LIGO/Virgo S200213t: Continued Swift UVOT and XRT observations of ZTF20aamvmzj (AT2020cja)
Abstract
We report continued Swift/UVOT and XRT observations of ZTF20aamvmzj (AT2020cja; Kasliwal et al., GCN Circ. 27051) found by Zwicky Transient Facility during the search for the EM counterpart of the LVC event S200213t (LIGO/VIRGO Collaboration GCN Circ. 27042). This object was also observed by Lulin (Li et al., GCN Circ. 27082) and spectroscopically by DBSP (Ho et al., GCN Circ. 27074). The Swift/UVOT detection was reported in Oates et al., (GCN Circ. 27153). Swift/UVOT and XRT has monitored this source from 6.7 days until 29 days after the LIGO/VIRGO trigger (LIGO/VIRGO Collaboration GCN Circ. 27042). During this time the source was observed to decay and we no longer detect the source in any filter. In the following we give preliminary 3 sigma upper limits, combining images from the last two observations, using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373): Filter T_start(s) T_stop(s) Exp(s) 3sigUL v 1714547 2505112 428 > 19.8 b 1713986 2504817 428 > 20.7 u 1713871 2504756 428 > 20.2 w1 1713647 2504694 857 > 20.2 m2 1714661 2505297 1238 > 20.5 w2 1714102 2505050 1717 > 20.8 The magnitudes in the table are not corrected for the Galactic extinction due to the significant reddening of E(B-V) = 0.23 in the direction of the burst (Schlegel et al. 1998). Combining all 14.4 ks of XRT data collected to date, no source is detected down to a count rate of 6.7x10^-4 count s^-1. This corresponds to a 3-sigma upper limit of 2.9x10^-14 erg cm^-2 s^-1, assuming a standard power-law spectrum with NH=3x10^20 cm^-2, and photon index (Gamma)=1.7. This circular is an official product of the Swift team.
- Publication:
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GRB Coordinates Network
- Pub Date:
- March 2020
- Bibcode:
- 2020GCN.27400....1O