This file contains both GRBs 070429A and 070429B. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6355 SUBJECT: GRB 070429: Swift detection of a burst DATE: 07/04/29 01:51:27 GMT FROM: David Palmer at LANL S. D. Barthelmy (GSFC), C. B. Markwardt (GSFC/UMD), K. L. Page (U Leicester), D. M. Palmer (LANL), G. Sato (GSFC/ISAS), M. Stamatikos (NASA/ORAU) and R. L. C. Starling (U Leicester) report on behalf of the Swift Team: At 01:35:10 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 070429 (trigger=277571). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 297.687, -32.388 which is RA(J2000) = 19h 50m 45s Dec(J2000) = -32d 23' 16" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is typical for image trigger GRBs, the BAT light curve shows little obvious variation. A detailed light curve will require the data downlinked via Malindi. The XRT began observing the field at 01:37:42 UT, 153 seconds after the BAT trigger. XRT found a fading, uncatalogued X-ray source located at RA, Dec 297.7034, -32.4052 which is RA(J2000) = 19h 50m 48.8s Dec(J2000) = -32d 24' 18.7" with an uncertainty of 4.7 arcseconds (radius, 90% containment). This location is 79 arcseconds from the BAT on-board position, within the BAT error circle. The initial flux in the 2.5s image was 2.9e-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 161 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 typical 3-sigma upper limit has been about 18.5 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 the expected extinction corresponding to E(B-V) of 0.17 magnitudes. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6356 SUBJECT: GRB 070429: ROTSE-III Optical Limits DATE: 07/04/29 01:57:07 GMT FROM: Eli Rykoff at U of Michigan/ROTSE E.S. Rykoff (U Mich), B. E. Schaefer (Louisiana State), H. Swan (U Mich), report on behalf of the ROTSE collaboration: ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, responded to GRB 070429 (Swift trigger 277571, GCN 6355, Barthelmy, et al), producing images beginning 6.7 s after the GCN notice time. An automated response took the first image at 01:36:46.7 UT, 96.6 s after the burst, under good conditions. We took 10 5-sec, 10 20-sec exposures; imaging is ongoing. These unfiltered images are calibrated relative to USNO A2.0 (R). 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 16.1-17.1; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 01:36:46.7 01:36:51.7 5 16.2 96.6 N 01:36:46.7 01:38:04.4 77 17.3 96.6 Y 01:38:19.4 01:43:08.1 288 18.0 189.3 Y //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6358 SUBJECT: GRB 070429B: Swift detection of a short burst DATE: 07/04/29 03:41:59 GMT FROM: Craig Markwardt at NASA/GSFC/UMD C. B. Markwardt (GSFC/UMD), L. M. Barbier (NASA/GSFC), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), J. K. Cannizzo (NASA/UMBC), M. M. Chester (PSU), N. Gehrels (NASA/GSFC), S. D. Hunsberger (PSU), W. B. Landsman (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), G. Sato (GSFC/ISAS) and R. L. C. Starling (U Leicester) report on behalf of the Swift Team: At 03:09:04 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 070429B (trigger=277582). Swift slewed to the burst following a 165 second delay due to the Earth-limb constraint. The BAT on-board calculated location is RA, Dec 328.024, -38.844 which is RA(J2000) = 21h 52m 06s Dec(J2000) = -38d 50' 37" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a short spike with a duration of about 700 msec. The peak count rate was ~3000 counts/sec (15-350 keV), at ~0 sec after the trigger. No source was automatically found onboard by the XRT; however, 213s of downlinked data suggest there is a possible source at RA, DEC (degrees) = 328.01551, -38.82670 which is RA(J2000) = 21h 52m 03.7s Dec(J2000)= -38d 49' 36.1" with an uncertainty of 9.1 arcsec (90% containment). UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 247 seconds after the BAT trigger. No afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 25% of the BAT error circle, and fully covers the possible XRT position. The typical 3-sigma upper limit has been about 18.5 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 reddening of E(B-V)=0.026. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6359 SUBJECT: GRB 070429B: ROTSE-III Optical Limits DATE: 07/04/29 03:56:35 GMT FROM: Brad Schaefer at LSU B. E. Schaefer (Louisiana State), W. Rujopakarn (U Mich), E.S. Rykoff (U Mich), report on behalf of the ROTSE collaboration: ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, responded to the short-burst GRB 070429B (Swift trigger 277582; Markwardt et al. GCN 6358), producing images beginning 7.9 s after the GCN notice time. An automated response took the first image at 03:09:30.9 UT, 26.5 s after the burst, under excellent conditions. We took 10 5-sec, 10 20-sec 20 60-sec exposures, and observations are continuing. These unfiltered images are calibrated relative to USNO A2.0 (R). Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma BAT error circle and within the error circle for the possible XRT source, for both single images and coadding into sets of 10; the field is not crowded. Individual images have limiting magnitudes ranging from 15.5-17.5; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 03:09:30.9 03:09:35.9 5 15.5 26.5 N 03:09:30.8 03:10:56.5 85 17.3 26.4 Y 03:27:43.5 03:39:11.4 687 18.5 1119.1 Y //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6360 SUBJECT: GRB 070429B: Swift XRT refined analysis DATE: 07/04/29 13:19:19 GMT FROM: Andy Beardmore at U Leicester A.P. Beardmore, K.L. Page, P.A. Evans, R.L.C. Starling (U. of Leicester), C. Guidorzi (INAF-OAB, Univ. Bicocca), and C. Markwardt (GSFC/UMD) report on behalf of the Swift XRT team : We have analysed the first three orbits of Swift XRT data from GRB 070429B (trigger number 277582, Markwardt et al. GCN circular 6358), which has a total photon counting mode exposure of 5.8ks. Due to a delayed slew because of an Earth-limb constraint, the XRT arrived on the source 244s after the BAT trigger. The tentative X-ray source identified in GCN 6358 is clearly detected in the first orbit of data, and is absent thereafter. The refined XRT position from 2.4ks of data in the first orbit is RA, DEC (J2000) = 328.0159, -38.8284 which is RA(J2000) = 21d 52m 03.82s DEC(J2000) = -38d 49' 42.2" with an uncertainty of 5.1 arcsec (radius, 90% containment). This is 61 arcsec from the inital BAT position and 6.2 arcsec from the initial X-ray position reported in GCN 6358. An XRT light curve created from the first orbit of data, binned with a minimum of 10 counts/bin, reveals a decaying source. A powerlaw fit yields a poorly constrained decay slope of 0.94+/-0.47. The X-ray spectrum from the first orbit (covering 254 to 2691 seconds after the BAT trigger), modelled with an absorbed powerlaw and fit using Cash statistics, gives a photon index of 2.5+1.3-1.2. An upper limit of 5.9e21 cm^-2 on the column density was found, compared with the Galactic value of 1.8E+20 cm^-2 in this direction. The absorbed (unabsorbed) 0.3-10.0keV flux for this spectrum was 5.9E-13 (1.1E-12) ergs cm^-2 s^-1. Assuming the source continues to decay at the same rate, we predict an XRT count rate of 3.0e-4 count/s at T+24 hours, which corresponds to an observed (unabsorbed) flux of 1.5E-14 (2.8E-14) ergs cm^-2 s^-1. This circular is an official product of the Swift XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6361 SUBJECT: GRB 070429A: optical and NIR observations DATE: 07/04/29 13:31:00 GMT FROM: Antonio Deugarte at IAA-CSIC A. de Ugarte Postigo, A.J. Castro-Tirado, M. Jelinek, P. Kubanek, R. Cunniffe, S. Vitek, J. Gorosabel (IAA-CSIC), I. Skillen (ING) L. Sabau-Graziati (INTA) report: Robotic observations from the 0.6m BOOTES-IR telescope in R and z bands started at 3:50 UT (3.25 hours after the burst), as soon as the object became visible