//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31684 SUBJECT: GRB 220305A: Swift detection of a burst DATE: 22/03/05 16:21:41 GMT FROM: David Palmer at LANL R. Caputo (GSFC), C. Gronwall (PSU), J.D. Gropp (PSU), J. A. Kennea (PSU), A. Y. Lien (U Tampa), K. L. Page (U Leicester), D. M. Palmer (LANL) and T. M. Parsotan (GSFC/UMBC/CRESSTII) report on behalf of the Neil Gehrels Swift Observatory Team: At 16:13:08 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 220305A (trigger=1095215). Due to a viewing constraint, Swift did not immediately slew. The BAT on-board calculated location is RA, Dec 107.584, -37.708 which is RA(J2000) = 07h 10m 20s Dec(J2000) = -37d 42' 29" 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 40 sec. The peak count rate was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger. Due to an observing constraint, Swift will not slew until T0+46.5 minutes. There will be no XRT or UVOT data until this time. Burst Advocate for this burst is R. Caputo (regina.caputo 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: 31685 SUBJECT: GRB 220305A: Swift-XRT observations DATE: 22/03/05 17:44:49 GMT FROM: Phil Evans at U of Leicester D.N. Burrows (PSU), J.A. Kennea (PSU), S. Campana (INAF-OAB), G. Cusumano (INAF-IASF PA), P.A. Evans (U. Leicester) and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team: The XRT began observing the field of GRB 220305A at 17:03:25.5 UT, 3016.9 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 107.59841, -37.68016 which is equivalent to: RA(J2000) = 07h 10m 23.62s Dec(J2000) = -37d 40' 48.6" with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 108 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 in excess of the Galactic value (2.59 x 10^21 cm^-2, Willingale et al. 2013), with an excess column of 8.1 (+6.60/-5.31) x 10^21 cm^-2 (90% confidence). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31686 SUBJECT: Swift GRB 220305A: Global MASTER-Net observations report DATE: 22/03/05 17:56:47 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, T.Pogrosheva, E.Minkina, A.Chasovnikov, V.Topolev, V.Grinshpun, D.Kuvshinov, D. Cheryasov (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), B.L.Carrasco, J.R.Valdes,V.Chavushyan, C.J.Martinez, V.M.Patino Alvarez, M.L.H.Rodriguez (INAOE, OAGH) 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 220305A ( R. Caputo et al., GCN 31684) errorbox 5464 sec after notice time and 5486 sec after trigger time at 2022-03-05 17:44:35 UT, with upper limit up to 16.4 mag. Observations started at twilight. The observations began at zenith distance = 16 deg. The sun altitude is -8.2 deg. The galactic latitude b = -12 deg., longitude l = 249 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1902942 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 5577 | MASTER-SAAO | P\ | 180 | 16.0 | 5776 | MASTER-SAAO | P\ | 180 | 16.4 | The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31688 SUBJECT: GRB 220305A: Enhanced Swift-XRT position DATE: 22/03/05 20:29:02 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 1712 s of XRT Photon Counting mode data and 5 UVOT images for GRB 220305A, 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 = 107.59853, -37.68033 which is equivalent to: RA (J2000): 07h 10m 23.65s Dec (J2000): -37d 40' 49.2" with an uncertainty of 2.2 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: 31689 SUBJECT: GRB 220305A: Fermi GBM observation DATE: 22/03/05 23:40:22 GMT FROM: Joe Mangan at UCD R. Dunwoody (UCD), J. Mangan (UCD) and C.Meegan (UAH) report on behalf of the Fermi GBM Team: "At 11:33:20.48 UT on 05 March 2022, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 220305A (trigger 668172805 / 220305481). The on-ground calculated location, using the GBM trigger data, is RA = 174, DEC = -34 (J2000 degrees, equivalent to 11 h 36 m, -34 d 00 '), with a statistical uncertainty of 1.5 degrees. The angle from the Fermi LAT boresight at the GBM trigger time is 35 degrees. The GBM light curve consists of three emission episodes, the most prominent occurring around T0+50s, with a duration (T90) of about 172.8 s (50-300 keV). The time-averaged spectrum for the first emission episode, from T0-12.3 to T0+12.3, is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.6 +/- 0.5 and the cutoff energy, parameterized as Epeak, is 60.9 +/- 9.1 keV. The event fluence (10-1000 keV) in this time interval is (6.8 +/- 0.8)E-07 erg/cm^2. The time-averaged spectrum for the second emission episode, from T0+39.9 to T0+60.4, is best fit by a Band function with Epeak = 320.7 +/- 35.7 keV, alpha = -0.9 +/- 0.1, and beta = -1.9 +/- 0.1. The event fluence (10-1000 keV) in this time interval is (1.78 +/- 0.03)E-05. The time-averaged spectrum for the third emission episode, from T0+164.9 to T0+193.5, is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.3 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 205.2 +/- 42.8 keV. The event fluence (10-1000 keV) in this time interval is(3.5 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+49.6 s in the 10-1000 keV band is 19.5 +/- 0.4 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog:https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page:https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31690 SUBJECT: Correction to GCN 31689: Fermi GBM Report of GRB 220305A should be GRB 220305B DATE: 22/03/06 00:27:22 GMT FROM: Adam Goldstein at Fermi-GBM, USRA R. Dunwoody (UCD), J. Mangan (UCD), and C.Meegan (UAH) report on behalf of the Fermi GBM Team: "At 11:33:20.48 UT on 05 March 2022, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 220305B (trigger 668172805 / 220305481). The on-ground calculated location, using the GBM trigger data, is RA = 174, DEC = -34 (J2000 degrees, equivalent to 11 h 36 m, -34 d 00 '), with a statistical uncertainty of 1.5 degrees. The angle from the Fermi LAT boresight at the GBM trigger time is 35 degrees. The GBM light curve consists of