TITLE:   GCN CIRCULAR
NUMBER:  34049
SUBJECT: ZTF23aaoohpy (AT2023lcr/ATLAS23msn): Swift/UVOT detection
DATE:    23/06/21 11:43:05 GMT
FROM:    Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and S. R. Oates (U. Birmingham) report on behalf of the Swift/UVOT team:

Follow-up observations of the optical fast transient ATLAS23msn/ZTF23aaoohpy/AT2023lcr (Swain et al., GCN 34022; Gompertz et al., GCN 34023; Kumar et al., GCN 34025; Adami et al., GCN 34030; Perley et al., GCN 34031; Jiang et al., GCN 34040; Perley et al., GCN 34041; Fulton et al., 34042; Chen et al., GCN 34043, Belkin et al., GCN 34047) were carried out with the Neil Gehrels Swift Observatory between 2023-06-20 12:57:02 UT and 2023-06-20 14:54:56 UT, in which a source was detected by the XRT (Adreoni, GCN 34044).

A source was also detected in the Swift UVOT data in the UVM2 filter at the position given by Swain et al., (GCN 34022). Possible detections are also obtained in the U, UVW1 and UVW2 filters but at a significance below 3 sigma. Preliminary tentative detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the summed exposures are:

FILTER  EXP(s)  MAG           Significance of   Upper Limits (3o)
                                Detection
v       157                                      >19.6
b       157                                      >20.6
u       157     20.6 ± 0.5     2.1 sigma         >20.1
w1      315     20.4 ± 0.5     2.1 sigma         >20.0
m2     1489     20.8 ± 0.3     3.9 sigma
w2      629     21.0 ± 0.4     2.5 sigma         >20.7

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.05 in the direction of the burst (Schlegel et al. 1998)