GRB100628A

This page lists all entries on GRB100628A in GRBweb

Summary IPN Swift GCN 10895 GCN 10896 GCN 10898 GCN 10899 GCN 10900 GCN 10901 GCN 10902 GCN 10904 GCN 10907 GCN 10908 GCN 10909 GCN 10910 GCN 10911 GCN 10941 GCN 10942 GCN 10943 GCN 10946

Summary table
Variable Value Source
T0 8:16:40 UTC GCN_circulars,Swift Det
ra 225.9430° Swift
decl -31.6530° Swift
pos_error 1.63e-02° Swift
T90 0.036 s Swift
T90_start 8:16:40 UTC Swift
fluence 2.50e-08 erg/cm² Swift
redshift 0.3860
T100 0.036 s
GBM_located False
mjd 55375.34490740741 GCN_circulars,Swift Det
IPN table
GRB_name GRB100628A
ra 225.9667°
decl -31.6667°
pos_error 5.00e-02°
Swift table
GRB_name GRB100628A
t_trigger 8:16:40 UTC
ra 225.9430°
decl -31.6530°
pos_error 1.63e-02°
T90 0.036 s
fluence 2.50e-08 erg/cm²
GCN 10895 table
GRB_name GRB100628A
GCN_number 10895
Detection_method Swift Det
t_trigger 8:16:40 UTC
ra 225.9680°
decl -31.6610°
Circular_text TITLE: GCN CIRCULAR NUMBER: 10895 SUBJECT: GRB 100628A: Swift detection of a short hard burst DATE: 10/06/28 08:48:19 GMT FROM: Scott Barthelmy at NASA/GSFC S. Immler (CRESST/GSFC/UMD), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), S. Campana (INAF-OAB), C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC), V. Mangano (INAF-IASFPA), J. Mao (INAF-OAB), P. T. O'Brien (U Leicester), C. Pagani (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), P. Romano (INAF-IASFPA), M. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC) and R. L. C. Starling (U Leicester) report on behalf of the Swift Team: At 08:16:40 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100628A (trigger=426114). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 225.968, -31.661 which is RA(J2000) = 15h 03m 52s Dec(J2000) = -31d 39' 38" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows single hard spike with a duration of about 0.1 sec. The peak count rate was ~4500 counts/sec (15-350 keV), at ~0 sec after the trigger. We believe this trigger to be real because the count rate is above the cosmic ray shower level, the duration is longer than produced by a shower, and the signal is distributed across the detector plane. The XRT began observing the field at 08:18:06.8 UT, 86.0 seconds after the BAT trigger. No source was detected in the promptly available XRT data. We are waiting for the full dataset to detect and localise the XRT counterpart. UVOT took a finding chart exposure of 150 seconds with the White filter starting 89 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 25% of the BAT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the BAT 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 0.17. Burst Advocate for this burst is S. Immler (immler AT milkyway.gsfc.nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)
GCN 10896 table
GRB_name GRB100628A
GCN_number 10896
Detection_method Swift-BAT Det
ra 225.9430°
decl -31.6530°
Circular_text TITLE: GCN CIRCULAR NUMBER: 10896 SUBJECT: GRB 100628A: Swift-BAT refined analysis DATE: 10/06/28 16:16:49 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), T. Sakamoto (GSFC/UMBC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), S. Immler (CRESST/GSFC/UMD), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), A. M. Parsons (GSFC), G. Sato (ISAS), M. Stamatikos (ORAU/GSFC), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+577 sec from the recent telemetry downlink, we report further analysis of BAT GRB 100628A (trigger #426114) (Immler, et al., GCN Circ. 10895). The BAT ground-calculated position is RA, Dec = 225.943, -31.653 deg, which is RA(J2000) = 15h 03m 46.2s Dec(J2000) = -31d 39' 10.2" with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 70%. The mask-weighted light curve shows two overlapping peaks starting at ~T_zero to ~T+0.04 sec. T90 (15-350 keV) is 0.036 +- 0.009 sec (estimated error including systematics). The time-averaged spectrum from T-0.004 to T+0.036 sec is equally well fit by the exponential cutof powerlaw and a blackbody: Exponential cutoff: photon index -2.67 +1.8/-3.7, and Epeak of 74.1 +- 11.4 keV (chi squared 60.5 for 56 d.o.f.). Blackbody: kT = 19.8 +- 2.9 (chi squared 61.0 for 57 d.o.f.). The total fluence in the 15-150 keV band is 2.5 +- 0.5 x 10^-8 erg/cm2 and the 1-sec peak flux measured from T-0.48 sec in the 15-150 keV band is 0.5 +- 0.1 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.26 +- 0.25 (chi squared 81.3 for 57 d.o.f.). All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/426114/BA/
