[Aavso-photometry] Transit observations of exoplanet GJ 436 b at CBA Belgium Observatory

[Tonny Vanmunster]

Dear colleagues,

I have just posted my transit observations of the newly discovered exoplanet
GJ 436 b on my website (www.cbabelgium.com). Rather unexpectedly, the skies
cleared out this evening over CBA Belgium Observatory, shortly before the
start of the transit. Photometric conditions were not ideal (bit of haze),
but I started a photometry session using a 0.35-m f/6.3 telescope and SBIG
ST-7XME CCD camera with V filter. The resulting lightcurve clearly shows the
full transit.

The actual transit has started a bit later than predicted (on
Transitsearch.org) and its duration was also a bit shorter than predicted.
This is in agreement with the fact that the Transitsearch.org prediction was
made for a central transit, which is not the case for GJ 436 b. Based on my
observations, I found following data :

- ingress : 2007 May 17 at 23h01m UT
- egress : 2007 May 17 at 23h53m UT
- mid-transit : 2007 May 17 at 23h28m UT
- duration : 52 min
- depth : 0.007 mag 

There's also a strange "dip" in the ligth curve near JD +0.41, for which I
have no direct explanation.

Best regards,
Tonny 

Tonny Vanmunster
CBA Belgium Observatory
http://www.cbabelgium.com 
 
PERANSO : The Light Curve and Period Analysis Software
http://www.peranso.com