This file contains both bursts: GRB 070520 A and B //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6423 SUBJECT: GRB 070520: Swift detection of a burst DATE: 07/05/20 13:21:43 GMT FROM: Scott Barthelmy at NASA/GSFC P. Romano (Univ. Bicocca & INAF-OAB), S. D. Barthelmy (GSFC), M. M. Chester (PSU), N. Gehrels (NASA/GSFC), C. Gronwall (PSU), C. Guidorzi (Univ Bicocca&INAF-OAB), V. Mangano (INAF-IASFPA), F. E. Marshall (NASA/GSFC), C. Pagani (PSU), D. M. Palmer (LANL), M. Stamatikos (NASA/ORAU), R. L. C. Starling (U Leicester) and S. D. Vergani (DIAS-DCU) report on behalf of the Swift Team: At 13:05:10 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 070520 (trigger=279817). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 193.316, +74.993 which is RA(J2000) = 12h 53m 16s Dec(J2000) = +74d 59' 36" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). This is an 88-sec image trigger, and as such the TDRSS lightcurve does not show anything significant above background, as is typical for image triggers. The XRT began observing the field at 13:07:48 UT, 159 seconds after the BAT trigger. XRT found a X-ray source located at RA, Dec 193.3636, +74.9909 which is RA(J2000) = 12h 53m 27.2s Dec(J2000) = 74d 59' 27.2" with an uncertainty of 5.4 arcseconds (radius, 90% containment). This location is 45 arcseconds from the BAT on-board position, within the BAT error circle. The initial flux in the 2.5s image was 1.1e-09 erg/cm2/s (0.2-10 keV). UVOT took a finding chart exposure of 77 seconds with the White (160-650 nm) filter starting 168 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 is 19.6 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 0.02. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6424 SUBJECT: GRB 070520: Xinglong EST optical Upper Limit DATE: 07/05/20 15:06:24 GMT FROM: L.P. Xin at NAOC L.P. Xin, M.Zhai, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng, Y. Urata, and W.K. Zheng on behalf of EAFON report: We have imaged the field of GRB 070520 (P. Romano et al., GCN 6423) with the EST 1m telescope at Xinglong Observatory? Observation started from 13:14:54 UT, 579s after the burst with R band filter, we derieved 3 sigam limit is ~20.6 in our 20*60s co-added images withmean time ~20minutes. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6425 SUBJECT: GRB 070520B: Swift detection of a burst DATE: 07/05/20 18:14:26 GMT FROM: Scott Barthelmy at NASA/GSFC A. Moretti (INAF-OAB), S. D. Barthelmy (GSFC), M. M. Chester (PSU), N. Gehrels (NASA/GSFC), C. Gronwall (PSU), J. A. Kennea (PSU), V. Mangano (INAF-IASFPA), P. T. O'Brien (U Leicester), D. M. Palmer (LANL), P. Romano (Univ. Bicocca & INAF-OAB), M. Stamatikos (NASA/ORAU), E. Troja (INAF-IASFPA) and S. D. Vergani (DIAS-DCU) report on behalf of the Swift Team: At 17:44:53 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 070520B (trigger=279898). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 121.951, +57.617 which is RA(J2000) = 08h 07m 48s Dec(J2000) = +57d 37' 00" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single peak with a duration of about 5 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~0 sec after the trigger. This burst occurred during a Malindi data downlink session which buffered the initial notices for up to 12 minutes. The XRT began observing the field at 17:46:31 UT, 98 seconds after the BAT trigger. Using prompt downlinked data XRT found a bright and flaring uncatalogued X-ray source located at RA, Dec 121.8798, 57.6092 which is RA(J2000) = 08h 07m 31.1's Dec(J2000) = +57d 36' 33.1'' with an uncertainty of 4.3 arcsec (radius, 90% containment). This location is 138 arcseconds from the BAT on-board position, within the BAT error circle. The initial flux in the 2.5s image was 1.5e-09 erg/cm2/s (0.2-10 keV). UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 107 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 at the XRT position is 19.5 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 Galactic reddening of E(B-V)=0.04. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6427 SUBJECT: GRB 070520A: Swift-XRT refined analysis DATE: 07/05/20 21:45:39 GMT FROM: Pat Romano at OAB-Swift P. Romano (Univ Bicocca&INAF-OAB), A. Moretti (INAF-OAB), C. Guidorzi (Univ Bicocca&INAF-OAB), S.D. Vergani (DIAS-DCU) report on behalf of the Swift team: We have analysed the first four orbits of XRT data on GRB 070520A (Romano et al., GCN Circ. 6423) with total observing times of 79 s in Windowed Timing mode (from T+165 to T+244 s) and 6.5 ks in Photon Counting mode (from T+3565 s). The Photon Counting mode image provides a refined XRT position at RA,DEC(J2000) = 193.36131,+74.99038 which is RA(J2000) = 12h 53m 26.72s Dec(J2000) = +74d 59' 25.4" with an uncertainty of 4.1 arcsec (radius, 90% containment). This is 2.6 arcsec from the initial X-ray position, and 43 arcsec from the initial BAT position (Romano et al., GCN Circ. 6423). The XRT light curve exhibits an initial flaring behaviour throughout the first orbit (in the WT data, i.e., up to T+244 s) with an underlying power-law with slope 4.4+/-0.5. The PC data start at T+3565 s, when the count rate had decreased by three orders of magnitude. The PC data power-law slope is 0.1+/-0.4. The mean WT spectrum, extracted during the flaring activity, can be fit with an absorbed power law with a photon index of 3.1+/-0.2 and a column density of (2.2+/-0.4)E21 cm^-2 significantly in excess of the Galactic value (2.3E20 cm^-2; Dickey & Lockman, 1990). The absorbed (unabsorbed) 0.3-10.0keV flux for the WT spectrum is 5.2E-10 (1.5E-9) ergs cm^-2 s^-1. Assuming the source continues to decay at the present rate, we predict an XRT count rate of 1E-4 counts/s at T+24 hours, which corresponds to an unabsorbed flux of 5E-15 ergs cm^-2 s^-1. This circular is an official product of the Swift XRT team. [GCN OPS NOTE(21may07): Per author's request, the sentence starting "The absorbed (unabsorbed) 0.3-10.0keV flux ..." was added.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6428 SUBJECT: GRB 070520A, Swift-BAT refined analysis DATE: 07/05/21 00:01:27 GMT FROM: Scott Barthelmy at NASA/GSFC C. Markwardt (GSFC/UMD), L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), D. Palmer (LANL), A. Parsons (GSFC), P. Romano (Univ. Bicocca & INAF-OAB), 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 to T+963 sec from recent telemetry downlinks, we report further analysis of BAT GRB 070520A (trigger #279817) (Romano, et al., GCN Circ. 6423). The BAT ground-calculated position is RA, Dec = 193.255, 75.005 deg which is RA(J2000) = 12h 53m 1.1s Dec(J2000) = 75d 0' 16.6" with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 67%. The mask-weighted light curve shows single peak with a long tail. The peak starts at ~T+10 sec, peaks at T+35 sec, and ends at ~T+105 sec. The long tail appears to extend out to T+370+/-30 sec at the 0.02 +/- 0.01 ph/cm2/sec level. T90 (15-350 keV) is 18 +- 3 sec (estimated error including systematics). The time-averaged spectrum from T+25.5 to T+45.4 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.60 +- 0.33. The fluence in the 15-150 keV band is 2.5 +- 0.5 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+35.80 sec in the 15-150 keV band is 0.4 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6429 SUBJECT: GRB 070520B, Swift-BAT