GCN 10898 table
GRB_name GRB100628A
GCN_number 10898
Detection_method INTEGRAL
Circular_text TITLE: GCN CIRCULAR NUMBER: 10898 SUBJECT: GRB 100628A: INTEGRAL SPI-ACS light curve DATE: 10/06/28 18:45:54 GMT FROM: Volker Beckmann at APC V. Beckmann (APC), M. Beck, C. Ferrigno, V. Savchenko, Ievgen Vovk (ISDC), J. Borkowski (CAMK/Torun), D. Gtz (CEA/Saclay), S. Mereghetti (INAF/IASF-Milano), and A. von Kienlin (MPE) report on behalf of the INTEGRAL SPI-ACS GRB team: GRB 100628A, detected in Swift/BAT data (Immler et al., GCN 10895; Barthelmy et al., GCN 10896), is detectable also in the data of the SPI Anti-Coincidence System (ACS) on-board INTEGRAL. The SPI-ACS light curve shows the peak of the burst at 2010-06-28T08:16:41 with a maximum count-rate of ~600 counts/50msec. The duration of the GRB is about 0.05 seconds. The SPI-ACS light curves are available (both as images and data files) at http://isdc.unige.ch/Soft/ibas/ibas_acs_web.cgi The light curves, binned at 50 ms, are derived from 91 independent detectors with different lower energy thresholds (mainly between 50 keV and 150 keV) and an upper threshold at about 100 MeV. The ACS response varies as a function of the GRB incident angle. For these reasons we caution that the count rates cannot be easily translated into physical flux units. It is not possible to localize a burst based on the SPI-ACS data. ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.
GCN 10899 table
GRB_name GRB100628A
GCN_number 10899
Detection_method Swift Other
ra 15.0000°
decl -31.0000°
Circular_text TITLE: GCN CIRCULAR NUMBER: 10899 SUBJECT: GRB 100628A: Swift XRT detection of a possible X-ray afterglow DATE: 10/06/28 20:24:02 GMT FROM: Rhaana Starling at U of Leicester R.L.C. Starling (U. Leicester) and S. Immler (CRESST/GSFC/UMD) report on behalf of the Swift-XRT team: We have analysed 8.7 ks of XRT data for GRB 100628A (Immler et al. GCN Circ. 10895), from 93 s to 18.8 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. A source is detected at the 3-sigma confidence level within the BAT refined error circle (Barthelmy et al. GCN Circ. 10896) at the position: RA (J2000) = 15 03 52.95 Dec (J2000) = -31 39 41.7 with an error of 5.2 arcsec (radius, 90% containment). This is 91.8 arcsec from the BAT refined position. The possible source has a count rate of 0.0023+/-0.0007 count/s. We cannot determine whether the source is fading at this time. This circular is an official product of the Swift-XRT team.
GCN 10900 table
GRB_name GRB100628A
GCN_number 10900
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 10900 SUBJECT: GRB100628A: RTT150 optical observations DATE: 10/06/28 22:25:30 GMT FROM: Rodion Burenin at IKI, Moscow R. Burenin, G. Khorunzhev, S. Sazonov (IKI), I. Khamitov (TUG), M. Pavlinsky, R. Sunyaev (IKI), I. Bikmaev, N. Sakhibullin (KSU/AST), Z. Eker (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.) report: The field of GRB100628A (Immler et al., GCN 10895) was observed with Russian-Turkish 1.5-m telescope (RTT150, Bakirlitepe, TUBITAK National Observatory, Turkey). We obtained a serie of Rc images, centered at June 28, 19:10 UT, i.e. approximately 11 hours after the burst. We do not find any new optical source inside the XRT error circle of possible X-ray afterglow (Starling et al., GCN 10899) as compared to DSS red plate.
