//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 33129 SUBJECT: GRB 221231A: Fermi GBM Final Real-time Localization DATE: 22/12/31 21:57:19 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely LONG GRB At 21:46:05 UT on 31 Dec 2022, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 221231A (trigger 694215970.129412 / 221231907). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 332.7, Dec = 36.5 (J2000 degrees, equivalent to J2000 22h 10m, 36d 30'), with a statistical uncertainty of 5.2 degrees. The angle from the Fermi LAT boresight is 50.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221231907/quicklook/glg_skymap_all_bn221231907.png The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221231907/quicklook/glg_healpix_all_bn221231907.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221231907/quicklook/glg_lc_medres34_bn221231907.gif //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 33132 SUBJECT: GRB 221231A: Swift/BAT-GUANO arcminute localization of a possibly short burst DATE: 23/01/01 06:08:19 GMT FROM: Aaron Tohuvavohu at U Toronto Swift/BAT did not localize GRB 221231A onboard (T0: 2022-12-31T21:46:05 UTC, Fermi/GBM GCN 33129). The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu, arXiv:2111.01769), detects the burst in a 0.256 s analysis time bin with a sqrt(TS) of 14. An arcminute localization is found with DeltaLLHOut of 18.2 and a DeltaLLHPeak of 7.9. The burst duration as seen by BAT is less than 0.5 seconds. See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretations of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut. The BAT position is RA, Dec = 336.260, +25.138 deg which is RA(J2000) = 22h 25m 02.47s Dec(J2000) = +25d 08′ 18.6″ with an estimated uncertainty of 5 arcmin radius. XRT and UVOT follow-up has been requested. Results of follow-up observations will be reported in future circulars. GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 33133 SUBJECT: GRB 221231A: Swift ToO observations DATE: 23/01/01 06:37:59 GMT FROM: Phil Evans at U of Leicester P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a ToO observation of the Swift/BAT-GUANO GRB 221231A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021534 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the Swift/BAT-GUANO event. Any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 33135 SUBJECT: GRB 221231A: Swift-XRT observations DATE: 23/01/01 16:54:31 GMT FROM: Phil Evans at U of Leicester M. Perri (SSDC & INAF-OAR), A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU), J. D. Gropp (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Swift/BAT-GUANO-detected burst GRB 221231A, collecting 5.0 ks of Photon Counting (PC) mode data between T0+32.4 ks and T0+44.3 ks. Five uncatalogued X-ray sources have been detected, however none of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Sources 2 and 5 are inside the error box of Swift/BAT-GUANO, but source 5 is associated with a known source. Details of these sources are given below: Source 1: RA (J2000.0): 336.3458 = 22:25:22.98 Dec (J2000.0): +25.1723 = +25:10:20.3 Error: 6.5 arcsec (radius, 90% conf.) Count-rate: (9.1 [+7.3, -5.4])e-4 ct s^-1 Distance: 303 arcsec from Swift/BAT-GUANO position. Source 2: RA (J2000.0): 336.2560 = 22:25:1.44 Dec (J2000.0): +25.1298 = +25:07:47.2 Error: 3.1 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: 0.0107 [+0.0022, -0.0020] ct s^-1 Distance: 34 arcsec from Swift/BAT-GUANO position. Flux: (5.44 [+1.13, -1.00])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 3: RA (J2000.0): 336.2019 = 22:24:48.46 Dec (J2000.0): +25.0298 = +25:01:47.3 Error: 5.4 arcsec (radius, 90% conf.) Count-rate: (1.87 [+0.97, -0.73])e-3 ct s^-1 Distance: 435 arcsec from Swift/BAT-GUANO position. Flux: (7.8 [+4.0, -3.1])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 4: RA (J2000.0): 336.2146 = 22:24:51.50 Dec (J2000.0): +25.2635 = +25:15:48.7 Error: 8.9 arcsec (radius, 90% conf.) Count-rate: (1.48 [+0.87, -0.64])e-3 ct s^-1 Distance: 474 arcsec from Swift/BAT-GUANO position. Flux: (2.7 [+1.6, -1.2])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 5: RA (J2000.0): 336.2452 = 22:24:58.84 Dec (J2000.0): +25.1872 = +25:11:14.1 Error: 5.7 arcsec (radius, 90% conf.) Count-rate: (5.6 [+1.8, -1.5])e-3 ct s^-1 Distance: 182 arcsec from Swift/BAT-GUANO position. Flux: (1.12 [+0.37, -0.30])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/ToO_GRBs/00021534. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 33136 SUBJECT: GRB 221231A: AKO Upper Limit DATE: 23/01/01 17:47:10 GMT FROM: Mohammad Odeh at Al Khatim Observatory M44 Mohammad Odeh of Al-Khatim Observatory (AKO) operated by the International Astronomical Center, in Abu Dhabi, UAE. As a follow up for the GRB 221231A detected by Fermi/GBM (GCN 33129) and the observations of the Swift/BAT-GUANO (Perri et al., GCN 33135), we observed the localization of the five detected uncatalogued X-ray sources mentioned in GCN 33135. Our observation was done with our 0.36m f/7.7 robotic telescope on 01 January 2023 around 15:27 (UT), 17.7 hours after the GRB trigger. We obtained multiple 180-sec exposures in Ic filter. We did not detect any afterglow within the mentioned locations. The following upper limit was calculated using Atlas catalogue as a reference: ---------------------------------------------------------------------------- - JD (mid), T_mid-T0(hrs), Exposure (sec), Filter, Lim_mag ---------------------------------------------------------------------------- - 2459946.143993, 17.7, 5 x 180 (stacked), Ic, > 18.8 ---------------------------------------------------------------------------- - These magnitudes are not corrected for galactic extinction. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 33139 SUBJECT: GRB 221231A: Swift-XRT afterglow detection DATE: 23/01/02 11:54:58 GMT FROM: Phil Evans at U of Leicester M. Perri (SSDC & INAF-OAR), A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU), J. D. Gropp (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has conducted further observations of the field of the Swift/BAT-GUANO-detected burst GRB 221231A. The observations now extend from T0+32.7 ks to T0+120.0 ks. Of the sources reported by Perri et al. (GCN Circ. 33135), "Source 2" is fading with >3-sigma significance, and is therefore likely the GRB afterglow. Using 4154 s of PC mode data and 2 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 336.25600, +25.12978 which is equivalent to: RA (J2000): 22h 25m 01.44s Dec(J2000): +25d 07' 47.2" with an uncertainty of 3.0 arcsec (radius, 90% confidence). This position is 34 arcsec from the Swift/BAT-GUANO position. The light curve can be modelled with a power-law decay with a decay index of alpha=1.1 (+0.6, -0.5). The results of the XRT-team automatic analysis of the likely afterglow are at https://www.swift.ac.uk/ToO_GRBs/00021534/Source2.php. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/00021534. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 33146 SUBJECT: GRB 221231A: Fermi GBM Observation DATE: 23/01/04 05:01:54 GMT FROM: Stephen Lesage at Fermi-GBM Team S. Lesage (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 21:46:05 UT on 31 December 2022, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 221231A (trigger 694215970/221231907). which was also detected by Swift BAT (A. Tohuvavohu et al. 2023, GCN 33132) and Swift XRT GCN (M. Perri et al. 2023, 33139). The Fermi GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 61 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 5 s (50-300 keV). The time-averaged spectrum from T0-0.06 to T0+4.93 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.2 +/- 0.4 and the cutoff energy, parameterized as Epeak, is 200 +/- 40 keV. The event fluence (10-1000 keV) in this time interval is (4.4 +/- 0.4)E-07 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0 s in the 10-1000 keV band is 3.9 +/- 0.2 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: 33149 SUBJECT: GRB 221231A: 3.6m DOT optical upper limit DATE: 23/01/04 13:56:14 GMT FROM: Amit Kumar Ror at ARIES Amit K. Ror, Rahul Gupta, S. B. Pandey, A. Aryan, A. Ghosh, Dimple, and K. Misra (ARIES) report: We observed the field of GRB 221231A detected by Fermi/GBM (2022, GCN 33129) using the 3.6m Devasthal Optical Telescope of ARIES Nainital. We have taken multiple frames having an exposure time of 200 sec in the r filter. We stacked the images after the alignment. We did not find any evidence of an afterglow candidate inside the Swift XRT error circle (Perri et al. 2023, GCNs 33135 and 33139). We obtained the limiting mag of ~ 21.7 mag at ~ 1.87 days post-detection. The non-detection of the optical afterglow is consistent with Odeh 2023, GCN 32876. The limiting magnitudes quoted are not corrected for the Galactic and host extinction in the direction of the burst. Photometric calibration is performed using the standard stars from the Pan-STARRS catalog. This circular may be cited. 3.6m Devasthal Optical Telescope (DOT) is a recently commissioned facility in the Northern Himalayan region of India (long: 79 41 04E, lat: 29 21 40N, alt: 2540m) owned and operated by the Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital ( https://www.aries.res.in). The authors of this GCN circular thankfully acknowledge the consistent support from the staff members to run and maintain the 3.6m DOT.