//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22265 SUBJECT: GRB 171222A: Swift detection of a burst DATE: 17/12/22 16:42:04 GMT FROM: Judith Racusin at GSFC J. L. Racusin (NASA/GSFC), A. Deich (PSU), S. W. K Emery (UCL-MSSL), J.D. Gropp (PSU), J. A. Kennea (PSU), H. A. Krimm (NSF/USRA), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), B. Sbarufatti (PSU) and A. Tohuvavohu (PSU) report on behalf of the Swift Team: At 16:24:59 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 171222A (trigger=799669). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 148.293, +35.622 which is RA(J2000) = 09h 53m 10s Dec(J2000) = +35d 37' 18" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is usual with an image trigger, the BAT light curve does not show any significant features. The XRT began observing the field at 16:27:49.5 UT, 169.7 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 148.27784, 35.62759 which is equivalent to: RA(J2000) = 09h 53m 06.68s Dec(J2000) = +35d 37' 39.3" with an uncertainty of 4.0 arcseconds (radius, 90% containment). This location is 48 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 6.69e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 250 seconds with the U filter starting 175 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 19.2 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 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.01. 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: 22266 SUBJECT: GRB 171222A: Enhanced Swift-XRT position DATE: 17/12/22 21:08:18 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 689 s of XRT Photon Counting mode data and 1 UVOT images for GRB 171222A, 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 = 148.27736, +35.62712 which is equivalent to: RA (J2000): 09h 53m 6.57s Dec (J2000): +35d 37' 37.6" with an uncertainty of 3.0 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: 22269 SUBJECT: GRB 171222A: NOT Optical Afterglow DATE: 17/12/23 01:06:51 GMT FROM: Daniel Perley at Liverpool JMU D. A. Perley (LJMU), D. Malesani (DARK/NBI), K. Heintz (Univ. Iceland, DARK/NBI), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), and J. J. Lehiten (MPS) report on behalf of a larger collaboration: We obtained observations of GRB 171222A (Racusin et al., GCN 22265) using StanCam on the Nordic Optical Telescope, beginning at 00:08:31 UT on 2017-12-23. Imaging was obtained in both R and I bands. In the raw images we identify an optical source, not visible in pre-imaging from Pan-STARRS, at the following location within the XRT error circle (Osborne et al. GCN 22266): RA = 09:53:06.73 Dec = +35:37:35.5 We suggest that this source is the optical afterglow of GRB 171222A. Provisional photometry relative to nearby USNO stars gives a magnitude of R = 21.44 +/- 0.09 (at 7.67 hours after the GRB trigger). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22271 SUBJECT: GRB 171222A: Swift-XRT refined Analysis DATE: 17/12/23 05:49:30 GMT FROM: Phil Evans at U of Leicester V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), A. Tohuvavohu (PSU), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and J.L. Racusin report on behalf of the Swift-XRT team: We have analysed 8.1 ks of XRT data for GRB 171222A (Racusin et al. GCN Circ. 22265), from 176 s to 39.8 ks after the BAT trigger. The data comprise 386 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 22266). The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=2.05 (+0.39, -0.25). At T+285 s the decay steepens to an alpha of 4.51 (+0.43, -0.18). The light curve breaks again at T+533 s to a decay with alpha=7.78 (+0.22, -1.07), and again at T+712 s s to alpha=2.9 (+/-0.6), before a final break at T+2103 s s after which the decay index is 0.09 (+0.24, -0.27). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.28 (+/-0.04). The best-fitting absorption column is 6.2 (+/-0.8) x 10^20 cm^-2, in excess of the Galactic value of 1.1 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.99 (+0.15, -0.12) and a best-fitting absorption column consistent with the Galactic value. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.2 x 10^-11 (3.3 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.1 (+2.4, -0.0) x 10^20 cm^-2 Galactic foreground: 1.1 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.99 (+0.15, -0.12) If the light curve continues to decay with a power-law decay index of 0.09, the count rate at T+24 hours will be 0.021 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.7 x 10^-13 (7.0 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/00799669. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22272 SUBJECT: GRB 171222A: Redshift from 10.4m GTC/OSIRIS DATE: 17/12/23 07:06:51 GMT FROM: Antonio de Ugarte Postigo at IAA-CSIC A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), L. Izzo (HETH/IAA-CSIC), D.A. Kann (HETH/IAA-CSIC), C.C. Thoene (HETH/IAA-CSIC), D. A. Perley (LJMU), D. Malesani (DARK/NBI), K.E. Heintz (Univ. Iceland, DARK/NBI), D. Garcia (GTC) report on behalf of a larger collaboration, We observed the afterglow of GRB 171222A (Racusin et al. GCN 22265; Osborne et al. GCN 22266; Perley et al. GCN 22269) using the 10.4m GTC telescope equipped with OSIRIS. Observations consisted of 3x900s exposures using grism R1000B, covering the range from 3700 to 7880 AA. The mean time of the combined spectrum is 3:11 UT (10.77 hr after the burst). The combined spectrum shows a power-law continuum over the complete spectral range with several weak absorption features. We identify the strongest of them as Ly-alpha at a redshift of 2.409, with marginal detections of SiII, SiIV and CIV at the same redshift, which we identify as the redshift of the GRB. An intervening system at z=1.678 is also identified through the detection of MgII absorption. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22273 SUBJECT: GRB 171222A: MASTER-Net OT observations DATE: 17/12/23 11:26:55 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs N.Tyurina, V. Lipunov, E. Gorbovskoy,V.Kornilov, D.Kuvshinov, A.V.Krylov, I.Gorbunov, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko Lomonosov Moscow State University, Sternberg Astronomical Institut of MSU R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA), National University of San Juan, Argentina H. Levato, C. Saffe Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE), San Juan, Argentina 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 O.Gres, K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk, Irkutsk State University V.Yurkov, Yu.Sergienko Blagoveschensk Educational State University, Blagoveschensk A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory MASTER-IAC robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in IAC (Tenerife) was pointed to the Swift GRB171222A (Racusin et al., GCN #22265;) 47159 seconds (~ 13h ) after trigger time at 2017-12-23 05:31:03 UT. The 5-sigma upper limit has been about 19.3 at single (180 s) and 20.9 at coadd (10x180 = 1800 s ) images. We see OT detected by (Perley et al., GCN #22269; de Ugarte Postigo et al., GCN #22272 ) at X-ray position (Osborne et al., GCN #22266; D'Elia et al., GCN #22271). The OT unfiltered magnitude is about ~ 21. The observations made on zenit distance = 11 degrees, galaxy latitude b = 52 degree. The moon (21 % bright part) below the horizon (The altitude of the Moon is -73 degree ). The sun altitude is -30.5 degree. The object can be observed till sunrise at 2017-12-23 07:54:43 . This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22274 SUBJECT: GRB 171222A: Nanshan-1m optical afterglow detection DATE: 17/12/23 14:00:59 GMT FROM: Dong Xu at NAOC/CAS X. Zhang, P. Zong, J.H. Liu (XAO), H.X. Feng, Z.P. Zhu, D. Xu (NAOC), H.B. Niu, J.Z. Liu, A. Esamdin, L. Ma, Y. Zhang (XAO) report on behalf of a larger collaboration: We observed the field of GRB 171222A (Racusin et al., GCN 22265) using the 1m telescope located at Nanshan, Xinjiang, China. We obtained 6x300s R-band frames, starting at 18:14:36 UT on 2017-12-22, i.e., 1.83 hr after the BAT trigger. An uncatalogued and fading optical transient (OT) is detected at the XRT position (Osborne et al., GCN 22266) as well as the NOT position (Perley et al., GCN 22269) in our images. Preliminary photometry results are as follows: Tmid-T0 Exposure Filter Mag(R) MagErr(R) (hr) (s) 1.87 1x300 R 20.86 0.21 2.68 3x300 R 21.47 0.22 7.87 2x300 R 21.72 0.22 Photometry is calibrated with nearby USNO-B1.0 stars (R2 magnitudes), and errors are only statistical values. We thus conclude that this OT is the optical afterglow of GRB 171222A. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22275 SUBJECT: GRB 171222A: Swift/UVOT Upper Limits DATE: 17/12/23 14:09:12 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 171222A 176 s after the BAT trigger (Racusin et al., GCN Circ. 22265). No optical afterglow consistent with the enhanced XRT position (Osborne et al. GCN Circ 22266) or the NOT position (Perley et al., GCN Circ 22269) is detected in the initial UVOT exposures. The optical afterglow was detected however by Perley et al. (GCN Circ 22269), Tyurina et al. (GCN Circ. 22273), and a redshift was reported by de Ugarte Postigo (GCN Circ. 22272). 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 u_FC 176 426 246 >20.6 u 176 1026 393 >20.3 b 432 1795 175 >20.3 v 482 1846 175 >19.2 uvw1 531 1895 175 >19.4 uvm2 506 1870 175 >19.3 uvw2 458 1821 175 >19.6 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22276 SUBJECT: GRB 171222A: Nanshan-0.36m optical upper limit DATE: 17/12/23 14:34:17 GMT FROM: Dong Xu at NAOC/CAS H.J. Tan (CCU), H.X. Feng, Z.P. Zhu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School) report We observed the field of GRB 171222A (Racusin et al., GCN 22265) using the 0.36m robotic telescope located at Nanshan, Xinjiang, China. Observations started at 17:04:17 UT on 2017-12-22, i.e., 39.3 mins after the BAT trigger, and all imaged were taken without filter. No optical source is detected at the XRT position (Osborne et al., GCN 22266) as well as the NOT position (Perley et al., GCN 22269), down to a limiting magnitude of m(R)~19.3, calibrated with the USNO B1 field. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22277 SUBJECT: GRB 171222A: Fermi GBM detection DATE: 17/12/23 17:13:20 GMT FROM: Matthew Stanbro at UAH/Fermi M. Stanbro (UAH), C. M. Hui (NASA/MSFC) and C. Meegan (UAH) reports on behalf of the Fermi GBM Team: At 16:25:10.54 UT on 22 December 2017, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 171222A (trigger 535652715/171222684) which was also detected by the Swift/BAT and XRT (Racusin et al. 2017, GCN 22265). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 43 degrees. The GBM light curve shows a single peak with a duration (T90) of about 80.4s (50-300 keV). The time-averaged spectrum from T0+0.0s to T0+78.8s is adequately fit by a power law function with an exponential high-energy cutoff. The power law index is -1.09+/- 0.27 and the cutoff energy, parameterized as Epeak, is 29.18 +/- 2.73 keV. The event fluence (10-1000 keV) in this time interval is (2.27 +/- 0.13)E-06 erg/cm^2. The 1s peak photon flux measured starting from T0+60.1s in the 10-1000 keV band is 2.3 +/- 0.2 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: 22279 SUBJECT: GRB 171222A: AROMA-N optical observation DATE: 17/12/24 10:01:22 GMT FROM: Takanori Sakamoto at AGU Y. Kitaoka, T. Sakamoto (AGU) We observed the field of GRB 171222A detected by Swift (Racusin et al. GCN circ. 22265) with the 0.3 m AROMA-N telescope located at Aoyama Gakuin University (Sagamihara, Japan). Due to the introduction issue of the telescope, we only obtained one 120 sec image which contains the location of the GRB. The image was taken in the R filter starting from December 12 on 18:53:26 (UT) about 140 minutes after the trigger and stopped on 18:55:26 (UT). We do not detect the optical afterglow in this image at the location of the X-ray afterglow (Osborne et al. GCN circ. 22266). The estimated five sigma upper limit is ~15.3 using the USNO-B1 catalog. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22280 SUBJECT: GRB 171222A: Swift-BAT refined analysis DATE: 17/12/24 12:41:04 GMT FROM: Hans Krimm at NASA-GSFC/NSF D. M. Palmer (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), 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-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 171222A (trigger #799669) (Racusin, et al., GCN Circ. 22265). The BAT ground-calculated position is RA, Dec = 148.273, 35.624 deg which is RA(J2000) = 09h 53m 05.4s Dec(J2000) = +35d 37' 24.9" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 60%. The mask-weighted light curve shows multiple overlapping peaks in three groupings. The first runs from approximately T-10 sec to T+50 sec, the second from T+50 sec to T+90 sec, and the third, weakest group from T+90 sec to T+200 sec. T90 (15-350 keV) is 174.8 +- 22.7 sec (estimated error including systematics). The time-averaged spectrum from T+8.00 to T+209.82 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.07 +- 0.17. The fluence in the 15-150 keV band is 1.9 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+61.34 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/799669/BA/