//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20575 SUBJECT: GRB 170202A: Swift detection of a burst with an optical afterglow DATE: 17/02/02 18:53:46 GMT FROM: Scott Barthelmy at NASA/GSFC J. L. Racusin (NASA/GSFC), S. D. Barthelmy (GSFC), S. B. Cenko (GSFC), A. Cholden-Brown (PSU), J. A. Kennea (PSU), H. A. Krimm (CRESST/NSF/USRA), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 18:28:02 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170202A (trigger=736407). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 152.529, +5.002 which is RA(J2000) = 10h 10m 07s Dec(J2000) = +05d 00' 06" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows 4 main peaks with a total duration of about 40 sec. The peak count rate was ~4800 counts/sec (15-350 keV), at ~16 sec after the trigger. The XRT began observing the field at 18:29:14.8 UT, 72.5 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 152.51422, 5.01213 which is equivalent to: RA(J2000) = 10h 10m 03.41s Dec(J2000) = +05d 00' 43.7" with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 64 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. We cannot determine whether the source is fading at the present time. No spectrum from the promptly downlinked event data is yet available to determine the column density. The initial flux in the 2.5 s image was 2.21e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 83 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 10:10:03.49 = 152.51455 DEC(J2000) = +05:00:41.8 = 5.01161 with a 90%-confidence error radius of about 0.75 arc sec. This position is 0.5 arc sec. from the center of the XRT error circle. The estimated magnitude is 18.46 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02. Burst Advocate for this burst is J. L. Racusin (judith.racusin 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: 20576 SUBJECT: GRB 170202A : Xinglong TNT optical observation DATE: 17/02/02 20:09:09 GMT FROM: L.P. Xin at NAOC L. P. Xin, W. X, Li, J. Y. Wei, Y. L. Qiu, J. S. Deng, J. Wang, X. H. Han, C. Wu and H. L. Li report: We observed GRB 170202A (Racusin et al. GCN 20575) with Xinglong 0.8-m TNT telescope at 18:29:00 UT, 58 sec after the burst. The optical afterglow (Racusin et al. GCN 20575 ) was detected in our white and R-band images, with a coordinate of RA=10:10:03.48 DEC=05:00:42.29 Epoch=J2000 Which is consistent with report by UVOT detection ( Racusin et al. GCN 20575). The brightness of the optical afterglow is about 18.9 mag at the mid time of 69 sec afer the burst, calibrated by the USNO B1.0 star (RA=10:10:03.29 DEC=04:59:37.4 R2=14.95mag). The observations are continuous. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20577 SUBJECT: GRB 170202A: Mini-MegaTORTORA upper limits DATE: 17/02/02 20:42:54 GMT FROM: Sergey Karpov at SAO RAS S.Karpov, G.Beskin (SAO RAS and Kazan Federal University, Russia), S.Bondar, E.Ivanov, E.Katkova, N.Orekhova, A.Perkov (OJS RPC PSI, Russia), A.Biryukov (SAI MSU and Kazan Federal University, Russia), V.Sasyuk (Kazan Federal University, Russia) Mini-MegaTORTORA nine-channel wide-field monitoring system with high temporal resolution responded to the BAT trigger and observed the position of GRB 170702A (Racusin et al. GCN 20575) since 2017-02-02 18:28:50 UT (T+47.8 s) and until 2017-02-02 18:39:04 UT (T + 662.0 s). The system acquired a series of 5 s exposure frames with all 9 channels pointed to the object location in white light, with and without polarimetric filters installed. No transient object is detected over this interval, with detection limit on a single frame V=13.0 mag. Co-adding 9 simultaneous frames improves the detection limit to V=14.0 mag at the mid-time of first exposure (Tmid = T+50.3 s, 5 s exposure). Mini-MegaTORTORA belongs to Kazan Federal University and is located at Special Astrophysical Observatory near Russian 6-m telescope. