[vsnet-grb-info 7692] GRB 090424: THO optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9246
SUBJECT: GRB 090424: THO optical observations
DATE:    09/04/25 05:35:50 GMT
FROM:    Veli-Pekka Hentunen at Taurus Hill Obs,A95  <veli-pekka.hentunen at kassiopeia.net>

Markku Nissinen (Taurus Hill Observatory) and Veli-Pekka Hentunen (Taurus
Hill Observatory) report:


We used 0.35m C14 XLT telescope with SBIG ST-8XME CCD at Taurus Hill Observatory
(Varkaus, Finland) for follow-up observations of GRB090424. The observations 
were started on April 24, at 19:59 UTC (5.8 hours after the burst) and stopped
on April 24, at 23:11 UTC. Sixteen unfiltered 600 seconds images were taken. 
We detected clear optical afterglow object at the position of RA 12h 38m 05s.12 and DEC 
+16o 50' 15".2 with respect to POSSII F/USNO-B1.0 which is in good correlation 
with enhanced Swift XRT-UVOT position. Upper limit for the observations is >20.4 mag.
Quoted upper limit has been derived using POSSII F and USNO-B1.0 field stars 
as reference.

Filter     Tmid(s)      Exp(s)     Mag (CR) USNO-B1.0
                
u         20:14:23      600      19.55+/-0.37
u         20:37:30      600      19.95+/-0.38
u         21:32:48      600      20.15+/-0.34

A jpeg preview of the observation showing the position of the afterglow is 
available at this URL: http://cutenews.kassiopeia.net/data/upimages/grb090424_ticks.jpg