TAROT and GRANDMA follow-up of AT2018cow/ATLAS18qqn

ATel #11757; A. Klotz (IRAP), S. Antier (LAL), M. Boer (Artemis), N. Christensen (Artemis), B. Cordier (CEA), M. Coughlin (Caltech), D. Coward (UWA), B. Gendre (UWA), X. Han (NAOC), J. Wang (NAOC), N. Leroy (LAL), J. Mao (YNAO), K. Noysena (Artemis/IRAP), A. Peyrot (AGORA), J. P. Teng (AGORA), P. Thierry (Auragne obs.), D. Turpin (NAOC), F. Vachier (IMCCE), J. Y. Wei (NAOC), C. Wu (NAOC), W. Zheng (UC Berkeley) for the GRANDMA and TAROT teams
on 21 Jun 2018; 20:45 UT
Credential Certification: Sarah Antier (antier@lal.in2p3.fr)

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We observed the field of ATLAS18qqn/AT2018cow (Smartt et al. ATel #11727) consecutively in L filter (Astronomik facturer) with RC telescope of 60 cm at Les Makes Observatory (La Reunion, France). Observations began at 2018-06-20 17:04 UT and ended at 2018-06-20 22:09 UT. 8 images were taken. We also observed the field of ATLAS18qqn/AT2018cow with TAROT-La Reunion (TRE) and Tarot-Chile (TCH). Observations began at 2018-06-20 17:30 UT and ended at 2018-06-21 06:42 UT. 16 images were taken with filters C, r, g, i. Calibrating the images taken in filters L, C and r in the AB photometric system, we deduce a fading with a slope of 0.75 mag/day. The fading is consistent with our previous observations (Zheng et al., ATel #11743) and other photometric reports : Ahumada et al. (ATel #11752), Im et al. (ATel #11750), Watson et al. (ATel #11751), Smart et al. (ATel #11742, #11727), Fremling et al. (ATel #11738), Chen et al. (ATel #11734, #11729). We greatly thank the AGORA association for making the observations.