Transit
Observations of Exoplanet TrES-1
I
herewith include updated information on my transit
observations of exoplanet TrES-1, dd September 1st,
2004. Full details on the observation are given in
an article, featuring on the Sky
& Telescope website. That includes a picture
of the raw (unprocessed) transit light curve, that I
initially obtained. It was based on a single
comparison star.
Meanwhile, I have
used the technique of ensemble photometry (using
7 comparison stars) to increase the accuracy of my
observations. This has resulted in a better
photometric light curve, which is reproduced below.
Each data point or bin is the average value of 5
subsequent CCD measurements. Also shown is the
standard deviation per bin. Overall, I obtained a
photometric accuracy of 0.003 mag.
Photometric light curve of the TrES-1
transit observation dd Sep 1, 2004
(c) Tonny Vanmunster, CBA Belgium Observatory
Based on the improved
data, I furthermore derive :
- magnitude drop : 0.025 mag
- time of ingress (heliocentric) : 2004, Sep 1 at
21h23m UT +/- 2 min (about 10 min later than the
transitsearch ephemeris)
- time of egress (heliocentric) : 2004, Sep 1 at 23h50m
UT +/- 3 min (about 4 min later than predicted)
- duration central transit : 147 min
(published value : 152 min)