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20578 SUBJECT: GRB 170202A: MASTGlobal ER-Net bright OT nonmonotonic light curve DATE: 17/02/02 21:28:25 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, N.Tyurina, E. Gorbovskoy, V.V.Kornilov, D.Kuvshinov, P.Balanutsa, A.Kuznetsov, V.V.Chazo, A.V.Krylov, I.Gorbunov Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University V.Yurkov, A. Gabovich, Yu.Sergienko Blagoveschensk Educational State University, Blagoveschensk A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Senik Kislovodsk Solar Station of the Pulkovo Observatory K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk, O. Ershova Irkutsk State University R. Podesta, Carlos Lopez and Federico Podesta Observatorio Astronomico Felix Aguilar (OAFA) Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Blagoveschensk was pointed to the GRB170202.77 37 sec after notice time and 49 sec after trigger time at 2017-02-02 18:28:58 UT. On our first (10s exposure) set we found 1 optical transient within SWIFT error-box (ra=152.525 dec=5.00139 r=0.05) brighter then 16.5 RA, DEC = 10h 10m 03s.5 , + 5d 0m 41s.8 Mag = 16.2 MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Tunka was pointed to the GRB170202.77 69 sec after notice time and 85 sec after trigger time at 2017-02-02 18:29:33 UT. On our first (20s exposure) set we found optical transient within SWIFT error-box (ra=152.525 dec=5.00111 r=0.05) brighter then 17.8. MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in SAAO was pointed to the GRB170202.77 4070 sec after notice time and 4082 sec after trigger time at 2017-02-02 19:36:11 UT. On our 18-th (180s exposure) set we found optical transient within SWIFT error-box (ra=152.525 dec=5.00111 r=0.05) brighter then 17.00. MASTER-Amur light curve is available at http://master.sai.msu.ru/static/OT/MASTERGRB170202A.jpg //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20579 SUBJECT: GRB 170202A: LCO Sutherland observations DATE: 17/02/02 22:32:33 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi (U. Ferrara), S. Kobayashi, I.A. Steele (LJMU), A. Gomboc (U. Nova Gorica), C.G. Mundell (U. Bath) on behalf of a large collaboration report: We observed Swift GRB 170202A (Racusin et al. GCN 20575) on February 02, from 21:19 UT (2.8 hours since the GRB) with 1-m LCO telescope units in Sutherland with SDSS r and i filters. We detect the optical afterglow (Racusin et al. GCN 20575; Xi et al. GCN 20576; Lipunov et al. GCN 20578) at the Swift-UVOT position with the following values: Mid Time Exposure Filter Magnitude (AB) (hours) (s) ------------------------------------------------------- 2.9 4x120 SDSS-R 19.65 +- 0.15 3.0 4x120 SDSS-I 19.32 +- 0.18 ------------------------------------------------------- as calibrated against nearby SDSS sources. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20580 SUBJECT: GRB 170202A: Zadko observatory - Gingin optical observations DATE: 17/02/02 22:55:17 GMT FROM: Alain Klotz at IRAP-CNRS-OMP A. Klotz, D. Turpin (IRAP-CNRS-OMP), D. Macpherson (UWA/ICRAR), D. Coward (UWA), M. Boer, R. Laugier (UNS-CNRS-OCA), Gendre B. (UVI - Etelman Obs.), A. Williams (PO-UWA), R. Martin (PO-UWA) report: We imaged the field of GRB 170202A detected by SWIFT (trigger 736407) with the Zadko robotic telescope (D=100cm) located at the observatory - Gingin, Australia. The observations started 58s after the GRB trigger (42s after the notice). The elevation of the field decreased from 51 degrees above horizon and weather conditions were very good. The first image is trailed with a duration of 60.0s (see the description in Klotz et al., 2006, A&A 451, L39). We detect the optical transcient described by Racusin et al. (GCNC 20575), Xin et al. (GCNC 20576) and Lipunov et al. (GCNC 20578). We calibrated magnitudes using the same reference star than Xin et al. (GCNC 20576). The afterglow increases slowly and continuously from 73s (i.e. the limiting magnitude R~19) until 400s (R=16.5). After 550s the flux start to decrease with a standard temporal decay alpha=-1 until 5000s (R=19). Extrapolation with this rate gives R=22.3 at t0+1day. So we encourage to perform spectrometry. N.B. Zadko Magnitudes are not corrected for galactic dust extinction. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20581 SUBJECT: GRB 170202A: Kanata optical and infrared observations DATE: 17/02/02 23:12:08 GMT FROM: Michitoshi Yoshida at HASC,Hiroshima U Mori, H., Nakaoka, T., Kawabata, M., Hirochi, J., Kawahara, N., Yoshida, M., Kawabata, K. and Uemura, M. (Hiroshima Univ.) on behalf of the OISTER collaboration We performed R-band and Ks-band imaging observations around the error circle of GRB 170202A (Racusin et al., GCN 20575) with the optical imager HOWPol and opt-NIR imager HONIR attached to Kanata telescope of Hiroshima University. The observations took place at 2017-02-02 18:33:37 UT (mid time of the observation). We detected the optical transient reported by Xin et al.