AstroNote 2021-226

We report the following aperture photometry of recent transients obtained with the 60 cm Helen Sawyer Hogg (HSH) telescope at the Complejo Astronómico El Leoncito (Casleo; Argentina) on 2021-08-26 UT. Series of 20 exposures of 60 s in VRI and 90 s in B were combined in each band before performing aperture photometry relative to field stars in the ATLAS All Sky Reference Catalogue 2 (REFCAT2; Tonry et al. 2018, ApJ, 867, 105). The field star magnitudes were converted from Sloan to Johnson system using the coefficients in Table 6 of Tonry et al. 2012, ApJ, 750, 99.

The following photometry was obtained:
Transient ATLAS21bgjq (AT2021weu; TNS Report No. 120736)
UT time at start of the observation: 2021-08-26 4:53
Filter: R
JD        FILTER MAG ERROR
2459452.711     R     18.1   0.1

Transient ATLAS21bgtl (AT2021wvp; TNS Report No. 121436)
UT time at start of the observation: 2021-08-25 23:26
Filters: BVRI
JD       FILTER MAG ERROR
2459452.488   B    16.7    0.1
2459452.510   V    16.7    0.2
2459452.528   R    16.5    0.1
2459452.544   I    16.4    0.1

Transient: ATLAS21bgni (AT2021wwl; TNS Report No. 121394)
UT time at start of the observation: 2021-08-26 7:50
Filters: V and R
JD       FILTER MAG ERROR
2459452.834    V     17.6    0.2
2459452.851    R     17.3    0.1