GRB171020A

This page lists all entries on GRB171020A in GRBweb

Summary IPN Swift GCN 22028 GCN 22029 GCN 22030 GCN 22031 GCN 22032 GCN 22033 GCN 22034 GCN 22035 GCN 22036 GCN 22037 GCN 22038 GCN 22039 GCN 22040 GCN 22041 GCN 22042

Summary table
Variable Value Source
T0 23:07:10 UTC GCN_circulars,Swift Det
ra 39.2484° Swift
decl 15.2041° Swift
pos_error 1.81e-04° Swift
T90 41.9 s Swift
T90_start 23:07:10 UTC Swift
fluence 1.20e-06 erg/cm² Swift
redshift 1.8700 GCN_circulars,Optical
T100 41.9 s
GBM_located False
mjd 58046.96331018519 GCN_circulars,Swift Det
IPN table
GRB_name GRB171020A
ra 39.2625°
decl 15.1833°
pos_error 5.00e-02°
redshift 1.8700
Swift table
GRB_name GRB171020A
t_trigger 23:07:10 UTC
ra 39.2484°
decl 15.2041°
pos_error 1.81e-04°
T90 41.9 s
fluence 1.20e-06 erg/cm²
redshift 1.8700
GCN 22028 table
GRB_name GRB171020A
GCN_number 22028
Detection_method Swift Det
t_trigger 23:07:10 UTC
ra 39.2620°
decl 15.1860°
Circular_text TITLE: GCN CIRCULAR NUMBER: 22028 SUBJECT: GRB 171020A: Swift detection of a burst DATE: 17/10/20 23:28:53 GMT FROM: Kim Page at U.of Leicester K. L. Page (U Leicester), A. P. Beardmore (U Leicester), J.D. Gropp (PSU), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), B. Sbarufatti (PSU) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 23:07:10 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 171020A (trigger=780845). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 39.262, +15.186 which is RA(J2000) = 02h 37m 03s Dec(J2000) = +15d 11' 10" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 50 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~2 sec after the trigger. Note that the BAT light curve might be contaminated by Swift J0243.6+6124, which has a period of 9.86 s (ATel #10809). The XRT began observing the field at 23:09:35.2 UT, 144.4 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 39.2482, 15.2038 which is equivalent to: RA(J2000) = 02h 36m 59.57s Dec(J2000) = +15d 12' 13.5" with an uncertainty of 2.2 arcseconds (radius, 90% containment). This location is 80 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 1.55 x 10^21 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 147 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.19. Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk). 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.)
GCN 22029 table
GRB_name GRB171020A
GCN_number 22029
Detection_method Optical
ra 39.2484°
decl 15.2044°
Circular_text TITLE: GCN CIRCULAR NUMBER: 22029 SUBJECT: GRB 171020A: NOT optical afterglow detection DATE: 17/10/21 00:19:15 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst D. Malesani (DARK/NBI), M. Stone (Turku Univ.), K. Karhunen (Turku Univ.), A. de Ugarte Postigo (IAA/CSIC and DARK/NBI), and D. Xu (NAOC/CAS), report on behalf of a larger collaboration: We observed the field of GRB 171020A (Page et al., GCN 22028) with the Nordic Optical Telescope equipped with the AlFOSC imager and spectrograph. Observations were carried out in the r and z filters, starting on 2017 Oct 20.979 UT (22.9 min after the trigger). Within the XRT error circle, we detect an uncatalogued source at coordinates (J2000): RA = 02:36:59.62 Dec = +15:12:16.0 By comparison with nearby stars from the Pan-STARRS catalog, we measure r = 20.98 +- 0.03 AB. As this object is not visible in the deeper, archival Pan-STARRS images, and given the coincidence with the X-ray counterpart, we suggest this object to be the optical afterglow of GRB 171020A.
GCN 22030 table
GRB_name GRB171020A
GCN_number 22030
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 22030 SUBJECT: GRB 171020A: Mini-MegaTORTORA upper limits on simultaneous optical emission DATE: 17/10/21 00:31:17 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 has been observing the Swift field of view before, during and after the time of Swift BAT trigger corresponding to GRB171020A (Page et al, GCN 22028). The whole burst localization region has been covered since 2017-10-20 23:00:07.90 UT (T0-422 s) and until 2017-10-20 23:10:17.68 UT (T0+187 s, thus including the whole gamma-ray activity interval) with temporal resolution of 0.1 s in white light. Dedicated real-time transient detection pipeline did not detect any events longer than 0.3 s and brighter than approximately V=10.5 mag during this interval. Visual inspection of co-added images with 10 s effective exposure (summation of 100 consecutive frames each) has not revealed any variable source down to V=12.0 mag during that interval. Also, the multi-regime follow-up (when all channels except for the one containing the trigger are repointed towards it and observe it with various exposures with and without photometric and polarimetric filters installed) has been initiated at 2017-10-20 23:08:12.0 UT (T0+61.25 s). The inspection of 10 s exposure frames acquired in white light between 2017-10-20 23:08:12.0 UT (T0+61.25 s) and 2017-10-20 23:09:43 UT (T0+152.25 s) did not reveal any source brighter than V=13.5 mag at the position of the burst. Mini-MegaTORTORA belongs to Kazan Federal University and is located at Special Astrophysical Observatory near Russian 6-m telescope. The message may be cited.
