Columbia University Astronomy and 

MDM Observatory GRB Team

GRB 991014: POSS-II Plate
(J2000) 06 51 06.5, +11 35 38.2
WFC 6' radius error circle
(NFI 1.5' radius error circles from GCN #427)


GCN Circular #423: GRB 991014, Optical Observations
J. Thorstensen (Dartmouth), R. Uglesich, J. Halpern, N. Mirabal
(Columbia U.), E. Costa, M. Feroci, L. Piro (IAS/CNR, Rome)
report on behalf of the MDM Observatory GRB follow-up team
and the BeppoSAX team:

"We imaged the field of GRB 991014 in the R band starting on
Oct. 15.38 UT, 11.2 hours after the burst, using the MDM 
Observatory's 1.3m and 2.4m telescopes.  The entire 6' radius 
error circle from the BeppoSAX WFC (Gandolfi, GCN #417) was covered
at the 1.3m, and the entire 2' radius NFI error circle of a possible
X-ray afterglow (BeppoSAX MAIL n. 99/28) was covered at the 2.4m.
There was no new object brighter than the digitized POSS-II limit in 
the WFC error circle.

We reobserved the NFI error circle on the 2.4m on Oct. 16.42 UT.
Seeing was 1.1-1.2 arcseconds on both nights, and the 5 sigma
limiting magnitude was R = 23.1.  No variable object was detected
in the NFI error circle.  This magnitude limit is referenced to a
USNO star at position (J2000) RA 06:51:03.17, Dec +11:36:42.6 which
has R = 17.61 +/- 0.02 according to the recent calibration of
Henden et al. (GCN #422).

This message may be cited."

GRB 991014: MDM 2.4m R-band CCD Image
1999 Oct. 16.42 - 30 minutes exposure
Circled calibration star has R = 17.61 (GCN #422)

2.4m CCD

GCN Circular #428: GRB 991014, Optical Observations
R. Uglesich, J. Halpern (Columbia U.), & J. Thorstensen (Dartmouth)

"In addition to the MDM observations reported in GCN #423, we
reobserved the entire 6' radius error circle of the BeppoSAX WFC
(Gandolfi, GCN #417) with the 1.3m because it is not known if either
of the reported NFI X-ray sources (in 't Zand et al. GCN #427) is
associated with the GRB.  The 1.3m observations were centered on 
Oct. 15.45 UT and Oct. 16.48 UT, and reach a  5-sigma limiting
magnitude of R = 22.6 on the first night, and R = 22.8 on the second 
night.  We used a non-standard, broad R filter which nevertheless
calibrates very well with Landolt (1992) standards that we obtained.
We find R = 17.64 for the star mentioned in GCN #423, which is consistent
with the USNO calibration (R = 17.61 +/- 0.02).  Although we have not yet 
carried out a detailed photometric analysis of the entire WFC circle,
careful visual inspection reveals no variable object to a limit of 
approximately R > 22.6 at 13 hours after the burst.  The images from
the MDM 2.4 reported in GCN #423 cover the error circles of both of 
the NFI sources, and our previously reported limit of R > 23.1 at
11.2 hours still applies.

We also note that Galactic extinction in this direction is estimated 
to be E(B-V) = 0.202 from IRAS dust maps (Schlegel et al. 1998),
so A_R is a modest 0.54 magnitudes.

A CCD image of the field of the NFI sources is posted at

This message may be cited."

John Thorstensen
Robert Uglesich
Jules Halpern
Dartmouth College Physics and Astronomy,
Columbia University Astronomy and Astrophysics, and MDM Observatory

MDM Observatory