refined analysis DATE: 07/05/21 00:15:51 GMT FROM: Scott Barthelmy at NASA/GSFC T. Sakamoto (GSFC/ORAU), 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), A. Moretti (INAF-OAB), D. Palmer (LANL), A. Parsons (GSFC), 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 to T+592 sec from recent telemetry downlinks, we report further analysis of BAT GRB 070520B (trigger #279898) (Moretti, et al., GCN Circ. 6245). The BAT ground-calculated position is RA, Dec = 121.886, 57.588 deg which is RA(J2000) = 08h 07m 32.7s Dec(J2000) = 57d 35' 15.3" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 59%. The mask-weighted light curve shows two overlapping peaks starting at T-4 sec, peaking at T+1 sec, and ending with a long tail at T+200 sec. T90 (15-350 keV) is 66 +- 4 sec (estimated error including systematics). The time-averaged spectrum from T-5.0 to T+71.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.15 +- 0.21. The fluence in the 15-150 keV band is 9.2 +- 1.1 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.74 sec in the 15-150 keV band is 0.4 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6430 SUBJECT: GRB 070520A: MITSuME Akeno optical upper limits DATE: 07/05/21 04:19:51 GMT FROM: Nobuyuki Kawai at Tokyo Tech T. Ishimura, T. Shimokawabe, N. Vasquez, Y. Yatsu, Y. Kudou and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB070520A (Romano et al., GCN 6423) with the 3-color 50cm MITSuME Telescope at Akeno, Japan starting at 13:15:15 UT, 10 min after the trigger, under a clear, but windy condition. 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 UL) ----------------------------------------------------------- Ic 13:15:15 15:06:06 60s * 91 20.3 Rc 13:15:15 15:06:06 60s * 91 21.2 g' 13:15:15 15:06:06 60s * 91 21.1 ----------------------------------------------------------- //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6438 SUBJECT: GRB 070520B: Swift-XRT refined analysis DATE: 07/05/21 10:41:47 GMT FROM: Alberto Moretti at Obs Brera Merate A. Moretti (INAF-OAB), P. Romano (Univ Bicocca&INAF-OAB), C. Guidorzi (Univ Bicocca&INAF-OAB), S.D. Vergani (DIAS-DCU) report on behalf of the Swift team: We have analysed the first three orbits of XRT data on GRB 070520B (Moretti et al., GCN Circ. 6425) with total observing times of 284 s in Windowed Timing mode (from T+104 to T+388 s) and 5.2 ks in Photon Counting mode (from T+388 s). The Photon Counting mode image provides a refined XRT position at RA,DEC(J2000) = 121.87964,+57.60896, which is RA(J2000) = 08h 07m 31.11s Dec(J2000) =+57d 36' 32.3" with an uncertainty of 4.0 arcsec (radius, 90% containment). This is 1.0 arcsec from the initial X-ray position, and 76 arcsec from the refine BAT position (Sakamoto et al., GCN Circ. 6429). The XRT light curve (LC) exhibits an initial mildly steep decay (slope 2.5) in the interval (100,170) seconds from the trigger. An intense FRED-like flare is present between 170 and 390 seconds. In the second and third orbits the LC shows a decay with a slope is 1.0+/-0.3. The first WT spectrum, extracted before the flare, can be fit with an absorbed power law with a photon index of 2.5+/-0.2 and a column density of (2.1+/-0.4)E21 cm^-2 significantly in excess of the Galactic value (4.22E20 cm^-2; Dickey & Lockman, 1990). The mean WT spectrum, extracted during the flare, can be fit with an absorbed power law with a photon index of 2.6+/-0.1 and a column density of (2.5+/-0.2)E21 cm^-2 again significantly in excess of the Galactic value. The absorbed (unabsorbed) 0.3-10.0keV mean flare flux is 9.4E-10 (2.1E-9) ergs cm^-2 s^-1. Errors are quoted at 90% confidence level. Assuming the source continues to