TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3478
SUBJECT: GRB050525: Optical observations
DATE:    05/05/25 14:07:59 GMT
FROM:    Aaron Price at AAVSO  <aaronp@aavso.org>

D. T. Durig (Cordell-Lorenz Observatory, University of the South), A. Oksanen
(Nyrola Observatory), C. Pullen (AAVSO) and A. Price (AAVSO) report on behalf of
the AAVSO International High Energy Network on optical observations of GRB050525
(GCN #3466; Band et al.):

 An afterglow candidate is found at the location reported by Rykoff et al. (GCN
#3468) and Band et al. (GCN #3465). At 08:13 UT it is detected at an unfiltered
magnitude of 18-19 (fading over 100 mins centered on 08:13UT). The USNO star near
18 32 34.5 +26 20 24 can not completely be resolved from the afterglow candidate.
Full details and FITS image URL is below.

 Name: Dr. Douglas T. Durig
 email: ddurig@sewanee.edu
 Observer: Dr. D. T. Durig ( CLW01)
 Site: Cordell-Lorenz Observatory
 Location: Sewanee, Tenn., USA
 LatitudeLongitude: 35 12 N 85 55 W
 Elevation: 600 m
 Scope: SCT 0.30 m
 ScopeFocalRatio: f/5.8  1765 mm
 CCDVendor: SBIG STL-1001E
 CCDDetector: KAF 1001E
 CCDSize: 1024x1024
 CCDPixelScale: 2.8
 CCDFOV: 48x48 full, 12x12 quarter frame cropped
 Object: GRB050525
 ObsDate: 2005 05 25
 ObsMidPointTime: 08 13 25
 TimePerFrame: 120 sec
 NumberOfFrames: 75
 Filters: CR
 Processing: dark, flat, register, co-add, 1/4 frame crop
 Seeing: 5-6 arc sec
 LimitingMag: 19.5-20 ???
 Sky: very clear but breezy with Bright Moonlight
 afterglowmag: 18-19
 afterglowerr: 1
 compstars: 1300 UCAC ref stars in full frame
 Report: The USNO star near 18 32 34.5 +26 20 24 can not completely be resolved 
from the afterglow candidate, but I do see it fade by around 1 mag over a little 
over 100 min by summing a series of 30 consecutive 120 sec exposures. I get a 
measured position of 18 32 33.9 +26 20 23 and 18 mag at 7:23 UT falling to 19 mag 
at 9:03 UT, but this includes some contribution from the USNO star.
 comments: UT         dec.day      CR mag
7:23:28    25.30796    18.0
7:40:09    25.31955    18.2
7:56:43    25.33105    18.3
8:13:25    25.34265    18.3
8:30:10    25.35428    18.3
8:46:49    25.36584    18.6
9:03:28    25.37741    19.0

A FITS image has been uploaded to 
ftp://ftp.aavso.org/grb/Dr.DouglasT.Durig_GRB050525_2453516.00275_.fits

The AAVSO thanks the Curry Foundation for their continued support of the 
AAVSO International High Energy Network.