//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29521 SUBJECT: GRB 210217A: Swift detection of a burst with an optical counterpart DATE: 21/02/17 23:36:33 GMT FROM: David Palmer at LANL K. K. Simpson (PSU), J.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (PSU), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), M. J. Moss (GWU), D. M. Palmer (LANL), B. Sbarufatti (PSU) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 23:25:42 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210217A (trigger=1033264). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 97.610, +68.715 which is RA(J2000) = 06h 30m 26s Dec(J2000) = +68d 42' 53" 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 ~3400 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 23:27:20.1 UT, 97.8 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 97.58675, 68.72497 which is equivalent to: RA(J2000) = 06h 30m 20.82s Dec(J2000) = +68d 43' 29.9" with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 47 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 https://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 8.69 x 10^20 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 103 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 06:30:19.93 = 97.58305 DEC(J2000) = +68:43:30.6 = 68.72516 with a 90%-confidence error radius of about 0.63 arc sec. This position is 6.2 arc sec. from the center of the XRT error circle. The estimated magnitude is 18.72 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 0.103. Burst Advocate for this burst is K. K. Simpson (kira.simpson1984 AT gmail.com). 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/) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29523 SUBJECT: GRB 210217A: NEXT early optical afterglow observations DATE: 21/02/18 00:20:00 GMT FROM: Dong Xu at NAOC/CAS Z.P. Zhu (NAOC, HUST), S.Y. Fu, X. Liu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report: We observed the field of GRB 210217A (Simpson et al., GCN 29521) using the NEXT-0.6m optical telescope located at Nanshan, Xinjiang, China. Observations automatically started at 23:27:06 UT on 2021-02-17, i.e., 84 s after the BAT trigger. A series of 3x40 s, 4x60 s and 10x90 s frames in the Sloan r-filter have been obtained, and observations are ongoing. An uncatalogued decaying optical transient is detected at the Swift/UVOT position (Simpson et al., GCN 29521), which is thus concluded to be the optical afterglow of burst. The afterglow has r = 18.6 +/- 0.2 mag in our first image, calibrated with nearby PS1 stars. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29525 SUBJECT: GRB 210217A: Enhanced Swift-XRT position DATE: 21/02/18 03:26:12 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 396 s of XRT Photon Counting mode data and 1 UVOT images for GRB 210217A, 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 = 97.58507, +68.72536 which is equivalent to: RA (J2000): 06h 30m 20.42s Dec (J2000): +68d 43' 31.3" with an uncertainty of 1.9 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: 29533 SUBJECT: GRB 210217A: KAIT Optical Observations DATE: 21/02/18 17:57:39 GMT FROM: Weikang Zheng at UC Berkeley WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on behalf of the KAIT GRB team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, responded to the Swift GRB 210217A (Simpson et al., GCN 29521) starting at ~4.27 hours after the Swift trigger. A total of 30x60s images were obtained in the clear (roughly R) filters. We marginally detect the optical afterglow (Simpson et al., GCN 29521; Zhu et al., GCN 29523) in the coadd image with a mag of 20.8 +/- 0.3, calibrated to the Pan-STARRS1 catalog. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29534 SUBJECT: GRB 210217A: Swift-BAT refined analysis DATE: 21/02/18 18:01:32 GMT FROM: Amy Lien at GSFC T. Sakamoto (AGU), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), K. K. Simpson (PSU), 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 210217A (trigger #1033264) (Simpson et al., GCN Circ. 29521). The BAT ground-calculated position is RA, Dec = 97.578, 68.715 deg which is RA(J2000) = 06h 30m 18.6s Dec(J2000) = +68d 42' 55.4" with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 30%. The mask-weighted light curve shows a single-peaked FRED-like structure that starts and peaks at ~T0, and ends at ~T+5 s. T90 (15-350 keV) is 4.22 +- 1.15 sec (estimated error including systematics). The time-averaged spectrum from T-0.65 to T+4.89 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.01 +- 0.16. The fluence in the 15-150 keV band is 6.8 +- 0.7 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.13 