2006, Jun 12/13
Following my co-discovery
announcement of exoplanet XO-1b, I was able to
make another transit observation on the night of
June 12/13, 2006. Sky conditions were quite good,
except for the moonlight. The transit took place in
the second half of the night, and my observations
had to be stopped shortly after mid-transit, due to
twilight (one will notice the decreasing quality of
the observations towards the end of the session).
The graph below shows the transit lightcurve.
Observations were made with a 0.35-m f/6.3 telescope
and SBIG ST-7XME CCD camera, using a Cousins R
filter. The gray dots are XO-1 measurements of
1-minute exposures and the red dots are 3-point
averages (non-overlapping). The error bars indicate
the standard deviation for each 3-point average.
Dates are heliocentric Julian date (HJD). The bottom
part of the graph shows the comparison star
measurements (same principle). I used GSC 2041:186
as a comparison star. The standard deviation
on the comparison star measurements is 0.0027 mag.
Predicted ingress and mid-transit times, based on
the ephemeris elements given in the ApJ discovery
paper of XO-1b, are labeled with a vertical
2006, Jun 16/17
One oribital cycle after my previous
XO-1b transit observations above, sky conditions
again were favourable in Belgium.