decay at the present rate, we predict an XRT count rate of 1E-3 counts/s at T+24 hours, which corresponds to an unabsorbed flux of 5E-14 ergs cm^-2 s^-1. This circular is an official product of the Swift XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6439 SUBJECT: GRB 070520A: Swift UVOT Upper Limits DATE: 07/05/21 13:26:54 GMT FROM: Stefan Immler at NASA/GSFC S. Immler (USRA/GSFC) and P. Romano (Univ. Bicocca & INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT observed the field of GRB 070520A starting 152 s after the BAT trigger (Romano et al., GCN 6423). We do not find any source in any of the UVOT observations inside the XRT error circle. The 3-sigma upper limits for detecting a source inside the XRT error circle in the co-added frames are: Filter T_start(s) T_stop(s) Exp(s) Mag (3-sigma UL) White 168 4793 345 >20.2 V 152 11162 1288 >19.6 B 4389 6021 393 >20.0 U 4184 16822 1142 >20.3 UVW1 3979 16047 1279 >20.1 UWM2 3774 11805 1021 >20.4 UVW2 4799 10249 1082 >20.5 The values quoted above are not corrected for the expected Galactic extinction corresponding to a reddening of E(B-V) = 0.02 mag towards the direction of the burst (Schlegel et al. 1998). [GCN OPS NOTE(21may07): Per author's request, the typo in the first sentence was corrected (070525A --> 070520A).] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6441 SUBJECT: GRB 070520A: Subaru Observations DATE: 07/05/21 16:14:41 GMT FROM: Nobuyuki Kawai at Tokyo Tech T. Hattori, K. Aoki (Subaru Telescope, NAOJ), and N. Kawai (Tokyo Tech) report on behalf of the Subaru GRB team: "We observed the field of GRB 070520A (Romano et al., GCN 6423) with FOCAS on the Subaru Telescope in the z'-band from 06:32(UT) to 07:27(UT) May 21 with a total exposure of 1920 sec (120s*16) under a non-photometric condition with occasional clouds. In the XRT error circle (Romano et al., GCN 6427), we find a possible afterglow candidate as a low-significance source (1.5 sigma) at RA=12:53:26.52, Dec=74:59:26.6 with a positional uncertainty of 0.4", and a rough estimation of the magnitude z' ~ 24. The image may be viewed at http://www.hp.phys.titech.ac.jp/nkawai/grb/070520A/ " //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6442 SUBJECT: GRB 070520B: Swift/UVOT Upper Limits DATE: 07/05/21 20:04:41 GMT FROM: Frank Marshall at GSFC F.E. Marshall (NASA/GSFC) and A. Moretti (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT observed the field of GRB 070520B starting 107 s after the BAT trigger (Moretti et al., GCN Circ. 6425). We do not find any source in any of the UVOT observations inside the refined XRT error circle (Moretti et al., GCN Circ. 6438). The 3-sigma upper limits for detecting a source inside the XRT error circle in the first finding chart (FC) exposure and co-added frames are: Filter T_start(s) T_stop(s) Exp(s) Mag (3-sigma UL) White (FC) 107 207 98 >20.3 White 107 6197 491 >21.0 V 213 11338 1356 >20.1 B 4360 5992 393 >20.3 U 4155 5788 393 >20.0 UVW1 3950 5583 393 >19.9 UWM2 3745 12043 1094 >20.5 UVW2 4769 10411 1152 >20.9 The values quoted above are not corrected for the expected Galactic extinction corresponding to a reddening of E(B-V) = 0.04 mag towards the direction of the burst (Schlegel et al. 1998). [GCN OPS NOTE(03jun07): Per author's request, the typo in the Subject-line was changed from "075020B" to "070520B".] