV, etc.) in our first 1800 sec spectroscopic observation we determine a refined redshift for GRB 061222b of z=3.355." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5963 SUBJECT: GRB 061222B: REM NIR/optical observations DATE: 06/12/22 05:48:20 GMT FROM: Stefano Covino at Brera Astronomical Observatory S. Covino, E. Di Stefano, E. Molinari, G. Chincarini, F.M. Zerbi, V. Testa, G. Tosti, F. Vitali, P. Conconi, L.A. Antonelli, G. Cutispoto, G. Malaspina, L. Nicastro, E. Palazzi, E. Meurs, and P. Goldoni report on behalf of the REM/ROSS team: We imaged the field of GRB 061222B (Racusin et al. GCN 5957) with the robotic 60-cm REM telescope located at La Silla (Chile). A first set of observations was performed automatically in the optical and near infrared (V,R,I and z', J, H, K bands). A preliminary analysis allows to marginally detect the afterglow identified by Berger (GCN 5956) at H ~ 16.0 at 4:14:48 UT. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5964 SUBJECT: GRB 061222A, Swift-BAT refined analysis DATE: 06/12/22 06:36:47 GMT FROM: Scott Barthelmy at NASA/GSFC GRB 061222A, Swift-BAT refined analysis J. Tueller (GSFC), L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), T. Ukwatta (UMD) on behalf of the Swift-BAT team: Using the data set from T-240 to T+302 sec from the recent telemetry downlink, we report further analysis of BAT GRB 061222A (trigger #252588) (Grupe, et al., GCN Circ. 5954). The BAT ground-calculated position is RA, Dec = 358.258, 46.527 deg which is RA(J2000) = 23h 53m 1.9s Dec(J2000) = 46d 31' 37.3" with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 70%. The mask-weighted lightcurve shows the emision starting at T-100 sec with a small peak at T_zero, and then a 10-sec FRED peak starting at T+25 sec. It is followed by two 10-sec peaks at T+50 and T+65 sec; then a large peak at T+88 sec with a FWHM of ~12 sec and the emission returns to background at T+115 sec. T90 (15-350 keV) is 72 +- 3 sec (estimated error including systematics). At this time, there is a gap in the downlinked data from T-180 sec to T-110. A further Circular will be issued if there is burst activity in this interval. The time-averaged spectrum from T-2.5 to T+117.7 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.39 +- 0.04. The fluence in the 15-150 keV band is 8.3 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+86.54 sec in the 15-150 keV band is 9.2 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5966 SUBJECT: GRB 061222A: Swift-XRT refined analysis DATE: 06/12/22 07:11:40 GMT FROM: Dirk Grupe at PSU/Swift-XRT D. Grupe (PSU) reports on behalf of the Swift/XRT team We have analyzed the first orbit of GRB 061222A (Grupe et al., GCN 5954) with total observing times of 117s in Windowed Timing mode and 1476s in Photon Counting mode in the Swift XRT. The Photon Counting mode image provides a refined XRT position at RA, Dec= 358.263708, +46.53297, which is RA(J2000) = 23h 53m 03.29s Dec(J2000) = +46d 31' 58.7" with an error of 3.5" (90% confidence). This position is 2.4" away from the preliminary XRT position reported in GCN 5954. The X-ray light curve displays the end of a flare as seen in the BAT (at the beginning of the XRT observation this flare had an initial count rate of about 100 counts/s) and decays with a slope of 0.26+/-0.03. Spectral fits to the Windowed Timing mode data show an absorption column density significantly in excess of the Galactic value (1.01e21 cm**-2) with an excess absorption column density of (3.7+/-0.3)e21 cm**-2 and a energy spectral slope beta-x=1.34+/-0.08. Following the relation given in Grupe et al. 2006 (AJ submitted, astro-ph/0612104) the high excess