TITLE:   GCN CIRCULAR
NUMBER:  21579
SUBJECT: LIGO/Virgo G298048: Continued observation for DLT17ck
DATE:    17/08/19 00:18:04 GMT
FROM:    Sheng Yang at UC Davis  <sngyang@ucdavis.edu>

Sheng Yang (INAF-OAPd, UC Davis), Stefano Valenti(UC Davis), David Sand (UA), Leonardo Tartaglia (UA, UC Davis), Enrico Cappellaro(INAF-OAPd), Dan Reichart, Josh Haislip (UNC) report on behalf of the Gravitational Wave Follow-Up by DLT40.

We report the second epoch for DLT17ck/SSS17a, the possible counterpart of G298048 in NGC 4993 detected by Coulter et al. (LVC GCN  21529), Allam et  al. (LVC GCN 21530), Yang et al. (LVC GCN 21531), Melandri et al. (LVC GCN 21532), Arcavi et al. (LVC GCN 21538), Lipunov et al., (LVC GCN 21546). Using data from the PROMPT 5 0.41m telescope located at CTIO, DLT40 observation began at 2017 August 18.99 UT and shows the source at magnitude R = 18.00 +/- 0.06 mag. Compared with our discovery detections, R~17.3 mag in Yang et al. (LVC GCN 21531), the source is declining. We also report last our non-detection at 2017 July 27.99 UT, during the monitoring of NGC4993 with the DLT40 search. The magnitude limit is up to 19.1 mag (open filter scaled to r band).