sec in the 15-150 keV band is 5.1 +- 0.5 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/1033264/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29535 SUBJECT: GRB 210217A: Liverpool Telescope First Hour Observations DATE: 21/02/18 22:17:33 GMT FROM: Manisha Shrestha at Liverpool John Moores U M. Shrestha (Liverpool JMU), R. Smith (LJMU) , A. Melandri (INAF), I.A. Steele (LJMU), S. Kobayashi (LJMU), C. Mundell (Univ. Bath), A. Gomboc (Univ. Nova Gorica), C. Guidorzi (Univ. Ferrara) report on behalf of a wider collaboration: We observed the field of Swift GRB 210217A (GCN 29521) with the 2.0m Liverpool Telescope (LT), La Palma on 2021 Feb 17 starting at 23:28:51.056 UT using the IO:O optical camera in the r’, i’, and z’ bands. Data were calibrated with respect to nearby APASS secondary standard stars for r’ and i’ bands and SDSS secondary standard stars for z’ band. We confirm the optical counterpart reported by Swift UVOT and NEXT (GCN 29523). At T=194 seconds after the BAT trigger time, we measure r’ = 18.51 +/- 0.3 mag which is close to 18.6 +/- 0.2 mag detected by NEXT team (GCN 29523). The r’ band light curve made with IO:O observations show a power law decay over the first hour in flux vs time with alpha = 0.48. At T = 690 seconds after the BAT trigger time, we measure i’ = 18.77 +/- 0.1 mag and at T = 868 seconds after the trigger we measure z’ = 18.67 +/-0.1 mag. ________________________________ Important Notice: Liverpool John Moores University was established as a Higher Education Corporation under section 121 of the Education Reform Act 1988. Further information about Liverpool John Moores University can be found at https://www.ljmu.ac.uk/about-us The information in this email and any attachments is for the sole use of the intended recipient(s). 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For information about how we process personal data and monitor communications please see our Privacy Notice. https://www.ljmu.ac.uk/legal/privacy-and-cookies //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29536 SUBJECT: Fermi GBM Sub-Threshold Detection of GRB 210217A DATE: 21/02/18 22:22:40 GMT FROM: Joshua Wood at MSFC/Fermi-GBM C. Fletcher (USRA) reports on behalf of the Fermi-GBM Team: Swift-BAT detected GRB 210217A at 23:25:42 UT (GCN 29521). There was no Fermi-GBM onboard trigger around the event. An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM identified a high reliability transient consistent in both time and location with the Swift BAT event. Link: https://gcn.gsfc.nasa.gov/notices_gbm_sub/635297147.fermi The GBM targeted search [1], the most sensitive, coherent search for GRB-like signals also identified a transient most significantly on the 1.024 s timescale, with a log likelihood ratio of 72 and a location consistent with the Swift BAT event. The GBM targeted search event was found with the highest significance with a "normal" spectrum (Band function with Epeak = 230 keV, alpha = -1.0, beta = -2.3) for a GRB. [1] Goldstein et al. 2019 arXiv:1903.12597 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29538 SUBJECT: GRB 210217A: Swift-XRT refined Analysis DATE: 21/02/19 02:58:08 GMT FROM: Phil Evans at U of Leicester D.N. Burrows (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , J. D. Gropp (PSU), J.A. Kennea (PSU) and K.K. Simpson report on behalf of the Swift-XRT team: We have analysed 6.8 ks of XRT data for GRB 210217A (Simpson et al. GCN Circ. 29521), from 109 s to 80.4 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 29525). The light curve can be modelled with a power-law decay with a decay index of alpha=0.79 (+/-0.05). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.97 (+0.23, -0.22). The best-fitting absorption column is 2.5 (+0.9, -0.8) x 10^21 cm^-2, in excess of the Galactic value of 8.7 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.7 x 10^-11 (5.1 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.5 (+0.9, -0.8) x 10^21 cm^-2 Galactic foreground: 8.7 x 10^20 cm^-2 Excess significance: 3.3 sigma Photon index: 1.97 (+0.23, -0.22) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01033264. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29539 SUBJECT: GRB 210217A: 1.3m DFOT optical detection DATE: 21/02/19 19:32:22 GMT FROM: Amit Kumar at ARIES, India Amit Kumar (ARIES), Rahul Gupta (ARIES), Ankur Ghosh (ARIES), Dimple (ARIES), Tushar Tripathi (ARIES), Shubham Kishore (ARIES), Amar Aryan (ARIES), Shashi B. Pandey (ARIES), Brajesh Kumar (ARIES), and Kuntal Misra (ARIES) report: We observed the optical afterglow of the Swift detected GRB 210217A (Simpson et al. GCN 29521; Evans et al., GCN 29525) with the 1.3m Devsthal Fast Optical Telescope (DFOT) at Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital (India), on 2021-02-18 from UT 17:31:22 to 19:09:31 (corresponding to 18.094 to 19.730 hours from the GRB trigger time). We observed a series of 30x120s exposures in the Bessel R filter and a series of 20x120s exposures in the Bessel I filter. We clearly detected the optical afterglow of GRB 210217A in the stacked frames within the Swift XRT error circle (Simpson et al. GCN 29521) as also reported by Zhu et al., GCN 29523; Zheng & Filippenko GCN 29533; Shrestha et al. GCN 29535. The estimated preliminary magnitudes are as follows: T_start-T0 (hours) Start Date (UTC) Filter Magnitude (mag) ----------------------------------------------------------- ----------------------------------------------------------- 18.09 2021-02-18T17:31:22 R 21.80 +- 0.08 19.73 2021-02-18T19:09:31 I 21.56 +- 0.12 The magnitudes are not corrected for the Galactic extinction in the direction of the burst. Photometric calibration is performed using the standard stars from the USNO-B1.0 catalog. This circular may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29555 SUBJECT: GRB 210217A: Swift/UVOT Detection DATE: 21/02/23 14:27:28 GMT FROM: Kira Simpson at PSU GRB 210217A: Swift/UVOT Detection K. K. Simpson (PSU) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 210217A 103 s after the BAT trigger (Simpson et al., GCN Circ. 29521). A source consistent with the XRT position *** POSITION REFERENCE is GCN_Notice *** is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 06:30:19.90 = 97.58291 (deg.) Dec (J2000) = +68:43:30.6 = 68.72517 (deg.) with an estimated uncertainty of 0.46 arc sec. (radius, 90% confidence). Preliminary detections 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 103 253 147 18.80 +/- 0.06 u 315 508 190 18.64 +/- 0.11 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.102 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29577 SUBJECT: GRB 210217A: Mondy optical observations DATE: 21/02/26 18:35:21 GMT FROM: Alexei Pozanenko at IKI, Moscow N.Pankov (HSE), S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP) report on behalf of IKI GRB FuN: We observed the field of GRB 210217A (Simpson et al., GCN 29521) with AZT-33IK telescope of Sayan observatory (Mondy) on 2021-02-19 and XX. Within enhanced XRT position (Evans et al., GCN 29525) we do not detect afterglow (Simpson et al., GCNs 29521,29555; Zhu et al., GCN 29523; Zheng et al., GCN 29533; Shrestha et al., GCN 29535; Kumar et al., GCN 29539). Preliminary photometry of the filed is following Date UT start t-T0 Filter Exp. OT Err. UL(3sigma) (mid, days) (s) 2021-02-19 13:10:59 1.58579 R 2190 n/d n/d 22.2 2021-02-21 16:05:26 3.71250 R 3150 n/d n/d 22.8 2021-02-19+2021-02-21 2.65193 R 5850 n/d n/d 22.9 The photometry is based on the nearby USNO-B1.0 star USNO-B1.0_id R2 1587-088041 17.94 A light curve of afterglow of GRB 210217A (based on published photometry) and upper limits can be found in http://grb.rssi.ru/GRB210217A/GRB210217A_LC.jpg Using upper upper limit we may suggest a possible jet break of the light curve we may suggest a jet break between 1.58 and 3.71 days after power law decay with index alpha of -0.48 (Shrestha et al., GCN 29535). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29591 SUBJECT: GRB 210217A: 3.6m DOT optical observations DATE: 21/03/01 07:26:44 GMT FROM: Dimple Panchal at ARIES, India Dimple (ARIES), K. Misra (ARIES), A. Ghosh (ARIES), R. Gupta (ARIES), A. Kumar (ARIES), B. Kumar (ARIES), S.B. Pandey (ARIES) report: We carried out the follow-up observations of GRB 210217A ( Simpson et al. GCN #29521) with Aries Devasthal Faint Object Spectrograph and Camera (ADFOSC) mounted on the 3.6m Devasthal Optical Telescope (DOT) at Devasthal observatory of Aryabhatta Research Institute of observational sciencES (ARIES), India. We detected the optical afterglow (Simpson et al. GCNs #29521,29555; Zhu et al. GCN #29523; Zheng et al. GCN #29533; Shrestha et al. GCN #29535; Kumar et al., GCN #29539) at ~ 1.7 days after the burst. Preliminary photometry is following : Date UT start Filter Exp. (s) Mag err 2021-02-19 15:47:38 r 4*900 22.32 0.17 2021-02-20 16:30:35 r 10*300 >22.60 ---- The reported magnitudes are calibrated with the nearby PanSTARRS field and are not corrected for Galactic extinction in the direction of the burst. Using our data along with the data taken from Zhu et al. GCN #29523; Zheng et al. GCN #29533; Kumar et al., GCN #29539, we obtain a decay index of 0.47 +- 0.03 consistent with the value quoted by Shrestha et al. # GCN 29535. .