absorption column density suggests that this burst is at a redshift z<3.0. Even though the observations were shortly interrupted by a new burst, GRB 06122B (Racusin et al., GCN 5957), we continue observing GRB 061222A with Swift throughout the next hours. More analysis of the data will be presented in the GCN report. This circular is an official product of the Swift XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5967 SUBJECT: GRB 061222B: SARA upper limit DATE: 06/12/22 08:36:17 GMT FROM: Adria C. Updike at Clemson U A. C. Updike and D. H. Hartmann (Clemson University) report on behalf of the Clemson GRB Follow-Up Team: We imaged the field of GRB 061222B 45 minutes after Swift Trigger 252593 with the SARA 0.9m at Kitt Peak under good weather conditions. We obtained 20 180-second exposures in the R band. We find no fading OT candidate at the position noted by E. Berger (GCN 5956) in the stacked images down to a limiting magnitude of R = 19.0 +/- 0.2 mag (based on calibration to USNO A2.0). The Clemson Unversity GRB Response Site may be found at: http://people.clemson.edu/~kgarime/burst/index.php The SARA Homepage can be found at: http://saraobservatory.org This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5968 SUBJECT: GRB 061222B: BOOTES-IR optical observations DATE: 06/12/22 09:16:20 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia A. de Ugarte Postigo, M. Jelínek, A. J. Castro-Tirado, V. Casanova, J. Gorosabel, R. Cunniffe, S. Vitek (IAA-CSIC Granada), P. Kubánek (Univ. de Valencia), R. Hudec (ASU-CAS Ondrejov) and L. Sabau-Graziati (INTA Madrid), report: "Following the detection of GRB 061222B by SWIFT (GCN 5957), the field was imaged with the 60-cm BOOTES-IR robotic telescope located at Observatorio de Sierra Nevada (Granada, Spain). Observations were taken in the R-band starting at 04:12:44 U.T. (i.e. 102 s after the onset of the event). On a co-add of several images (30s total time) taken at 04:18:46 (464 s after the GRB trigger), the optical afterglow (GCNC 5956) is detected with R = 17.7 +/- 0.5. The high airmass (~4.3) prevented taking high quality data. Further analysis is ongoing." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5970 SUBJECT: GRB061222B: Swift-XRT Refined Analysis DATE: 06/12/22 14:00:47 GMT FROM: Judith Racusin at PSU J. L. Racusin, J. Kennea (PSU), J. P. Osborne, and K. L. Page (U Leicester) report on behalf of the Swift XRT team: We have analyzed the first two orbits of Swift-XRT data on GRB 061222B (Racusin et al. GCN 5957), with a total exposure of 119 seconds in Window Timing (WT) mode and 906 seconds in Photon Counting (PC) mode. This provides a refined XRT position at RA, Dec = 105.35321, -25.8594 which is: RA(J2000) = 7h 01m 24.77s Dec(J2000) = -25d 51' 33.9" with an estimated error radius of 3.7 arcseconds (90% confidence). This position is 20 arcseconds from the initial BAT position (Racusin et al. GCN 5957), 1.8 arcseconds from the initial XRT position (Racusin et al. GCN 5957), and 3.1 arcseconds from the optical candidate discovered by Berger et al. (GCN 5956). The 0.3-10 keV X-ray light curve between 145s and 4900s after the trigger can be fit with a broken power-law with an initial decay slope of 3.26 +/- 0.10, a break at 450s, and a post-break slope of 1.24 +/- 0.15. The X-ray spectrum from the WT data covering the time period from T+145s to T+264s is well fit by an absorbed power-law with a photon index of 2.6 +/- 0.2 and column density of (4.0 +/-0.6 )e21 cm**-2. We note the Galactic column density in the direction of the source is 2.7e20 cm**-2. The unabsorbed 0.3-10 keV flux for this spectrum is 8.7e-10 erg/cm**2/s. Assuming the X-ray