TITLE:   GCN CIRCULAR
NUMBER:  33832
SUBJECT: LIGO/Virgo/KAGRA S230518h: Swift/UVOT Upper Limits for Swope candidates: SSS23a, SSS23b and SSS23c
DATE:    23/05/20 12:10:28 GMT
FROM:    Samantha Oates at University of Birmingham <samantha.oates@alumni.ucl.ac.uk>

LIGO/Virgo/KAGRA S230518h: Swift/UVOT Upper Limits for Swope candidates: SSS23a, SSS23b and SSS23c 

S. R. Oates (U. of Birmingham), A. A. Breeveld (MSSL-UCL), P. Brown (TAMU),
M. De Pasquale (U. Messina), C. Gronwall (PSU), N. Klingler (NASA-GSFC/UMBC/CRESST II),
N. P. M. Kuin (UCL-MSSL), F. E. Marshall (NASA/GSFC), M. J. Page (UCL-MSSL),
M. H. Siegel (PSU), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB),
S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC), A. D’Aì (INAF-IASFPA), P. D’Avanzo (INAF-OAB),
V. D’Elia (ASI-SSDC & INAF-OAR), S. Dichiara (PSU), P.A. Evans (U. Leicester),
R.A.J. Eyles-Ferris (U. Leicester), D. Hartmann (Clemson University),
J.A. Kennea (PSU), S. Laha (NASA/GSFC), A.Y. Lien (GSFC/UMBC), A. Melandri (INAF-OAB),
J.A. Nousek (PSU), P. O’Brien (U. Leicester), J.P. Osborne (U. Leicester),
K.L. Page (U. Leicester), D. M. Palmer (LANL), S. Ronchini (PSU), T. Sbarrato (INAF-OAB),
B. Sbarufatti (INAF-OAB), G. Tagliaferri (INAF-OAB), A. Tohuvavohu (U. Toronto),
E. Troja (U Tor Vergata, INAF) report on behalf of the Swift team:

We report Swift/UVOT observations of the candidates SSS23a, SSS23b and SSS23c (Coulter et al.,
GCN Circ. 33829) found by the Swope 1-m telescope during the search for the EM counterpart
of the LVC event S230518h (LIGO/VIRGO/KAGRA Collaboration GCN Circ. 33813). 

Swift/UVOT observations of the Swope candidates began 1.5 days after the LVK trigger
(LIGO/VIRGO/KAGRA Collaboration GCN Circ. 33813). We do not detect any of the 3 Swope candidates
in the UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the exposures are:

Target   Filter   T_start(s)   T_stop(s) Exp(s)     3sigUL

SSS23a      u       129503      135881     288      >19.2
SSS23a     w1       129079      135788     585      >19.9
SSS23a     m2       128445      135607     879      >20.2
SSS23a     w2       129713      136188     753      >20.1
         	      	                   
SSS23b      u       140770      140997     223      >19.1
SSS23b     w1       140310      140765     448      >19.8
SSS23b     m2       139622      140304     671      >20.1
SSS23b     w2       141004      141319     309      >19.6
         	      	                   
SSS23c      u       130526      141885     131      >18.7
SSS23c     w1       130415      141799     264      >19.3
SSS23c     m2       130250      141633     395      >19.6
SSS23c     w2       130586      142008     133      >19.0

This circular is an official product of the Swift team.