TITLE:   GCN CIRCULAR
NUMBER:  33238
SUBJECT: AT2023avj: X-ray Detection with Swift/XRT
DATE:    23/01/30 22:36:51 GMT
FROM:    Anna Ho at UC Berkeley  <annayqho@berkeley.edu>

Anna Y. Q. Ho (Cornell) reports on behalf of a larger collaboration:

We observed the fast optical transient AT2023avj (Wang et al., GCN Circ.
33226 and AstroNote 2023-17) with Swift/XRT beginning at 2023-01-27 14:46
UT, or 5.3d after the first ZTF detection. In a 4.6ks exposure, we detect
X-ray emission with a count rate of 0.003 +/- 0.001 ct/s. Using WebPIMMS
[1] we estimate [2] that this corresponds to an unabsorbed 0.3-10 keV flux
density of 1.1E-13 ergs/cm2/s, similar to the flux density of GRB
afterglows at this phase.

No GRB counterpart has been reported.

We thank the Swift staff for rapidly approving and scheduling our
observations.

[1] https://heasarc.gsfc.nasa.gov/cgi-bin/Tools/w3pimms/w3pimms.pl [2]
Using a hydrogen column density of 1.6E20/cm2 (Willingale, R., et al. 2013,
MNRAS, 431, 394) and a power-law index of 2