GCN 10901 table
GRB_name GRB100628A
GCN_number 10901
Detection_method Swift-UVOT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 10901 SUBJECT: GRB 100628A: Swift/UVOT Upper Limits DATE: 10/06/28 22:48:13 GMT FROM: Stefan Immler at NASA/GSFC S. Immler (CRESST/GSFC/UMD) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 100628A 90 s after the BAT trigger (Immler et al., GCN Circ. 10895). No optical afterglow consistent with the XRT position (Starling et al., GCN Circ. 10899) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 90 239 147 >20.2 u_FC 302 551 246 >19.4 white 90 11409 1498 >21.4 v 631 12968 1099 >19.5 b 557 7133 471 >20.1 u 302 6928 697 >20.2 w1 680 6722 471 >19.6 m2 4882 6517 393 >19.3 w2 607 12315 1176 >20.3 The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.17 in the direction of the burst (Schlegel et al. 1998).
GCN 10902 table
GRB_name GRB100628A
GCN_number 10902
Detection_method Other
ra 225.9723°
decl -31.6639°
Circular_text TITLE: GCN CIRCULAR NUMBER: 10902 SUBJECT: GRB 100628A: Magellan near-IR observations DATE: 10/06/29 03:31:31 GMT FROM: Edo Berger at Harvard E. Berger (Harvard), T. Guver (U. of Arizona), W. Fong, R. Chornock (Harvard) report: "We observed the location of the potential X-ray afterglow (GCN 18099) of the short GRB 100628A (GCN 10895) with the PANIC infrared imager on the Magellan/Baade 6.5-m telescope on 2010 June 29.07 UT (17.4 hours after the burst). A total of 27 min on source were obtained in the J-band with seeing of about 1.1 arcsec. We do not detect any sources within the XRT error circle to a limit of about J>20.6 mag (Vega; 5-sigma). However, surrounding the XRT error circle are several apparent galaxies located at the following positions (J2000; astrometry relative to USNO-B with rms of about 0.25" in each coordinate): G1: RA = 15:03:53.34, DEC = -31:39:50.2 G2: RA = 15:03:53.61, DEC = -31:39:37.6 G3: RA = 15:03:52.43, DEC = -31:39:44.2 G4: RA = 15:03:52.85, DEC = -31:39:36.9 G5: RA = 15:03:52.85, DEC = -31:39:35.8 A finder marking the location of these objects relative to the XRT error circle is available from: http://www.cfa.harvard.edu/~eberger/grb100628_panic_2010June29.jpg Additional observations are planned to check for variability in any of the sources."
GCN 10904 table
GRB_name GRB100628A
GCN_number 10904
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 10904 SUBJECT: GRB100628A : MOA optical upper limit DATE: 10/06/29 05:31:35 GMT FROM: Suzuki Daisuke at MOA-II D. Suzuki, K. Omori, F. Hayashi, S. Kobara, H. Naito and T. Sako (STE Lab. , Nagoya Univ.) on behalf of the MOA Collaboration repot : We searched for an optical afterglow of GRB100628A (GCN 10895, S. Immler et al.) starting from 08:16:43 UT on 2010 June 28 ( 3 minutes after the burst) with the MOA-II 1.8m telescope at Mt.John observatory in New Zealand. In a single image of a 300 sec exposure with a wideband Red filter (center wavelength ~ 750nm and FWHM ~ 250nm), we did not find any object within the error circle of the Swift XRT source position (GCN 10899, R.L.C. Starling et al.). A 3 sigma upper limit is set in the I magnitude at 22.7 mag. This photometry was done by using the DoPhot and calibrated against the USNO-B1.0 catalog stars, and not corrected for the Galactic extinction.
