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)

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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.