//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16788 SUBJECT: GRB 140907A: Swift detection of a burst with an optical counterpart DATE: 14/09/07 16:34:45 GMT FROM: David Palmer at LANL H. A. Krimm (CRESST/GSFC/USRA), V. D'Elia (ASDC), C. Gronwall (PSU), L. Izzo (URoma/ICRA), K. L. Page (U Leicester), D. M. Palmer (LANL) and T. N. Ukwatta (LANL) report on behalf of the Swift Team: At 16:07:08 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 140907A (trigger=611933). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 48.147, +46.595 which is RA(J2000) = 03h 12m 35s Dec(J2000) = +46d 35' 42" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single spiky peak structure with a duration of about 40 sec. The peak count rate was ~3100 counts/sec (15-350 keV), at ~15 sec after the trigger. The XRT began observing the field at 16:08:32.3 UT, 83.6 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source with an enhanced position: RA, Dec 48.1461, 46.6051 which is equivalent to: RA(J2000) = 03h 12m 35.06s Dec(J2000) = +46d 36' 18.2" with an uncertainty of 2.2 arcseconds (radius, 90% containment). This location is 36 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 consistent with the Galactic value of 3.13 x 10^21 cm^-2 (Willingale et al. 2013). The initial flux in the 2.5 s image was 5.46e-10 erg cm^-2 s^-1 (0.2-10 keV). Automated analysis of the UVOT data products is not available, however there appears to be a new bright optical source at the XRT position in the prompt finding chart exposure. More information will be available when the full dataset is received. Burst Advocate for this burst is H. A. Krimm (hans.krimm AT 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: 16789 SUBJECT: GRB 140907A : Optical observations from Nanshan DATE: 14/09/07 18:03:54 GMT FROM: Dong Xu at DARK/NBI D. Xu (DARK/NBI), X. Gao (Urumqi No.1 Senior High School, Xinjiang), G.-J. Feng, A. Esamdin, L. Ma (XAO), Z.-J. Xu (Nanjing Putian Telecommunications Co. Ltd., Jiangsu) report: We observed the field of GRB 140907A (Krimm et al., GCN 16788) using the 35cm robotic telescope and the 1m optical telescope located at Nanshan, Xinjiang, China. The observations started at 16:18:42 UT on 2014-09-07 at the 35cm telescope without any filter, and 16:34:28 UT at the 1m telescope in the R filter. The afterglow is well detected in our images at coordinates R.A. (J2000) = 03:12:34.98 Dec. (J2000) = +46:36:17.2 Error radius: ~ 0.7 arcsec which is fully consistent with the UVOT position. Generally, the afterglow has been decaying, and follows are the preliminary measurements from the 35cm telescope: Mid-Time Mag 2014/09/07.68001 16.7 2014/09/07.68083 16.7 2014/09/07.68164 16.7 2014/09/07.68244 16.9 2014/09/07.68325 17.0 2014/09/07.68405 17.1 2014/09/07.68485 17.0 2014/09/07.68565 16.9 2014/09/07.68646 17.2 with a typical error of 0.2 magnitude, calibrated with the R-band catalog of NET CMC-14. Observations are ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16791 SUBJECT: GRB140907A: Swift UVOT detection DATE: 14/09/07 20:08:13 GMT FROM: Paul Kuin at MSSL NPM Kuin (UCL/MSSL), and H. A. Krimm (CRESST/GSFC/USRA) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 140907A (Krimm et al., GCN Circ. No. 16788) 107 seconds after the trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 03:12:34.98 = 48.14575 DEC(J2000) = +46:36:17.5 = 46.60486 with a 90%-confidence error radius of about 0.75 arc sec, consistent with the optical position from Xu et al. (GCN.Circ.No . 16789). Preliminary magnitudes observed in the initial images using the UVOT photomatric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) are: Filter T_start(s) T_stop(s) Exp(s) Mag white 107 257 150 16.66 +/- 0.04 u 321 534 213 16.61 +/- 0.06 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.29 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16792 SUBJECT: GRB 140907A : Virtual Telescope optical observations DATE: 14/09/07 22:07:14 GMT FROM: Gianluca Masi at Bellatrix Astronomical Obs G. Masi and P. L. Catalano, the Virtual Telescope Project - Italy, report: We started observations of GRB 140907A (Krimm et al., GCN 16788) with the 17" robotic unit part of the Virtual Telescope (Ceccano, Italy) at 21:46:00 UT. An optical source is visible where described by D. Xu et al. (GCN 16789) in a image coming from the sum of tfour, 300-seconds exposures, unfiltered. The position of the source is RA: 03 12 35.00 Decl.: +46 36 17.6 (J2000.0, mean residuals of 0.2") and the magnitude was estimated to be around 20.0, assuming R mags for the reference stars from UCAC-4. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16793 SUBJECT: GRB140907A: MITSuME Okayama Optical Observation DATE: 14/09/08 00:47:19 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 the MITSuME and OISTER collaboration: We observed the field of GRB 140907A (Krimm et al., GCNC 16788) 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 2014-09-07 16:21:50 UT (~15 min after the burst). We detected the previously reported afterglow (Xu et al., GCNC 16789; Kuin and Krimm, GCNC 16791) in all the three bands. Photometric results of the OT are listed below. We used GSC 2.3 catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' g'_err Rc Rc_err Ic Ic_err ----------------------------------------------------------------------- 0.01381 16:27:01 540.0 18.2 0.2 17.2 0.1 16.6 0.1 ------------------------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16795 SUBJECT: GRB 140907A: Enhanced Swift-XRT position DATE: 14/09/08 01:03:06 GMT FROM: Phil Evans at U of Leicester M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 2873 s of XRT Photon Counting mode data and 7 UVOT images for GRB 140907A, 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 = 48.14575, +46.60472 which is equivalent to: RA (J2000): 03h 12m 34.98s Dec (J2000): +46d 36' 17.0" with an uncertainty of 1.4 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: 16796 SUBJECT: GRB 140907A: Swift-XRT refined Analysis DATE: 14/09/08 07:35:05 GMT FROM: Phil Evans at U of Leicester A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), M.C. Stroh (PSU), D.N. Burrows (PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB) and H.A. Krimm report on behalf of the Swift-XRT team: We have analysed 8.8 ks of XRT data for GRB 140907A (Krimm et al. GCN Circ. 16788), from 73 s to 40.5 ks after the BAT trigger. The data comprise 89 s in Windowed Timing (WT) mode (the first 9 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 Goad et al. (GCN Circ. 16795). The light curve can be modelled with an initial power-law decay with an index of alpha=3.1 (+0.8, -0.7), followed by a break at T+119 s to an alpha of 0.822 (+0.023, -0.025). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.01 (+0.14, -0.13). The best-fitting absorption column is 3.8 (+0.7, -0.6) x 10^21 cm^-2, in excess of the Galactic value of 3.1 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.9 x 10^-11 (6.0 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 3.8 (+0.7, -0.6) x 10^21 cm^-2 Galactic foreground: 3.1 x 10^21 cm^-2 Excess significance: 1.9 sigma Photon index: 2.01 (+0.14, -0.13) If the light curve continues to decay with a power-law decay index of 0.822, the count rate at T+24 hours will be 0.024 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.1 x 10^-13 (1.4 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00611933. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16797 SUBJECT: GRB 140907A: redshift from the 10.4m GTC telescope DATE: 14/09/08 08:01:07 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia A.J. Castro-Tirado (IAA-CSIC/ISA-UMA), J. Gorosabel (IAA-CSIC/UPV-EHU) and A. Garcia-Rodriguez (GTC-IAC), report on behalf of a larger collaboration: We observed the optical afterglow of GRB 140907A (Krimm et al. GCN 16788; Kuin et al. GCN 16791; Masi et al. GCN 16792, Kuroda et al. GCN 16793) with the 10.4m GTC (+OSIRIS). Spectroscopic observations started at 05:29:33 UT (13.4 hours post GRB). Two 500s spectra were obtained with the R1000B and R1000R grisms, covering the range between 3800 and 9900 A, at a resolution of ~1000. A preliminary reduction based on archival calibration lamps, reveals the Mg II doublet plus several Fe II lines at a common redshift of z = 1.21, which we identify as the redshift of the GRB. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16798 SUBJECT: GRB 140907A: Fermi GBM Detection DATE: 14/09/08 15:32:05 GMT FROM: Binbin Zhang at UAH Bin-Bin Zhang (UAH) reports on behalf of the Fermi GBM Team: "At 16:07:11.80 UT on 07 September 2014, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 140907A (trigger 431798834 / 140907672), which was also detected by the Swift/BAT (Krimm et al 2014, GCN 16788) The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 16 degrees. The GBM light curve consists of a single pulse with multiple peaks. The total duration (T90) is about 35 +/- 10 s (50-300 keV). The time-averaged spectrum from T0-12 s to T0+22 s is best fit by a power law function with an exponential high-energy cutoff.  The power law index is -0.97 +/- 0.08  and the cutoff energy, parameterized as Epeak, is 113 +/- 7 keV. The event fluence (10-1000 keV) in this time interval is (5.5 +/- 0.2)E-06 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+8.9 s in the 10-1000 keV band is 4.2 +/- 0.3  ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16799 SUBJECT: GRB 140907A: Swift-BAT refined analysis DATE: 14/09/08 16:12:53 GMT FROM: Hans Krimm at NASA-GSFC T. Sakamoto (AGU), 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 (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (LANL) (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 140907A (trigger #611933) (Krimm, et al., GCN Circ. 16788). The BAT ground-calculated position is RA, Dec = 48.133, 46.596 deg which is RA(J2000) = 03h 12m 31.9s Dec(J2000) = +46d 35' 43.8" with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 65%. The mask-weighted light curve shows a single peak with superimposed spikes, running from approximately T-10 to T+40 sec. T90 (15-350 keV) is 79.2 +- 31.4 sec (estimated error including systematics). The time-averaged spectrum from T-91.2 to T+39.9 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.72 +- 0.07. The fluence in the 15-150 keV band is 4.3 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+17.47 sec in the 15-150 keV band is 2.5 +- 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/611933/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16800 SUBJECT: GRB 140907A: T100 observations DATE: 14/09/08 16:49:15 GMT FROM: Eda Sonbas at NASA/GSFC E. Sonbas (Adiyaman Univ.), U. Temiz, H. Avdan (Cukurova Univ.), T. Guver (Istanbul Univ.), E. Gogus (Sabanci Univ.), S. Eryilmaz (TUG), K. Yakut (Ege Univ.), H. Kirbiyik (TUG) report on behalf of a larger collaboration We observed the field of Swift GRB 140907A (Krimm et al., GCN#16788) with the 1.0 meter T100 telescope (Bakirlitepe, TUBITAK National Observatory, Turkey), starting September, 7, 23:54:47 UT (~ 7.794 hours after the trigger). Observations were carried out in the R filter. The afterglow is clearly detected in 300 s in the R band images. Using USNO-B1 star USNO-B1 1366-0072923 (R.A.=48.155, Dec=+46.614) in the field, the magnitude of the OT was estimated as follows; t-t0 (hr) exp.(s) filt mag err (+/-) 7.794 300 R 19.65 0.20 We are grateful to TUBITAK National Observatory for prompt scheduling the observations and technical support. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16802 SUBJECT: GRB 140907A: Discovery Channel Telescope observations DATE: 14/09/09 03:26:20 GMT FROM: Antonino Cucchiara at NASA/GSFC A. Cucchiara (NASA-GSFC),S.B. Cenko (NASA-GSFC), J. Capone (UMD), V. Toy (UMD), E. Troja (NASA-GSFC), A. Kutyrev (NASA-GSFC), S. Veilleux (UMD), and S. Gezari (UMD) report on behalf of a larger collaboration: "On September 08.37UT (approximately 16.5h after the discovery) we observed the optical counterpart of GRB 140907A (Krimm et al. GCN 16788, Xu et al. GCN 16789, Kuin et al. GCN 16791) with the Large Monolithic Imager (LMI) on the 4.3m Discovery Channel Telescope (DCT) at Happy Jack, AZ. We observed in g', r', and i' bands for a total of 6, 6 and 4 minutes respectively. Using a set of stars from the APASS catalogue we derived the following magnitude for the afterglow: g' = 21.54 +- 0.17 r' = 20.92 +- 0.15 i' = 20.42 +- 0.16 We thank the DCT staff, in particular S. Strosahl and H. Larson for their support in performing these observations." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16803 SUBJECT: GRB 140907A: MITSuME Akeno Optical Observation DATE: 14/09/09 07:25:07 GMT FROM: Taketoshi Yoshii at Tokyo Tech Y. Tachibana, Y. Saito, T. Yoshii, H. Ohuchi, Y. Yano, S. Kurita, Y. Ono, T. Fujiwara, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 140907A (Krimm et al., GCN Circular #16788) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The observation started on 2014-09-07 17:05:39 UT (~1 h after the burst). We detected the previously reported optical afterglow (Xu et al., GCN Circular #16789, Kuin and Krimm, GCN Circular #16791, Kuroda et al., GCN Circular #16793) in the g',Rc and Ic band. The measured magnitudes are listed below. T0+[day] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------------------------------ 0.04064 17:09:16 360 19.2+/-0.2 18.2+/-0.2 17.3+/-0.1 0.07348 18:07:29 300 >19.2 >18.3 >17.7 ------------------------------------------------------------------------------ T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used GSC2.3 catalog for flux calibration. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16804 SUBJECT: GRB 140907A: Nishi-Harima NIR Observations DATE: 14/09/09 07:55:31 GMT FROM: Akira Arai at Nishi-Harima Astro. Obs/U of Hyogo J. Takahashi, A. Arai, S. Honda, Y. Takagi, K. Morihana (Univ. of Hyogo) report on behalf of Nayuta team and OISTER collaboration: We observed the field of GRB 140907A (H. A. Krimm et al., GCN 16788) with Nishiharima Infrared Camera (NIC) attached to the Nayuta 2-m telescope at the Nishi-Harima Astronomical Observatory. The observations were started at 19:00 UT on 2014-09-07. We detected the near-infrared afterglow in J, H and Ks bands. Photometric results of our observations are shown below. We used 2MASS 03123451+4635419, 03123283+4635411, and 03123016+4635375 as reference stars for photometry. # MID-UT Tmid-T0 T-EXP J_mag H_mag Ks_mag ----------------------------------------------------------------------- 19:07:32 3.0 600 17.5 +/- 0.2 17.0 +/- 0.1 16.6 +/- 0.3 ------------------------------------------------------------------------ Tmid-T0: Elapsed time after the burst (hours) T-EXP: Total Exposure time (seconds) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16806 SUBJECT: GRB 140907A: MASTER optical observations DATE: 14/09/09 13:03:53 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V. Lipunov, M.Pruzhinskaya, V.Kornilov, D.Kuvshinov, N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, D.Denisenko, A.Sankovich Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov, A. Gabovich Blagoveschensk Educational State University, Blagoveschensk K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University V.Krushinski, I.Zalozhnih, A. Popov Ural Federal University, Kourovka A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) Claudio Mallamaci, Carlos Lopez and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA) MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Blagoveschensk was pointed to the GRB140907A 6987 sec after notice time and 7504 sec after trigger time at 2014-09-07 18:12:13 UT directly after weather conditions became suitable. On our first (180s exposure) set we found optical transient within Swift error-box (ra=03 12 34 dec=+46 36 18 r=0.050000) on coadditional images in two epoch. The protometry results available at Table 1. Table 1. Date and Time start T_trig-Tmid Exptime Mag err.mag 2014-09-07 18:12:13.4 7809 540 19.0 0.2 2014-09-07 19:23:43.6 12547 1260 19.4 0.2 The approximate power law index (alpha) from 7000 to 13000 seconds after the trigger is about 0.81 +- 0.1 (F ~ t^-alpha). Another two MASTER-II robotic telescop located in Kislovodsk and Tunka made upper limit observations only in earlier time due to weather conditions and high zenith distance of object. MASTER II in Tunka was pointed to the GRB140907A 1021 sec after trigger time at 2014-09-07 16:24:10 directly after weather conditions became suitable. On our first (180s exposure) image we haven`t found optical transient up to 16m. MASTER II in Kislovodsk starting observations GRB140907A 17 sec after notice time and 77 sec after trigger time at 2014-09-07 16:08:25 using FERMI GBM coordinates. However OT position was not covered by MASTER-II. The telescope pointing by Swift trigger 22 sec after notice time and 540 after trigger time at 2014-09-07 16:16:08. On first (110s exposure) image we haven`t found optical transient up to 12.5 m. The zenith distance of object z~85 d. Our white (clear) band is well described by a parity 0.8R+0.2B (USNO B1). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16809 SUBJECT: GRB 140907A: TShAO observations DATE: 14/09/09 20:54:38 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (IKI), A. Pozanenko (IKI), W. Mundrzyjewski (Fesenkov Astrophysical Institute), V. Tereshenko (Fesenkov Astrophysical Institute) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 140907A (Krimm et al., GCN 16788)with Zeiss-1000 (East) telescope of Tien Shan Astronomical Observatory starting on Sep. 07, (UT) 17:05. We took several images in R-filter. Within enhanced XRT error circle (Goadet al., GCN 16795) we clearly detect the afterglow(Xu et al., GCN 16789; Kuin and Krimm, GCN 16791). Preliminary photometry of first and last exposures is following Date UT start t-T0,d Exp,s Filter OT OT_err (mid) 2014-09-07 17:33:41 0.06357 600 R 18.94 0.08 2014-09-07 23:22:46 0.30598 600 R 20.22 0.07 The photometry is based on nearby USNO-B1.0 stars, R2 magnitudes. Preliminary light curve of the afterglow of GRB 140907A obtained between (UT) 17:33:41 and 23:22:46 can be found in http://grb.rssi.ru/GRB140907A/GRB14907A_lc.png . Within the time interval ( 17:33:41 - 23:22:46 ) the LC might be approximated by power law with a power law index ~-2 which could suggest the jet-brake within this interval. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16810 SUBJECT: GRB 140907A: 1.23m CAHA optical observations DATE: 14/09/10 00:32:37 GMT FROM: Javier Gorosabel at IAA-CSIC J. Ugarte (UPV-EHU), S. Perez-Hoyos (UPV-EHU), A. Sanchez-Lavega (UPV-EHU), R. Hueso (UPV-EHU), J. Gorosabel (IAA-CSIC/UPV-EHU) report on behalf of the BEGIRA project: We observed the GRB 140907A (GCN 16788) optical afterglow (GCN 16789, GCN 16791, GCN 16792, GCN 16793, GCN 16797, GCN 16800, GCN 16802, GCN 16803, GCN 16804, GCN 16806, GCN 16809) with the 1.23m CAHA telescope. The observations were carried out in the R and I-bands on Sep 8.96168-9.21435 UT (30.96-37.05 hours post GRB). The optical afterglow is clearly detected with a magnitude I(Vega)=21.4, calibrated against the USNO B1.0 catalog. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16814 SUBJECT: GRB 140907A: Mondy optical observations DATE: 14/09/11 16:53:02 GMT FROM: Alexei Pozanenko at IKI, Moscow 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 140907A (Krimm et al., GCN 16788) with with AZT-33IK telescope of Sayan observatory (Mondy). We obtained several images on Sep., 08 and Sep. 9. Within enhanced XRT error circle (Goadet al., GCN 16795) we clearly detect the afterglow (Xu et al., GCN 16789; Kuin and Krimm, GCN 16791). Preliminary photometry is following: date UT start t-T0 Filter Exp. OT OT_err (mid, days) (s) 2014-09-08 15:38:52 1.00888 R 82*60 21.26 0.08 2014-09-09 14:35:11 1.97786 R 120*60 22.50 0.20 The photometry is based on the same USNO-B1.0 stars which were used in GCN 16809: ID RA Dec R2 1366-0072961 03:12:42.62 +46:36:01.4 15.84 1365-0072251 03:12:34.50 +46:35:42.0 14.55 1365-0072223 03:12:30.14 +46:35:37.7 15.57 The light curve can be found in http://grb.rssi.ru/GRB140907A/GRB14907A_lc1.png //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16818 SUBJECT: GRB 140907A: Continued DCT Observations DATE: 14/09/13 15:49:21 GMT FROM: S. Bradley Cenko at NASA/GSFC S. B. Cenko, A. Cucchiara (NASA-GSFC), J. Capone, V. Toy (UMD), E. Troja, A. Kutyrev (NASA-GSFC), S. Veilleux, and S. Gezari (UMD) report on behalf of a larger collaboration: We re-observed the field of the Swift GRB 140907A (Krimm et al., GCN 16788) with the Large Monolithic Imager on the 4.3m Discovery Channel Telescope (DCT). Observations were obtained in the r' filter beginning at 11:28 UT on 2014 Sep 10 (~ 2.8 d after the Swift trigger) for a total exposure time of 720 s. Using nearby point sources from the APASS catalog for calibration, we measure a magnitude of r' = 22.79 +/- 0.07 mag for the optical afterglow (Xu et al., GCN 16789; Kuin et al., GCN 16791). Compared with our previous epoch of DCT imaging, we infer a corresponding power-law decay index of alpha = 1.2 +/- 0.1.