//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26876 SUBJECT: GRB 200125A: Swift detection of a burst DATE: 20/01/25 11:44:25 GMT FROM: David Palmer at LANL A. Y. Lien (GSFC/UMBC), C. Gronwall (PSU), J.D. Gropp (PSU), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), K. K. Simpson (PSU), A. Tohuvavohu (U Toronto) and E. Troja (NASA/GSFC/UMCP) report on behalf of the Neil Gehrels Swift Observatory Team: At 11:31:39 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 200125A (trigger=952164). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 228.047, -8.148 which is RA(J2000) = 15h 12m 11s Dec(J2000) = -08d 08' 53" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of at least 40 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~5 sec after the trigger. The XRT began observing the field at 11:33:30.7 UT, 111.5 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 228.0471, -8.1436 which is equivalent to: RA(J2000) = 15h 12m 11.30s Dec(J2000) = -08d 08' 37.0" with an uncertainty of 4.9 arcseconds (radius, 90% containment). This location is 15 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. The initial flux in the 2.5 s image was 3.86e-09 erg cm^-2 s^-1 (0.2-10 keV). There are no UVOT data available at this time. Burst Advocate for this burst is A. Y. Lien (amy.y.lien 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/) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26878 SUBJECT: GRB 200125A: Enhanced Swift-XRT position DATE: 20/01/25 14:53:51 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team. Using 1010 s of XRT Photon Counting mode data and 3 UVOT images for GRB 200125A, 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 = 228.04801, -8.14452 which is equivalent to: RA (J2000): 15h 12m 11.52s Dec (J2000): -08d 08' 40.3" with an uncertainty of 2.5 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: 26881 SUBJECT: Swift GRB 200125A: Global MASTER-Net observations report DATE: 20/01/26 00:56:23 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 200125A ( A. Y. Lien et al., GCN 26876) errorbox 47603 sec after trigger time at 2020-01-26 00:45:02 UT, with upper limit up to 18.5 mag. The observations began at zenith distance = 71 deg. The sun altitude is -32.2 deg. The galactic latitude b = 40 deg., longitude l = 352 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1268985 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 47693 | MASTER-SAAO | C | 180 | 18.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26882 SUBJECT: GRB 200125A: RATIR Optical Observations DATE: 20/01/26 01:39:15 GMT FROM: Alan M Watson at UNAM Alan M. Watson (UNAM), Nat Butler (ASU), 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 200125A (Lien et al., GCN Circ. 26876) 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 2020/01 25.48 to 2020/01 25.56 UTC (0.03 to 1.89 hours after the BAT trigger), obtaining a total of 1.40 hours exposure in the r and i bands. We detect a a source within the enhanced Swift-XRT error circle (Beardmore et al., GCN Circ. 26878). In comparison with the USNO-B1 and 2MASS catalogs, we obtain the following detections: r = 21.02 +/- 0.05 i = 19.54 +/- 0.02 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: 26883 SUBJECT: GRB 200125A: Nanshan-0.6m optical upper limit DATE: 20/01/26 02:55:33 GMT FROM: Dong Xu at NAOC/CAS X. Liu, D. Xu, Z.P. Zhu, B.Y. Yu, Y. Ma (NAOC), X. Gao (Urumqi No.1 Senior High School) report: We observed the field of GRB 200125A (Lien et al., GCN 26876) using the NEXT-0.6m telescope located at Nanshan, Xinjiang, China. Observations started at 23:06:52 UT on 2020-01-25 (i.e., 11.59 h after the BAT trigger), and 10x300 s Sloan r-band frames were obtained. No optical afterglow is detected within the enhanced Swift-XRT error circle (Beardmore et al., GCN Circ. 26878) in our stacked image, down to a limiting magnitude of r ~ 21.0, calibrated with the nearby PanSTARRS field. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26884 SUBJECT: GRB 200125A: Swift-XRT refined Analysis DATE: 20/01/26 11:44:06 GMT FROM: Phil Evans at U of Leicester A. Tohuvavohu (U. Toronto), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), B. Sbarufatti (PSU) and A.Y. Lien report on behalf of the Swift-XRT team: We have analysed 5.7 ks of XRT data for GRB 200125A (Lien et al. GCN Circ. 26876), from 127 s to 28.1 ks after the BAT trigger. The data comprise 286 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 26878). a rise, withpower-law index . A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.523 (+/-0.029). The best-fitting absorption column is 3.05 (+0.17, -0.16) x 10^21 cm^-2, in excess of the Galactic value of 7.7 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.17 (+0.19, -0.18) and a best-fitting absorption column of 1.3 (+0.5, -0.4) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.1 x 10^-11 (4.2 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.3 (+0.5, -0.4) x 10^21 cm^-2 Galactic foreground: 7.7 x 10^20 cm^-2 Excess significance: 2.0 sigma Photon index: 2.17 (+0.19, -0.18) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00952164. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26885 SUBJECT: Correction to GRB 200125A: Swift-XRT refined analysis DATE: 20/01/26 11:59:01 GMT FROM: Kim Page at U.of Leicester K.L. Page reports on behalf of the Swift-XRT team: The automated Swift-XRT refined analysis circular (GCN Circ. 26884) provided an incomplete description of the X-ray light-curve of GRB 200125A. The PC mode data collected between 10 and 28 ks show an approximately constant count rate of ~0.15 count s^-1. We therefore do not give a prediction for T+24 hours. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00952164. This circular is an official product of the Swift-XRT team. [GCN OPS NOTE(26jan20): Per author's request, the url was corrected from http://www.swift.ac.uk/xrt_products/00950330 to http://www.swift.ac.uk/xrt_products/00952164.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26887 SUBJECT: GRB 200125A: TNG detection of a NIR counterpart candidate DATE: 20/01/26 13:33:30 GMT FROM: Paolo D'Avanzo at INAF-OAB A. Melandri, P. D'Avanzo (INAF-OAB), V. D’Elia (ASI-SSDC), W. Boschin, G. Mainella (INAF-TNG) on behalf of the CIBO collaboration report: We observed the field of GRB 200125A (Lien et al., GCN Circ. 26876) with the Italian 3.58m TNG telescope equipped with NICS in imaging mode. A series of images were obtained with the Ks and J filters on 2020-01-26 from 05:25 to 06:39 UT (i.e. from about 17.9 to 19.1 hours after the burst). We detect a source at the following coordinates: RA(J2000), Dec (J2000) = 15:12:11.30, -08:08:38.5 (+/- 0.5”). This position is consistent with the most updated XRT localisation (https://www.swift.ac.uk/xrt_positions/ ). We assume this is the same source detectd in the optical by Watson et al. (GCN Circ. 26882). From preliminary photometry, we estimate for this object a magnitude Ks ~ 17.2 (Vega, calibrated assuming K = 12.1 for the 2MASS star at RA(J2000), Dec (J2000) = 15:12:05.10, -08:07:06.9). [GCN OPS NOTE(26jan20): Per OPS, the Circular referenced in the first sentence (26976) was changed to 26876).] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26889 SUBJECT: GRB 200125A: AbAO optical upper limit DATE: 20/01/26 18:25:59 GMT FROM: Alexei Pozanenko at IKI, Moscow S. Belkin (IKI), A. Pozanenko (IKI), R. Ya. Inasaridze (AbAO ), E. Mazaeva (IKI), A. Volnova (IKI), V. R. Ayvazian (AbAO ), G.V. Kapanadze (AbAO), I. Molotov (KIAM) report on behalf of larger IKI GRB follow-up collaboration: We observed GRB 200125A (Lien et al., GCN 26876) with AS-32 (0.7m) telescope of Abastumani Observatory starting on Jan. 26 (UT) 01:32:27. We obtained several 60 s exposures in R-filter. We do not detect any source within enhanced Swift-XRT position (Beardmore et al., GCN 26878) in the stacked image. In particular we do not detect counterpart candidate (Watson et al., GCN 26882; Melandri et al., GCN 26887) Photometry of the field is following Date UT start t-T0 Filter Exp. OT Err. UL(3sigma) (mid, days) (s) 2020-01-26 01:32:27 0.520 R 56*60 n/d n/d 21.2 Photometry is based on nearby USNO-B1.0 stars (R2 magnitude): USNO-B1.0_id R2 0818-0339924 16.46 0818-0339917 16.94 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26891 SUBJECT: GRB 200125A: Further RATIR Optical Observations and Confirmation of Fading DATE: 20/01/26 21:08:51 GMT FROM: Alan M Watson at UNAM Alan M. Watson (UNAM), Nat Butler (ASU), 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 200125A (Lien et al., GCN Circ. 26876) 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 2020/01 26.42 to 2020/01 26.56 UTC (22.62 to 25.89 hours after the BAT trigger), obtaining a total of 2.52 hours exposure in the r and i bands. The source we reported previously (Watson et al., GCN Circ. 26882) has faded, confirming that it is the afterglow. In