[vsnet-grb-info 8035] GRB 090625B: Faulkes Telescope South observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9574
SUBJECT: GRB 090625B: Faulkes Telescope South observations
DATE:    09/06/25 17:20:34 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi at fe.infn.it>

C. Guidorzi (U. Ferrara), D. Bersier (Liverpool JMU), P. O'Brien,
N. Tanvir (U. Leicester) on behalf of a large collaboration report:

On 2009 June 25 at 13:28:21 UT the 2-m Faulkes Telescope South
automatically began observing the INTEGRAL GRB 090625B
(Gotz et al., GCN Circ. 9572).

Observations started 120 seconds after the IBAS trigger time and
were performed using the B, V, R and i' filters. We could not find any
uncatalogued object inside the XRT error circle (Mao et al., GCN Circ.
9573) down to the following limiting magnitudes:

For single frames:

Mid Time   Exposure  Filter   Limit
  (s)       (s)              (mag)
-------------------------------------
141         3x10      R       > 19.3
526           10      i'      > 18.5
-------------------------------------

For coadded frames:

Time Range Exposure  Filter   Limit
  (min)     (s)               (mag)
-------------------------------------
22.5-45.2    420      R       > 21.0
25.4-48.2    420      i'      > 20.3
-------------------------------------

Calibration was performed using a few USNOB1 nearby stars, adopting
R2 and I values.