//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15760 SUBJECT: GRB 140129A: Swift detection of a burst with an optical afterglow DATE: 14/01/29 03:35:31 GMT FROM: David Palmer at LANL A. Melandri (INAF-OAB), W. H. Baumgartner (GSFC/UMBC), M. G. Bernardini (INAF-OAB), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), A. Y. Lien (NASA/GSFC/ORAU), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU), C. A. Swenson (PSU) and T. N. Ukwatta (MSU) report on behalf of the Swift Team: At 03:23:59 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 140129A (trigger=585128). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 37.869, -1.587 which is RA(J2000) = 02h 31m 29s Dec(J2000) = -01d 35' 11" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peaked structure with a duration of about 5 sec. The peak count rate was ~500 counts/sec (15-350 keV), at ~4 sec after the trigger. The XRT began observing the field at 03:25:52.9 UT, 113.5 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 37.89128, -1.59554 which is equivalent to: RA(J2000) = 02h 31m 33.91s Dec(J2000) = -01d 35' 43.9" with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 85 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (2.55 x 10^20 cm^-2, Kalberla et al. 2005), with an excess column of 2.2 (+1.80/-1.58) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 116 seconds after the BAT trigger. There is a candidate afterglow in the list of sources generated on-board at RA(J2000) = 02:31:33.81 = 37.89087 DEC(J2000) = -01:35:43.3 = -1.59536 with a 90%-confidence error radius of about 1.10 arc sec. This position is 1.6 arc sec. from the center of the XRT error circle. The estimated magnitude is 16.74. No correction has been made for the expected extinction corresponding to E(B-V) of 0.03. Burst Advocate for this burst is A. Melandri (andrea.melandri AT brera.inaf.it). 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: 15761 SUBJECT: GRB 140129A: P60 optical afterglow detection DATE: 14/01/29 04:15:45 GMT FROM: Daniel Perley at Caltech D. A. Perley (Caltech) and S. B. Cenko (NASA/GSFC) report on behalf of a larger calibration: The Palomar 60-inch telescope automatically responded to the Swift trigger for GRB 140129A (Melandri et al., GCN 15760) and began taking images at 03:27:37.8 UT, about 3.6 minutes post-GRB trigger. We detect a bright source, not present in USNO B1.0, at the following location consistent with the Swift XRT and UVOT error circles: RA = 02:31:33.78 dec = -01:35:42.88 (J2000) The source is detected in r, i, and z filters, and fades rapidly from r=16.29 to r=19.44 between UT 03:28 and 04:07. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15762 SUBJECT: GRB 140129A: RATIR Optical and NIR Observations DATE: 14/01/29 04:49:03 GMT FROM: Antonino Cucchiara at NASA/GSFC A. Cucchiara (NASA-GSFC), Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM), Carlos Román-Zúńiga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report: We began observing the field of GRB 140129A (Melandri, et al., GCN 15760) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir at 2014/01 29.15 (12.6 minutes after the BAT trigger). For a source within the Swift-XRT error circle, in comparison with the SDSS DR9 and 2MASS, we obtain the following detections: Filter mag(T0+0.12.6 minutes) mag(12.6 to 44.4 minutes) r 18.05 +/- 0.01 18.80 +/- 0.01 i 17.85 +/- 0.02 18.67 +/- 0.02 Z 17.72 +/- 0.03 18.50 +/- 0.03 Y 17.82 +/- 0.04 18.33 +/- 0.03 J 17.65 +/- 0.05 18.35 +/- 0.04 H 17.68 +/- 0.07 18.19 +/- 0.05 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. Further observations are underway. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15763 SUBJECT: GRB 140129A: ROTSE-III Detection of Optical Counterpart DATE: 14/01/29 05:14:59 GMT FROM: Farley V. Ferrante at Southern Methodist U/ROTSE F. V. Ferrante (SMU), W. Zheng (UC Berkeley), R. Kehoe (SMU), G. Dhungana (SMU) report on behalf of the ROTSE GRB team: The 0.45m ROTSE-IIIb telescope located at McDonald Observatory, Texas, responded to GRB 140129A (Swift trigger 585128; Melandri, et al., GCN 15760). The first image was at 03:24:58.3 UT, 57.0 s after the burst (8.3 s after the GCN notice time). The unfiltered images are calibrated relative to USNO A2.0. We confirm the afterglow candidate reported by UVOT and detect a bright source which fades rapidly from magnitude 14.1 to 16.0 between UT 03:24:58.3 and 03:26:55.7. Continuing observations are in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15764 SUBJECT: GRB 140129A: Enhanced Swift-XRT position DATE: 14/01/29 10:29:34 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 4216 s of XRT Photon Counting mode data and 7 UVOT images for GRB 140129A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 37.89093, -1.59545 which is equivalent to: RA (J2000): 02h 31m 33.82s Dec (J2000): -01d 35' 43.6" with an uncertainty of 1.5 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15767 SUBJECT: GRB 140129A: Swift-XRT refined Analysis DATE: 14/01/29 15:35:39 GMT FROM: Phil Evans at U of Leicester M.C. Stroh (PSU), B.P. Gompertz (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. Maselli (INAF-IASFPA), D.N. Burrows (PSU), J.A. Kennea (PSU) and A. Melandri report on behalf of the Swift-XRT team: We have analysed 9.3 ks of XRT data for GRB 140129A (Melandri et al. GCN Circ. 15760), from 99 s to 19.2 ks after the BAT trigger. The data comprise 45 s in Windowed Timing (WT) mode (the first 8 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN. Circ 15764). The light curve can be modelled with a power-law decay with a decay index of alpha=0.89 (+/-0.03). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.94 (+0.13, -0.12). The best-fitting absorption column is 4.0 (+2.5, -1.4) x 10^20 cm^-2, consistent with the Galactic value of 2.6 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.6 x 10^-11 (4.0 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 4.0 (+2.5, -1.4) x 10^20 cm^-2 Galactic foreground: 2.6 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.94 (+0.13, -0.12) If the light curve continues to decay with a power-law decay index of 0.89, the count rate at T+24 hours will be 8.7 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.1 x 10^-13 (3.5 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00585128. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15768 SUBJECT: GRB 140129A: Swift/UVOT Observations DATE: 14/01/29 16:52:45 GMT FROM: Craig Swenson at PSU/Swift C. A. Swenson (PSU) and A. Melandri (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 140129A 117 s after the BAT trigger (Melandri et al., GCN Circ. 15760). A source consistent with the XRT position (Evans et al. GCN Circ. 15764) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 02:31:33.78 = 37.89076 (deg.) Dec (J2000) = -01:35:43.4 = -1.59539 (deg.) with an estimated uncertainty of 0.50 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 117 267 147 16.51 ± 0.03 v 605 1250 78 18.69 ± 0.24 b 531 551 20 17.76 ± 0.14 u 275 525 246 16.98 ± 0.04 w1 654 17641 1357 20.77 ± 0.22 m2 5292 13449 1054 >21.2 w2 753 11858 1102 >22.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15769 SUBJECT: GRB 140129A, Swift-BAT refined analysis DATE: 14/01/29 17:40:59 GMT FROM: Amy Lien at GSFC C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/UMBC), A. Melandri (INAF-OAB), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 140129A (trigger #585128) (Melandri, et al., GCN Circ. 15760). The BAT ground-calculated position is RA, Dec = 37.851, -1.594 deg which is RA(J2000) = 02h 31m 24.2s Dec(J2000) = -01d 35' 40.1" with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 57%. The mask-weighted light curve shows a single peak structure starts at ~T+1.2 s, peaks at ~T+2.5 s, and ends at ~ T+4.6 s. T90 (15-350 keV) is 2.99 +- 0.79 sec (estimated error including systematics). The time-averaged spectrum from T+1.25 to T+4.62 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.08 +- 0.33. The fluence in the 15-150 keV band is 1.3 +- 0.3 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+1.91 sec in the 15-150 keV band is 0.9 +- 0.2 ph/cm2/sec. 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/585128/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15771 SUBJECT: GRB 140129A: MITSuME Okayama upper limits DATE: 14/01/30 00:13:58 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of MITSuME collaboration: We observed the field of GRB 140129A (Melandri et al., GCNC 15760) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory. The observation started on 2014-01-29 09:31:12 UT (~6.1 h after the burst). We could not detect the previously reported afterglow (Melandri et al., GCNC 15760; Perley and Cenko, GCNC 15761) in all the three bands. Three sigma upper limits of the OT are listed below. We used GSC2.3 catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' Rc Ic ----------------------------------------------------- 0.29723 10:32:00 4020.0 >19.6 >19.7 >18.9 ----------------------------------------------------- T0+ : Elapsed time after the burst [day] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15772 SUBJECT: GRB140129A: RAPTOR Observations of the Early Afterglow DATE: 14/01/30 00:45:09 GMT FROM: James Wren at LANL J. Wren, W.T. Vestrand, P. Wozniak, and H. Davis, of Los Alamos National Laboratory report: The RAPTOR network of robotic optical telescopes made follow-up observations of Swift trigger 585128 (Melandri, et al., GCN 15760). Our narrow-field instruments in Los Alamos, NM, began imaging at 03:25:05.19 UT, 65.7 seconds after the BAT trigger time. Our RAPTOR-T robotic telescope measured the counterpart simultaneously in SDSS g', r', i', and z' bands through the first 1000 seconds after the BAT trigger. In r' band, the counterpart is at magnitude 14.72 +- 0.04 at T+68.22 seconds. By T+217.21, the source had faded to r' magnitude 16.24 +- 0.07, consistent with the P60 observations (Perley, et al., GCN 15761). The counterpart fades monotonically during the observation interval. Our images were calibrated to the SDSS DR9 catalog. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15773 SUBJECT: GRB 140129A: P200 spectroscopy DATE: 14/01/30 01:58:46 GMT FROM: Daniel Perley at Caltech D. A. Perley (Caltech), M. Rafelski, D. Masters (IPAC), and J. X. Prochaska (UCO/Lick) report: We obtained spectroscopy of the optical afterglow of GRB 140129A (Melandri et al., GCN 15760) with the Double Spectrograph at the 5m Palomar Hale telescope beginning at 04:56:25.2 UT, approximately 1.5 hours after the GRB trigger. Based on our P60 imaging, the GRB afterglow was r~20 mag at this point and the S/N of the spectrum is low, although the trace is clearly detected in each of three 600s exposures. The spectral range covers from the atmospheric cutoff to 8700 Angstroms. The spectrum is featureless, showing no significant absorption lines over our spectral range (although the EW sensitivity limit is poor). The absence of a DLA feature suggests a redshift of z<1.8 (more conservatively, the lack of IGM absorption down to the atmospheric cutoff indicates z<2.1). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15775 SUBJECT: GRB 140129A: CARMA early observations DATE: 14/01/30 08:47:10 GMT FROM: Daniel Perley at Caltech D. A. Perley (Caltech) reports on behalf of a larger collaboration: We observed the position of GRB 140129A (Melandri et al., GCN 15760) with the Combined Array for Research in Millimeter Astronomy starting at 04:57:21 UT, 94 minutes after the GRB trigger. Observations continued until 06:10:30 UT (source elevation = 19 degrees). No source is detected at the optical afterglow location to a limiting flux of <1.8 mJy (3 sigma). We thank C. Hull, N. Volgneau, and the CARMA staff for this rapid observation. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15779 SUBJECT: GRB 140129A: Continued RATIR Optical and NIR Observations DATE: 14/01/30 16:17:02 GMT FROM: Nat Butler at UC berkeley Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (ORAU/GSFC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM), Carlos Román-Zúńiga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report: We observed the field of GRB 140129A (Melandri, et al., GCN 15760) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2014/01 30.13 to 2014/01 30.23 UTC (23.82 to 26.22 hours after the BAT trigger), obtaining a total of 1.36 hours exposure in the r and i bands and 0.56 hours exposure in the Z, Y, J, and H bands. For a source within the Swift-XRT error circle, in comparison with the SDSS DR9 and 2MASS, we obtain the following detections and upper limits (3-sigma): r 22.67 +/- 0.13 i 22.32 +/- 0.11 Z 22.19 +/- 0.27 Y 21.94 +/- 0.37 J > 21.78 H > 21.28 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. The afterglow has faded by several magnitudes in all bands since our observations last night (Cucchiara et al., GCN 15762). We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15781 SUBJECT: GRB 140129A: Khureltogot optical limit DATE: 14/01/31 09:54:37 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (IKI), N. Tungalag (Research Centre of Astronomy and Geophysics MAS ) V. Voropaev (KIAM), I.Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 140129A (Melandri et al., GCN 15760) on Jan., 29 with ORI-40 telescope of Khureltogot observatory (Mongolia). We took several unfiltered images of 60 s exposure. Within enhanced XRT error circle (Evans et al., GCN 15764) we do not detect the optical afterglow (Melandri et al., GCN 15760). Details of the photometry are following: UT start t-T0 Filter Exp. OT UL (3 sigma) (mid, days) (s) 12:02:22 0.38515 None 68x60 n/d 20.0 The photometry is based 3 SDSS stars, R (gri -> R transformations by Lupton 2005): SDSS id R J023133.01-013533.5 18.121 J023122.45-013411.0 18.797 J023137.01-013606.5 19.143 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15782 SUBJECT: GRB 140129A: Continued RATIR Optical and NIR Observations DATE: 14/01/31 15:09:30 GMT FROM: Nat Butler at Az State U Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (ORAU/GSFC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM), Carlos Román-Zúńiga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report: We again observed the field of GRB 140129A (Melandri, et al., GCN 15760) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2014/01 31.11 to 2014/01 31.20 UTC (47.35 to 49.51 hours after the BAT trigger), obtaining a total of 1.38 hours exposure in the r and i bands and 0.58 hours exposure in the Z, Y, J, and H bands. The afterglow observed previously by RATIR (Cucchiara, et al., GCN 15762; Butler, et al., GCN 15779) is no longer detected. In comparison with the SDSS DR9 and 2MASS, we obtain the following upper limits (3-sigma): r > 22.99 i > 22.59 Z > 21.59 Y > 21.14 J > 20.82 H > 20.49 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15783 SUBJECT: GRB 140129A: 5 GHz VLA observations DATE: 14/02/05 15:41:46 GMT FROM: Alessandra Corsi at GWU A. Corsi (GWU) reports on behalf of a larger collaboration: We observed the field of the Swift GRB 140129A (Melandri et al., GCN #15760) using the the Karl G. Jansky Very Large Array (VLA) in C-band, and starting at 00:57:45 UT on 30 Jan 2014. A provisional reduction shows no radio emission above the 3-sigma level of 30uJy (the map rms is ~10uJy at 5 GHz) within the Swift XRT error-circle (Evans et al. GCN #15764). The flux density at the P60 optical afterglow position (Perley & Cenko, GCN #15761) is -8 +/-10 uJy at 5 GHz. We thank the VLA staff for executing these observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16054 SUBJECT: GRB 140129A: Mondy optical observations DATE: 14/03/31 16:05:39 GMT FROM: Alina Volnova at SAI MSU GRB 140129A: Mondy optical observations A. Volnova (IKI), E. Klunko (ISTP), M. Eselevich (ISTP), I. Korobtsev (ISTP), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 140129A (Melandri et al., GCN 15760)with AZT-33IK telescope of Sayan observatory (Mondy) starting on on Jan. 29 (UT) 12:21:46. We took several images in R-filter of 60 s exposure. Within enhanced XRT error circle (Evans, GCN 15764) we detected the optical afterglow (Melandri et al., GCN 15760). The details of the photometry are the following: UT start t-T0 Filter Exp. OT (mid, days) (s) 12:21:46 0.38805 R 42x60 21.39 +/- 0.25 The photometry is based 3 SDSS stars, R (gri -> R transformations by Lupton 2005): SDSS id R J023133.01-013533.5 18.121 J023122.45-013411.0 18.797 J023137.01-013606.5 19.143