LIGO/Virgo G270580: AGILE MCAL and Super-AGILE Observations
Abstract
In response to the LIGO/Virgo GW event G270580 (GCN #20486) at T0 = 2017-01-20 12:30:59.350 UTC, the analysis of the AGILE data near T0 shows that the onboard data acquisition was interrupted due to the passage over the South Atlantic Anomaly (SAA), which covered the time interval (T0 - 280; T0 + 216) s. A preliminary AGILE-GW data processing identified two Mini-Calorimeter (MCAL) data acquisitions before and after the SAA passage. The first data interval (following an internal trigger) started at T1 = 12:26:14 UTC, and ended at T2 = 12:26:22 UTC. The second one, started at T3 = 12:36:16 UTC, and ended at T4 = 12:36:24 UTC. An analysis of these data does not reveal any significant transient event in the energy range 0.4-100 MeV. A preliminary three-sigma upper limit (UL) is obtained for a 1 s integration time at different celestial positions within the accessible G270580 localization region, for a typical fluence of 8.8e-7 erg cm^-2, in the 400-10000 keV energy range assuming a spectral photon index of 1.4. The Super-Agile (SA) detector had a partial coverage of the G270580 localization region at T0. No significant detection was obtained in the SA light curve (20-60 keV), for a stable background within +/- 100 s from T0. SA is an X-ray coded mask instrument with 40x40 deg field of view at half-sensitivity. Furthermore, a search in the AGILE anticoincidence (AC) and GRID ratemeters data did not produce any significant detection. The GRID large-FoV (2.5 sr) imaging instrument had no exposure near T0 of the G270580 localization region. The GRID data analysis in the energy range 30 MeV - 10 GeV is in progress, and the results will be reported in a following GCN.
- Publication:
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GRB Coordinates Network
- Pub Date:
- January 2017
- Bibcode:
- 2017GCN.20489....1L