TITLE:   GCN CIRCULAR
NUMBER:  24325
SUBJECT: LIGO/Virgo S190425z: No i-band detection of the Swift/UVOT transient in SkyMapper observations
DATE:    19/04/28 07:54:48 GMT
FROM:    Seo-Won Chang at SkyMapper  <seowon.chang@anu.edu.au>

Seo-Won Chang (ANU/OzGrav), Christian Wolf (ANU/OzGrav), Christopher A. Onken (ANU), Lance Luvaul (ANU), Susan Scott (ANU/OzGrav) report on behalf of the SkyMapper Transient survey collaboration:


We checked the SkyMapper observations at the location of the Swift UVOT candidate (Breeveld et al. GCN 24296). These images were taken with the 1.35-m ANU SkyMapper telescope at Siding Spring Observatory about 6 hours after the GW detection in response to LIGO/Virgo GW trigger S190425z (LVC collaboration, GCN 24168).  We do not see any transient down to an i-band (779/140 nm) magnitude of 20 (AB mag) at the two epochs: 2019-04-25 14:17:00 and 2019-04-25 14:25:53 UT. Our magnitude limits were obtained by calibrating with the zero-point from the SkyMapper Data Release 2 (Onken et al. 2019).