TrES-1 transit of September
4th, 2004
Following my successful TrES-1 transit
observation of Sep
1st, 2004, I had the opportunity to again
observe a transit of TrES-1, just one orbital period
after its previous passage in front of its host
star.
Sep 4th,
2004 was a clear night over CBA Belgium Observatory,
although the sky was slightly hazy. Around 20h38m UT, I pointed
one of the CBA Belgium Observatory telescopes at
TrES-1's host star and started an unfiltered
time-series photometry session. Several hours later,
around 01h23m UT (Sep 5, 2004) the session was
concluded because of fog making further observations
impossible (fortunately, this was past egress).
The
resulting transit lightcurve is shown below. I used ensemble
photometry with a set of 7 comparison stars to
reduce the observations. Each dot or bin in the
light curve is the average differential magnitude of
3 subsequent CCD images.
A
rough inspection of the light curve seems to confirm
my initial findings : again, ingress and egress
happened later (about 10 min) than predicted by the
TrES-1 ephemeris on transitsearch.org.
