Further observations of the star field of the Integral source IGR
J11305-6256 were done at the Bronberg Observatory on 18 May 2004 using the
usual CBA Pretoria instrumentation: LX200 12" f/3.7 with CCD camera SBIG /
ST-7XME, unfiltered

No new source was seen on the stacked image with a limiting magnitude around
20.0CR.

However, by comparing the images taken on 15 and 18 May, there seems to be a
distinct change in one of the objects on the images. It shows starlike on
the 15/5 image but extended on the 18/5 image.

A possible explanation for this could be a colourshift of the emitted
radiation due to a change-over from a hot source to a cooler (possibly
extended / secondary emission) one. The effect on the observing image could
be further boosted by the fact that longer wave radiation would undergo a
focus shift onto the CCD camera due to chromatic aberration in the focal
reducer.

The location of this source with reference to the UCAC2 frame (2000):

11 30 29.93 -62 54 49.7

Interesting to note is that this source is visible on both DSS2-red and
DSS2-NIR and that the POSS red plate shows it starlike and the NIR plate
not.


Tentatively this source is hereby proposed as a possible counterpart of  IGR
J11305-6256 on the base of variability of the source appearance.

The following observations apply:

possible counterpart of IGR J11305-6256   20040515.741   17.5CR
possible counterpart of IGR J11305-6256   20040518.841   17.6CR


At least one more observation of this star field is planned.

This report may be cited and images can be requested from
lagmonar@csir.co.za


Berto Monard
Bronberg Observatory / CBA Pretoria