J/MNRAS/473/1512 AMI 15.7GHz GRB catalogue (Anderson+, 2018) ================================================================================ The Arcminute Microkelvin Imager catalogue of gamma-ray burst afterglows at 15.7 GHz. Anderson G.E., Staley T.D., van der Horst A.J., Fender R.P., Rowlinson A., Mooley K.P., Broderick J.W., Wijers R.A.M.J., Rumsey C., Titterington D.J. =2018MNRAS.473.1512A (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: GRB ; Gamma rays ; Radio sources Keywords: gamma-ray burst: general - radio continuum: transients Abstract: We present the Arcminute Microkelvin Imager (AMI) Large Array catalogue of 139 gamma-ray bursts (GRBs). AMI observes at a central frequency of 15.7GHz and is equipped with a fully automated rapid-response mode, which enables the telescope to respond to high-energy transients detected by Swift. On receiving a transient alert, AMI can be on-target within 2-min, scheduling later start times if the source is below the horizon. Further AMI observations are manually scheduled for several days following the trigger. The AMI GRB programme probes the early-time (<1d) radio properties of GRBs, and has obtained some of the earliest radio detections (GRB 130427A at 0.36 and GRB 130907A at 0.51d post-burst). As all Swift GRBs visible to AMI are observed, this catalogue provides the first representative sample of GRB radio properties, unbiased by multiwavelength selection criteria. We report the detection of six GRB radio afterglows that were not previously detected by other radio telescopes, increasing the rate of radio detections by 50 per cent over an 18-month period. The AMI catalogue implies a Swift GRB radio detection rate of >~15 per cent, down to ~0.2mJy/beam. However, scaling this by the fraction of GRBs AMI would have detected in the Chandra & Frail (2012, Cat. J/ApJ/746/156) sample (all radio-observed GRBs between 1997 and 2011), it is possible ~44-56 per cent of Swift GRBs are radio bright, down to ~0.1-0.15mJy/beam. This increase from the Chandra & Frail (2012, Cat. J/ApJ/746/156) rate (~30 per cent) is likely due to the AMI rapid-response mode, which allows observations to begin while the reverse-shock is contributing to the radio afterglow. Description: The radio observations of GRBs presented in this paper were obtained using AMI, which is a radio interferometer consisting of eight 12.8m diameter dishes with baselines between 18 and 110m. As all the observations were conducted prior to 2015 June, the effective frequency range was 13.9-17.5GHz using channels 3-7, each with a bandwidth of 0.72GHz, with channels 1, 2 and 8 being disregarded due to their susceptibility to radio frequency interference (RFI). Through the AMI GRB follow-up programme, we have produced the first catalogue of radio afterglows that is representative (i.e. not biased by target selection informed by prior knowledge of the event) of the radio properties of Swift-detected GRBs down to 0.2mJy/beam at 15.7GHz. This catalogue includes 139 GRBs, 132 of which were detected with Swift, and is made up of AMI observations up to >90d post-burst. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 83 227 The AMI 15.7GHz GRB catalogue: GRBs that have been detected or possibly detected with AMI table2.dat 91 783 The AMI 15.7GHz GRB catalogue: GRBs that were not detected with AMI, have a possible steady source association or a concatenated detection -------------------------------------------------------------------------------- See also: IX/51 : GRB list (1990-2014) (Ruggeri+, 2016) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 7 A7 --- GRB Name of GRB (1) 9- 10 A2 --- Flag Radio detection flag (2) 12- 20 A9 --- Tel Best Swift telescope position (3) 22- 31 A10 "date" Date Date of AMI observation (4) 32 A1 --- n_Date [C] C for Concat (4) 33- 40 F8.2 d Start ? Start of observation in Modified Julian Date (MJD) format 42- 44 F3.1 h Int ? Length of AMI observation 46- 50 F5.2 d DayPburst ? Number of days post-burst since the start of the AMI observation 52- 56 F5.2 min MinPburst ? Number of minutes post-burst since the start of the AMI observation (5) 60 A1 --- Det [*] * indicates the observations where the listed peak flux is a radio detection (6) 62- 66 F5.2 mJy/beam Fpeak ? Peak flux at 15.7GHz of the radio afterglow (7) 68- 73 F6.2 mJy/beam e_Fpeak ? Error in the peak flux at 15.7GHz measurement (1 sigma) (8) 75- 78 F4.1 --- Signi Significance of the flux measured in units of sigma above the local RMS 80- 83 F4.2 mJy/beam RMS The global RMS of the middle quarter of the AMI image -------------------------------------------------------------------------------- Note (1): All GRBs in this table are classed as long GRBs. All GRB observations from GRB 130907A onwards followed the updated ALARRM strategy (see Section 2.1). GRB 130702A and GRB 140320C were discovered by Fermi and Integral, respectively. Note (2): Radio detection abbreviations as follows: A = new radio GRB discovered with AMI AC = new radio GRB discovered with AMI that was only detected in the concatenated image R = radio afterglow first detected with another radio telescope P = possible new candidate radio GRB discovered with AMI Note (3): Best Swift telescope position used to search for a radio counterpart BAT = Swift Burst Alert Telescope XRT = Swift X-ray Telescope UVOT = Swift Ultraviolet/Optical Telescope. For GRB 150413A, the best optical position provided by the MASTER II robotic telescope (Ivanov et al. 2015, GCN, 17689) was used instead. Note (4): Date of the AMI observation in yyyy-mm-dd. C = Concat = concatenation of all epochs with the same pointing (in the case of GRB 120320A, two observations were taken with different pointings so the concatenated image is the same as the 2012-04-05 epoch). Note (5): This time is only provided for those AMI observations where the start time was <=0.01 days post-burst. Note (6): * indicates those GRBs for which the listed AMI peak flux is the measured flux of a radio source (signal-to-noise >=4) that is coincident with the best known Swift position of the GRB (i.e. within 3 positional sigma). All other listed fluxes are derived from a forced Gaussian fit at the best known Swift position. Note (7): Peak flux density as reported by PySE. Note (8): The 1 sigma error bar is the flux error output by PySE added in quadrature to the AMI 5% calibration error. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 7 A7 --- GRB Name of GRB (1) 9 A1 --- Type Short (S) or long (L) duration GRB 11- 12 A2 --- Flag Radio detection flag (2) 15- 20 A6 --- Tel Best Swift telescope position (3) 22- 31 A10 "date" Date Date of AMI observation (4) 32 A1 --- n_Date [C] C for Concat (4) 33- 40 F8.2 d Start ? Start of observation in Modified Julian Date (MJD) format 42- 45 F4.1 h Int ? Length of AMI observation 47- 52 F6.2 d DayPburst ? Number of days post-burst since the start of the AMI observation 56- 60 F5.2 min MinPburst ? Number of minutes post-burst since the start of the AMI observation (5) 63 A1 --- Det [*] * indicates the observations where the listed peak flux is a radio detection (6) 65- 70 F6.2 mJy/beam Fpeak Peak flux 15.7GHz of the radio afterglow (7) 72- 79 F8.2 mJy/beam e_Fpeak Error in the peak flux 15.7GHz measurement (1 sigma) (8) 82- 85 F4.1 --- Signi Significance of the flux measured in units of sigma above the local RMS 88- 91 F4.2 mJy/beam RMS The global RMS of the middle quarter of the AMI image -------------------------------------------------------------------------------- Note (1): All GRB observations from GRB 130813A onwards followed the updated ALARRM strategy (see Section 2.1). GRB 140320B was discovered by Integral and GRB 140508A, GRB 140606B, GRB 140623A, and GRB 140801A were discovered by Fermi. Note (2): Radio detection abbreviations R = radio afterglow first detected with another radio telescope S = AMI detected coincident radio source is likely steady C = coincident radio source detected in AMI concatenated image CS = coincident radio source detected in AMI concatenated image that is confirmed to be a steady source N = no detection Note (3): Best Swift telescope position used to search for a radio counterpart BAT = Swift Burst Alert Telescope XRT = Swift X-ray Telescope UVOT = Swift Ultraviolet/Optical Telescope. For GRB 130521A, the best optical position provided by Skynet/PROMPT (James et al., 2013, GCN, 14713) was used instead. Note (4): Date of the AMI observation in yyyy-mm-dd. C = Concat = concatenation of all epochs with the same pointing Note (5): This time is only provided for those AMI observations where the start time was <=0.01 days post-burst Note (6): * indicates those GRBs for which the listed AMI peak flux is the measured flux of a radio source (signal-to-noise >=4) that is coincident with the best known Swift position of the GRB (i.e. within 3 positional sigma). All other listed fluxes are derived from a forced Gaussian fit at the best known Swift position. Note (7): Peak flux density as reported by PySE. The PySE fitting algorithm failed on the 2012-04-05 and 2012-04-08 AMI observations of GRB 120311A and all of the GRB 121128A observations. The forced fits were instead conducted using MIRIAD and the reported significance is just the forced fitted peak flux divided by the global RMS. Note (8): The 1 sigma error bar is the flux error output by PySE added in quadrature to the AMI 5% calibration error. -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Patricia Vannier [CDS] 06-Aug-2020