GCN 22031 table
GRB_name GRB171020A
GCN_number 22031
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 22031 SUBJECT: GRB 171020A: Confirmation of OT fading DATE: 17/10/21 03:32:12 GMT FROM: Moskvitin Alexander at SAO RAS A. Moskvitin (SAO RAS), O. Spiridonova (SAO RAS), A. Volnova (IKI RAS) We observed the field of GRB 171020A (Page et al., GCN 22028) with the 1-m telescope of SAO RAS, Zeiss-1000 on 2017.10.20, starting at 23:18 UT, i.e. ~11 minutes after the trigger. The OT (Malesani et al., GCN 22029) is clearly detected in the individual 300 sec. frames. The coordinates of OT: R. A. = 02:36:59.62; Dec. = +15:12:15.6 (J2000). Date UT start t - T0 Filter Exp. OT Err. UL (mid, days) (s) 2017.10.20 23:18:05 0.02016 Rc 6*300 20.9 +/- 0.1 22.3 23:55:27 0.04827 Rc 7*300 21.5 +/- 0.1 22.5 The temporal decay slope is about -0.3, F ~ (t-T0)^alpha. The calibration were made against the nearby USNO-B1.0 stars (R2 magnitudes): 1051-0026883 02:37:00.38 +15:11:09.6 18.59 1052-0027787 02:36:57.49 +15:12:36.8 16.62 1052-0027776 02:36:50.26 +15:12:39.8 18.15
GCN 22032 table
GRB_name GRB171020A
GCN_number 22032
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 22032 SUBJECT: GRB 171020A: Correction of alpha in GCN 22031 DATE: 17/10/21 03:49:17 GMT FROM: Moskvitin Alexander at SAO RAS A. Moskvitin (SAO RAS), O. Spiridonova (SAO RAS), A. Volnova (IKI RAS) In our previous GCN 22031 we reported incorrect slope. The correct decay slope is about -0.6 +/- 0.2. We apologize for any confusion caused by the earlier report.
GCN 22033 table
GRB_name GRB171020A
GCN_number 22033
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 22033 SUBJECT: GRB 171020A: LT observations DATE: 17/10/21 06:30:48 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath), A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU) on behalf of a large collaboration report: The 2-m Liverpool Telescope automatically began observing Swift GRB 171020A (Page et al. GCN 22028) on October 20, 23:10:12 UT (3.0 minutes from the GRB trigger time) with the RINGO3 polarimeter and the IO:O camera in the SDSS-R filter. We clearly detect the optical afterglow (Malesani et al, GCN 22029; Moskvitin et al., GCN 22031) with the following magnitude: Mid Time Exposure Filter Magnitude (AB) (min) (s) ------------------------------------------------------- 35.8 6x10 SDSS-R 21.12 +- 0.14 ------------------------------------------------------- as calibrated against nearby Pan-STARRS objects.
GCN 22034 table
GRB_name GRB171020A
GCN_number 22034
Detection_method Swift-XRT Det
ra 39.2484°
decl 15.2041°
Circular_text TITLE: GCN CIRCULAR NUMBER: 22034 SUBJECT: GRB 171020A: Enhanced Swift-XRT position DATE: 17/10/21 08:10:11 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 5393 s of XRT Photon Counting mode data and 8 UVOT images for GRB 171020A, 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 = 39.24837, +15.20413 which is equivalent to: RA (J2000): 02h 36m 59.61s Dec (J2000): +15d 12' 14.9" with an uncertainty of 1.6 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.