GCN 10907 table
GRB_name GRB100628A
GCN_number 10907
Detection_method Swift Other
ra 15.0000°
decl -31.0000°
Circular_text TITLE: GCN CIRCULAR NUMBER: 10907 SUBJECT: GRB 100628A: Swift XRT refined position DATE: 10/06/29 14:16:43 GMT FROM: Rhaana Starling at U of Leicester R.L.C. Starling, A.P. Beardmore (U. Leicester) and S. Immler (CRESST/GSFC/UMD) report on behalf of the Swift-XRT team: We have analysed further Swift XRT data totalling 24.77 ks of exposure for GRB 100628A (Immler et al. GCN Circ. 10895), from 93 s to 80.75 ks after the BAT trigger. The source reported in Starling & Immler (GCN Circ. 10899) is still detected, but we cannot confirm any fading at this time. We report a significantly revised position, incorporating the new data and using an exposure map corrected psf-centroid fitting method, of RA (J2000) = 15 03 53.52 Dec (J2000) = -31 39 49.7 with an error of 4.7 arcsec (radius, 90% containment). This is still within the BAT refined error circle (Barthelmy et al. GCN Circ. 10896), 10.8 arcsec from the initial XRT position. This position is 2.3 arcsec from the galaxy G1 reported in Berger et al. (GCN Circ. 10902). This circular is an official product of the Swift-XRT team.
GCN 10908 table
GRB_name GRB100628A
GCN_number 10908
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 10908 SUBJECT: GRB 100628A: Coincidence of source "G1" with revised XRT error circle DATE: 10/06/29 14:23:29 GMT FROM: Edo Berger at Harvard E. Berger (Harvard) reports: "Inspection of our PANIC J-band image from 2010 June 29.07 UT (GCN 10902) at the location of the revised XRT error circle (GCN 10907) reveals that the galaxy designated "G1" is now located within the error circle, about 2.4 arcsec from its center. A revised finder is available from: http://www.cfa.harvard.edu/~eberger/grb100628_panic_2010June29_v2.jpg Additional observations are planned to check for variability."
GCN 10909 table
GRB_name GRB100628A
GCN_number 10909
Detection_method Swift-BAT Det
ra 225.9727°
decl -31.6651°
Circular_text TITLE: GCN CIRCULAR NUMBER: 10909 SUBJECT: GRB 100628A: Gemini North Observations DATE: 10/06/29 17:46:37 GMT FROM: Andrew Levan at U.of Leicester A.J. Levan (U. Warwick), N.R. Tanvir, K. Wiersema (U. Leicester), S.B. Cenko (UC Berkeley) report on behalf of a larger collaboration: "We obtained two epochs of observations of GRB 100628A (Immler et al. GCN 10895) with Gemini-North. The first was obtained starting at 28 Jun, 08:59 UT, approximately 43 minutes after the burst, with a second obtained on 29 Jun 05:50 UT, ~21.5 hours after the burst. A total of 1200s of exposure time were obtained in the i-band. Our images covers ~90% of the BAT refined error circle (Barthelmy et al GCN 10896), including the position of the candidate X-ray afterglow identified by Starling et al. (GCN 10899; 10907). Digital image subtraction performed between the two epochs does not reveal any candidate variable sources between the two epochs, to an approximate limiting magnitude of i~24. In particular, we do not find any evidence for variability in any of the galaxies identified by Berger et al. (GCN 10902) surrounding the XRT location, including G1, which now lies within the XRT error circle (Starling et al. GCN 10907; Berger et al. GCN 10908) We also note the presence of two, apparently point like sources lying within the refined XRT error circle, at locations of S1: RA(J2000) 15:03:53.45 DEC(J2000) -31:39:54.2 S2: RA(J2000) 15:03:53.73 DEC(J2000) -31:39:48.4 Both are unresolved at the resolution of our observations, but neither show apparent variability between the two epochs. An image, showing the field as observed by Gemini-North can be found at http://www.star.le.ac.uk/~anl/100628A We thank the staff of Gemini-North for their assistance with these observations."
