//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31407 SUBJECT: GRB 220107B: Tiled Swift observations DATE: 22/01/08 04:36:42 GMT FROM: Phil Evans at U of Leicester P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a series of observations, tiled on the sky, of the Fermi/LAT GRB 220107B. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00103 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. The probability of finding serendipitous sources, unrelated to the Fermi/LAT event is high: 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: 31409 SUBJECT: GRB 220107B: Fermi-LAT detection DATE: 22/01/08 06:05:07 GMT FROM: Magnus Axelsson at Stockholm U. M. Arimoto (Kanazawa Univ.), N. Di Lalla (Stanford Univ.), M. Axelsson (KTH & Stockholm Univ.) and S. Cutini (INFN Perugia) report on behalf of the Fermi-LAT Collaboration: On January 7th, 2022, Fermi-LAT detected high-energy emission from GRB 220107B, which was also detected by Fermi-GBM (trigger 663274898/220107793). The best LAT on-ground location is found to be RA, Dec = 216.5, 20.0 (degrees, J2000) with an error radius of 0.22 deg (90% containment, statistical error only). This was 54 deg from the LAT boresight at the time of the GBM trigger: T0 = 19:01:33.52 UT. The data from the Fermi-LAT show a significant increase in the event rate after the GBM trigger that is temproally and spatially correlated with the GBM emission (2.3 degrees from the GBM location) with high significance. The photon flux above 100 MeV in the time interval 0-500s after the GBM trigger is 1.4E-5 +/- 2.4E-6 ph/cm2/s. The estimated photon index above 100 MeV is -2.14 +/- 0.17. The highest-energy photon is a 2.4 GeV event which is observed ~8 seconds after the GBM trigger. A Swift ToO has been approved for this burst. The Fermi-LAT point of contact for this burst is Sara Cutini (sara.cutini@pg.infn.it). The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31411 SUBJECT: GRB 220107B: Swift-XRT afterglow detection DATE: 22/01/08 09:33:21 GMT FROM: Phil Evans at U of Leicester J. D. Gropp (PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), A. Tohuvavohu (U. Toronto) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Fermi/LAT-detected burst GRB 220107B (Arimoto et al. GCN Circ. 31409) in a series of observations tiled on the sky. The total exposure time is 1.3 ks, distributed over 2 tiles; the maximum exposure at a single sky location was 1.0 ks. The data were collected between T0+35.7 ks and T0+36.2 ks, and are entirely in Photon Counting (PC) mode. An uncatalogued X-ray source is detected and is above the RASS 3-sigma upper limit at this position, and is therefore likely the GRB afterglow. Using 546 s of PC mode data and 1 UVOT image, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 216.40652, +20.17064 which is equivalent to: RA (J2000): 14h 25m 37.56s Dec(J2000): +20d 10' 14.3" with an uncertainty of 3.4 arcsec (radius, 90% confidence). This position is 11.5 arcmin from the Fermi/LAT position. The source has a mean count rate of 1.3e-01 ct/sec; while we cannot determine at the present time whether it is fading, the fact that the source is well above RASS limit strongly suggests it is the X-ray afterglow of GRB 220107B. More data are currently being collected. The results of the XRT-team automatic analysis of the likely afterglow are at https://www.swift.ac.uk/xrt_products/TILED_GRB00103/Source1.php. The results of the full analysis of the tiled XRT observations are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00103. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31412 SUBJECT: GRB 220107B: AstroSat CZTI detection DATE: 22/01/08 13:20:02 GMT FROM: Gaurav Waratkar at IIT,Bombay A. Suresh (IITB), V. Prasad (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed detection of a long GRB 220107B, which was also detected by Fermi-GBM (trigger 663274898/220107793), Fermi-LAT (Axelsson et al., GCN 31409) and Swift-XRT (Gropp et al., GCN 31411). The source was clearly detected in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2022-01-07 19:01:45.50 UT. Quadrant B was noisy, and we exclude it from further analysis. The measured peak count rate associated with the burst is 372 (+44 -42) cts/s above the background in the combined data of three quadrants (out of four), with a total of 2558 (+225 -239) cts. The local mean background count rate was 382 (+2 -2) cts/s. Using cumulative rates, we measure a T90 of 19 (+3 -1) s. It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2022-01-07 19:01:35.775 UT. The measured peak count rate is 826 (+81 -85) cts/s above the background in the combined Veto data of four quadrants, with a total of 5424 (+496 -555) cts. The local mean background count rate was 1721 (+4 -5) cts/s. We measure a T90 of 22 (+2 -3) s from the cumulative Veto light curve. CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb [1]. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. Links: ------ [1] http://astrosat.iucaa.in/czti/?q=grb //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31414 SUBJECT: GRB 220107B: Fermi GBM observations DATE: 22/01/08 15:59:52 GMT FROM: Peter Veres at UAH P. Veres and C. Meegan (both UAH) report on behalf of the Fermi GBM Team: "At 19:01:33.52 UT on 7 January 2022, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 220107B (trigger 663274898 / 220107793), which was also detected by the Fermi LAT (Arimoto et al., GCN 31409). The GBM on-ground location is consistent with the LAT position. The GBM light curve consists of multiple separated pulses with a duration (T90) of about 25 s (50-300 keV). The time-averaged spectrum from T0-1.7 s to T0+27 s is best fit by a Band function with Epeak = 391 +/- 21 keV, alpha = -0.86 +/- 0.03, and beta = -2.40 +/- 0.16. The event fluence (10-1000 keV) in this time interval is (2.68 +/- 0.03)E-5 erg/cm^2. The 1-sec peak photon flux measured starting from T0+12.0 s in the 10-1000 keV band is 14.4 +/- 0.3 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: 31417 SUBJECT: GRB 220107B: Nanshan/NEXT optical upper limits and host galaxy candidate DATE: 22/01/09 04:04:47 GMT FROM: Dong Xu at NAOC/CAS S.Q. Jiang, S.Y. Fu (NAOC), Z.P. Zhu (NAOC, HUST), X. Liu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report: We observed the field of GRB 220107B detected by Fermi (Arimoto et al., GCN 31409; Veres & Meegan, GCN 31414) and AstroSat (Suresh et al., GCN 31412), using the NEXT-0.6m telescope located at Nanshan, Xinjiang, China. We obtained 6x300 s frames in the Sloan r-band and 5x300 s frames in Sloan z-band, starting at 21:30:31 UT on 2022-01-08. No optical source is detected in our stacked images at the Swift-XRT position (Gropp et al., GCN 31411). Preliminary photometric results are as follows: Tmid-T0 (hr) Filter Upper Limit(5-sigma) 26.97 r >21.3 27.44 z >19.3 calibrated with the nearby PanSTARRS field. In addition, from Legacy Survey there exists a faint source at the border of the Swift-XRT error circle at coordinates R.A. (J2000) = 14:25:37.66 and Dec. (J2000) = +20:10:17.01, and magnitudes of g ~ 24.62, r ~ 24.51, z ~ 23.32 as well as a photo_redshift = 1.13 +/- 0.23. The source is not present in SDSS and PanSTARR, and might be the host of the burst. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31418 SUBJECT: GRB 220107B: MITSuME Akeno optical upper limits DATE: 22/01/09 09:54:23 GMT FROM: Masafumi Niwano at Tokyo Institute of Tech M. Niwano, R. Hosokawa, Y. Imai, K. L. Murata, Y. Takamatsu, N. Ito, R. Noto, S. Sato, M. Takaku, R. Yamaguchi, Y. Yatsu, and N. Kawai (TokyoTech) report on behalf of the MITSuME collaboration: We observed the field of GRB 220107B (M. Arimoto et al. GCN Circular #31409, P. A. Evans et al. #31407, J. D. Gropp et al. #31411,  A. Suresh et al. #31412, P. Veres and C. Meegan #31414, S.Q. Jiang et al. #31417) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope Akeno. The observation with a series of 60 sec exposures started at 2022-01-08 17:04:13 UT (22 hours after Fermi trigger). We stacked the images with good conditions. We did not detect any uncatalogued sources within the XRT error region (J. D. Gropp et al. GCN Circular #31411). We obtained the 5-sigma limits of the stacked images as follows. T0+[hours] MID-UT T-EXP[sec] 5-sigma limits ------------------------------------------------------------------------------------------------ 22.0 2022-01-08 18:58:13 11820 g'>20.7, Rc>20.9, Ic>20.1 ------------------------------------------------------------------------------------------------ T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used PS1 catalog for flux calibration. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31427 SUBJECT: Confirmation of the X-ray afterglow of GRB 220107B DATE: 22/01/10 14:39:41 GMT FROM: Kim Page at U.of Leicester K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed a second follow-up observation of the Fermi/LAT-detected GRB 220107B (Arimoto et al., GCN 31409), ~184 ks after the trigger. The source suggested to be the X-ray counterpart in GCN 31411 (Gropp et al.) has clearly faded, with a power-law slope of alpha = 1.54 (+0.32, -0.24), and is therefore confirmed as the X-ray afterglow. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31430 SUBJECT: Konus-Wind detection of GRB 220107B DATE: 22/01/10 19:42:50 GMT FROM: Anna Ridnaia at Ioffe Institute A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 220107B (Fermi-LAT detection: Arimoto et al., GCN 31409; AstroSat CZTI detection: Suresh et al., GCN 31412; Fermi-GBM observation: Veres and Meegan et al., GCN 31414) triggered Konus-Wind at T0=68494.81 s UT (19:01:34.810). The burst light curve shows a multipeaked structure started at ~T0-1.2 s with a total duration of ~26.4 s. The emission is seen up to ~4 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB220107_T68494/ As observed by Konus-Wind, the burst had a fluence of 4.20(-0.78,+0.91)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+1.728 s, of 8.07(-2.17,+2.27)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+32.768 s) is best fit in the 20 keV - 4 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.73(-0.19,+0.27), the high energy photon index beta = -2.18(-0.38,+0.22), the peak energy Ep = 309(-65,+72) keV (chi2 = 54/69 dof). The spectrum near the maximum count rate (measured from T0+0.256 to T0+8.192 s) is best fit in the 20 keV - 4 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.58(-0.17,+0.20), the high energy photon index beta = -2.21(-0.37,+0.21), the peak energy Ep = 334(-56,+68) keV (chi2 = 54/70 dof). All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.