//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31787 SUBJECT: GRB 220325A: Swift detection of a burst DATE: 22/03/25 17:27:31 GMT FROM: David Palmer at LANL M. Ferro (INAF-OAB), M. G. Bernardini (INAF-OAB), R. Brivio (INAF-OAB), P. D'Avanzo (INAF-OAB), J.D. Gropp (PSU), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), S. Laha (GSFC/UMBC), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), T. M. Parsotan (GSFC/UMBC/CRESSTII), T. Sbarrato (INAF-OAB), B. Sbarufatti (PSU) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 17:16:23 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 220325A (trigger=1099310). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 269.485, -7.031 which is RA(J2000) = 17h 57m 56s Dec(J2000) = -07d 01' 50" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about ~8 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 17:18:13.2 UT, 110.2 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 269.48760, -7.03776 which is equivalent to: RA(J2000) = 17h 57m 57.02s Dec(J2000) = -07d 02' 15.9" with an uncertainty of 3.9 arcseconds (radius, 90% containment). This location is 26 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. No spectrum from the promptly downlinked event data is yet available to determine the column density. UVOT took a finding chart exposure of 150 seconds with the White filter starting 114 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 0.915. Burst Advocate for this burst is M. Ferro (matteo.ferro AT inaf.it). 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: 31789 SUBJECT: GRB 220325A: MASTER Global Robotic Net optical observations DATE: 22/03/25 20:18:18 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.Lipunov, D.Vlasenko, A.Kuznetsov, O.Gress, E.Gorbovskoy, N.Tyurina, P.Balanutsa, K.Zhirkov, A.Chasovnikov, G.Antipov, V.Senik, D.Kuvshinov, V.Topolev,Ya.Kechin, Yu.Tselik (Lomonosov Moscow State University, SAI, Physics Department), C.Francile, R. Podesta, C.Lopez, F. Podesta (Observatorio Astronomico Felix Aguilar OAFA), D.A.H.Buckley (SAAO), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory), N.M.Budnev (ISU,API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational State University) MASTER-Amur robotic telescope (Global MASTER-Net: http://observ.pereplet.ru,Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) was pointed to the SWIFT GRB 220325A ( M. Ferro et al., GCN 31787) errorbox 3287 sec after notice time (3306 sec after trigger time) at 2022-03-25 18:11:29 UT between rain with snow with upper limit up to 15.1 mag. The observations started at zenith distance = 69 deg. The sun altitude was -28.4 deg. The galactic latitude b = 8 deg., longitude l = 21 deg. Real time updated cover map is available: https://master.sai.msu.ru/site/master2/observ.php?id=1921440 The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31790 SUBJECT: GRB 220325A: Enhanced Swift-XRT position DATE: 22/03/25 20:47:24 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 1551 s of XRT Photon Counting mode data and 3 UVOT images for GRB 220325A, 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 = 269.48753, -7.03592 which is equivalent to: RA (J2000): 17h 57m 57.01s Dec (J2000): -07d 02' 09.3" with an uncertainty of 2.4 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: 31791 SUBJECT: Fermi GBM Sub-Threshold Detection of GRB 220325A DATE: 22/03/26 03:41:37 GMT FROM: Joshua Wood at MSFC/Fermi-GBM J. Wood (NASA/MSFC) reports on behalf of the Fermi-GBM Team: There was no Fermi-GBM onboard trigger around the time of GRB 220325A, which was detected by Swift-BAT at 17:16:23 UT on 25 March, 2022 (Ferro et al. GCN 31787). An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM identified GRB 220325A with medium reliability [1], with a localization consistent with the Swift-BAT location at the ~2 sigma level, and a discovery timescale of 2.751 s. The start time of the GBM sub-threshold detection coincides with the time of the peak photon flux observed by Swift-BAT. The GBM targeted search [2], the most sensitive, coherent search for GRB-like signals also identified a transient most significantly on the 2.048 s timescale, with a location consistent with the Swift-BAT event at the ~2 sigma level and a signal-to-noise ratio of 12.3, using the standard search protocol. The GBM targeted