(GCN 20576), Lipunov et al. (GCN 20578) and Guidorzi et al. (GCN 20579) in our R-band and Ks-band images. The detected magnitude of the OT and five sigma upper limit (in Vega magnitude) of the observations are listed below. # T0+ MID-UT T-EXP R mag. R err R limit ----------------------------------------------------- 335 18:33:37 30 16.35 0.3 18.0 ----------------------------------------------------- # T0+ MID-UT T-EXP Ks mag. Ks err Ks limit ----------------------------------------------------- 3208 19:21:30 1320 17.1 0.4 18.6 ----------------------------------------------------- T0+ : Elapsed time after the burst [sec] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20582 SUBJECT: GRB 170202A: NOT afterglow observations DATE: 17/02/02 23:31:00 GMT FROM: Thomas Kruehler at MPE Garching T. Kruehler (MPE Garching), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), and Pasi J. Hakala (FINCA) report on behalf of the Nordic GRB collaboration: We observed the field of GRB 170202A (Racusin et al. GCN 20575) with the NOT equipped with ALFOSC. Photometry in the r and i-band filter started at 22:46 UTC on 2017-02-02, 4.3 hr after the GRB trigger. Calibrating our images against magnitudes of field stars from the SDSS catalog, we measure a preliminary brightness of the optical afterglow (Racusin et al. GCN 20575, Xin et al. GCN 20576, Lipunov et al. GCN 20578, Guidorzi et al. GCN 20579, Klotz et al. GCN 20580, Mori et al. GCN 20581) of r = 20.1 +- 0.1 mag. This magnitude is not corrected for the expected foreground extinction corresponding to a reddening of E_B-V = 0.02 mag (Schlafly & Finkbeiner 2011). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20584 SUBJECT: GRB 170202A: Redshift from OSIRIS/GTC DATE: 17/02/03 00:22:15 GMT FROM: Antonio de Ugarte Postigo at IAA-CSIC A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), L. Izzo (IAA-CSIC), C. Thoene (IAA-CSIC), D.A. Kann (IAA-CSIC, TLS), P. Pessev (GRANTECAN, IAC, ULL), A. Perez (GRANTECAN) report on behalf of a larger collaboration: We observed the afterglow of GRB 170202A (Racusin et al. GCN 20575) using OSIRIS at the 10.4m GTC telescope at the Roque de los Muchachos observatory (La Palma, Spain). The observation started at 23:22 UT (4.91 hr after the burst) and included observations with grisms R1000B and R1000R covering the ranges 3700 - 7800 AA and 5100 - 9300 AA respectively. The blue spectra shows a strong signal with multiple features being especially significant Lyman-alpha (both in absorption and emission), the full Ly-forest, NV, SII, SiII, SiII*, OI, CII, SiIV, CIV and AlII at a common redshift of 3.645, which we identify as the redshift of the GRB. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20585 SUBJECT: GRB 170202A: MITSuME Akeno Optical Observation DATE: 17/02/03 00:47:37 GMT FROM: Yutaro Tachibana at Tokyo Tech Y. Saito, R. Itoh, Y. Tachibana, K. Morita, Y. T. Yoshii, H. Ohuchi, Y. Yano, Y. Ono, T. Fujiwara, S. Harita, Y. Muraki, K. Saisho, Y. Ozawa, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We searched for the optical counterpart of GRB 1710202A (J. L. Racusin et al., GCN Circular #20575) 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 2017-02-02 18:28:41 UT (39 sec after the burst). We detected the optical counterpart (J. L. Racusin et al., GCN Circular #20575 ) in g', Rc and Ic band. The measured magnitudes were listed as follows. T0+[sec] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------------------------------------------------------- 54 18:28:56 30 >18.4 >17.7 >17.0 92 18:29:34 30 >19.1 17.01 +/- 0.12 17.08 +/- 0.25 131 18:30:13 30 17.61 +/- 0.13 16.38 +/- 0.09 15.89 +/- 0.12 ------------------------------------------------------------------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used GSC2.3 catalog for flux calibration. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20586 SUBJECT: GRB 170202A: Enhanced Swift-XRT position DATE: 17/02/03 04:26:17 GMT FROM: Phil Evans at U of Leicester J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 2000 s of XRT Photon Counting mode data and 4 UVOT images for GRB 170202A, 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 = 152.51441, +5.01136 which is equivalent to: RA (J2000): 10h 10m 3.46s Dec (J2000): +05d 00' 40.9" 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: 20587 SUBJECT: GRB 170202A: Swift/UVOT Detection DATE: 17/02/03 05:18:40 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) and J. L. Racusin (NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 170202A 84 s after the BAT trigger (Racusin et al., GCN Circ. 20575). A source consistent with the enhanced XRT position (Osborne et al., GCN 20586) and is detected in the initial UVOT exposures. No detection in the U and UV filters is consistent with the reported redshift (de Ugarte Postigo et al, GCN Circ. 20584). The preliminary UVOT position is: RA (J2000) = 10:10:03.49 = 152.51454 (deg.) Dec (J2000) = +05:00:41.8 = 5.01161 (deg.) with an estimated uncertainty of 0.44 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 84 233 147 18.31 +/- 0.05 v 625 1419 97 18.27 +/- 0.20 b 551 1345 78 19.18 +/- 0.19 u 295 1837 363 >21.1 w1 675 1812 136 >19.6 w2 1030 1050 19 >19.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20588 SUBJECT: GRB 170202A: Xinglong 2.16m photometry and spectroscopic redshift DATE: 17/02/03 07:31:00 GMT FROM: Dong Xu at NAOC/CAS D. Xu (NAOC), Y. Qin (Geneva Observatory), Y.D. Hu (IAA-CSIC), H.J. Wang, H. Wu, M. He, H.X. Feng, Z.P. Zhu (NAOC) report: We observed the optical afterglow of GRB 170202A (Racusin et al., GCN 20575) using the 2.16-m telescope at Xinglong, Hebei, China, equipped with the BFOSC camera. The observation started at 18:59:32 UT on 2017-02-02 (i.e., 31.5 mins after the BAT trigger), 4x120s R-band photometry was obtained, followed by 1x3600s spectroscopy using the G4+385LP grism setting, covering the wavelength of ~3600 - 8500 AA. The optical afterglow has m(R)~18.0 mag from the first R-band exposure, calibrated with the nearby SDSS stars. Preliminary analysis shows that the spectrum is featured by a prominent Lyman_alpha trough, a Lyman forest blue to the trough, together with Si IV, C IV and other potential absorption lines red to the trough, all at a common redshift of z = 3.65. This redshift value is consistent with measurement in de Ugarte Postigo et al. (GCN 20584). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20590 SUBJECT: GRB 170202A VLT/X-shooter redshift [minor correction] DATE: 17/02/03 09:55:04 GMT FROM: Jesse Palmerio at IAP J. Palmerio (Univ. Paris VI, IAP), T. Kruehler (MPE Garching), D. Xu (NAOC,CAS), D. Malesani, J. P. U. Fynbo (DARK/NBI) report on behalf of a larger collaboration: We observed the optical afterglow of GRB 170202A (Racusin et al. GCN 20575) with the ESO Very Large Telescope UT 2 (Kueyen) equipped with the X-shooter spectrograph, covering the wavelength range 3500-25000 AA. Spectroscopy started at 04:10:05 UT on 2017-02-03 (i.e., 9.7 hr after the GRB) and consisted of 4 exposures of 600 s each. The spectrum exhibits several absorption features such as Lya, CIV, SiIV, FeII, SiII, MgII as well as the [OIII]5007 emission line, all at a common redshift of z=3.645, consistent with A. de Ugarte Postigo et al. (GCN 20584) and D. Xu et al. (GCN 20588). We conclude this is the redshift of the GRB. We acknowledge the excellent support from the ESO staff, particularly Fernando J. Selman, A. Mehner in obtaining these observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20591 SUBJECT: GRB 170202A: T100 observations DATE: 17/02/03 10:29:03 GMT FROM: Eda Sonbas at NASA/GSFC E. Sonbas (Adiyaman Univ.), T. Guver, M. De Pasquale (Istanbul Univ.), E. Gogus (Sabanci Univ.), O. Erece, M. Kocak, H. Kirbiyik, H. Esenoglu (TUG) report on behalf of a larger collaboration We observed the field of Swift GRB 170202A (Racusin et al., GCN#20575) with the 1.0 meter T100 telescope (Bakirlitepe, TUBITAK National Observatory, Turkey), starting February, 2, 20:12:45.56 UT (~ 1.7 hours after the trigger). Observations were carried out in the R filter. The afterglow is detected in the R band images with an exposure time of 300 s. Using USNO-B1 stars USNO-B1 0950-0184329 (R.A.