emission continues to decline at the same rate, we predict a 0.3-10 keV XRT count rate of 1e-3 count/s at T+24hr, which corresponds to an observed 0.3-10 keV flux of 3.6e-14 erg/cm**2/s. After the initial first orbit and partial second orbit of automated observations, the automated target was changed back to GRB061222A due to XRT thermal constraints. Observations of GRB061222B will continue at a later time. This circular is an official product of the Swift XRT Team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5972 SUBJECT: GRB 061222B: Swift/UVOT Upper limits DATE: 06/12/22 17:47:43 GMT FROM: Shashi Pandey at MSSL S. B. Pandey (UCL-MSSL), J. L. Racusin (PSU), S. R. Oates (UCL-MSSL) report on the behalf of the Swift UVOT team: The Swift/UVOT observed the field of GRB061222B starting 136 sec after the BAT trigger (GCN Circ. 5957). We do not detect the afterglow candidate reported in GCN Circ.5956 in our V band exposures. This is in accordance with the observed redshift of z=3.355 (GCN Circ. 5962) for the burst. The determined 3-sigma upper limits for V band settling, finding-chart exposures and for the co-added frames of the observed UVOT filters are: Filter T_start T_stop Exp(s) Mag (3-sigma upper limit) ----------------------------------------------------------------- V settling 136 145 9 17.29 V finding 146 546 393 19.77 V 136 890 475 19.86 B 624 4884 141 20.29 U 600 4755 235 19.98 UVW1 576 4551 255 19.76 UVM2 552 4346 255 19.96 UVW2 640 794 38 18.64 ----------------------------------------------------------------- The values quoted above are not corrected for the expected Galactic extinction of E_{B-V} = 0.38 mag towards the burst direction (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5973 SUBJECT: GRB061222A Swift/UVOT: Upper Limits DATE: 06/12/22 18:11:23 GMT FROM: Samantha Oates at MSSL S.R Oates(UCL-MSSL), D. Grupe(PSU), S.B.Pandey(UCL-MSSL) report on the behalf of the Swift UVOT team: The Swift/UVOT began observing the field of GRB 061222A 92 seconds after the BAT trigger (Grupe et al., GCN Circ.5954). No optical afterglow candidate is detected in the XRT error circle within the first V and White exposures or in later coadded images. The 3 sigma upper limits for each UVOT filter are given below: Filter Tstart Tend Exposure 3sigUL ------------------------------------------------- V finding 215 615 393 19.6 White finding 111 209 97 20.0 V 745 24842 5310 20.4 B 693 24112 2713 20.8 U 669 1591 78 19.4 w1 645 1711 83 19.2 m2 621 1701 97 19.3 w2 721 1653 58 19.3 White 110 1629 322 20.6 ------------------------------------------------- The values quoted above are not corrected for the expected Galactic extinction of E_{B-V} = 0.099 mag (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5974 SUBJECT: GRB 061222B, Swift-BAT refined analysis DATE: 06/12/22 20:38:24 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), J. L. Racusin (PSU), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC) on behalf of the Swift-BAT team: Using the data set from T-239.0 to T+903.1 sec from the recent telemetry downlink, we report further analysis of BAT GRB 061222 (trigger #252593) (Racusin, et al., GCN Circ. 5957). The BAT ground-calculated position is RA, Dec = 105.352, -25.865 deg which is RA(J2000) = 7h 1m 24.6s Dec(J2000) = -25d 51' 55.6" with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 16%. The burst had a single gradual peak with several sub peaks. T90 (15-350 keV) is 40 +- 5 sec (estimated error including systematics). At this time, there is a gap in the downlinked data from T+480 sec to T+660 and T+720 to T+840 sec. A further Circular will be issued if burst activity is found in these intervals. The time-averaged spectrum from T+35.1 to T+84.3 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.98 +- 0.13. The fluence in the 15-150 keV band is 2.2 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+59.16 sec in the 15-150 keV band is 1.5 +- 0.4 ph/cm2/sec. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5975 SUBJECT: GRB 061222A: Gemini Afterglow Candidate DATE: 06/12/23 03:26:07 GMT FROM: S. Bradley Cenko at Caltech S. B. Cenko (Caltech) and D. B. Fox (Penn State) report on behalf of a larger collaboration: We have imaged the field of GRB061222A (Grupe et al, GCN 5954) with the Near-Infrared Imager mounted on the Gemini-North telescope. Observations were taken in the Ks filter at a mean epoch of ~ 5:50 Dec. 22 UT. Inside the revised XRT error circle (Grupe et al, GCN 5966), we find one faint source at location (J2000.0): RA: 23:53:03.40 Dec: +46:31:58.5 (+/- 1.0"). Based on several 2MASS stars in the field, we measure a magnitude of Ks ~ 20.5, with large uncertainty dominated by both the faintness of the object and photometric uncertainty. At this point we cannot determine if the object is variable or not. Further observations are planned. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5976 SUBJECT: GRB 061222A: Xinglong Optical Limit DATE: 06/12/23 19:36:16 GMT FROM: W.K. Zheng at NAOC M.Zhai, L.P. Xin, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng and W.K. Zheng on behalf of EAFON report: We have imaged the field of GRB 061222A with the 2.16m telescope at Xinglong Observatory. A 30 minutes R band image is obtained 9.97 hours after the burst.The afterglow candidate (S.B. Cenko et al., GCN5975) was not detected and no new source was seen with 3-simga limit magnitude R~22.4 derived from USNO B1.0 This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5977 SUBJECT: GRB 061222B: MITSuME Akeno optical upper limits DATE: 06/12/24 15:32:47 GMT FROM: Nobuyuki Kawai at Tokyo Tech T. Ishimura, Y. Yatsu, T. Shimokawabe, N. Vasquez, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the error box of GRB061222B (Racusin et al., GCN 5957) with the 3-color 50cm MITSuME Telescope at Akeno, Japan starting at 12:52:28 UT, 8.7 hours after the trigger. In the co-added images of Ic, Rc, and g' bands, we did not detect the afterglow (Berger, GCN 5956). The 3-sigma limiting magnitudes based on USNO-B1.0 (I-band) and NOMAD (R-band,g'-band) stars are following. Filter start time end time Exp(s) Mag (3-sigma upper limit) ----------------------------------------------------------------- Ic 12:52:28 13:29:50 60s * 29 18.3 Rc 12:52:28 13:29:50 60s * 29 19.7 g' 12:52:28 13:29:50 60s * 29 19.4 ----------------------------------------------------------------- //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5978 SUBJECT: GRB 061222A: Confirmation of Gemini Afterglow Candidate DATE: 06/12/24 19:33:26 GMT FROM: S. Bradley Cenko at Caltech S. B. Cenko (Caltech) and D. B. Fox (Penn State) report on behalf of a larger collaboration: We have further refined the processing of our first epoch of Gemini Ks-band imaging of GRB061222A (see GCN 5975). Using 12 2MASS stars in the field, we report a refined position for the afterglow candidate of: RA: 23:53:03.419 Dec: +46:31:58.60 with an uncertainty of +/- 0.2" in each coordinate (J2000.0). Using our full set of Ks-band images, we calculate a magnitude of Ks = 20.7 +/- 0.3 at a mean epoch of 5:35 Dec. 22 UT (~ 2.1 hr after the burst). We obtained a second epoch of Ks-band imaging from Gemini on the following evening (mean epoch 4:53 Dec. 23 UT, ~ 25.4 hr after the burst). The object reported above faded by ~ 1.2 mag, confirming this source as the afterglow of GRB061222A. The corresponding decay rate is quite shallow, with a decay index alpha ~ 0.4 (assuming no contribution from the host galaxy). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5979 SUBJECT: GRB 061222A: MITSuME Akeno optical upper limits DATE: 06/12/24 23:19:43 GMT FROM: Nobuyuki Kawai at Tokyo Tech T. Ishimura, Y. Yatsu, T. Shimokawabe, N. Vasquez, and N. Kawai (TokyoTech) report on behalf of the MITSuME collaboration: We observed the error box of GRB061222A (Grupe et al., GCN 5954) with the 3-color 50cm MITSuME Telescope at Akeno, Japan starting at 8:48:53 UT, 5.3 hours after the trigger. In the co-added images of Ic, Rc, and g' bands, we did not detect any new source in the XRT error circle. The 3-sigma limiting magnitudes based on USNO-B1.0 (I-band) and NOMAD (R-band,g'-band) stars are following. Filter start time end time Exp(s) Mag (3-sigma upper limit) ----------------------------------------------------------------- Ic 8:48:53 09:32:23 60s * 36 19.6 Rc 8:48:53 09:32:23 60s * 36 20.4 g' 8:48:53 09:32:23 60s * 36 20.6 ----------------------------------------------------------------- //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5981 SUBJECT: GRB 061222B: TAROT La Silla observatory early optical observations DATE: 06/12/25 01:48:01 GMT FROM: Alain Klotz at CESR-CNRS Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report: We solve technichal problems that prevent to acces to the first trailed image of GRB 061222B obtained with TAROT located at the European Southern Observatory, La Silla observatory, Chile. The observations started 84.1s after the GRB trigger (4s after the notice). The trailed image allows to follow continuously variable source during the 60s integration time (see technichal description in Klotz et al., 2006, A&A 451, L39). The GRB expected trail is blended with the trail of the USNO-B1 star 0641-0103259 of R=14.7 after 24s. During the 24 first seconds we do not detect the optical transient brighter than R~17.7. Moreover, we confirm the optical detection in the first non trailed image (Klotz et al. GCN Circ. 5960) taken in the range t0+150 to t0+180s. To summarize: t0+ 84s to t0+108s : R > 17.7 t0+108s to t0+144s : R > 14.7 t0+150s to t0+180s : R = 18.2 +/- 0.5 (GCNC 5960) t0+185s to t0+215s : R > 18.2 t0+150s to t0+534s : R = 19.9 (GCNC 5959) Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5969 SUBJECT: GRB 061222A: Observation with the KANATA 1.5m telescope DATE: 06/12/22 12:26:00 GMT FROM: Makoto Uemura at Hiroshima U M. Uemura, A. Arai, and T. Uehara (Hiroshima Univ.), report on behalf of the KANATA GRB team: We perfomed optical imaging of the field of GRB061222A (GCN 5954, 5964, 5966) at 9:43-10:05 UT 22 Dec. using the TRISPEC attached to the KANATA 1.5-m telescope at Higashi-Hiroshima Observatory, Japan. We obtained 7 R-band images with a 123-s exposure time. The images were calibrated with neighbor stars in the USNO A2.0 catalog (r mag.). No new object was found within the XRT error circle. The limit magnitude is estimated to be 21.6 (3-sigma). UT Time after the burst (s) Limit mag in R Exp. Time Dec. 22.41537 23355 21.6 123 * 7 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5971 SUBJECT: GRB 061222B: Observation with the KANATA 1.5m telescope DATE: 06/12/22 15:50:42 GMT FROM: Makoto Uemura at Hiroshima U M. Uemura, A. Arai, and T. Uehara (Hiroshima Univ.), report on behalf of the KANATA GRB team: We perfomed optical imaging of the field of GRB061222B (GCN 5957) at 15:10-15:17 UT 22 Dec. using the TRISPEC attached to the KANATA 1.5-m telescope at Higashi-Hiroshima Observatory, Japan. We obtained 4 R-band images with a 123-s exposure time. The