comparison with the USNO-B1 and 2MASS catalogs, we obtain the following detections: r = 23.03 +/- 0.29 i = 21.27 +/- 0.05 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: 26892 SUBJECT: GRB 200125A: Swift/UVOT Upper Limits DATE: 20/01/27 01:22:25 GMT FROM: Kira Simpson at PSU GRB 200125A: Swift/UVOT Upper Limits K. K. Simpson (PSU) and A. Y. Lien (GSFC/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 200125A 179 s after the BAT trigger (Lien et al., GCN Circ. 26876). No optical afterglow consistent with the XRT position (Beardmore et al. GCN Circ. 26878) 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 179 329 147 >20.4 white 179 4176 344 >21.1 v 4387 4586 197 >18.4 b 3771 3971 197 >19.9 u 337 414 75 >18.9 w1 4796 4835 38 >18.6 m2 4591 4791 197 >19.3 w2 4182 4382 197 >20.2 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.08 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26894 SUBJECT: GRB 200125A: Further Swift-XRT observations DATE: 20/01/27 08:39:42 GMT FROM: Phil Evans at U of Leicester P.A. Evans, K.L. Page (U. Leicester) and A.Y. Lien (GSFC/UMBC) report on behalf of the Swift-XRT team: We provide an update on the XRT light curve evolution of GRB 200125A (GCN Circs. 26876 and 26885). The XRT light curve shows early, strong flaring activity which is interrupted at T0+414 s as the GRB went into Earth eclipse; by the time of the next observation (T0+3.8 ks) the light curve had faded by 4 orders of magnitude to ~0.1 ct/sec (2e-12 erg cm^-2 s^-1; 0.3-10 keV). It has remained approximately at this level, with some small variation, until our most recent data point at T0+113 ks (=T0+1.3 d). This suggests a very long-lived ‘plateau’ phase. Such long-duration plateaux are rare but not unique. Due to the expectation of a break at some, unknown point in the (probably) near future, we are unable to predict what the flux will be over the coming days. Observations are ongoing. The latest results can be viewed via: https://www.swift.ac.uk/xrt_products/00952164/ This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26897 SUBJECT: GRB 200125A: Swift-BAT refined analysis DATE: 20/01/27 18:18:42 GMT FROM: Amy Lien at GSFC C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), 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-170 to T+808 sec from the recent telemetry downlink, we report further analysis of BAT GRB 200125A (trigger #952164) (Lien et al., GCN Circ. 26876). The BAT ground-calculated position is RA, Dec = 228.069, -8.142 deg which is RA(J2000) = 15h 12m 16.6s Dec(J2000) = -08d 08' 31.3" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 42%. The mask-weighted light curve shows a multi-pulse structure that starts at ~T-40 s and ends at ~T+430 s. The three main pulses occurs at ~T0, ~T+200 s, and ~T+300 s, respectively. The highest peak is at ~T+287 s. The burst went out of the BAT FOV at T+501 s. T90 (15-350 keV) is 350.83 +- 34.03 sec (estimated error including systematics). The time-averaged spectrum from T-36.22 to T+427.74 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.95 +- 0.08. The fluence in the 15-150 keV band is 8.7 +- 0.4 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+286.67 sec in the 15-150 keV band is 4.0 +- 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/952164/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26935 SUBJECT: Konus-Wind observation of GRB 200125A DATE: 20/01/29 14:55:46 GMT FROM: Anna Ridnaia at Ioffe Institute A. Ridnaia, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, and T. Cline on behalf of the Konus-Wind team, report: The long GRB 200125A (Swift-BAT trigger #952164: Lien et al., GCN 26876; Markwardt et al., GCN 26897) was detected by Konus-Wind in the waiting mode. The burst light curve shows three emission pulses in the interval from ~T0(BAT)-35 s to ~T0(BAT)+315 s. The K-W light curve of this burst is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB200125A/ As observed by Konus-Wind, the burst had a fluence of 2.04(-0.16,+0.22)x10^-5 erg/cm2 and a 2.944-s peak flux, measured from ~T0(BAT)+287.4 s, of 2.80(-0.58,+0.62)x10^-7 erg/cm2/s (both in the 20 - 1500 keV energy range). The K-W 3-channel time-integrated spectrum (from ~T0(BAT)-33.5 s to ~T0(BAT)+316.8 s) is best described by simple power-law model with photon index of -2.14(-0.09,+0.1), chi2=0.08/1 dof. All the quoted errors are estimated at the 1 sigma confidence level. All the presented results are preliminary.