GCN Circular 345

N. Masetti, E. Palazzi, E. Pian, F. Frontera (ITESRE, CNR, Bologna),
D. Gardiol, S. Benetti, A. Zacchei, A. Magazzu' (TNG), M. Della Valle
(Univ. of Padua), E. Costa, M. Feroci and L. Piro (IAS, CNR, Rome) report:

"We imaged the error box of the X-ray transient source SAX J0835.9+5118
(Piro, GCN #333) with TNG plus OIG CCD camera on 1999 May 20.890 - 20.920 
UT (five V frames; seeing 1."2 - 1".5) and on 1999 May 21.934 - 21.955 UT
(one R and two V frames; seeing 0".9). The exposure time was 300s for all
images.

Calibration of V and R frames was performed using the photometry by
Henden et al. (GCN #339).
A limiting magnitude of V ~ 22.5 was obtained in each frame of the first
night, while the limits V ~ 23 and R ~ 23 were reached in the images
acquired on the second night (3-sigma limits).

Comparison among the V frames of May 20 and 21 shows no object which
varied by more than 0.3 magnitudes (at a 3-sigma level) down to V ~ 22.

The optical counterpart (Bloom et al., GCN #335) of the radio source
detected by Frail et al. (GCN #334) appears star-like as earlier noted by
other authors (GCN #336, #338, #341) with magnitudes V = 21.08 +- 0.05 and
R = 20.68 +- 0.05. Some scatter of 0.1 mag around the mean V magnitude of
the object is seen, thus probably indicating the presence of flickering
or of some other optical variability.

The irregular galaxy reported by Pedersen et al. (GCN #340) has 
V = 20.20 +- 0.05 and R = 19.60 +- 0.05 in our frames and does not show
any variability in the V band between the two nights. We see in our images
that the faint knot noted by Pedersen et al. southeast of the galaxy
appears brighter in the R band than in V.

The R magnitudes of both objects are in agreement with the values reported 
by Halpern et al. (GCN #343).


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