Gamma-ray Burst 240122A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #35593
  H. Negoro (Nihon U.), W. Iwakiri (Chiba U.), M. Serino (AGU), M. Nakajima, K. Kobayashi, M. Tanaka, Y. Soejima, Y. Kudo (Nihon U.), T. Mihara, T. Kawamuro, S. Yamada, T. Tamagawa, N. Kawai, M. Matsuoka (RIKEN), T. Sakamoto, S. Sugita, H. Hiramatsu, H. Nishikawa, A. Yoshida (AGU), Y. Tsuboi, S. Urabe, S. Nawa, N. Nemoto, E.Goto (Chuo U.), M. Shidatsu, Y. Niida (Ehime U.), I. Takahashi, M. Niwano, S. Sato, N. Higuchi, Y. Yatsu (Tokyo Tech), S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, S. Ogawa, T. Kurihara (JAXA), Y. Ueda, K. Setoguchi, T. Yoshitake, Y. Nakatani, Y. Okada (Kyoto U.), M. Yamauchi, Y. Hagiwara, Y. Umeki, Y. Otsuki (Miyazaki U.), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU), and M. Sugizaki (NAOC)
  The MAXI/GSC nova alert system triggered on a faint uncatalogued X-ray transient source at 10:28:03 UT on January 22, 2024. Because our localization program did not run, we can not provide a precise error region. The source position determined with the nova alert system (Negoro et al. 2016) is (R.A., Dec) = (92.827 deg, -19.031 deg) = (06 11 18, -19 01 51) (J2000) with an uncertainty of more than 30 arc-min. The burst duration is about 10 sec, and the 2-10 keV X-ray flux around the peak was about 150 mCrab. There was no significant excess flux in the previous transit at 08:55 UT and in the next transit at 12:00 UT with an upper limit of 20 mCrab for each.
• GCN Circular #35595
  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 MAXI GRB 240122A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00119
  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 MAXI 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.
• GCN Circular #35596
  A. Kumar; B. P. Gompertz; K. Ackley; G. Ramsay; R. Starling; M. J. Dyer; J. Lyman; K. Ulaczyk; F. Jimenez-Ibarra; D. O'Neill; D. Steeghs; D. K. Galloway; V. Dhillon; P. O'Brien; K. Noysena; R. Kotak; R. P. Breton; L. K. Nuttall; E. Pall'e and D. Pollacco report on behalf of the GOTO collaboration:
  The Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022) serendipitously covered the localisation region of MAXI/GSC detected GRB 240122A (Negoro et al. GCN 35593) at 11:11:43 UT on 2024-01-22 (43.6 minutes after trigger). Each observation consisted of 4x45s exposures in the GOTO L-band (400-700 nm).
  Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using recent survey observations of the same pointings. Source candidates were initially filtered using a classifier (Killestein et al. 2021) and cross-matched against a variety of contextual and minor planet catalogues. Human vetting was carried out in real time on any candidates that passed the above checks.
  We identify 1 new optical transient (GOTO24eu/AT2024apy) within the MAXI/GSC uncertainty region. We find no evidence of this source prior to the GRB trigger time in the previous GOTO epoch at 2024-01-21 12:06:42 (22.4 hours prior), to a 5 sigma limiting magnitude of L > 19.8. The source was also not present in the ZTF observations provided by the Lasair broker (Smith et al. 2019), or the ATLAS forced photometry server (Shingles et al. 2021).

  Name | RA(J2000) | Dec(J2000) | Filter | Mag(AB)
  GOTO24eu/AT2024apy | 06:12:12.91| -19:08:38.81 | L | 17.06 +/- 0.04
  

  Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction.
  Observations are ongoing. GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC).
• GCN Circular #35597
  B. P. Gompertz (U. Birmingham) reports for a larger collaboration:
  We observed the position of the GOTO candidate optical counterpart (Kumar e= t al, GCN 35596) to the MAXI-detected GRB 240122A (Negoro et al, GCN 35593) with the IO:O optical camera on the 2m robotic Liverpool Telescope. Observ= ations consisted of 3x60s exposures in each of the SDSS r, i, and z filters under seeing of 2.1=E2=80=9D, beginning at 23:36:51 UT on 2024-01-22, 13.1= hours after the GRB trigger. We do not detect the source to a 3-sigma limi= ting magnitude of r(AB) > 19.36. This non-detection indicates fading of more than two magnitudes in the ~12.4 hours since the GOTO detection. Magnitudes were calibrated to PS1 stars and are not corrected for Galactic extinction.
• GCN Circular #35598
  C. C. Thoene (ASU-CAS), A. de Ugarte Postigo (CNRS/OCA and LAM), J. F. Agui= Fernandez (CAHA), L. Izzo (INAF/Capodimonte), J. P. U. Fynbo (DAWN/NBI), N= . R. Tanvir (U. Leicester), M. Blazek (CAHA), S. Geier, A. Garcia-Rodriguez= , Miguel Rivero Mendez (both GTC) report:
  We obtained spectroscopy of the optical afterglow (Kumar et al. GCN 35596) of the MAXI/GSC GRB 240122A (Negoro et al. GCN 35593) with OSIRIS+ at the 1= 0.4m GTC at a mean epoch of 0.5357 days after the GRB. The observation cons= isted of 3x900s exposures using grism R1000B, which covers the range betwee= n 3700 and 7780 AA at a resolving power of about 600. The observation was s= trongly impacted by the nearby Moon and poor seeing.
  A preliminary reduction of the spectrum shows a continuum with multiple abs= orption features. We determine the redshift of the GRB indentifying Lyman a= lpha and Lyman beta as well as absorption features of SiII, SiIV, CI, CII, CIV and FeII at a common redshift of z=3.162. We note that the Lyman seri= es is rather weak compared to typical GRB sight lines.
• GCN Circular #35599
  A. Saccardi (GEPI, Observatoire de Paris), B. Sbarufatti (INAF-OAB), D. B. Malesani (DAWN/NBI & Radboud Univ.), L. Izzo (INAF-OACn & DARK/NBI), A. de Ugarte Postigo (CNRS/OCA & LAM), S. Campana (INAF-OAB), A. J. Levan (Radboud Univ. & Warwick Univ.), D. Hartmann (Clemson University) report on behalf of the Stargate collaboration:
  Following the discovery of GOTO24eu/AT2024apy (Kumar et al. 2024, GCN 35596) within the error box of MAXI/GSC GRB 240122A (Negoro et al. 2024, GCN 35593), we acquired a spectrum of the optical counterpart candidate using the ESO/VLT/UT3 (Melipal) equipped with the X-shooter spectrograph. It covers the wavelength range 3000-21000 AA, and consists of 4 exposures of 1200 s each. Observations started at 02:25:37 UT on Jan 23 2024 (~16 hr after the trigger).
  We detect a continuum over the entire wavelength range. From the detection of a rather weak Lya absorption at ~5060 AA and multiple absorption features, which we interpret as being due to SiII, CII, MgII, SiIV and CIV, we infer a common redshift of z = 3.162 (consistent with Thoene et al. 2024, GCN 35598). We conclude this is the redshift of the burst. We also note the presence of additional absorption features likely due to multiple intervening systems, one of them very strong at z = 2.757 with a broad Lya at ~4570 AA.
  We acknowledge the excellent support from the ESO observing staff in Paranal, in particular Felipe Gaete and Jonathan Smoker.
• GCN Circular #35600
  E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR), D.N. Burrows (PSU), J. D. Gropp (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
  Swift-XRT has performed follow-up observations of the MAXI-detected burst GRB 240122A in a series of observations tiled on the sky. The total exposure time is 3.6 ks, distributed over 7 tiles; the maximum exposure at a single sky location was 1.3 ks. The data were collected between T0+29.5 ks and T0+35.6 ks, and are entirely in Photon Counting (PC) mode.
  Four uncatalogued X-ray sources are detected, of which one ("Source 3") is above the RASS 3-sigma upper limit at this position, and is therefore likely the GRB afterglow. Using 930 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 = 93.05391, -19.14418 which is equivalent to:

  RA (J2000): 06h 12m 12.94s
  Dec(J2000): -19d 08' 39.0"
  

  with an uncertainty of 2.9 arcsec (radius, 90% confidence). This position is 14.5 arcmin from the MAXI position, and it is consistent with the GOTO optical detection (GCN 35596, Kumar et al. 2024).
  The light curve can be modelled with a power-law decay with a decay index of alpha=2.5 (+0.7, -2.1).
  A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.82 (+0.33, -0.25). The best-fitting absorption column is consistent with the Galactic value of 1.0 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 3.3 x 10^-11 (3.6 x 10^-11) erg cm^-2 count^-1.
  A summary of the PC-mode spectrum is thus:

  Total column:	     1.0 (+/-0.8) x 10^21 cm^-2
  Galactic foreground: 1.0 x 10^21 cm^-2
  Excess significance: <1.6 sigma
  Photon index:	     1.82 (+0.33, -0.25)
  