GCN 22035 table
GRB_name GRB171020A
GCN_number 22035
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 22035 SUBJECT: GRB 171020A: Swift-XRT refined Analysis DATE: 17/10/21 10:34:06 GMT FROM: Phil Evans at U of Leicester A. Tohuvavohu (PSU), S. J. LaPorte (PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA) and K.L. Page report on behalf of the Swift-XRT team: We have analysed 7.5 ks of XRT data for GRB 171020A (Page et al. GCN Circ. 22028), from 128 s to 35.4 ks after the BAT trigger. The data comprise 10 s in Windowed Timing (WT) mode (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. 22034). The light curve can be modelled with an initial power-law decay with an index of alpha=2.23 (+0.45, -0.21), followed by a break at T+563 s to an alpha of 0.88 (+0.08, -0.07). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.58 (+0.17, -0.15). The best-fitting absorption column is 1.84 (+0.70, -0.28) x 10^21 cm^-2, consistent with the Galactic value of 1.6 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 4.5 x 10^-11 (5.3 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.84 (+0.70, -0.28) x 10^21 cm^-2 Galactic foreground: 1.6 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 1.58 (+0.17, -0.15) If the light curve continues to decay with a power-law decay index of 0.88, the count rate at T+24 hours will be 5.4 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.4 x 10^-13 (2.9 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/00780845. This circular is an official product of the Swift-XRT team.
GCN 22036 table
GRB_name GRB171020A
GCN_number 22036
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 22036 SUBJECT: R: GRB 171020A: Swift-XRT refined Analysis DATE: 17/10/21 13:00:44 GMT FROM: Remo Rufinni at ICRA again a very energetic one. please see R Prof. Remo Ruffini Director of ICRANet Piazza della Repubblica 10 65122 Pescara (PE) Italy mobile: +39 339 4752566 Tel. Rome +39 06 49914304 Tel. Pescara +39 085 23054201 Fax: +39 085 4219252 e-mail: ruffini@icra.it ________________________________________ Da: GCN Circulars [gcncirc@capella2.gsfc.nasa.gov] Inviato: sabato 21 ottobre 2017 12.46 A: Remo Ruffini - Icra Oggetto: GRB 171020A: Swift-XRT refined Analysis TITLE: GCN CIRCULAR NUMBER: 22035 SUBJECT: GRB 171020A: Swift-XRT refined Analysis DATE: 17/10/21 10:34:06 GMT FROM: Phil Evans at U of Leicester A. Tohuvavohu (PSU), S. J. LaPorte (PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA) and K.L. Page report on behalf of the Swift-XRT team: We have analysed 7.5 ks of XRT data for GRB 171020A (Page et al. GCN Circ. 22028), from 128 s to 35.4 ks after the BAT trigger. The data comprise 10 s in Windowed Timing (WT) mode (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. 22034). The light curve can be modelled with an initial power-law decay with an index of alpha=2.23 (+0.45, -0.21), followed by a break at T+563 s to an alpha of 0.88 (+0.08, -0.07). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.58 (+0.17, -0.15). The best-fitting absorption column is 1.84 (+0.70, -0.28) x 10^21 cm^-2, consistent with the Galactic value of 1.6 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 4.5 x 10^-11 (5.3 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.84 (+0.70, -0.28) x 10^21 cm^-2 Galactic foreground: 1.6 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 1.58 (+0.17, -0.15) If the light curve continues to decay with a power-law decay index of 0.88, the count rate at T+24 hours will be 5.4 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.4 x 10^-13 (2.9 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/00780845. This circular is an official product of the Swift-XRT team.
GCN 22037 table
GRB_name GRB171020A
GCN_number 22037
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 22037 SUBJECT: GRB 171020A: RATIR Optical and NIR Observations DATE: 17/10/21 15:28:40 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), 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), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report: We observed the field of GRB 171020A (Page, et al., GCN 22028) 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 2017/10 21.16 to 2017/10 21.50 UTC (4.60 to 12.98 hours after the BAT trigger), obtaining a total of 5.30 hours exposure in the r and i bands and 2.20 hours exposure in the Z, Y, J, and H bands. We detect the NOT optical transient (Malesani, et al., GCN 22029), which continues to fade (see also, Moskvitin, et al., GCN 22031). In comparison with the USNO-B1 and 2MASS catalogs, we obtain the following detections and upper limit (3-sigma): r = 22.91 +/- 0.12 i = 22.76 +/- 0.11 Z > 21.44 Y = 21.72 +/- 0.35 J = 21.54 +/- 0.23 H = 21.69 +/- 0.35 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.
