//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6948 SUBJECT: GRB 071020A: ROTSE-III Detection of Optical Counterpart DATE: 07/10/20 07:17:21 GMT FROM: Brad Schaefer at LSU B. E. Schaefer (Louisiana State), T.A. McKay (U Mich), F. Yuan (U Mich), report on behalf of the ROTSE collaboration: ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 071020A (Swift trigger 294835). The first image was at 07:02:52.5 UT, 25.6 s after the burst (9.5 s after the GCN notice time). The unfiltered images are calibrated relative to USNO A2.0. We detect a 13.6 magnitude, fading source with coordinates: 07:58:39.9 +32:51:41.4 (J2000), with positional uncertainty of 1" or better start UT mag mlim(of image) ---------------------------------- 07:02:52.9 13.6 16.4 This source is not visible in DSS (second epoch), 2MASS or the MPChecker database. A jpeg image is available at http://www.rotse.net/images/gsb294835_3b00_img.jpg Continuing observations are in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6949 SUBJECT: GRB 071020: Swift detection of a bright burst DATE: 07/10/20 07:18:57 GMT FROM: Scott Barthelmy at NASA/GSFC S. T. Holland (CRESST/USRA/GSFC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), C. Guidorzi (Univ Bicocca&INAF-OAB), C. Pagani (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (NASA/UMBC), R. L. C. Starling (U Leicester) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 07:02:26 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 071020 (trigger=294835). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 119.664, +32.861 which is RA(J2000) = 07h 58m 39s Dec(J2000) = +32d 51' 40" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a double peak structure with a duration of about 5 sec. The peak count rate was ~22000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 07:03:28 UT, 61 seconds after the BAT trigger. In 268 s of promptly downlinked data XRT found a bright, fading, uncatalogued X-ray source located at RA, Dec 119.6656, 32.8611 which is RA(J2000) = 07 58 39.74 Dec(J2000) = +32 51 40.0 with an uncertainty of 4.3 arcsec (radius, 90% containment). This location is 5 arcseconds from the BAT on-board position, within the BAT error circle. The initial flux in the 2.5s image was 1.8e-09 erg/cm2/s (0.2-10 keV). There will be no UVOT data products for this burst, because it is still in engineering mode after the recent recovery to the new 3-gyro mode. Burst Advocate for this burst is S. T. Holland (sholland 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.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6950 SUBJECT: GRB071020 - SDSS Pre-burst Observations DATE: 07/10/20 07:30:59 GMT FROM: Richard J. Cool at U.of AZ/Steward Obs Richard J. Cool (Arizona), Daniel J. Eisenstein (Arizona), David W. Hogg (NYU), Michael R. Blanton (NYU), David J. Schlegel (LBNL), J. Brinkmann (APO), Donald Q. Lamb (Chicago), Donald P. Schneider (PSU), and Daniel E. Vanden Berk (PSU) report: The Sloan Digital Sky Survey (SDSS) imaged the field of burst GRB071020 prior to the burst. As these data should be useful as a pre-burst comparison and for calibrating photometry, we are supplying the images and photometry measurements for this GRB field to the community. Data from the SDSS, including 5 FITS images, 3 JPGS, and 3 files of photometry and astrometry, are being placed at http://mizar.as.arizona.edu/~grb/public/GRB071020 We supply FITS images in each of the 5 SDSS bands of a 8'x8' region centered on the GRB position (ra=119.664 (07:58:39.4), dec=32.8610 (32:51:39.6); Swift-BAT TRIGGER 294835), as well as 3 gri color-composite JPGs (with different stretches). The units in the FITS images are nanomaggies per pixel. A pixel is 0.396 arcsec on a side. A nanomaggie is a flux-density unit equal to 10^-9 of a magnitude 0 source or, to the extent that SDSS is an AB system, 3.631e-6 Jy. The FITS images have WCS astrometric information. In the file GRB071020_sdss.calstar.dat, we report photometry and astrometry of 741 bright stars (r<20.5) within 15' of the burst location. The magnitudes presented in this file are asinh magnitudes as are standard in the SDSS (Lupton 1999, AJ, 118, 1406). Beware that some of these stars are not well-detected in the u-band; use the errors and object flags to monitor data quality. In the files GRB071020_sdss.objects_flux.dat and GRB071020_sdss.objects_magnitudes.dat, we report photometry of 975 objects detected within 6' of the GRB position. We have removed saturated objects and objects with model magnitudes fainter than 23.0 in the r-band. The fluxes listed in GRB071020_sdss.objects_flux.dat are in nanomaggies while the magnitudes listed in GRB071020_sdss.objects_magnitudes.dat are asinh magnitudes. All quantities reported are standard SDSS photometry, meaning that they are very close to AB zeropoints and magnitudes are quoted in asinh magnitudes. Photometric zeropoints are known to about 2% rms. None of the photometry is corrected for dust extinction. The Schlegel, Finkbeiner, and Davis (1998) predictions for this region are A_U=0.335 mag, A_g=0.246 mag, A_r = 0.179 mag, A_i=0.135 mag, and A_z=0.096 mag. The file GRB071020_sdss.spectro.dat contains a list of the 3 objects with SDSS spectroscopy within 6 arcminutes of the GRB position. In addition to the redshift and 1-sigma error for each object, this file also lists the object spectroscopic classification. SDSS astrometry is generally better than 0.1 arcsecond per coordinate. Users requiring high precision astrometry should take note that the SDSS astrometric system can differ from other systems such as those used in other notices; we have not checked the offsets in this region. More detailed information pertaining to our SDSS GRB releases can be found in our initial data release paper (Cool et al. 2006, PASP 118, 733). See the SDSS DR4 documentation for more details: http://www.sdss.org/dr5. These data have been reduced using a slightly different pipeline than that used for SDSS public data releases. We cannot guarantee that the values here will exactly match those in the data release in which these data are included. In particular, we expect the photometric calibrations to differ by of order 0.01 mag. This note may be cited, but please also cite the SDSS data release paper, Adelman-McCarthy et al. (2006, ApJS, 172, 634), when using the data or referring to the technical documentation. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6951 SUBJECT: GRB 071020: ROTSE-III Analysis of Optical Counterpart DATE: 07/10/20 08:07:20 GMT FROM: Fang Yuan at ROTSE F. Yuan (U Mich), E.S. Rykoff (UCSB), T.A. McKay (U Mich), B. E. Schaefer (Louisiana State), R. Quimby (Caltech), H. Swan (U Mich), report on behalf of the ROTSE collaboration: ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 071020 (Swift trigger 294835; Holland, et al., GCN6949) and detected the optical counterpart (Schaefer, et al., GCN 6948). During our first 80 seconds observation (starting 25.6 sec after the burst), the OT faded with a decay index of 1.52 +/- 0.03. We notice that the burst location is 9.7h^-1 kpc from the central bulge of SDSS J075843.38+325141.7, a galaxy with an old stellar population located at z=0.0166. DR6 SDSS data suggest this galaxy as M_r ~ -19.4, and a central velocity dispersion of 135 km/s. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6952 SUBJECT: GRB 071020: VLT spectroscopy DATE: 07/10/20 13:40:12 GMT FROM: Pall Jakobsson at U Hertfordshire Pall Jakobsson (U. Hertfordshire), Paul M. Vreeswijk, Jens Hjorth, Daniele Malesani, Johan P.U. Fynbo and Christina C. Thoene (DARK, NBI) report: Using FORS2 on the Very Large Telescope, we have obtained a 10 min spectrum (grism 300V) of the optical afterglow (OA) of GRB 071020 (Holland et al., GCN 6949). The acquisition image shows the proposed OA (Schaefer et al., GCN 6948) to have R ~ 20.4 on Oct 20.377 (2.0 hours post burst). The spectrum displays Fe II (2586,2600) and the Mg II doublet (2796,2803) in absorption corresponding to a redshift of z = 2.145 (based on a preliminary wavelength calibration). Hence, the GRB is unrelated to the nearby z = 0.0166 galaxy reported by Yuan et al. (GCN 6951). We note that this is a lower limit to the GRB redshift. There is some indication of a flux drop in the OA spectrum around 4300 A, implying that the GRB redshift could be z ~ 2.5 if due to the Ly-alpha break. We thank the Paranal staff for excellent support, especially Emanuela Pompei. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6953 SUBJECT: GRB 071020A: IR Imaging with PAIRITEL DATE: 07/10/20 16:20:34 GMT FROM: Josh Bloom at UC Berkeley J. S. Bloom, D. A. Perley (UC Berkeley) and D. L. Starr (UC Berkeley, LCOGT) report: "We observed the field of the optical transient (Schaefer et al. GCN 6948) of GRB 071020A (Holland et al. GCN 6949) with the 1.3m PAIRITEL on Mt. Hopkins starting at 2007-10-20 09:18 UT (~2h16m after the GRB, once the field was within telescope limits). In a stack of 2190 sec total integration time (mean time = 2007-10-20 09:46 UT), we detect the source in the J-band at position: ra= 07:58:39.78 dec = +32:51:40.4 (J2000; rms uncertainty relative to 2MASS of 250 mas in each coordinate) with J=19.06 +/- 0.23 mag and H=18.71 +/- 0.30 (only marginally detected). The source appears to have faded in subsequent imaging." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6954 SUBJECT: GRB 071020, Swift-BAT refined analysis DATE: 07/10/20 16:46:43 GMT FROM: Scott Barthelmy at NASA/GSFC J. Tueller (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), S. T. Holland (CRESST/USRA/GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), J. Norris (U. Denver), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), T. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+625 sec from recent telemetry downlinks, we report further analysis of BAT GRB 071020 (trigger #294835) (Holland, et al., GCN Circ. 6949). The BAT ground-calculated position is RA, Dec = 119.666, 32.857 deg, which is RA(J2000) = 07h 58m 39.9s Dec(J2000) = 32d 51' 25" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 90%. The mask-weighted lightcurve shows at least 8 overlapping pulses in the initial burst. They all have approximately the same peak flux values. This emission starts at ~T-3 sec, peaks at ~T-1.5 sec, and ends at ~T+0.9 sec. T90 (15-350 keV) is 4.2 +- 0.2 sec (estimated error including systematics). The spectral lag for this burst is: 59 +7-9 msec for the 150-300 to 25-50 keV bands, and 10 +8-7 msec for the 50-100 to 15-25 keV bands. The time-averaged spectrum from T-3.0 to T+7.4 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.11 +- 0.05. The fluence in the 15-150 keV band is 2.3 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-0.36 sec in the 15-150 keV band is 8.4 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level. Folding in the borderline results of the T90, the hardness ratio, the spectral lag, and very marginal detection of extended emission in the lightcurve; we think this is a Long burst, but we can not rule out the possibility of a SHB classification. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6955 SUBJECT: GRB 071020: Swift-XRT refined analysis DATE: 07/10/20 19:03:38 GMT FROM: Andy Beardmore at U Leicester A.P. Beardmore, K.L. Page, P.A. Evans (U. Leicester) and S.T. Holland (CRESST/USRA/GSFC) report on behalf of the Swift-XRT team: The Swift-XRT began observing the BAT GRB 071020 (trigger #294835) at 07:03:28 UT, 61 seconds after the BAT trigger. In a 1.23ks exposure Photon Counting mode image obtained during the first orbit we find a refined XRT position of RA, Dec (J2000) = 119.66521, 32.86079 which is RA(J2000) = 07:58:39.65 Dec(J2000) = +32:51:38.8 with an estimated uncertainty of 4.0 arcsec (radius, 90 percent containment). This is 13.9 arcsec from the refined BAT position (Tueller et al., GCN 6954), 4.1 arcsec from the position of the ROTSE-IIIb afterglow (Schaefer et al., GCN 6948), and 2.3 arcsec from the PAIRITEL position (Bloom et al., GCN 6953). Due to a high CCD operating temperature caused by the unfavourable sky position of the burst, along with bright Earth activated hot-pixels, the XRT remained in Windowed Timing mode for orbits 2 to 5 at which point the initial Swift observations were halted for today. However, using the XRT data available at these times, the 0.3-10.0keV X-ray light curve from T+68s to T+17.6ks shows a powerlaw decline with a decay index of 1.11+/0.02. The Windowed Timing mode spectrum from the first orbit (T+68s to T+315s) is well fit by an absorbed powerlaw with a photon index of 1.86+/-0.07 and a redshifted column density of (4.3+/-1.7)e21 cm^-2 (at z=2.145, Jakobsson et al., GCN 6952), in addition to the 5.1e20 cm^-2 galactic column density in this direction. The observed 0.3-10.0 keV flux during this time is (6.1+/-0.2)e-10 erg cm^-2 s^-1. Assuming the X-ray light curve decays at the same rate we predict an XRT count rate of 0.014 count s^-1 at T+24 hours, which corresponds to an observed 0.3-10keV flux of 6.0e-13 erg cm^-2 s^-1. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6956 SUBJECT: GRB071020A: Xinglong TNT Optical afterglow observations DATE: 07/10/20 22:33:55 GMT FROM: L.P. Xin at NAOC L.P. Xin, M. Zhai, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng, J. Wang, Y. Urata and W.K. Zheng on behalf of EAFON report: We have imaged the field of GRB071020A (Barthelymy et al GCN6949) using the TNT 0.8 telescope at Xinglong observatory. A series of R-band images were obtained from 17:08:19.4, 10.1 hours after the burst. In our 15*600s combined image,  we detected afterglow (Schaefer et al GCN6947, Beardmore et al GCN 6955), The estimated brightness derived from USNO-B1.0 was R=21.14 +/- 0.08 at 11.5 hours after the burst (mean time of the stacked image). Further observations are encouraging. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6960 SUBJECT: Konus-Wind observation of GRB 071020 DATE: 07/10/21 13:31:43 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and T. Cline on behalf of the Konus-Wind team report: The long GRB 071020 (Swift-BAT trigger #294835: Holland et al., GCN 6949, Tueller et al., GCN 6954) triggered Konus-Wind at T0=25346.637 s UT (07:02:26.637). The burst light curve shows a multipeaked structure with a duration of ~3.5 s. As observed by Konus-Wind the burst had a fluence of 7.71(-4.76, +0.39)x10^-6 erg/cm2, and a 64-ms peak flux measured from T0+2.416 s of 6.04(-3.88, +1.12)x10^-6 erg/cm2/s (both in the 20 keV - 2 MeV energy range). The time-integrated spectrum of the burst (from T0 to T0+8.448 s) is well fitted (in the 20 keV - 2 MeV range) by a power law with exponential cutoff model: dN/dE ~ E^(-alpha)*exp(-E*(2-alpha)/Ep) with alpha = 0.65(-0.32, +0.27) and Ep = 322(-53, +80) keV (chi2 = 64.4/61 dof). Fitting by GRBM (Band) model yields only an upper limit on the high energy photon index: beta < -1.97. All the quoted errors are at the 90% confidence level. Assuming z = 2.145 (Jakobsson et al., GCN 6952) and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.3, Omega_\Lambda = 0.7, the isotropic bolometric energy release is E_iso ~8x10^52 erg, and the maximum bolometric luminosity is (L_iso)_max ~2x10^53 erg/s. The Konus-Wind light curve of this GRB is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB071020_T25346/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6970 SUBJECT: GRB 071020: Fading slowly? DATE: 07/10/22 01:04:37 GMT FROM: Myungshin Im at Seoul Nat U M. Im, I. Lee (Seoul National University), and Y. Urata (Saitama University) on behalf of the EAFON team: Using the Mt. Lemmon (Arizona, US) 1.0m telescope operated by the Korea Astronomy Space Science Institute, we observed GRB071020 (GCN 6949, Holland et al.), beginning at 09:01:45 UT on Oct 21. (1.0825 days after the burst). We confirm the afterglow (GCN6948 Schaefer, McKay, & Yuan; GCN6956, Xin et al.; GCN6953, Bloom et al.). Compared with the photometry in the report by Xin et al. (GCN6956), our data suggest that the afterglow is not fading signficiantly over the 12 hrs span and may even be brightenning by a small amount. Since the target is still bright enough for small telescopes, we encourage the further observations of this object. Photometry of the object is given below. t_start (UT) Filter exp (sec) R-mag err ----------------------------------------------------- Oct. 21, 09:01:45 R 15x300 20.93 0.09 This message may be cited. We acknowldege the help for a series of LOAO GRB observations by the LOAO operators, J.H. Yoon and I.K. Baek. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6978 SUBJECT: Radio detection of GRB 071020 with the VLA DATE: 07/10/22 18:59:06 GMT FROM: Poonam Chandra at U Virginia/NRAO P. Chandra (UVA/NRAO) and D. A. Frail (NRAO) report on behalf of the Caltech-NRAO-Carnegie GRB Collaboration: "We observed the field centered on the XRT position of the Swift burst GRB 071020 (GCN 6949) using the VLA at a frequency of 8.46 GHz. The observations were taken at a mean time of 11.21 UT on 22nd Oct 07. We detect the radio afterglow of GRB 071020 at the following position: RA(J2000) 07 58 39.78 Dec(J2000) +32 51 39.56 The flux density of the GRB is 186+/-26 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: 6979 SUBJECT: GRB 071020: SARA observations DATE: 07/10/22 20:23:05 GMT FROM: Adria C. Updike at Clemson U Adria C. Updike, Dieter H. Hartmann (Clemson University) and Todd Hillwig (Valparaiso University) report on behalf of the Clemson GRB Follow-Up Team: We observed the field of GRB 071020 (GCN 6949, Holland et al.) beginning 1 hour after the trigger with the SARA 0.9m telescope on Kitt Peak. In 48 minutes of stacked exposures, we detect the afterglow (GCN 6948, Schaefer et al.) in the R band at 19.7 +/- 0.2, calibrated relative to 10 field stars in the USNO B1.0 catalog. Observations ended at 2 hours and 11 minutes after the burst. This message may be cited. Information on the SARA observatory may be found at http://astro.fit.edu/sara/sara.html . //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6981 SUBJECT: Optical observations of GRB 071020 DATE: 07/10/23 11:25:46 GMT FROM: AAVSO GRB Network at AAVSO Veli-Pekka Hentunen (Taurus Hill Observatory, Varkaus, Finland) reports to the AAVSO International High Energy Network the following optical observations of GRB071020 (GCN #6949, Holland et al.): Markku Nissinen, Henri Taino and Veli-Pekka Hentunen report the detection of the optical afterglow of GRB 071020 (Holland et al., GCN 6949; Schaefer et al., GCN 6948; Yuan et al., GCN 6951; Xin et al., GCN 6956). The afterglow was observed unfiltered approximately 17 hours post-burst, using a 0.3-meter Meade LX200 at Taurus Hill Observatory. The source was detected with marginal signal to noise at an unfiltered magnitude of 20.9 +/- 0.3, with an observational mid-point time of 2007 October 20, 23:54:37 UT. The magnitude is calibrated relative to GSC 0247201072 (GSC1.2) with a magnitude of 13.54. The afterglow magnitude is consistent with an earlier observation by Xin et al. (GCN 6956) as well as with a later observation by Im et al. (GCN 6970). The AAVSO thanks the Curry Foundation for their continued support of the AAVSO International High Energy Network. [GCN OPS NOTE(23oct07): Per submiter's request, "6979" was changed to "6949" in th 3rd line.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6984 SUBJECT: GRB 071020: BTA spectroscopy DATE: 07/10/24 15:00:41 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia T. A. Fatkhullin, V. V. Sokolov (SAO-RAS Nizhnij Arkhyz), S. Guziy (Nikolaev St. Univ.), A. de Ugarte Postigo (ESO Santiago), D. Pérez-Ramírez (Univ. de Jaén and U. Leicester), J. Gorosabel, M. Jelínek and A. J. Castro-Tirado (IAA-CSIC Granada), on behalf of a larger collaboration, report: "Following the detection of GRB 071020 by SWIFT (Holland et al. GCN Circ. 6949) we obtained optical spectroscopy with the 6.0m BTA telescope (+SCORPIO) of the SAO-RAS. In spite of poor weather conditions (dense cirrus) we managed to get 4 x 1200s spectra of the proposed optical afterglow (Schaefer et al. GCN Circ. 6948). The data were taken on Oct 21.05 U.T. (i.e. 18 hr after the event), with the VPHG 400 grism (range 3700-9000 A). We identify absorption lines from Fe II (2344, 2586 and 2600) and possibly C IV (1548-1550) and Fe II (1608), at z = 2.142 ± 0.002. This confirms the lower limit to the GRB 071020 redshift derived from VLT spectroscopy (Jakobsson et al., GCN Circ. 6952). Moreover, we do not see any flux drop in the OA spectrum around 4300 A as the VLT spectrum may suggest. However, there are indications of a flux drop at ~3870A but the low S/N ratio in this range prevents us to draw any further conclusion." This message can be quoted. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7006 SUBJECT: GRB071020, optical upper limit DATE: 07/10/26 12:37:21 GMT FROM: Eri Sonoda at U of Miyazaki/Japan R. Hara, E.Sonoda, H.hayasi, N.Ohmori, K.Kono H. Tanaka, M.Yamauchi (University of Miyazaki) We have observed the field covering the error circle of GRB071020 (GCN 6954, J. Tueller et al.) with the unfiltered CCD camera on the 30-cm telescope at University of Miyazaki. The observation was started 15:29:35 UT, ~507 min. after the Swift trigger time. We have compared our data of 30 sec exposures with the USNO-A2.0 catalog,there is no new source at the reported position (GCN 6948, B.E.Schaefer et al. GCN 6949, S.T.Holland et al. GCN 6978, P. Chandra et al.) the upper limits are as follows: -------------------------------------------------------------- Start(UT) End(UT) Num. of frames Limit (mag.) -------------------------------------------------------------- 15:31:27 15:31:57 1 ~16.5 15:31:27 16:24:39 20 ~17.0 --------------------------------------------------------------- //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7026 SUBJECT: GRB 071020: MITSuME Akeno optical observations DATE: 07/10/31 11:38:14 GMT FROM: Nobuyuki Kawai at Tokyo Tech T. Ishimura, Y. Yatsu, T. Shimokawabe, N. Kawai (Tokyo Tech) and M. Yoshida (NAOJ) report on behalf of the MITSuME collaboration: We observed the field of GRB 071020 (Holland et al. , GCN6949) with the 3-color 50cm MITSuME Telescope at Akeno, Japan from UT 16:21 to UT 19:53 on Oct. 20, 9.3 hours after the trigger. In the co-added images of Ic and Rc bands, we detected the optical afterglow reported by Schaefer et al. (GCN 6948). Photometric calibration was done using the USNO-B1.0 (Ic-band) and NOMAD (g'- and Rc-bands) catalogs. The results are following: Filter start end Exposure Mag ------------------------------------------------------ g' 16:21:13 19:53:55 149 x 60s >21.1 (3 sigma upper limit) Rc 16:21:13 19:53:55 149 x 60s 21.2 +/- 0.3 Ic 16:21:13 19:53:55 149 x 60s 19.8 +/- 0.3 ------------------------------------------------------ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7146 SUBJECT: GRB071020: optical observations DATE: 07/12/11 22:46:19 GMT FROM: Alexei Pozanenko at IKI, Moscow S. Sergeev, V. Rumyantsev (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the optical afterglow (Schaefer et al. GCN 6948) of GRB071020 (Tueller et al. GCN 6954) in I and B bands on Oct.10-11 between (UT) 23:51:34 - 01:11:47 with AZT-8 telescope of CrAO. We detected the afterglow in I-band, and not detected it in B-band. Based on SDSS stars (Cool et al. GCN 6950) RA=119.66618, Dec=32.84706; RA=119.68899, Dec=32.84803; RA=119.66782, Dec=32.85465 we estimated brightness of the optical afterglow on a stacked images: T0+, Exposure, Filter, mag., UL (mid time) 0.730 d 12x90 s I 20.5 +/-0.3 20.5 0.728 d 12x180 s B n/d 21.0 The message may be cited.