three emission episodes, the most prominent occurring around T0+50s, with a duration (T90) of about 172.8 s (50-300 keV). The time-averaged spectrum for the first emission episode, from T0-12.3 to T0+12.3, is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.6 +/- 0.5 and the cutoff energy, parameterized as Epeak, is 60.9 +/- 9.1 keV. The event fluence (10-1000 keV) in this time interval is (6.8 +/- 0.8)E-07 erg/cm^2. The time-averaged spectrum for the second emission episode, from T0+39.9 to T0+60.4, is best fit by a Band function with Epeak = 320.7 +/- 35.7 keV, alpha = -0.9 +/- 0.1, and beta = -1.9 +/- 0.1. The event fluence (10-1000 keV) in this time interval is (1.78 +/- 0.03)E-05. The time-averaged spectrum for the third emission episode, from T0+164.9 to T0+193.5, is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.3 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 205.2 +/- 42.8 keV. The event fluence (10-1000 keV) in this time interval is(3.5 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+49.6 s in the 10-1000 keV band is 19.5 +/- 0.4 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog:https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page:https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31691 SUBJECT: Fermi GRB 220305A: Global MASTER-Net observations report DATE: 22/03/06 04:15:27 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, T.Pogrosheva, E.Minkina, A.Chasovnikov, V.Topolev, V.Grinshpun, D.Kuvshinov, D. Cheryasov (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), B.L.Carrasco, J.R.Valdes,V.Chavushyan, C.J.Martinez, V.M.Patino Alvarez, M.L.H.Rodriguez (INAOE, OAGH) A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational State University) MASTER-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 220305A ( R. Dunwoody et al., GCN 31689) errorbox 56245 sec after notice time and 56274 sec after trigger time at 2022-03-06 03:11:15 UT, with upper limit up to 18.3 mag. The observations began at zenith distance = 25 deg. The sun altitude is -46.7 deg. The galactic latitude b = 26 deg., longitude l = 287 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1902853 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 56305 | 2022-03-06 03:11:15 | MASTER-OAFA | (11h 29m 45.56s , -35d 27m 42.1s) | C | 60 | 15.9 | 58403 | 2022-03-06 03:46:13 | MASTER-OAFA | (11h 29m 45.60s , -35d 28m 47.3s) | C | 60 | 18.3 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31695 SUBJECT: GRB 220305A: Swift-XRT refined Analysis DATE: 22/03/06 09:54:42 GMT FROM: Phil Evans at U of Leicester V. D'Elia (SSDC & INAF-OAR), A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB) and R. Caputo report on behalf of the Swift-XRT team: We have analysed 6.2 ks of XRT data for GRB 220305A (Caputo et al. GCN Circ. 31684), from 3.0 ks to 43.5 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 31688). The light curve can be modelled with a power-law decay with a decay index of alpha=1.22 (+0.11, -0.10). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.34 (+0.28, -0.26). The best-fitting absorption column is 8.3 (+2.0, -1.8) x 10^21 cm^-2, in excess of the Galactic value of 2.6 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 3.8 x 10^-11 (9.1 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 8.3 (+2.0, -1.8) x 10^21 cm^-2 Galactic foreground: 2.6 x 10^21 cm^-2 Excess significance: 5.3 sigma Photon index: 2.34 (+0.28, -0.26) If the light curve continues to decay with a power-law decay index of 1.22, the count rate at T+24 hours will be 7.0 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.7 x 10^-13 (6.3 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/01095215. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31696 SUBJECT: Fermi GBM Sub-Threshold Detection of GRB 220305A DATE: 22/03/06 16:47:37 GMT FROM: Joshua Wood at MSFC/Fermi-GBM J. Wood (NASA/MSFC) reports on behalf of the Fermi-GBM Team: Swift-BAT detected GRB 220305A at 16:13:08 UT on 05 March, 2022 (Caputo et al. GCN 31684). There was no Fermi-GBM onboard trigger around the time of the event. An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM identified no counterparts. The GBM targeted search [1], the most sensitive, coherent search for GRB-like signals identified a transient most significantly on the 8.192 s timescale, with a location consistent with the Swift-BAT event and a signal-to-noise ratio of 17.8, using the standard search protocol. 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. This analysis is preliminary. [1] Goldstein et al. 2019 arXiv:1903.12597 Note: Fermi-GBM also detected GRB 220305B at 11:33:20.48 UT on 05 March 2022 which was erroneously named GRB 220305A at the time of its initial publication (GCN 31689, 31690). GRB 220305B is a different burst than the one described here. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31698 SUBJECT: GRB 220305A: Swift-BAT refined analysis DATE: 22/03/06 18:33:18 GMT FROM: Amy Lien at GSFC M. Stamatikos (OSU), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC), R. Caputo (GSFC), T. Sakamoto (AGU) (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 220305A (trigger #1095215) (Caputo et al., GCN Circ. 31684). The BAT ground-calculated position is RA, Dec = 107.610, -37.703 deg which is RA(J2000) = 07h 10m 26.4s Dec(J2000) = -37d 42' 09.2" with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 25%. The mask-weighted light curve shows a single-pulse structure that starts at ~T-15 s, peaks at ~T0, and ends at ~T+11 s. The burst went out of the BAT FOV at T+225.7 s. T90 (15-350 keV) is 21.12 +- 3.65 sec (estimated error including systematics). The time-averaged spectrum from T-15.04 to T+11.02 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.66 +- 0.15. The fluence in the 15-150 keV band is 2.0 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-0.16 sec in the 15-150 keV band is 2.1 +- 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/1095215/BA/