[Aavso-photometry] [TransitSearch] GJ 436

[Tonny Vanmunster]

Dear colleagues,

Just a quick note to report that I'm currently observing a transit of GJ
436b from CBA Belgium Observatory (2007, May 17/18). The event is still
ongoing (egress just passed), and despite the depth of 0.006 mag only, the
resulting light curve clearly shows the transit. I will postprocess my
observations in half an hour or so, and will then post the lightcurve on my
website. I will let you know once it's there. 

I used a 0.35-m f/6.3 telescope with ST-7XME CCD and V-filter. Atmospheric
conditions were moderate (bit of haze).

Best regards,
Tonny

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

-----Original Message-----
From: transitsearch-bounces at ucolick.org
[mailto:transitsearch-bounces at ucolick.org] On Behalf Of arne
Sent: Thursday, May 17, 2007 9:46 PM
To: VALMECA
Cc: transitsearch at ucolick.org
Subject: Re: [TransitSearch] GJ 436

VALMECA wrote:
> Hi,
> 
> Thanks for the info's, I'll aim my 24"R-C on it this night, do I have 
> to use the R filter instead of the V for my images?
> I wait for your answer.
> Many thanks,too.
> 
Hi Serge,
Go as blue as you can; B is great, V is ok, but don't use Rc or Ic with the
24-inch.

This is a 10th magnitude star, and the longer your exposures, the less
scintillation you will have.  The transit of the known planet takes about an
hour, so resolutions of 60 seconds or so are just fine.
The transit depth is about 0.6percent, or 0.006mag, so it is a tough
project.  The other reason for going blue is that this is an intrinsically
red star, which tend to have molecular bands and the like in the redder
filters, making correlations with other observers more difficult.
Arne

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