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 bar.  
 

2006, Jun 16/17