[AAVSO-HEN] GRB 090417B: MITSuME Okayama optical upper limits

[grb at aavso.org]

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TITLE:   GCN CIRCULAR
NUMBER:  9143
SUBJECT: GRB 090417B: MITSuME Okayama optical upper limits
DATE:    09/04/18 06:21:01 GMT
FROM:    Michitoshi Yoshida at Okayama Astrophysical Obs  <yoshida at oao.nao.ac.jp>

D. Kuroda, M. Yoshida, K. Yanagisawa, Y. Shimizu, S. Nagayama,
H. Toda (OAO, NAOJ) and N. Kawai (Tokyo Tech) report on behalf
of the MITSuME collaboration:

We observed the field of GRB 090417B (Sbarufatti et al. GCN 9135)
with optical three color (g', Rc and Ic) CCD camera attached to
the MITSuME 50cm telescope of Okayama Astrophysical Observatory.
We started the observation at 15:29:29 UT, 566s after the burst.
There is no point source brighter than 20 mag within the XRT error
circle (Cummings et al. GCN 9139) in our 5940 sec exposure frames.
3-sigma upper limits to our observation are listed below.
We used GSC2.3 catalog for flux calibration.

 Mid-UT      Td         EXP-T           g'     Rc     Ic
-----------------------------------------------------------
15:34:43     880s    540s (9x60s)     >19.2  >18.8  >18.4
15:44:55    1492s   1560s (24x60s)    >19.9  >19.6  >19.1
15:59:37    2374s   3000s (50x60s)    >20.2  >19.9  >19.4
16:29:42    4179s   5940s (99x60s)    >20.3  >20.0  >19.5
-----------------------------------------------------------