TITLE:   GCN CIRCULAR
NUMBER:  2926
SUBJECT: GRB 041217: Optical observations
DATE:    04/12/30 20:36:44 GMT
FROM:    Arto Oksanen at Nyrola Obs., Finland  <oksanen@nyrola.jklsirius.fi>

D. T. Durig (Cordell-Lorenz Observatory, Sewanee, TN, USA) reports on behalf of 
the AAVSO International High Energy Network:

Observations of the Swift error circle for GRB041217 (Palmer et al., GCN 2853) 
were made with the Cordell-Lorenz Observatory 0.30m telescope + unfiltered CCD.

Eighteen 300-second exposures with UT midpoint of 2004-12-18T10:36 (1.1 days
after the burst) and twentythree 300-second exposures with UT midpoint of 
2004-12-20T10:26 (3.1 days) were stacked, with limiting sigma-3 magnitudes of 
20.0CR and 20.3CR based on USNOA2.0.  

The 47 arcmin x 47 arcmin field was centered at 10h 59m 53s -17d 51' 45" 
(J2000.0), covering all of the error circle. 

No new object is seen down to approximately CR=20.0 when comparing
against a DSS2-R image. 

The four candidates of Berger & Gonzalez (GCN 2859) are visible on both epochs 
but don't show significant fading.

Examing the images of the two epochs gives lower limit for an afterglow about 
20.0CR 1.1 days after the burst.

The combined FITS images can be found at:

ftp://ftp.aavso.org/grb/Dr.DougDurig_GRB041207_2453360.03964_.fits 
ftp://ftp.aavso.org/grb/Dr.DouglasT.Durig_GRB041217_2453358.03701_.fits 


The AAVSO International GRB network is greatful for a generous grant
from the Curry Foundation and to NASA for the financial support for the
High Energy Astrophysics Workshops for Amateur Astronomers.