[AAVSO-HEN] GRB 071112B: Gemini Image Differencing

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
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TITLE:   GCN CIRCULAR
NUMBER:  7107
SUBJECT: GRB 071112B: Gemini Image Differencing
DATE:    07/11/18 18:40:47 GMT
FROM:    Josh Bloom at UC Berkeley  <jbloom at astron.berkeley.edu>

D. Kocevski and J. S. Bloom (U.C.  Berkeley), on behalf of a larger  
collaboration, report:

"We performed image subtraction between multiple r-band observations  
of the error box of SHB 071112B (Perri et al. GCN 7058; Fenimore et  
al. 7071) on Gemini South.  The first epoch of observations began at  
2007-11-13 00h14m UTC (airmass ~2.0) followed by a second epoch ~4  
hours later at 2007-11-13 04h08m UTC (airmass ~2.6), with total  
exposures of 1800 sec and 1043 sec, seconds respectively.  Image  
subtraction using the public IPP package (*) software shows no  
variable sources to r=23.7 mag (3 sigma) within the >95% of the BAT  
error circle.  No further observations are planned."

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* See http://pan-starrs.ifa.hawaii.edu/project/IPP/software/