Further Swift XRT and UVOT observations of Swift J073006.8-193709.
ATel #15409; P. A. Evans (U. Leicester) and K. L. Page (U. Leicester)
on 1 Jun 2022; 12:01 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Phil Evans (pae9@star.le.ac.uk)
Subjects: Optical, Ultra-Violet, X-ray, Transient
Referred to by ATel #: 15412
Swift has reobserved the transient Swift J073006.8-193709 reported in ATEL #15404 on 2022 May 30-31, with the XRT and UVOT. While the X-ray source appears to be stable in flux, the optical/UV counterpart is clearly fading with suggestions of a more rapid fade at shorter wavelengths.
The X-ray source is found in both datasets to have a 0.3-10 keV count rate of 0.018 ± 0.03 ct/sec. A spectrum built from all observations of this object is well-described by a power-law with a photon index of 1.0 (± 0.4), and an absorption column of 1.9 (+3.0, -1.9) × 1021 cm-2. This gives an observed 0.3-10 keV flux of 8.9 (+2.4, -1.9) × 10-13 erg cm-2 s-1 (spectral errors at 90% confidence).
In the UVOT the source was clearly detected in all filters on 2022 May 30, but had faded notably by the following day, as shown in the table below.
Filter | MJD_mid | Magnitude (Vega) |
v |
59729.7806 | 18.03 ±0.21 |
59730.7480 | >18.97 |
b |
59729.7759 | 18.28 ±0.14 |
59730.7432 | 19.07 ±0.19 |
u |
59729.7749 | 17.68 ±0.12 |
59730.7423 | 18.86±0.22 |
uvw1 |
59729.7734 | 17.74 ±0.11 |
59730.7408 | 18.64±0.16 |
uvm2 |
59729.7862 | 18.18 ±0.07 |
59730.7529 | 19.42±0.12 |
uvw2 |
59729.7782 | 18.18 ±0.10 |
59730.7456 | 19.33±0.17 |
Further observations are planned.