  If the light curve continues to decay with a power-law decay index of 2.5, 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 3.8 x 10^-13 (4.2 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/00021645. The results of the full analysis of the tiled XRT observations are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00119.
  This circular is an official product of the Swift-XRT team.
• GCN Circular #35611
  Y.-D. Hu, F. Aceituno, E. Fernandez-Garcia, A. J. Castro-Tirado, M.D. Caballero-Garcia, R. Sanchez-Ramirez, I. Perez-Garcia, S.-Y. Wu, S. Guziy (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco, A. Reina (Univ. de Malaga), R. Fernandez-Munoz (IHSM/UMA-CSIC) and M. Jelinek (ASU-CAS), on behalf of a larger collaboration, report:
  Following the detection of GRB 240122A by MAXI/GSC (Negoro et al., GCNC 35593), we triggered the 0.6m BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC) in Algarrobo Costa (Malaga, Spain), and pointing to the burst position on Jan. 22 at 19:45 UT (i.e. ~9.3 hrs after trigger). In the co-added image (14 x 60 s, clear filter, affected by the bright moonlight), the optical afterglow reported by GOTO (Kumar et al. GCNC 35596), GTC (Thoene et al. GCNC 35598) and VLT (Saccardi et al. GCNC 35599) is not detected down to 17.6 mag, which is consistent with the limit reported by LT (GCNC 35597).
  Later on, we triggered the 1.5m telescope at Observatorio de Sierra Nevada (OSN) near Granada, Spain, starting on Jan. 22 at 23:46 UT (i.e. 13.3 hrs after trigger) in BVRI bands. The afterglow is clearly detected with I~20.1+-0.1 mag in the co-added image (7 x 90 s), and consistent with the enhanced XRT/Swift position (Ambrosi et al. GCNC 35600). Further imaging is ongoing.
  We thank the staff at both IHSM/UMA-CSIC La Mayora and OSN for their excellent support.
• GCN Circular #35613
  M. H. Siegel (PSU) and and V. D=E2=80=99Elia (SSDC & INAF-OAR) report on be= half of the Swift/UVOT team:
  The Swift/UVOT began settled observations of the field of GRB 240122A from 29.5 ks to 35.6 ks after the MAXI trigger (Negoro et al., GCN Circ. 35= 593). No optical afterglow consistent with either the optical (Kumar et al., GCN Circ. 35596) or X-ray (Ambrosi et al., GCN Circ. 3600) position is detected= in the initial UVOT exposures. The lack of detection in the u-band would be consistent wit= h the redshift of 3.162 given by Saccardi et al. (GCN Circ. 35599).
  Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures= of the candidate afterglow field are:

  Filter         T_start(s)   T_stop(s)      Exp(s)         Mag
  
  u                35166       35655          481         >20.4
  

  The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) =3D 0.064 in the direction of the burst (Schlegel et al. 1998).
• GCN Circular #35633
  O. Guiffreda (UMD), J. Durbak (UMD), A. S. Kutyrev (NASA/GSFC), E. Troja (U Rome), K. De (MIT), S. B. Cenko (NASA/GSFC)
  Following the MAXI/GSC detection (Negoro et al. GCN 35593), GOTO optical ca= ndidate GOTO24eu/AT2024apy (Kumar et al. GCN 35596), and the Swift afterglo= w detection (Ambrosi et al. GCN 35600), we observed the transient field usi= ng J and H filters with PRIME ~1.5 days after MAXI/GSC detection.
  At the position of the optical counterpart detected by GOTO, we detect an u= ncatalogued source in both J and H bands. Using nearby 2MASS stars for prel= iminary calibration we derive the following magnitudes, not corrected for G= alactic extinction:

  Filter | Mag(AB)        | SNR | Seeing | Total exposure time (s)=20
  
  -------|----------------|-----|--------|-------------------------
  
  J      | 21.02 +/- 0.20 | 6.3 | 1.373=E2=80=9D | 1802
  
  H      | 20.90 +/- 0.21 | 6.1 | 1.480=E2=80=9D | 1544
  

  PRIME is a 1.8m telescope with 1.56 square degree FOV (0.5 arcsec/pixel) lo= cated in Sutherland, South Africa.
  Further observations are planned.
  We thank the Osaka University observers at PRIME and the staff at SAAO for = their support with these observations.
• GCN Circular #35642
  G. E. Anderson (Curtin), A. Gulati (USyd), L. Rhodes (Oxford), J. K. Leung (UofT/HUJI), A. J. van der Horst (GWU), S. Chastain (UNM) on behalf of the PanRadio GRB collaboration
  The Australia Telescope Compact Array (ATCA) observed the MAXI-detected long GRB 240122A (Negoro et al., GCN 35593) at the GOTO (Kumar et al., GCN 35596) and Swift-XRT localisation (Ambrosi et al., GCN 35600) as part of the Large ATCA "PanRadio GRB" follow-up program C3542 (PI. Anderson).
  The observation took place on 2024-01-24 at 12:00 UT for 2.5 hours at 5.5 and 9 GHz. We detected a candidate radio afterglow at 9 GHz consistent with the GOTO and XRT position with a preliminary flux density of ~160 microJy with a RMS sensitivity of 20 microJy, and obtained a 3 sigma upper limit of 135 microJy at 5.5 GHz.
  Further observations are planned.
  We thank the CSIRO Space and Astronomy staff for supporting these observations. We acknowledge the Gomeroi people as the traditional owners of the Observatory site. The Australia Telescope Compact Array is part of the Australia Telescope National Facility (https://ror.org/05qajvd42) which is funded by the Australian Government for operation as a National Facility managed by CSIRO.