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GCN Circular 340

X-ray/GRB 1SAX J0835.9+5118, Optical Observation
1999-05-21T16:46:04Z (25 years ago)
Holger Pedersen at Copenhagen U Obs <>
H. Pedersen, J. Hjorth, B. L. Jensen (Copenhagen), A. O. Jaunsen (Oslo), 
R. Falomo (Padova), I. Burud (Liege), M. I. Andersen, H. Korhonen, 
H. Schwarz (NOT), E. Costa, L. Piro (IAS/CNR, Rome), and, 
E. Pian (Ist.TeSRE, Bologna), report:

We have used the ALFOSC instrument (field 6' x 6') at the NOT, La Palma,
to acquire three 4-minute R-band exposures of the position reported
from BeppoSAX (Gandolfi et al., IAU Circular No. 7174). 

The exposures were taken 1999 May 20.898 - 20.910 UT. The seeing was 0.7". 

Comparison to the DSS-2 did not reveal any new object. Comparison between 
the three exposures internally did not reveal any variable object. 

One object drew attention during our inspection of the images:
this is the SN-like configuration of an apparently unresolved object 
1.6" east, 0.5" south of a galaxy (which, in turn, is well visible on 
the DSS). The object may well be due to a surface brightness concentration 
in the said galaxy, or the chance superposition of a galactic star.

To test the visual impression, we have analyzed the images, using 
the deconvolution technique applied in GCN 320; unfortunately, the
low s/n ratio does not allow any clear distinction between resolved
and not resolved models.

The position of the object of concern is 
R.A. 08 h 35 m 52.44 s, Decl. +51o 18' 46.9" (J2000); uncertainty 0.5".
Its brightness is estimated at m(R) = 22.0 +- 0.5.  No variability is
indicated. For the galaxy, we find m(R) = 19.75 +- 0.3. The photometric
measurements stem from a standard calibration of the instrument, for
which m(R) = 16.71 for an object at 
R.A. 08 h 35 m 52.88 s, Decl. +51o 18' 06.2" (J2000). 

A 2' by 2' section of the sum-image, centered on the object is placed on . 

A gif-version will be provided later.

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