TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4023 SUBJECT: GRB050922C: Optical Observations DATE: 05/09/23 04:43:10 GMT FROM: Aaron Price at AAVSO D. T. Durig (Cordell-Lorenz Observatory - University of the South) and A. Price (AAVSO) report on behalf of the AAVSO International High Energy network on optical observations of GRB050922C. After glow reported by Rykoff et al (GCN #4011) was visible in 2 hours of exposures. The first three measurements are below and a link to the rest is in the full report at the bottom of the e-mail. Uncertainty is estimated at +/-0.2 mag. 09 23.03833 19.1 Rc 09 23.07725 19.5 Rc 09 23.10989 20.1 Rc The AAVSO would like to thank the Curry Foundation and NASA for their support of the AAVSO International High Energy Network. Name: Dr. Douglas T. Durig email: ddurig@sewanee.edu Observer: D. T. Durig, K. T. Crockett, L. R. Johnson Site: Cordell-Lorenz Observatory Location: Sewanee, TN, USA LatitudeLongitude: 35 12 N 85 55 W Elevation: 600 m Scope: SCT 0.30 m ScopeFocalRatio: f/5.9 1770 mm CCDVendor: SBIG ST-8E CCDDetector: KAF-1600E CCDSize: 1530x1020 binned 3x3 for 510x340 CCDPixelScale: 3.14 arc sec per pixel CCDFOV: 26.7x17.8 full, 13.3x8.9 cropped submitted Object: GRB050922C ObsDate: 2005 09 23 ObsMidPointTime: 01:51:14 UT TimePerFrame: 300 sec NumberOfFrames: best 24 out of 30 Filters: CR Processing: dark,flat, register,co-add, 1/2 frame crop Seeing: 5-6 arc sec LimitingMag: ~21.5 ??? Sky: clear, but very gusty winds afterglowmag: 19 fading to 20 over two hours time afterglowerr: 0.2 mag compstars: 94 UCAC, 188 B1.0 subframe Report: Full frame covers entire error box. After glow reported by Rykoff et al (GCN 4011) was visible in single 300 sec exposure but 6 frames were added to improved S/N for measurements. We measure a position of 21 09 33.10 -08 45 30.2 First three photometric measurements shown below. We have posted our first 2 hours of exposure at http://arthur.sewanee.edu/obsv/view.php comments: 09 23.03833 21 09 33.10 -08 45 30.2 19.1 R 09 23.07725 21 09 33.12 -08 45 30.4 19.5 R 09 23.10989 21 09 33.12 -08 45 30.7 20.1 R A FITS image has been uploaded to ftp://ftp.aavso.org/grb/Dr.DouglasT.Durig_GRB050922C_2453636.66853_.fits