[vsnet-grb-info 21641] GRB 190114C: UKIRT JHK observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23740
SUBJECT: GRB 190114C: UKIRT JHK observation
DATE:    19/01/16 15:08:40 GMT
FROM:    Myungshin Im at Seoul Nat U  <mim at astro.snu.ac.kr>

Myungshin Im, Gregory S. H. Paek, Changsu Choi (CEOU/SNU), on behalf of a
larger collaboration

We observed the afterglow of GRB 190114C (Gropp et al., GCN 23688; Tyurina
et al., GCN 23690, de Ugarte Postigo et al., GCN 23692, Lipunov et al. GCN
23693, Selsing et al. GCN 23695, Izzo et al. GCN 23699, Bolmer et al. GCN
23702, Castro-Tirado et al. GCN 23708, Kann et al. GCN 23710, Im et al. GCN
23717; Siegel et al. GCN 23725, Mazaeva et al. GCN 23727, D'Avanzo et al.
GCN 23729, Peak et al. GCN 23731, Kim et al. GCN 23732, Kumar et al.
GCN 23733) with the United Kingdom Infrared Telescope (UKIRT). The
observation started at 2019-01-16 05:06 UT or about 1.33 days after the
initial alert.

The afterglow is clearly detected in all J, H, K bands, and preliminary
magnitudes are derived from quick-look data, using nearby 2MASS stars as
photometry references.

Filter Date UT-start Vega_Mag (AB mag)
K   2019-01-16 05:06:05.011    15.5 +/- 0.1   (17.7 AB)
H   2019-01-16 05:26:45.974    16.5 +/- 0.1   (18.1 AB)
J    2019-01-16 05:47:58.042    17.5 +/- 0.1   (18.7 AB)

This shows an H-band fading of 1.4 mag with respect to the value reported
by D'Avanzo et al. (GCN 23729) which give an H-band fading rate of 1.2
mag/day.

Further observations are planned.
We thank the staffs at UKIRT for carrying out the observation.