GCN 10910 table
GRB_name GRB100628A
GCN_number 10910
Detection_method Optical
redshift 0.6700
Circular_text TITLE: GCN CIRCULAR NUMBER: 10910 SUBJECT: GRB 100628A: GROND optical/NIR observations of the host candidate DATE: 10/06/29 22:04:47 GMT FROM: Adria C. Updike at Clemson U A. Updike (Clemson University), M. Nardini, P. Afonso, A. Rau, T. Kruehler, and J. Greiner (all MPE Garching) report on behalf of the GROND team: We observed the field of GRB 100628A (Immler et al., GCN 10895) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPI/ESO telescope at La Silla Observatory (Chile). Observations started at 01:24 UT on June 29, 17.1 hours after the GRB trigger, and continued for 1.5 hours. In stacked images of 75 min total integration time in g'r'i'z' and 60 minutes in JHK we detect the possible host galaxy candidate G1 first noted in Berger et al., GCN #10902 and Berger, GCN #10908 inside the refined XRT position (Starling et al. GCN 10907) in all filters. Preliminary photometry yields the following AB magnitudes: g' = 22.8 +- 0.2 r' = 21.5 +- 0.1 i' = 20.6 +- 0.1 z' = 20.0 +- 0.1 J = 19.4 +- 0.1 H = 19.0 +- 0.1 K = 18.6 +- 0.1 calibrated against the GROND zeropoints and 2MASS field stars, and uncorrected for the expected mild foreground reddening in the direction of the burst of E(B-V) = 0.17 (Schlegel et al. 1998). Galaxy spectral template fitting using the publically available Lephare code (Arnouts & Ilbert 2009, http://www.cfht.hawaii.edu/~arnouts/LEPHARE/cfht_lephare/lephare.html) provides good fits of this very red spectral energy distribution with starburst or late type galaxies. In this interpretation, a photometric redshift of z=0.67 (+0.34, -0.12) is indicated. We caution that the error might be underestimated due to the missing photometric calibration in the g'r'i'z' bands. We note, however, that at this redshift the absolute magnitude would be rather bright, M_B ~ -22 mag.
GCN 10911 table
GRB_name GRB100628A
GCN_number 10911
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 10911 SUBJECT: GRB 100628A: Second epoch of Magellan near-IR observations DATE: 10/06/30 03:09:37 GMT FROM: Edo Berger at Harvard E. Berger (Harvard), T. Guver (U. of Arizona), W. Fong, R. Chornock (Harvard) report: "We re-observed the location of the potential X-ray afterglow (GCNs 18099, 10907) of the short GRB 100628A (GCN 10895) with the PANIC infrared imager on the Magellan/Baade 6.5-m telescope on 2010 June 29.98 UT (39.2 hours after the burst and 21.8 hours after our previous observation: GCN 10902). A total of 27 min on source were obtained in the J-band with seeing of about 0.5 arcsec. Digital image subtraction of the two epochs does not reveal any variable sources within the XRT error circle or in coincidence with the galaxy "G1" to a 5-sigma limit of J=21.6 mag at 17.2 hours after the burst. This result supports the conclusions of Levan et al. (GCN 10909)."
GCN 10941 table
GRB_name GRB100628A
GCN_number 10941
Detection_method Swift Other
ra 225.9684°
decl -31.6584°
Circular_text TITLE: GCN CIRCULAR NUMBER: 10941 SUBJECT: GRB 100628A: Swift XRT/UVOT refined analysis DATE: 10/07/06 21:54:09 GMT FROM: Rhaana Starling at U of Leicester R.L.C. Starling, P.A. Evans (U. Leicester) and S. Immler (CRESST/GSFC/UMD) report on behalf of the Swift XRT and UVOT teams, We have analysed 65.4 ks of Swift XRT data for GRB 100628A (Immler et al. GCN Circ. 10895). The X-ray source reported in Starling et al. (GCN Circ. 10907) shows no evidence for fading. We conclude that this source is not the X-ray afterglow of GRB 100628A. Further inspection of these data reveal another possible X-ray source close to the persistant source, detected in the first two orbits of data only (totalling 3.8 ks from T0+92 s to T0+7200 s). This source comprises just 7 counts, however the predicted background level is only 0.7 counts in this time interval. Using the Bayesian method described in Kraft, Burrows & Nousek (1991) we find a detection significance >99.999%. The 0.3-10 keV count rate during this interval is 0.0017 (+0.0008, -0.0006) counts/s. The source position is RA, Dec (J2000) = 225.96837, -31.65839, which is equivalent to: RA (J2000) = 15 03 52.41 Dec (J2000) = -31 39 30.2 with an uncertainty of 7 arcseconds (radius, 90% containment). In the subsequent XRT data (>T0+7200 s) the source is not detected; a 3-sigma upper limit on the 0.3-10 keV count rate is 5.7E-5 count/s. Therefore, if this source was real it has faded and can be considered a candidate X-ray afterglow. We caution that with so few total counts a background fluctuation or other spurious detection cannot be completely ruled out. No UVOT afterglow candidate is seen in any of the UVOT images at the XRT position down to the limits reported in GCN 10901. This circular is an official product of the Swift team.