images were calibrated with neighbor stars in the USNO A2.0 catalog (r mag.). We cannot significantly detect the afterglow at the position reported in GCN 5956 in our images. The limit magnitude is estimated to be 20.2 (3-sigma). UT Time after the burst (s) Limit mag in R Exp. Time Dec. 22.63480 39784 20.2 123 * 4 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5984 SUBJECT: Konus-Wind observation of GRB 061222A DATE: 06/12/27 14:29:39 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 most intense part of the long GRB 061222A (Swift-BAT trigger #252588; Grupe et al., GCN 5954; Tueller et al., GCN 5964) triggered Konus-Wind at T0=12614.682 s UT (03:30:14.682). The emission is clearly seen in the Konus-Wind data starting at T-T0~-80 s. As observed by Konus-Wind the burst had a duration of ~100 s, fluence 2.66(-0.23, +0.43)x10^-5 erg/cm2, the 64-ms peak flux measured from T0+5.312 s 5.65(-1.19, +1.42)x10^-6 erg/cm2/s (both in the 20 keV - 2 MeV energy range). The spectrum integrated over the most intense part of the burst (from T0 to T0+15.104 s) is well fitted (in the 20 keV - 2 MeV range) by GRBM (Band) model for which: the low-energy photon index is alpha = -0.94(-0.13, +0.14), the high energy photon index beta = -2.41(-1.21, +0.28), the peak energy Ep = 283(-42, +59) keV (chi2 = 64/60 dof). The fitting by a power law with exponential cutoff model: dN/dE ~ E^(-alpha)*exp(-E*(2-alpha)/Ep) in the same energy range yields alpha = 1.02(-0.11, +0.10) and Ep = 324(-41, +54) keV (chi2 = 67/61 dof). All the quoted errors are at the 90% confidence level. The Konus-Wind light curve of this GRB is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB061222_T12614/ [GCN OPS NOTE(28dec06): Per author's request, the author list was added.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5986 SUBJECT: GRB061222a: optical observations DATE: 06/12/31 14:39:16 GMT FROM: Alexei Pozanenko at IKI, Moscow Yu. Efimov, V. Rumyantsev (CrAO), A. Pozanenko (IKI), D. Sharapov (MAO) on behalf of larger GRB follow up collaboration report: We observed error box of GRB061222a (Grupe et al., GCN 5954) with Shajn 2.6m telescope of CrAO. A set of 60 s exposures was taken on Dec. 22 in R between (UT) 18:28 - 19:29. We do not detect afterglow registered in Ks (Cenko et al., GCN 5975, GCN 5978). No object is also detected in refined XRT error box (Grupe, GCN 5966). Based on the USNO A2.0 star (23 53 02.73 +46 32 18.50 17.60 R) we estimate 3 sigma limiting magnitude of a combined image (48*60 s) as R=23.8. Finding chart can be found in http://grb.rssi.ru/GRB061222a/GRB061222a_R_ZTSh.GIF //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5997 SUBJECT: VLA detection of GRB 061222A DATE: 07/01/06 02:26:44 GMT FROM: Poonam Chandra at U Virginia/NRAO Poonam Chandra (NRAO/UVA) and Dale A. Frail (NRAO) report on behalf of the Caltech-NRAO-Carnegie GRB Collaboration: "We used the Very Large Array to observe the field of view toward GRB 061222A (GCN 5954) at a frequency of 8.46 GHz on 2006 December 23 at 0.15 UT. The peak radio brightness at the XRT position (GCN 5966) is 285 uJy ± 68 uJy. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 5998 SUBJECT: VLA observation of GRB 061222B DATE: 07/01/06 02:31:25 GMT FROM: Poonam Chandra at U Virginia/NRAO Poonam Chandra (NRAO/UVA) and Dale A. Frail (NRAO) report on behalf of the Caltech-NRAO-Carnegie GRB Collaboration: "We used the Very Large Array to observe the field of view toward GRB 061222B (GCN 5957) at a frequency of 8.46 GHz on 2006 December 23 at 8.11 UT. The peak radio brightness at the XRT position (GCN 5970) is -34 uJy ± 54 uJy. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc."