TITLE:   GCN CIRCULAR
NUMBER:  29312
SUBJECT: ZTF21aaeyldq: 2.2m CAHA BVRI optical observations
DATE:    21/01/17 17:54:36 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, E. Fernandez-Garcia, A.J. Castro-Tirado, M.D. Caballero-Garcia, M.A. Castro-Tirado (IAA-CSIC), R.P. Hedrosa, I. Hermelo, I. Vico (CAHA) on behalf of a larger collaboration, report:

Following the detection of ZTF21aaeyldq (AT2021any) by the Zwicky Transient Facility (ZTF; Ho et al., GCNC 29305), we triggered the 2.2m CAHA telescope in Almeria (Spain) equipped with CAFOS. BVRI images were gathered starting on Jan 17, 00:02 UT (17.04 hours after first optical detection). Second epoch BVRI images were taken starting at 04:08 UT. The optical counterpart is clearly detected at the ZTF position (Ho et al., GCNC 29305, de Ugarte Postigo et al., GCN 29307, Kumar et al., GCNC 29308, Ahumada et al., GCNC 29309 and Zhu et al., GCNC 29310). We measure a first epoch R-band magnitude (non-extinction corrected) of R = 21.27+-0.13 mag at 00:15 UT, calibrated with the nearby stars present in the USNO-B1.0 catalog.

We thank the staff at CAHA observatory for their excellent support.