=152.492, Dec=+5.028) and USNO-B1 0949-0181744 (R.A.=152.514, Dec=+4.993) in the field, the magnitude of the OT was estimated as follows; t-t0 (hr) exp.(s) filt mag err (+/-) 1.75 300 R 18.98 0.07 Analysis of further observations with the same filter is ongoing. We thank to TUBITAK National Observatory for a partial support in using T100 telescope with project number 10CT100-95 and technical support. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20592 SUBJECT: GRB 170202A: Swift-XRT refined Analysis DATE: 17/02/03 11:12:09 GMT FROM: Phil Evans at U of Leicester P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), D.N. Burrows (PSU), A. Cholden-Brown (PSU), S. J. LaPorte (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), S.L. Gibson (U. Leicester), A. D'Ai (INAF-IASFPA) and J.L. Racusin report on behalf of the Swift-XRT team: We have analysed 6.7 ks of XRT data for GRB 170202A (Racusin et al. GCN Circ. 20575), from 64 s to 40.8 ks after the BAT trigger. The data comprise 131 s in Windowed Timing (WT) mode (the first 7 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 Osborne et al. (GCN Circ. 20586). The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=2.9 (+3.3, -0.6). At T+84.5 s the decay flattens to an alpha of -1.5 (+0.0, -2.0). The light curve breaks again at T+95.5 s to a decay with alpha=3.15 (+0.19, -0.17), and again at T+314 s s to alpha=0.01 (+0.17, -0.18), before a final break at T+2223 s s after which the decay index is 1.08 (+0.12, -0.17). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.94 (+0.09, -0.08). The best-fitting absorption column is 3.7 (+6.4, -3.7) x 10^21 cm^-2, at a redshift of 3.645, in addition to the Galactic value of 2.0 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.00 (+0.13, -0.12) and a best-fitting absorption column of 5.2 (+8.8, -5.2) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.2 x 10^-11 (3.5 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Galactic foreground: 2.0 x 10^20 cm^-2 Intrinsic column: 5.2 (+8.8, -5.2) x 10^21 cm^-2 at z=3.645 Photon index: 2.00 (+0.13, -0.12) If the light curve continues to decay with a power-law decay index of 1.08, the count rate at T+24 hours will be 0.018 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.9 x 10^-13 (6.4 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/00736407. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20593 SUBJECT: GRB 170202A: LCO FTN observations DATE: 17/02/03 11:36:23 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi (U. Ferrara), S. Kobayashi, I.A. Steele (LJMU), A. Gomboc (U. Nova Gorica), C.G. Mundell (U. Bath) on behalf of a large collaboration report: We observed Swift GRB 170202A (Racusin et al. GCN 20575) on February 03, from 10:30 to 10:40 UT (16 hours since the GRB) with the 2-m LCO FTN in Hawaii with SDSS r and i filters. We detect the optical afterglow with the following values: Mid Time Exposure Filter Magnitude (AB) (hours) (s) ------------------------------------------------------- 16.1 2x120 SDSS-R 21.10 +- 0.15 16.2 2x120 SDSS-I 20.94 +- 0.19 ------------------------------------------------------- as calibrated against nearby SDSS sources. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20594 SUBJECT: GRB 170202A: SQUEAN Observation DATE: 17/02/03 13:25:13 GMT FROM: Myungshin Im at Seoul Nat U Myungshin Im, Yongjung Kim, & Joonho Kim (CEOU/SNU) We observed the field of GRB 170202A (Racusin et al., GCN 20575) using the SQUEAN instrument on the 2.1m Otto Struve telescope at the McDonald Observatory, Texas. The observation started at 2017-02-03 10:26:26 UT, ​ ​ or about 16 hours after the BAT alert. We identify the afterglow at the location of the reported GRB position, with the following preliminary results based on the photometry calibration using SDSS stars in the vicinity. Filter Mag (AB) Mag_err Exp.time Start-time (UT) ​ r 21.1 0.08 180s x 3 10:26:26.6​ i 20.6 0.06 180s x 3 10:36:20.7 z 20.5 0.10 180s x 3 10:47:15.6 Further observations are planned. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20595 SUBJECT: GRB 170202A: RATIR Optical and NIR Observations DATE: 17/02/03 16:56:06 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), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report: We observed the field of GRB 170202A (Racusin, et al., GCN 20575) 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 2017/02 3.18 to 2017/02 3.57 UTC (9.92 to 19.17 hours after the BAT trigger), obtaining a total of 3.98 hours exposure in the r and i bands and 1.68 hours exposure in the Z and Y bands. For a source within the Swift-XRT error circle (Osborne, et al., GCN 20586), in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following detections: r = 20.68 +/- 0.01 i = 20.83 +/- 0.02 Z = 20.84 +/- 0.07 Y = 20.50 +/- 0.06 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20596 SUBJECT: GRB 170202A: Swift-BAT refined analysis DATE: 17/02/03 17:28:41 GMT FROM: Hans Krimm at NSF/NASA-GSFC S. D. Barthelmy (GSFC), J. R. Cummings (CPI), N. Gehrels (GSFC), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), J. L. Racusin (NASA/GSFC), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 170202A (trigger #736407) (Racusin, et al., GCN Circ. 20575). The BAT ground-calculated position is RA, Dec = 152.526, 5.021 deg which is RA(J2000) = 10h 10m 06.3s Dec(J2000) = +05d 01' 15.7" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 50%. The mask-weighted light curve shows a multi-peaked structure. The first peak starts at T+0 sec, peaks at T+3 sec and decays to near background by T+15 sec, at which time the second, larger peak begins. This structure peaks at T+17 sec, and the third overlapping peak has a maximum at T+21 sec, and decays to near background by T+50 sec, with some low-level emission extending out to T+80 sec. T90 (15-350 keV) is 46.2 +- 11.5 sec (estimated error including systematics). The time-averaged spectrum from T+0.25 to T+76.46 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.68 +- 0.07. The fluence in the 15-150 keV band is 3.3 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+16.04 sec in the 15-150 keV band is 4.7 +- 0.3 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/736407/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20598 SUBJECT: GRB 170202A: Etelman Observatory optical observations DATE: 17/02/03 22:24:51 GMT FROM: Bruce Gendre at ASDC B. Gendre (UVI), N. Orange (OrangeWave Innovative Science, LLC), D. Morris (UVI), A. Cucchiara (UVI), D. Drost (UVI), T. Giblin (USAF Academy), J. Hakkila (College of Charleston), A. Klotz (IRAP), J. Neff (NSF), D. Smith (UVI), J. Staff (UVI), P. Thierry (Auragne Observatory), R. Watlington (UVI), and L. Wentlent (UVI) report: We observed the field of GRB 170202A (Racusin et al. GCN 20575) with the 0.5m Virgin Island Robotic Telescope (VIRT) on February the 3rd, starting at 3:16 UT (8.8 hours after the trigger), until 10:30 UT. We performed a series of exposures in the clear filter. The weather conditions were variable with a typical estimated seeing of 2". We detected the afterglow observed by UVOT (Racusin et al., GCN 20575) on a combined image (spanning times from 10h to 11.92h after the trigger). Its magnitude, estimated by comparison to nearby USNO-B1 stars, was R = 20.8 +/- 0.3. Further analysis is in progress. Magnitudes have not been corrected for Galactic extinction. The VIRT is still in its commissioning phase. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20599 SUBJECT: GRB 170202A: Zadko observatory - Gingin optical observations DATE: 17/02/03 22:58:08 GMT FROM: Alain Klotz at IRAP-CNRS-OMP A. Klotz, D. Turpin (IRAP-CNRS-OMP), D. Macpherson (UWA/ICRAR), D. Coward (UWA), M. Boer, R. Laugier (UNS-CNRS-OCA), Gendre B. (UVI - Etelman Obs.), A. Williams (PO-UWA), R. Martin (PO-UWA) report: We continue to image the field of GRB 170202A with the Zadko robotic telescope (D=100cm) located at the observatory - Gingin, Australia (see Klotz et al. GCNC 20580 for early measures). The observations started 19.56h after the GRB trigger and were stopped at t0+22.99h. We stacked 25 images of 180s with no filter. We detect the optical transcient described by Racusin et al. (GCNC 20575), Xin et al. (GCNC 20576) and Lipunov et al. (GCNC 20578). We calibrated magnitudes using the same reference star than Xin et al. (GCNC 20576): t0+19.56h t0+22.99h R=21.8 +/-0.4 Magnitudes are not corrected for galactic dust extinction. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20601 SUBJECT: GRB 170202A: SQUEAN Observation (2nd night) DATE: 17/02/04 11:15:37 GMT FROM: Myungshin Im at Seoul Nat U Myungshin Im, Yongjung Kim, & Joonho Kim (CEOU/SNU) We continued the observation of the GRB 170202A afterglow with the SQUEAN instrument on the 2.1m Otto Struve telescope at the McDonald Observatory, Texas. The 2nd night observation started at 2017-02-04 09:45:52 UT, ​ ​or about 39.3 hours after the BAT alert. The afterglow shows the following preliminary magnitude based on the photometry calibration using SDSS stars in the vicinity. Filter Mag (AB) Mag_err Exp.time Start-time (UT) r 21.8 0.15 180s x 10 09:45:52​ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20604 SUBJECT: Konus-Wind observation of GRB 170202A DATE: 17/02/05 14:32:27 GMT FROM: Dmitry Frederiks at Ioffe Institute D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline, on behalf of the Konus-Wind team, report: The long GRB 170202A (Swift-BAT trigger #736407: Racusin et al., GCN 20575; Barthelmy et al., GCN 20596; T0(BAT)=18:28:02.373 UT) was detected by Konus-Wind (KW) in the waiting mode. The light curve shows a double-peaked with a duration of ~30 s. Modeling the KW 3-channel time-integrated spectrum (from T0(BAT)+0.907 s to T0(BAT)+30.347 s) by a power law with exponential cutoff (CPL) model dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields alpha = -1.16(-0.34,+0.59) and Ep = 247(-86,+166) keV. The energy fluence (20 keV-10 MeV) for this time interval is (5.9 ± 1.4)x10^-6 erg/cm2. Assuming the redshift z=3.645 (de Ugarte Postigo et al., GCN 20584) and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.27, and Omega_Lambda = 0.73, we estimate the burst isotropic energy release E_iso to ~1.7x10^53 erg and the rest-frame peak energy of the time-integrated spectrum, Ep,z, to ~1150 keV. The K-W light curve of this burst is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB170202A/ All the quoted errors are estimated at the 1 sigma confidence level. All the presented results are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20606 SUBJECT: GRB 170202A: SMARTS optical/IR afterglow observations DATE: 17/02/05 16:55:09 GMT FROM: Bethany Cobb at GWU B. E. Cobb (GWU) reports: Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 170202A (GCN 20575, Racusin et al.) at three different epochs: 0.41671 [2017-02-03 04:28 UT], 0.53096 [2017-02-03 07:13 UT] and 2.39175 [2017-02-05 03:52 UT] days post-burst. At each epoch, total summed exposure times amounted to 36 minutes in I and 30 minutes in J. The afterglow of GRB 170202A (e.g. GCN 20575, Racusin et al.; GCN 20576, Xin et al.; GCN 20578, Lipunov et al.) is detected in our early images, with the preliminary magnitudes (and 3-sigma limits) listed below. Note that the optical photometry is calibrated against USNO-B1.0 stars in the field, so suffers from a large photometric calibration error of about +/-0.3 magnitudes, which has not been included in the errors quoted below. The IR photometry is calibrated against the single 2MASS star in our field-of-view, so similarly may include a large (but unknown) calibration error. mid-exposure time (days post-burst) I mag J mag 0.41671 20.1+/-0.1 18.9+/-0.1 0.53096 20.6+/-0.1 >18.5 2.39175 >21.0 >18.6 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20666 SUBJECT: GRB 170202A: 15 GHz upper limits from AMI DATE: 17/02/12 19:20:00 GMT FROM: Kunal Mooley at Oxford U K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender (Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester) The AMI Large Array robotically triggered on the Swift alert for GRB 170202A (Racusin et al., GCN 20575) as part of the 4pisky program, and subsequent follow up observations were obtained up to 10 days post-burst. Our observations at 15 GHz on 2016 Feb 02.87, Feb 04.00, Feb 06.04, Feb 07.01 and Feb 09.00 (UT) do not reveal any radio source at the XRT location (Osborne et al., GCN 20586), with 3sigma upper limits of 451 uJy, 69 uJy, 81 uJy, 352 uJy and 105 uJy respectively. We thank the AMI staff for scheduling these observations. The AMI-GRB database is a log of all GRB follow up observations with the AMI, and is available at http://4pisky.org/ami-grb/.