GCN 22038 table
GRB_name GRB171020A
GCN_number 22038
Detection_method Swift-BAT Det
ra 39.2600°
decl 15.1990°
Circular_text TITLE: GCN CIRCULAR NUMBER: 22038 SUBJECT: GRB 171020A: Swift-BAT refined analysis DATE: 17/10/21 15:54:40 GMT FROM: Amy Lien at GSFC H. A. Krimm (NSF/USRA), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), K. L. Page (U Leicester) D. M. Palmer (LANL), 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+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 171020A (trigger #780845) (Page et al., GCN Circ. 22028). The BAT ground-calculated position is RA, Dec = 39.260, 15.199 deg which is RA(J2000) = 02h 37m 02.3s Dec(J2000) = +15d 11' 57.0" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 48%. The mask-weighted light curve shows a weak pulse that starts at ~T0 and ends at ~ T+45 s. T90 (15-350 keV) is 41.9 +- 9.2 sec (estimated error including systematics). The time-averaged spectrum from T-0.97 to T+46.68 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.04 +- 0.20. The fluence in the 15-150 keV band is 1.2 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+19.92 sec in the 15-150 keV band is 0.7 +- 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/780845/BA/
GCN 22039 table
GRB_name GRB171020A
GCN_number 22039
Detection_method Optical
redshift 1.8700
Circular_text TITLE: GCN CIRCULAR NUMBER: 22039 SUBJECT: GRB 171020A: NOT spectroscopic redshift DATE: 17/10/21 16:43:25 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst D. Malesani (DARK/NBI), J. P. U. Fynbo (NBI), K. E. Heintz (Univ. Iceland and DARK/NBI), M. Stone (Turku Univ.), K. Karhunen (Turku Univ.), report on behalf of a larger collaboration: Following our imaging sequence (Malesani et al., GCN 22029), we secured spectra of the optical afterglow of GRB 171020A (Page et al., GCN 22028), using the AlFOSC spectrograph at the Nordic Optical Telescope. A total of 4x1200 s exposure was secured using grism #4, covering the wavelength range ~3600-9400 AA. Spectroscopy started on 2017 Oct 21.005 UT (1 hr after the trigger). A faint trace is detected down to at least ~4000 A. Several weak absorption features are detected, which we interpret as due to Mg II, Fe II, and C IV all at a common redshift z = 1.87. We thank the NOT staff for support, in particular Amanda Djupvik and Sergio Armas.
GCN 22040 table
GRB_name GRB171020A
GCN_number 22040
Detection_method Swift-UVOT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 22040 SUBJECT: GRB 171020A: Swift/UVOT Upper Limits DATE: 17/10/22 06:43:09 GMT FROM: Sam LaPorte at PSU GRB 171020A: Swift/UVOT Upper Limits S. J. LaPorte (PSU) and K. L. Page (U. Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 171020A 147 s after the BAT trigger (Page et al., GCN Circ. 22028). No optical afterglow consistent with the XRT position (Page et al. GCN Circ. 22028) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 147 297 147 >20.6 u_FC 306 556 246 >20.2 white 147 7652 811 >21.4 v 636 6640 338 >19.4 b 562 7460 529 >20.8 u 306 7254 756 >20.2 w1 686 7050 491 >20.7 m2 6645 6845 197 >20.3 w2 1016 6435 216 >20.3 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.19 in the direction of the burst (Schlegel et al. 1998).
GCN 22041 table
GRB_name GRB171020A
GCN_number 22041
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 22041 SUBJECT: GRB 171020A: TAROT Calern observatory optical observations DATE: 17/10/22 13:08:21 GMT FROM: Alain Klotz at IRAP-CNRS-OMP Klotz A., Noysena.K., Atteia J.L. (CNRS-OMP-IRAP), Boer, M., Eymar, L. (CNRS-ARTEMIS), Gendre B. (UVI - Etelman Obs.) report: We imaged the field of GRB 171020A detected by SWIFT (trigger 780845) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France. The observations started 68s after the GRB trigger (13s after the notice). The elevation of the field increased from 58 degrees above horizon and weather conditions were 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 do not detect any OT with a limiting magnitude of: t0+68s to t0+128s : Rlim = 17.5 The OT (Malesani et al., GCN 22029) is detected in the median of three individual frames: t0+141s to t0+251s : R = 18.7 +/- 0.35 We co-added a series of exposures. The OT is no longer detected: t0+262s to t0+533s : Rlim = 18.9 Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction.
GCN 22042 table
GRB_name GRB171020A
GCN_number 22042
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 22042 SUBJECT: GRB 171020A: Continued RATIR Optical and NIR Observation DATE: 17/10/22 21:19:00 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), 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), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report: We observed the field of GRB 171020A (Page, et al., GCN 22028) 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 2017/10 22.13 to 2017/10 22.47 UTC (27.94 to 36.23 hours after the BAT trigger), obtaining a total of 5.27 hours exposure in the r and i bands and 2.21 hours exposure in the Z and Y bands. We contine to detect the optical transient (Malesani, et al., GCN 22029; also, Moskvitin, et al., GCN 22031; Butler, et al., GCN 22037). In comparison with the USNO-B1 and 2MASS catalogs, we obtain the following detections and upper limits (3-sigma): r = 23.25 +/- 0.14 i = 23.01 +/- 0.11 Z > 21.75 Y > 22.05 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. Compared to our observations last night, these data suggest either a slow afterglow fade (~t^-0.2) or that our measured flux contains flux from the GRB host galaxy. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir.