GCN Circular 33255

S. Yang (Stockholm), T.-W. Chen (TUM/MPA), H.-Y. Hsiao, Y.-C. Pan, C.-C. Ngeow, W.-J. Hou, C.-S. Lin, H.-C. Lin, and J.-K. Guo (IANCU) report:

We observed the field of ZTF23aabmzlp/AT2023azs
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 (Andreoni et al., GCN 33229
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), using the Lulin One-meter Telescope (LOT) at Lulin Observatory, Taiwan, to obtain g,r,i-band images as part of the Kinder collaboration (Chen et al., AstroNote 2021-92).

The first epoch of observations started at 20:51 UT on 28 of January 2023 (MJD = 59972.869), 0.61 days after the first detection from ZTF. The images were combined from 3 frames with 300 sec exposure time for g and r bands, and 2 frames with 300 sec exposure time for i band, taken under poor seeing conditions (4".0 average) and at a median airmass of 1.5. The second epoch was performed at 20:38 UT on 29 of January 2023 (MJD = 59973.860). The images were combined from 2 frames with 300 sec exposure time for each band, taken under variable seeing conditions (1".8 average) and at a median airmass of 1.5.

We used PSF photometry to measure the transient brightness with template subtraction using the SDSS images, and derived the following preliminary magnitudes and 3-sigma limits (all in the AB system):

2023-01-28:
g > 20.18 mag,
r > 19.21 mag, and
i > 19.13 mag.

2023-01-29:
g > 21.82 mag,
r = 21.78 +/- 0.15 mag, and
i = 21.34 +/- 0.13 mag.

Given magnitudes are calibrated against SDSS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V) = 0.01 mag in the direction of the counterpart (Schlafly & Finkbeiner 2011).

Our measurements of the photometric evolution of ZTF23aabmzlp/AT2023azs
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 are consistent with previous optical observations reported from Kumar et al., GCN 33230
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; Gupta et al., GCN 33237
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; Pankov et al., GCN 33239
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; Strausbaugh et al., GCN 33241
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.