GCN 10942 table
GRB_name GRB100628A
GCN_number 10942
Detection_method Swift-XRT Other
ra 225.9722°
decl -31.6640°
Circular_text TITLE: GCN CIRCULAR NUMBER: 10942 SUBJECT: GRB 100628A: Chandra observations DATE: 10/07/06 22:27:15 GMT FROM: Edo Berger at Harvard E. Berger (Harvard) reports: "We observed the field of the short GRB 100628 (GCN 10895) with the Chandra X-ray Observatory starting on 2010 July 2.79 UT for a total of 19.8 ksec. Within the XRT error circle (GCN 10907) we detect a single point source at the following coordinates (J2000): RA = 15:03:53.33 DEC = -31:39:50.5 This object is coincident with the bright core of the galaxy "G1" (GCNs 10902,10908). The flux of the object is about 4.8e-14 erg/cm^2/s, in good agreement with the flux measured with the Swift/XRT of about 4.6e-14 erg/cm^2/s (see Swift/XRT GRB lightcurve repository: http://www.swift.ac.uk/xrt_curves/00426114/). Given the position of the source and its constant flux we conclude that it is due to AGN activity and is therefore not related to GRB 100628 (see also GCN 10941). Furthermore, we do not detect any emission at the location of the new and possibly fading XRT source (GCN 10941) to a 3-sigma limit of <5e-15 erg/cm^2/s, about a factor of 15 times fainter than the initial XRT detection. We thank Harvey Tananbaum and the CXO scheduling staff for rapidly approving and executing this observation."
GCN 10943 table
GRB_name GRB100628A
GCN_number 10943
Detection_method Other
ra 225.9667°
decl -31.6590°
Circular_text TITLE: GCN CIRCULAR NUMBER: 10943 SUBJECT: GRB 100628A: Near-IR sources coincident with the possible X-ray afterglow DATE: 10/07/06 22:58:34 GMT FROM: Edo Berger at Harvard E. Berger (Harvard) reports: "We inspected the location of the new and possibly fading XRT source (GCN 10941) associated with the short GRB 100628 (GCN 10895) in our Magellan/PANIC images (GCNs 10902,10908,10911). Within the 7" radius circle we detect two extended sources at the following positions (J2000): G6: RA = 15:03:52.02, DEC = -31:39:32.5 G7: RA = 15:03:52.78, DEC = -31:39:33.7 Neither source shows any evidence for fading between our two PANIC observations from 0.65 and 21.8 hours after the burst."
GCN 10946 table
GRB_name GRB100628A
GCN_number 10946
Detection_method Other
redshift 0.1020
Circular_text TITLE: GCN CIRCULAR NUMBER: 10946 SUBJECT: GRB 100628A: Keck/LRIS Spectroscopy of Host Galaxy Candidate DATE: 10/07/08 13:54:02 GMT FROM: S. Bradley Cenko at Caltech S. B. Cenko, D. A. Perley, J. S. Bloom, A. N. Morgan (UC Berkeley), and A. Cucchiara (UCB/LBNL/UCSC) report on behalf of a larger collaboration: We have obtained spectra of the galaxy dubbed "G7" (Berger, GCN 10943) inside the possible X-ray afterglow error circle (Starling et al., GCN 10941) of the short GRB 100628A (Immler et al., GCN 10895) with the Low Resolution Imaging Spectrometer mounted on the 10 m Keck I telescope. Our observations began at 6:25 UT on 8 July 2010 and cover the wavelength range from 3500-10000 A. The spectrum is comprised of a series of narrow emission lines, clearly resolved into two spatially distinct components and joined by a bridge of faint continuum emission, possibly indicating an interacting or disturbed system. We identify the emission lines in both components as [O II], [O III], H-alpha, and H-beta at a common redshift of z = 0.102, which we therefore take to be the redshift of the galaxy "G7".