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6446 SUBJECT: GRB 070520A: SARA upper limit DATE: 07/05/22 00:25:10 GMT FROM: Adria C. Updike at Clemson U A. C. Updike, J. R. Puls, and D. H. Hartmann (Clemson University) report on behalf of the Clemson GRB Follow-Up Team: We used the 0.9m SARA telescope at Kitt Peak under decent weather conditions to image the field of GRB 070520A (GCN 6423, Romano et al.), beginning 17 hours after the burst. In 40 minutes of stacked exposures, we do not detect the object noted by Hattori et al. (GCN 6441) down to a limiting magnitude of 20 +/- 0.4 in the R-band. This magnitude is based on calibration to 9 USNO B1.0 stars. The SARA Homepage can be found at: http://saraobservatory.org This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6447 SUBJECT: GRB 070520B: SARA upper limit DATE: 07/05/22 00:26:39 GMT FROM: Adria C. Updike at Clemson U A. C. Updike, J. R. Puls, and D. H. Hartmann (Clemson University) report on behalf of the Clemson GRB Follow-Up Team: We used the 0.9m SARA telescope on Kitt Peak to image the field of GRB 070520B (GCN 6425, Moretti et al.) under decent weather conditions beginning 9.5 hours after the burst trigger (279898). In 52 minutes of stacked R-band exposures, we detect no new sources down to a limiting magnitude of 20.2 +/- 0.4 based on calibration to 8 USNO B1.0 stars. The SARA Homepage can be found at: http://saraobservatory.org This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6455 SUBJECT: GRB070520B: NIR observations DATE: 07/05/22 20:18:56 GMT FROM: Paul Price at IfA,UH T. Minezaki (IoA, Tokyo) and P.A. Price (IfA, Hawaii) report on behalf of a larger collaboration: We observed the position of GRB 070520B with the MAGNUM telescope + MIPS dual-beam imager in R and J bands, at a mean observation time of 12.69 hours after the BAT trigger (GCN #6425). We have only inspected the J-band images, since other reports have covered the optical (GCN ##6442,6447). We find no afterglow within the XRT error circle to a limit of J = 20.1 mag. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6484 SUBJECT: GRB070520: optical observation DATE: 07/06/02 16:32:32 GMT FROM: Vasilij Rumjantsev at CrAO V. Rumyantsev, D. Shakhovskoy (CrAO), V. Biryukov (CrAO, SAI MSU), A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed error box of GRB070520 (Romano et al., GCN 6423) with AZT-11 (1.25m) and 1-m Zeiss (Simeiz) telescopes of CrAO in R-band on May 20 bet= ween (UT)19:50 and 22:00. No object is found in a refined XRT error box (Romano et al., GCN 6427). Limiting magnitude of combined images is based on USNO A2.0: Mid time (UT), Exposure, R_Lim (3sigma), Telescope, Seeing May 20.896 6x300 21.6 AZT-11 3.6" May 20.835 53x60 22.4 1-m Zeiss 1.5" The combined image of 1-m Zeiss telescope can be found in http://grb.rssi.ru/GRB070520/GRB050720_z1000_Simeiz.gif This message may be cited. [GCN OPS NOTE(02jun07): The binary attachment was removed as well as the diagnostics from MIMEDefang reacting to that binary.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6485 SUBJECT: GRB070520B: optical observations DATE: 07/06/02 16:32:32 GMT FROM: Vasilij Rumjantsev at CrAO D. Shakhovskoy, V. Rumyantsev (CrAO), V. Biryukov (CrAO, SAI MSU), A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed error box of GRB070520B (Moretti et al., GCN 6425) with AZT-11 (1.25m) telescope of CrAO in R-band under not optimal weather conditions (seeing ~3.6 arcsec) on May 20 between (UT)18:47 and 19:21, i.e. starting 1 hour after burst onset. The weather condition No object is found in a refined XRT error box (Moretti et al., GCN 6438 ). Limiting magnitude of a combined image is based on USANO A2.0: Mid time (UT), Exposure, R_Lim (3sigma) May 20.753 6x300 21.0 The combined image can be found in http://grb.rssi.ru/GRB070520B/GRB070520B_AZT11.gif This message may be cited. [GCN OPS NOTE(02jun07): The binary attachment was removed as well as the diagnostics from MIMEDefang reacting to that binary.]