search event was found with the highest significance with a "soft" spectrum (Band function with Epeak = 70 keV, alpha = -1.9, beta = -3.7) for a GRB. This analysis is preliminary. [1] https://gcn.gsfc.nasa.gov/notices_gbm_sub/669921389.fermi [2] Goldstein et al. 2019 arXiv:1903.12597 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31793 SUBJECT: GRB 220325A: 1.3m DFOT Optical upper limit DATE: 22/03/26 09:35:16 GMT FROM: Rahul Gupta at ARIES, India Rahul Gupta, Amit Ror, Amit Kumar, Dimple, Ankur Ghosh, Amar Aryan, Krishan Chand, S. B. Pandey, and Kuntal Misra (ARIES) report: We observed the Swift-BAT and Fermi-GBM Sub-Threshold detected GRB 220325A ( Ferro et al., GCN 31787; Wood, GCN 31791) with 1.3m Devasthal Fast Optical Telescope (DFOT) located at Devasthal observatory of Aryabhatta Research Institute of Observational Sciences (ARIES), India. The observations were started on 2022-03-25 at ~ 22:15 UT, i.e., ~ 5 hours after the BAT trigger. We have taken multiple frames having an exposure time of 300 sec in the R filter. We stacked the images after the alignment. We did not detect any new optical source within the Swift XRT uncertainty circle (Osborne et al., GCN 31790) in our stacked image. We obtain the following 3-sigma upper limit in the stacked image. Date Start_UT T_start-T0 (hour) Filter Exp time (sec) Limiting magnitude ==================================================== 2022-03-25 22:15 ~5 R 300*20 > 21.7 The magnitude is 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: 31794 SUBJECT: GRB 220325A: Swift-XRT refined Analysis DATE: 22/03/26 10:49:46 GMT FROM: Phil Evans at U of Leicester K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU) and M. Ferro report on behalf of the Swift-XRT team: We have analysed 6.7 ks of XRT data for GRB 220325A (Ferro et al. GCN Circ. 31787), from 95 s to 35.5 ks after the BAT trigger. The data comprise 8 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 Osborne et al. (GCN Circ. 31790). The light curve can be modelled with a power-law decay with a decay index of alpha=0.67 (+/-0.06). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.51 (+0.28, -0.16). The best-fitting absorption column is 3.96 (+1.97, -0.09) x 10^21 cm^-2, consistent with the Galactic value of 3.9 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 5.2 x 10^-11 (6.5 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 3.96 (+1.97, -0.09) x 10^21 cm^-2 Galactic foreground: 3.9 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 1.51 (+0.28, -0.16) If the light curve continues to decay with a power-law decay index of 0.67, the count rate at T+24 hours will be 7.6 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.0 x 10^-13 (5.0 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/01099310. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31795 SUBJECT: GRB 220325A: LCO Optical Upper Limits DATE: 22/03/26 13:24:25 GMT FROM: Robert Strausbaugh at U. of the Virgin Islands R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (College of Marin) report on behalf of a larger collaboration: We observed Swift GRB 220325A (Ferro et al., GCN 31787) with the LCO 1-m Sinistro instrument at the McDonald Observatory, Texas, USA site, on March 26, from 09:25 to 09:53 UT (corresponding to 16.15 to 16.62 hours from the GRB trigger time) with the Bessel R and I filters. We performed a series of 3x300s exposures in I and R bands. We do not detect an optical counterpart within the XRT enhanced error region (Osborne et al., GCN 31790) in either band, consistent with other non-detections (Lipunov et al., GCN 31773; Gupta et al., GCN 31793). The following upper limits are calculated using the USNO-B.1 catalog as reference: R>21.08 I>20.14 These magnitudes are not corrected for galactic extinction. R.S. is funded by NSF AST grant #1831682 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31797 SUBJECT: GRB 220325A: Tautenburg observations DATE: 22/03/26 20:47:50 GMT FROM: Ana Nicuesa at TLS Tautenburg A. Nicuesa Guelbenzu, S. Klose, B. Stecklum, S. Melnikov, and U. Laux (all Tautenburg) report: We observed the field of GRB 220325A (Ferro et al. GCN 31787) with the Tautenburg 1.34m Schmidt telescope equipped with the TAUKAM 6k x 6k CCD camera. Observations consisted of 3x3 min exposures using the Sloan r, i, and z-band filter. The airmass was 2.1, the seeing relatively poor (3 arcsec). Inside the enhanced XRT error circle (Osborne et al., GCN 31790) we do not find any source down to the following magnitudes: r > 20.7 mag (AB, 3 sigma), mean time: 2022-03-26, 03:05:34 UT, i > 20.6 mag (AB, 3 sigma), mean time: 2022-03-26, 03:16:22 UT, z > 19.7 mag (AB, 3 sigma). mean time: 2022-03-26, 03:27:10 UT, calibrated against the Pan-STARRS catalog. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31799 SUBJECT: GRB 220325A: Swift-BAT refined analysis DATE: 22/03/28 15:14:06 GMT FROM: Sibasish Laha at GSFC S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), A. Y. Lien (U Tampa) C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU), M. Stamatikos (OSU) (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 220325A (trigger #1099310) (Ferro et al., GCN Circ. 31787). The BAT ground-calculated position is RA, Dec = 269.469, -7.055 deg which is RA(J2000) = 17h 57m 52.7s Dec(J2000) = -07d 03' 18.4" with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 52%. The BAT light curve showed a complex structure with a duration of about 6 sec. T90 (15-350 keV) is 3.50 +- 0.56 sec (estimated error including systematics). The time-averaged spectrum from T-0.97 to T+3.02 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.69 +- 1.13, and Epeak of 39.3 +- 8.9 keV (chi squared 63.15 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 2.9 +- 0.4 x 10^-07 erg/cm2 and the 1-sec peak flux measured from T+0.53 sec in the 15-150 keV band is 2.0 +- 0.3 ph/cm2/sec. A fit to a simple power law gives a photon index of 2.06 +- 0.17 (chi squared 69.80 for 57 d.o.f.). 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/1099310/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31801 SUBJECT: GRB 220325A: Swift/UVOT Upper Limits DATE: 22/03/28 16:02:38 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) and M. Ferro (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 220325A 114 s after the BAT trigger (Ferro et al., GCN Circ. 31787). No optical afterglow consistent with the XRT position (Osborne et al. GCN Circ. 31790) 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 114 264 147 >20.8 u_FC 326 576 246 >20.1 white 114 5035 488 >21.0 v 657 1234 78 >18.7 b 582 4893 255 >20.1 u 326 4688 481 >20.3 w1 707 726 19 >17.9 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.915 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31804 SUBJECT: GRB 220325A: GRANDMA observations DATE: 22/03/29 18:08:27 GMT FROM: Sarah Antier at OCA C. Andrade, M. Coughlin (UNM), K. Noysena (NARIT), W. Kiendrebeogo (UJS), I. Tosta e Melo (INFN-LNS), X. F. Wang (TSU/BJP), F. Navarete (NOIRLab/SOAR) J. Zhu (BJP), L. Wang (XAO), A. Iskandar (XAO), X. Zeng (XAO), L. Abe, Ph. Bendjoya, J.-P. Rivet (Lagrange/OCA), D. Vernet (Galilee/OCA), S. Antier, A. de Ugarte Postigo (Artemis/OCA), A. M. Fouad, A. Taky, A. Shokry, I. Elhousiny, A. Eid, M. Farouk (NRIAG), P.A. Duverne (IJCLAB) report on behalf of the GRANDMA collaboration: The GRANDMA telescope network responded to the alert of GRB 220325A (Palmer et al. GCN 31787). The first observations started 4.28 h after the BAT trigger time. No new object was detected within the XRT enhanced error region (Evans et al. GCN 31794). In the following table we report the preliminary photometry of our observations. Upper limits are reported at the 3-sigma limit, in the AB system. T-T0 (hr)| MJD    | Observatory| Exposure| Filter   | Upp.Lim. (AB) _____________________________________________________________________ 04.28 |59663.89971| SNOVA      | 9x300s  | Bessel R | 20.1 04.44 |59663.90475| NOWT       | 11x180s | Bessel R | 19.7 08.11 |59664.05765| KAO        | 22x50s  |  SDSS i  | 21.2 10.14 |59664.14304| C2PU       | 16x240s |  SDSS r  | 20.8 These limits are consistent with the non-detections previously reported (Gupta et al. GCN 31793, Strausbaugh et al. GCN 31795, Nicuesa Guelbenzu et al. GCN 31797). The photometry of NOWT and SNOVA was performed using field stars from the APASS catalog. The KAO and C2PU image have been processed using field stars from the PanSTARRS-DR1 catalog and with the MUPHOTEN pipeline (Duverne et al. 2021). The magnitudes are not corrected for the Galactic extinction in the direction of the burst. GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/).