//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 33505 SUBJECT: GRB 230322B: Swift detection of a burst with optical counterpart DATE: 23/03/22 21:25:32 GMT FROM: Kim Page at U.of Leicester S. B. Cenko (GSFC), J.D. Gropp (PSU), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), S. Laha (GSFC/UMBC), F. E. Marshall (NASA/GSFC), M. J. Moss (GWU), K. L. Page (U Leicester) and M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 21:10:37 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 230322B (trigger=1161127). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 16.565, -47.729 which is RA(J2000) = 01h 06m 16s Dec(J2000) = -47d 43' 42" 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 ~30 sec. The peak count rate was ~900 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 21:12:31.7 UT, 113.8 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 16.55359, -47.70106 which is equivalent to: RA(J2000) = 01h 06m 12.86s Dec(J2000) = -47d 42' 03.8" with an uncertainty of 1.9 arcseconds (radius, 90% containment). This location is 104 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. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (2.48 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.5 (+2.99/-2.59) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 118 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 01:06:12.85 = 16.55353 DEC(J2000) = -47:42:02.8 = -47.70079 with a 90%-confidence error radius of about 0.62 arc sec. This position is 0.7 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.60 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.017. Burst Advocate for this burst is S. B. Cenko (brad.cenko 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: 33506 SUBJECT: Swift GRB 230322B: Global MASTER-Net observations report DATE: 23/03/23 03:40:29 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev (Irkutsk State University, API), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (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 230322B ( S. B. Cenko et al., GCN 33505) errorbox 22856 sec after notice time and 22880 sec after trigger time at 2023-03-23 03:31:58 UT, with upper limit up to 15.7 mag. Observations started at twilight. The observations began at zenith distance = 85 deg. The sun altitude is -15.9 deg. The galactic latitude b = -69 deg., longitude l = 295 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2205479 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 22970 | MASTER-SAAO | C | 180 | 15.7 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 33507 SUBJECT: GRB 230322B: Enhanced Swift-XRT position DATE: 23/03/23 03:49:17 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 957 s of XRT Photon Counting mode data and 1 UVOT images for GRB 230322B, 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 = 16.55333, -47.70077 which is equivalent to: RA (J2000): 01h 06m 12.80s Dec (J2000): -47d 42' 02.8" with an uncertainty of 2.3 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: 33508 SUBJECT: GRB 230322B: Swift-XRT refined Analysis DATE: 23/03/23 06:31:41 GMT FROM: Phil Evans at U of Leicester J. D. Gropp (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), B. Sbarufatti (INAF-OAB), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAR), S. Dichiara (PSU), J.A. Kennea (PSU) and S.B. Cenko report on behalf of the Swift-XRT team: We have analysed 7.8 ks of XRT data for GRB 230322B (Cenko et al. GCN Circ. 33505), from 123 s to 24.7 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. 33507). The light curve can be modelled with a power-law decay with a decay index of alpha=0.61 (+/-0.05). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.09 (+0.21, -0.19). The best-fitting absorption column is 8.7 (+5.1, -4.4) x 10^20 cm^-2, in excess of the Galactic value of 2.5 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 3.1 x 10^-11 (3.8 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 8.7 (+5.1, -4.4) x 10^20 cm^-2 Galactic foreground: 2.5 x 10^20 cm^-2 Excess significance: 2.3 sigma Photon index: 2.09 (+0.21, -0.19) If the light curve continues to decay with a power-law decay index of 0.61, the count rate at T+24 hours will be 0.015 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.8 x 10^-13 (5.9 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/01161127. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 33512 SUBJECT: GRB 230322B: Swift/UVOT Detection DATE: 23/03/23 13:58:42 GMT FROM: Samantha Oates at MSSL S. R. Oates (U. of Birmingham) and S. B. Cenko (GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 230322B 119 s after the BAT trigger (Cenko et al., GCN Circ. 33505). A source consistent with the XRT position (Evans et al. GCN Circ. 33507) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 01:06:12.84 = 16.55350 (deg.) Dec (J2000) = -47:42:02.8 = -47.70079 (deg.) with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits 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 119 269 147 17.60 +/- 0.04 v 661 1061 58 >18.3 b 758 778 19 18.55 +/- 0.36 u 332 581 246 17.63 +/- 0.08 w1 710 1095 19 16.90 +/- 0.28 m2 1064 1084 19 17.17 +/- 0.35 w2 635 655 19 17.36 +/- 0.32 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.017 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 33519 SUBJECT: GRB 230322B: Swift-BAT refined analysis DATE: 23/03/25 17:01:17 GMT FROM: Amy Lien at GSFC S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), S. B. Cenko (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-826 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 230322B (trigger #1161127) (Cenko et al., GCN Circ. 33505). The BAT ground-calculated position is RA, Dec = 16.550, -47.709 deg which is RA(J2000) = 01h 06m 12.1s Dec(J2000) = -47d 42' 31.2" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 92%. The mask-weighted light curve shows a single-peaked FRED-like structure that starts at ~T-3 s, peaks at ~T0, and ends at ~T+11 s. T90 (15-350 keV) is 11.61 +- 2.17 sec (estimated error including systematics). The time-averaged spectrum from T-2.41 to T+11.12 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.07 +- 0.26. The fluence in the 15-150 keV band is 3.7 +- 0.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.02 sec in the 15-150 keV band is 1.1 +- 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/1161127/BA/