from the observatory. No source is detected inside the XRT error box. We have observed the field of GRB 070429A with the 4.2m WHT+LIRIS in J, H and K bands starting at 05:44:00 UT (4.148 hours after the burst). Preliminary reduction of the K-band data shows a faint source at the following coordinates (J2000 +/- 1"): R.A.: 19:50:48.90 Dec.: -32:24:17.0 A finding chart can be found at: http://www.iaa.es/~deugarte/GRBs/070429A/GRB070429A.gif Further analysis to check variability and colour of this source is ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6362 SUBJECT: GRB 070429A, Swift-BAT refined analysis DATE: 07/04/29 14:04:22 GMT FROM: Louis M Barbier at NASA/GSFC/Swift J. Cannizzo (GSFC/UMBC), 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), J. Tueller (GSFC) on behalf of the Swift-BAT team: Using the data set from T-239.0 to T+963.1 sec from the recent telemetry downlink, we report further analysis of BAT GRB 070429 (trigger #277571) (Barthelmy, et al., GCN Circ. 6355). The BAT ground-calculated position is RA, Dec = 297.695, -32.420 deg which is RA(J2000) = 19h 50m 46.9s Dec(J2000) = -32d 25' 12.1" with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 68%. The masked weighted light curve shows a single somewhat broad peak, extending out to T+50 sec, followed by several smaller peaks. T90 (15-350 keV) is 163 +- 5sec (estimated error including systematics). The time-averaged spectrum from T-12.4 to T+178.0 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.11 +- 0.27. The fluence in the 15-150 keV band is 9.2 +- 1.4 x 10-07 erg/cm2. The 1-sec peak photon flux measured from T+3.99 sec in the 15-150 keV band is 0.4 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6363 SUBJECT: GRB 070429A: Swift XRT refined analysis DATE: 07/04/29 16:11:08 GMT FROM: Rhaana Starling at U of Leicester R.L.C. Starling, A.P. Beardmore, K.L. Page, P.A. Evans (U. Leicester) and J. Cannizzo (GSFC/UMBC) report on behalf of the Swift XRT team: We have analysed Swift XRT data from the first orbit of Windowed Timing mode and two subsequent orbits in Photon Counting (PC) mode for GRB 070429A (trigger 277571, Barthelmy et al. GCN Circ 6355). Using 380s of overlapping XRT PC mode data and UVOT V-band data, we obtain an astrometrically corrected (using the USNO-B1 catalogue) X-ray position of RA, Dec (J2000) = 297.70333, -32.40497, which is RA(J2000) = 19h 50m 48.80s Dec(J2000) = -32d 24' 17.9" with an estimated uncertainty of 2.4 arcsec (90% error radius). This is 1.0 arcsec from the XRT position in GCN 6355 and 1.6 arcsec from the possible K-band optical transient report by de Ugarte Postigo et al. (GCN Circ 6361). The lightcurve is well fitted by a broken power law with alpha1=6.4+0.3/-0.4, Tbreak=235+2/-20 s and alpha2=3.2+0.3/-0.2. The PC mode spectrum can be fit with a single absorbed power law. The photon index is 1.8+0.4/-0.2 and the absorption is centred at 1.3E21 cm^-2 but is poorly constrained. The Galactic column towards this position is 0.9E21 cm^-2. The 0.3-10 keV flux is 1.25E-11 erg/cm^2/s, corresponding to 0.11 cts/s. We are now in a data gap for this source, whilst Swift is observing GRB 070429B, so the current decay rate is not known, hence we do not give a predicted count rate for 24hr. Further Swift observations of this source are planned. This circular is an official product of the Swift XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6364 SUBJECT: Swift/UVOT observations of GRB070429A DATE: 07/04/29 16:19:44 GMT FROM: Patricia Schady at MSSL/Swift P. Schady (MSSL/PSU) and J. Cannizzo (GSFC/UMBC) report on behalf of the Swift UVOT team: Swift/UVOT observed the field of GRB 070429A starting 211s after the BAT trigger. No new source is detected either within the refined XRT position (GCN 6363) or at the position reported by Ugarte Postigo et al. (GCN 6361) in any of the UVOT filters, in either single or co-added exposures. The 3-sigma upper limits for the co-added exposures in each filter are as follows: Filter T_mid Exp. Mag 3-sig UL (s) (s) White 850 253 19.43 V 1104 903 19.75 B 1700 107 19.30 U 1598 117 18.96 UVW1 3535 259 19.19 UVM2 3951 333 19.61 UVW2 1659 117 19.07 where T_mid is the weighted mid time of the co-added images. The reported upper limits are uncorrected for the estimated Galactic reddening of E(B-V) = 0.17 mag. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6365 SUBJECT: GRB 070429B, Swift-BAT refined analysis DATE: 07/04/29 16:37:10 GMT FROM: Scott Barthelmy at NASA/GSFC 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) on behalf of the Swift-BAT team: Using the data set from T-240 to T+963 sec from recent telemetry downlinks, we report further analysis of BAT GRB 070429 (trigger #277582) (Markwardt, et al., GCN Circ. 6358). The BAT ground-calculated position is RA, Dec = 328.006, -38.857 deg which is RA(J2000) = 21h 52m 1.4s Dec(J2000) = -38d 51' 24.8" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 66%. The mask-weighted lightcurve shows 3 or 4 overlapping peaks starting at ~T-0.2s sec and ending at ~T+0.5 sec. T90 (15-350 keV) is 0.5 +- 0.1 sec (estimated error including systematics). The time-averaged spectrum from T-0.2 to T+0.3 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.71 +- 0.23. The fluence in the 15-150 keV band is 6.3 +- 1.0 x 10^-8 erg/cm2. The 1-sec peak photon flux measured from T-0.45 sec in the 15-150 keV band is 1.8 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6366 SUBJECT: Swift/UVOT observations of GRB070429B DATE: 07/04/29 17:03:42 GMT FROM: Patricia Schady at MSSL/Swift P. Schady (MSSL/PSU) and C. Markwardt (GSFC/UMD) report on behalf of the Swift UVOT team: Swift/UVOT observed the field of GRB 070429B starting 297s after the BAT trigger. No new source is detected either within the refined XRT position (GCN 6360) in any of the UVOT filters, in either single or co-added exposures. The 3-sigma upper limits for the co-added exposures in each filter are as follows: Filter T_mid(s) Exp.(s) Mag 3-sig UL White 1009 302 19.68 V 1489 605 19.64 B 1812 184 19.83 U 2092 392 19.80 UVW1 1625 253 19.31 UVM2 1601 253 19.48 UVW2 1682 214 19.63 where T_mid is the weighted mid time of the co-added images. The reported upper limits are uncorrected for the estimated Galactic reddening of E(B-V) = 0.03 mag. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6367 SUBJECT: VLA observation of GRB 070429B DATE: 07/04/29 20:21:27 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 a short burst GRB 070429B (GCN 6358) at a frequency of 8.46 GHz on 2007 April 29th at 15.73 UT. The GRB is undetected and the peak radio flux at the SWIFT-XRT position (GCN 6360) is 04+/-100 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: 6368 SUBJECT: GRB070429B: possible host galaxy detection DATE: 07/04/30 01:16:44 GMT FROM: Antonino Cucchiara at PSU Cucchiara A. (PSU), D. B. Fox, S. B. Cenko, E. Berger: We observed the refined XRT error circle of GRB 070429B (GCN 6360) with GMOS on the Gemini-South telescope for a total of 900 sec in r-band starting on 2007 April 29 at 07:59:55 UT (~ 4 hr after the burst). Within the XRT error circle we find a single faint object located at: RA = 21:52:03.96 (J2000) DEC = -38:49:42.79 (J2000) The object appears to be extended and we cannot determine a possible fading at the moment. The r magnitude is 23.18 +- 0.15 calibrated using four stars from USNOB1 catalogue. We thank the Gemini-South staff for their support. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6370 SUBJECT: GRB070429B: position correction DATE: 07/04/30 21:20:31 GMT FROM: Antonino Cucchiara at PSU Cucchiara A. (PSU), S. B. Cenko (Caltech), D. B. Fox (PSU), E. Berger (Carnegie), and J. S. Bloom (UC-Berkeley) report on behalf of a larger collaboration: We re-analyzed our GMOS imaging data on GRB070429B (Cucchiara et al., GCN 6368). We found the position previously reported for the sole object in the XRT error circle was incorrect. An updated position for this object is: RA = 21:52:03.729 (J2000) DEC = -38:49:42.84 (J2000) This represents an offset of 2.70" W and 0.05" S from our previously reported location. The new position was calculated with respect to several USNO-B1 objects in the field. We estimate a positional uncertainty of 0.3" in each coordinate. We apologize for any inconvenience this may have caused. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6371 SUBJECT: GRB 070429A: optical observations DATE: 07/05/01 00:17:48 GMT FROM: Paul Price at IfA,UH P.A. Price (IfA, Hawaii) reports on behalf of a larger collaboration: We observed the XRT position of GRB 070429A (GCN ##6355,6363) with the Gemini North telescope + GMOS, commencing at 2007 Apr 29.58 UT (12.3 hours after the GRB). Observations consisted of 2x180 sec integrations in Sloan i' and 4x180 sec in Sloan z'. The source identified by de Ugarte Postigo et al. (GCN #6361) is well detected in these observations, though no statement as to its variability can yet be made. In addition, there is a fainter source within the XRT error circle, at coordinates: 19:50:48.77 -32:24:17.8 J2000 NIR imaging of this GRB has also been made, and will be reduced as practical. No further observations are planned. We thank the Gemini North staff for helpful support of these quick response observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6372 SUBJECT: GRB070429B: VLT observations DATE: 07/05/01 21:57:49 GMT FROM: Angelo Antonelli at Obs. Astro. di Roma L.A. Antonelli (INAF-OAR & ASDC), L. Stella (INAF-OAR), G. Tagliaferri (INAF- OABr), E. Jehin, L. Schmidtobreick (ESO),report on behalf of the MISTICI collaboration: We observed the refined XRT error circle of the short burst GRB 070429B (Beardmore et al, GCN 6360) with VLT-UT1 (Antu) and FORS2 in two different epochs. Images were taken in both the R and B bands starting on Apr. 29 at 09: 26:00 (about 5.5 hr after the burst) for a total exposure time of 900 sec in R band and 600 sec in B band. Another image of the field was taken in the R band only starting on Apr. 30 at 09:10:56 UT (about 29.5 hr after the burst) for a total exposure time of 1800 sec under better seeing conditions. At both epochs we found two objects within the XRT error circle: Object A is located well within the XRT error circle at: RA = 21:52:03.7 DEC = -38:49:42.9 Object B is located close to the border of the XRT error circle at: RA = 21:52:03.4 DEC = -38:49:43.1 Coordinates are J2000 and with an error of 0.2". Object A was detected in R band at both epochs with good S/N. It appears to be extended and consistent with the revised position of the object observed by Cucchiara et al (GCN 6370); its R magnitude is 23.2 +- 0.2, calibrated by using the USNO B1 catalogue. Object A was only marginally detected in the B band. Object B was marginally detected in the first R band observation, with a better detection during the second night at a R mag of 24.6+-0.3. Also object B seems extended. We find no evidence of a fading behaviour in either objects. Most likely one of them represents the host galaxy of GRB070429B. We thank the ESO Paranal staff for their excellent support. This message can be cited. ------------------------------------------------- This mail sent through IMP: http://horde.org/imp/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6373 SUBJECT: GRB 070429A: Swift XRT further analysis DATE: 07/05/02 14:59:51 GMT FROM: Rhaana Starling at U of Leicester R.L.C. Starling, P.A. Evans, K.L. Page and A. Beardmore (U. Leicester) report on behalf of the Swift XRT team: We have further analysed the Swift XRT data for GRB 070429A (Barthelmy et al., GCN Circ. 6355) out to 290 ks since the BAT trigger. The steep lightcurve decay reported in GCN Circ. 6363 has broken at T+1100 s to a slope of alpha~0.37. This plateau phase continues through the observations to date, out to about T0+290 