GRB250530C

This page lists all entries on GRB250530C in GRBweb

Summary Swift GCN 40585 GCN 40586 GCN 40587 GCN 40589 GCN 40591 GCN 40609

Summary table
Variable Value Source
T0 18:58:42 UTC GCN_circulars,Swift Det
ra 55.1703° Swift
decl -22.4483° Swift
pos_error 2.46e-04° Swift
GBM_located False
mjd 60825.79076388889 GCN_circulars,Swift Det
Swift table
GRB_name GRB250530C
t_trigger 18:58:42 UTC
ra 55.1703°
decl -22.4483°
pos_error 2.46e-04°
GCN 40585 table
GRB_name GRB250530C
GCN_number 40585
Detection_method Swift Det
t_trigger 18:58:42 UTC
ra 55.1430°
decl -22.4590°
Circular_text TITLE: GCN CIRCULAR NUMBER: 40585 SUBJECT: GRB 250530C: Swift detection of a burst DATE: 25/05/30 19:23:04 GMT FROM: Boris Sbarufatti at INAF-OAB R. Caputo (GSFC), R. Caputo (NASA/GSFC), R. Gupta (NASA GSFC), J. A. Kennea (PSU), M. J. Moss (GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), T. M. Parsotan (GSFC), C. Salvaggio (INAF-OAB), T. Sbarrato (INAF-OAB) and B. Sbarufatti (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team: At 18:58:42 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250530C (trigger=1319125). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 55.143, -22.459 which is RA(J2000) = 3h 40m 34s Dec(J2000) = -22d 27' 32" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). Due to a telemetry gap, the immediately-available BAT light curve does not start until T+8s. This shows possible activity out to T+40 s. The count rate was ~200 counts/sec (15-350 keV), at the start of available light curve. A more complete description of the emission, including the trigger time, will require the full downlinked data from the next ground pass. The XRT began observing the field at 19:00:29.8 UT, 106.9 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 55.17029, -22.44825 which is equivalent to: RA(J2000) = 03h 40m 40.87s Dec(J2000) = -22d 26' 53.7" with an uncertainty of 1.9 arcseconds (radius, 90% containment). This location is 98 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 (1.70 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.6 (+2.00/-1.76) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 111 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 0.025. 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/)
GCN 40586 table
GRB_name GRB250530C
GCN_number 40586
Detection_method Swift-XRT Det
ra 55.1709°
decl -22.4480°
Circular_text TITLE: GCN CIRCULAR NUMBER: 40586 SUBJECT: GRB 250530C: Enhanced Swift-XRT position DATE: 25/05/31 00:38:35 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 2203 s of XRT Photon Counting mode data and 5 UVOT images for GRB 250530C, 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 = 55.17085, -22.44801 which is equivalent to: RA (J2000): 03h 40m 41.00s Dec (J2000): -22d 26' 52.8" with an uncertainty of 2.0 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.
GCN 40587 table
GRB_name GRB250530C
GCN_number 40587
Detection_method Swift Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 40587 SUBJECT: Swift GRB 250530C: Global MASTER-Net observations report DATE: 25/05/31 04:17:20 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) 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 250530C ( R. Caputo et al., GCN 40585) errorbox 31007 sec after notice time and 31055 sec after trigger time at 2025-05-31 03:36:18 UT, with upper limit up to 18.6 mag. The observations began at zenith distance = 79 deg. The sun altitude is -23.6 deg. The galactic latitude b = -51 deg., longitude l = 216 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2887090 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 31086 | MASTER-SAAO | C | 60 | 18.6 | 31086 | MASTER- | C | 60 | 13.1 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.
GCN 40589 table
GRB_name GRB250530C
GCN_number 40589
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 40589 SUBJECT: GRB 250530C: Swift-XRT refined Analysis DATE: 25/05/31 11:31:46 GMT FROM: Phil Evans at U of Leicester M.A. Williams (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M. Ferro (INAF-OAB), R. Brivio (INAF-OAB), A. D'Ai (INAF-IASFPA), S. Dichiara (PSU), J.A. Kennea (PSU) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 7.7 ks of XRT data for GRB 250530C, from 90 s to 52.0 ks after the trigger. The data comprise 9 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The light curve can be modelled with a power-law decay with a decay index of alpha=0.80 (+/-0.04). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.55 (+0.20, -0.19). The best-fitting absorption column is 2.8 (+1.1, -0.9) x 10^21 cm^-2, in excess of the Galactic value of 1.7 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 5.0 x 10^-11 (6.1 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.8 (+1.1, -0.9) x 10^21 cm^-2 Galactic foreground: 1.7 x 10^20 cm^-2 Excess significance: 4.7 sigma Photon index: 1.55 (+0.20, -0.19) If the light curve continues to decay with a power-law decay index of 0.80, the count rate at T+24 hours will be 0.012 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.0 x 10^-13 (7.3 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/01319125. This circular is an official product of the Swift-XRT team.
GCN 40591 table
GRB_name GRB250530C
GCN_number 40591
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 40591 SUBJECT: GRB 250530C: BOOTES-7 optical upper limit DATE: 25/05/31 17:31:45 GMT FROM: I. Perez-Garcia at Institute of Astrophysics of Andalusia I. Perez-Garcia, E. Fernandez-Garcia, S.-Y. Wu, M. D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy, and A. J. Castro-Tirado (IAA-CSIC, Granada), C. Perez del Pulgar (Univ. of Malaga), L. Hernandez-Garcia (Univ. of Valparaiso), M. Gritsevich (Univ. of Helsinki), Y.-D. Hu (GXU), B.-B. Zhang (Nanjing Univ.), and A. Maury (Space Obs., San Pedro de Atacama), on behalf of a larger collaboration, report: Following the detection of GRB 250530C by Swift (Osborne et al., GCNC [40586](https://gcn.nasa.gov/circulars/40586)), the 0.6m BOOTES-7 robotic telescope at Space Observatory (San Pedro de Atacama, Chile) automatically responded to this high-energy event starting on May 21, 09:42:59 UT (i.e., 14.73 hour after detection), observing at low elevation (airmass ≈ 5). No optical transient is detected down to 16.4 mag (clear filter). On a coadd (11) of images at 09:51:43 UT (mid exposure time; i.e. 14.88 post burst), nothing is detected down to 18.2 mag. We would like to thank the staff at San Pedro de Atacama Space Observatory for their excellent support.
GCN 40609 table
GRB_name GRB250530C
GCN_number 40609
Detection_method Swift-BAT Det
ra 55.1460°
decl -22.4570°
Circular_text TITLE: GCN CIRCULAR NUMBER: 40609 SUBJECT: GRB 250530C: Swift-BAT refined analysis DATE: 25/06/02 19:11:33 GMT FROM: Mike Moss at NASA GSFC D. Sadaula (GSFC/UMBC), S. D. Barthelmy (GSFC), R. Caputo (NASA/GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+885 sec from the recent telemetry downlink, we report further analysis of BAT GRB 250530C (trigger #1319125) (Caputo, et al., GCN Circ. 40585). The BAT ground-calculated position is RA, Dec = 55.146, -22.457 deg which is RA(J2000) = 03h 40m 35.1s Dec(J2000) = -22d 27' 26.1" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 96%. The mask-weighted light curve displays a complex structure with multiple dim pulses. The T90 (15-350 keV) is 42.86 +- 6.04 sec (estimated error including systematics). The time-averaged spectrum from T-29.77 to T+21.26 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.32 +- 0.17. The fluence in the 15-150 keV band is 8.5 +- 0.9 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T-0.28 sec in the 15-150 keV band is 0.8 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1319125