AstroNote 2024-201

We report the observations of the FSRQ NVSS J004348+342626 (a.k.a. 5BZQJ0043+3426)  at redshift z = 0.966 (Ackermann et al., 2011 ApJ 743 171A) with the Large Array Survey Telescope (LAST, Ofek et al. 2023; Ben-Ami et al. 2023). The source was recently detected for the first time in the X-ray band by EP-WXT on 2024-07-17 and confirmed by Swift-XRT observations 1.5 days later (ATel#16725). Around the time of Swift-XRT observations, the Lulin optical observatory reported the source at r (AB) = 18.38 +/- 0.05, in a brighter state compared to archival observations from ZTF (ATel#16726).

We observed the source with no filter (clear) in multiple visits during sky survey operations on the nights of 3, 5, 13 and 14 July 2024, prior to the EP-WXT detection. The reported magnitudes are in the LAST native AB system, calibrated relative to the GAIA-DR3 Bp band (i.e., color term was fitted and the source color was assumed to be Bp-Rp=1 mag). 

From a preliminary analysis, we measure the following average fluxes in each night:

MJD = 60495.063 M = 19.05 +/- 0.09

MJD = 60497.016 M = 19.02 +/- 0.09

MJD = 60505.014 M = 18.92 +/- 0.08

MJD = 60505.950 M = 18.93 +/- 0.09

These values are consistent with previous LAST observations of the same field during sky-survey operations on 11 and 20 September 2023, where we measured the following average fluxes per night 

MJD = 60198.967 M = 18.88 +/- 0.08

MJD = 60207.943 M = 18.93 +/- 0.08

This suggests that the source was still not in flaring state in the days of July 2024 covered by our observations, up to ~3 days before the EP-WXT detection.

The average color term for these observations is 0.9. All errors include statistical and calibration errors (of about 0.05 mag).
 

LAST is a survey telescope array of the Weizmann Astrophysical Observatory (https://www.weizmann.ac.il/wao/).