ks, with a current count rate of ~0.006 count/s corresponding to a flux of 1.8e-12 erg/cm^-2/s. Probable X-ray flaring activity is seen during this phase. The duration of the plateau phase is longer than that normally observed in GRBs showing a similar phase (e.g. Nousek et al. 2006; O'Brien et al. 2006), hence the source remains X-ray bright. Continuation of optical and infrared observations of GRB 070429A is therefore strongly encouraged. This circular is an official product of the Swift XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6604 SUBJECT: GRB 070429B: NIR Observations DATE: 07/07/06 23:23:50 GMT FROM: Melissa Nysewander at STScI M. Nysewander, A. Fruchter and J. Graham (STScI) report on behalf of a larger collaboration: We observed the entire BAT error circle of the short GRB 070429B (Markwardt et al. GCN 6358) with ISPI on the Blanco 4-m at CTIO at a mean time of 06:10:28 UT on April 30, 2007 (1.13 days post burst) in 18 x 60-s J-band exposures, and again at a mean time of 06:23:04 UT on June 2, 2007, (34.2 days post burst) with the same exposure sequence. Due to the questionable nature of the faint XRT afterglow candidate (Beardmore et al. GCN 6360), we searched the entire BAT error circle by subtracting the two epochs using ISIS2 (Alard, 2000). We do not find any variation between the two epochs to the limiting magnitude of the first epoch, J ~ 21.5. Specifically, the source within the XRT error circle noted by Cucchiara et al. (GCN 6368) also did not vary between the two epochs. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7140 SUBJECT: GRB 070429B: Probable host galaxy and redshift DATE: 07/11/30 23:25:17 GMT FROM: Daniel Perley at U.C. Berkeley D. A. Perley, J. S. Bloom, M. Modjaz, D. Poznanski (UC Berkeley) and C. C. Thoene (DARK) report: On the night of 2007-07-18 we re-observed the field of GRB 070429B (GCN 6358, Markwardt et al.), likely to be a short-hard burst (T90 = 0.5 +- 0.1 s, GCN 6365, Tueller et al.) under photometric conditions using the Keck I telescope + LRIS, in g and R filters simultaneously for a total integration of 930s(g) / 840s(R) under relatively poor seeing. We further imaged the field using GMOS on Gemini-South on 2007-11-27 for 1200s in r filter under excellent seeing. The bright source reported by Cucchiara et al. (GCN 6368), designated object "A" by Antonelli et al. (GCN 6372) and likely the host galaxy of the GRB, is well-detected in R and r and weakly detected in g. Using Landolt standard stars we measure an aperture magnitude for this object (in a 2.1" radius aperture) of g = 24.79 +/- 0.14 R = 23.24 +/- 0.05 This is consistent within errors with the magnitudes reported by Cucchiara et al. and Antonelli et al. 4 and 5 hours after the burst, respectively. Image subtraction of the new Gemini imaging versus the earlier epoch (GCN 6368) reveals no variability to a limiting magnitude of R > 24.5, ruling out an afterglow contribution in the first epoch (4.84 hours after the burst) at this level. Object "B" is also detected in both filters, and also shows no evidence for variability. On the night of 2007-10-09 we performed longslit spectroscopy covering both targets ("A" and "B") in two integrations of 1500s each, using Keck I + LRIS. The trace of object "A" is faint and the spectrum is mostly featureless, but a faint line signature is observed centered at 7098 Angstroms, with a FWHM of 6 Angstroms. The feature appears present in both exposures, though this site is severely affected by a cosmic ray in one exposure. We identify this feature as most likely being the [OII]3727 doublet. Other line identifications (H-alpha, H-beta, or [OIII]) are disfavored due to the absence of corroborating lines that would be expected over our spectral range (3500-8900 Angstroms) in those cases. Association of this feature with [OII] indicates a redshift for this object of z=0.904. Calibrating relative to R-band photometry, we estimate a preliminary line flux of 3e-17 erg/s/cm^2, corresponding to an unextincted star formation rate (Kewley et al. 2002) of 0.7 M_sun/yr, comparable to that observed in previous short burst hosts. We note also the red color of this galaxy. No obvious trace or line features are observed for object B. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7145 SUBJECT: GRB 070429B: Possible UVOT Detection of an Optical Afterglow DATE: 07/12/10 15:32:47 GMT FROM: Stephen Holland at USRA/NASA/GSFC/SSC Holland, S. T. (CRESST/USRA/GSFC), de Pasquale, M. (UCL/MSSL), and Markwardt, C.~B. (CRESST/GSFC/UMD) report on behalf of the Swift/UVOT team: The Swift/UVOT observed the field of the short-hard GRB 070429B starting 230 s after the BAT trigger (Markwardt, et al., GCN Circ. 6358). We have re-examined this data in light of the redshift for the Antonelli, et al. (GCN Circ. 6372) source "A" reported by Perley, et al. (GCN Circ. 7140). We find weak evidence in the UVOT data for a fading source located inside the refined XRT error circle (Beardmore, et al., GCN Circ. 6360) at RA = 21:52:03.68 (J2000) Dec = -38:49:43.6 (J2000) with an uncertainty of 0.6 arcsec (90% confidence). This is 0.6 arcsec from the ground-based position of source "A". For a redshift of z = 0.904, and (H_0,Omega_M,Omega_Lambda) = (70,0.3,0.7) this corresponds to 4.7 proper kpc. This possible source is detected with a 3.9-sigma significance in a summed image (summed over all seven filters) between 591 and 2661 s after the BAT trigger. It is not detected in subsequent all-filter summed images. This possible UVOT source has the following magnitudes and upper limits. All magnitudes are on the UVOT system described in Poole, et al. (2007, MNRAS, in press). Filter T_start T_stop Exposure Mag Err Significance v 2002 2661 94 19.3 0.4 2.5 6805 7004 393 >20.1 3-sigma upper limit b 1460 2598 156 20.5 0.5 2.2 34,978 35,884 885 >22.0 3-sigma upper limit u 403 42,285 2260 >21.8 3-sigma upper limit uvw1 379 41,789 3075 >22.4 3-sigma upper limit uvm2 354 20,226 2192 >22.0 3-sigma upper limit uvw2 456 30,222 2378 >22.4 3-sigma upper limit white 591 977 117 21.6 0.5 2.2 6395 8027 393 >22.1 3-sigma upper limit The observations where the suspected source is weakly detected are all at less than one hour after the BAT trigger. The earliest reported ground-based detection of source "A" is Cucchiara, et al. (GCN Circ. 6368) who find r = 23.18 +/- 0.15 at approximately 4 hours. Perley, et al. (GCN Circ. 7140) find R = 23.24 +/- 0.05 at approximately 7 months, which implies that the source did not fade, and conclude that the "A" source is the host galaxy. They also find g = 24.29 +/- 0.14 at this time. If we assume that the SDSS g band is approximately similar to the UVOT v band then the expected v magnitude of the host at 2332 s (assuming a constant magnitude) is v ~= 24.3, which is 5 mag fainter than the UVOT detection at that time. This corresponds to a mean decay index of alpha ~= -2.5. The observed decay power-law indices from the UVOT data are alpha_v <= -0.6 +/- 0.3, alpha_b <= -0.5 +/- 0.2, and alpha_white <= -0.2 +/- 0.2. The shallow decay slope in the white filter, and the faintness of the White detection at early time (t_mid = 784 s) relative to the b and v detections at later times (t_mid = 2332 (v), 2029 (b)) suggest that the afterglow candidate may have increased in luminosity at some point between approximately 784 and 2029 s. We do not detect any source at the position of source "B" (Antonelli, et al., GCN Circ. 6372) down to the following limiting magnitudes. Filter T_start T_stop Exposure 3-Sigma Upper Limit v 230 31,793 2011 >21.5 b 427 35,115 1463 >22.3 u 403 42,285 2260 >21.9 uvw1 379 41,789 3075 >22.4 uvm2 354 20,226 2192 >22.0 uvw2 456 30,222 2378 >22.4 white 247 36,269 1088 >22.7 The values quoted above are not corrected for the expected Galactic extinction corresponding to a reddening of E_{B-V} = 0.03 mag (Schlegel, et al. 1998).