HAT-P-12b - A transiting "Hot Saturn" in CVn

Dear group,

A couple of weeks ago we had the announcement surrounding the discovery of the twelveth exoplanet by the HAT-P-Net exoplanet hunting team and involving the third find and example to-date of a "Hot Saturn".

This particular find involves a star which is somewhat dim at magnitude 12.84 (pretransit) and which dims to 12.865 during transit. In spite of many false starts due to very dim sporadic clouds which almost made me call it in, I managed to capture a very beautiful light curve over the course of four hours.

The exoplanet HAT-P-12b in the constellation of Canis Venatici completely orbits its parent star in only 77 hours and requires 140 minutes to transit it as viewed from Earth.

Aside from being the least dense of any massive gas giant exoplanet discovered so far, it is even less dense than Saturn itself.

For the resulting light-curve from last night based on 4 hours total data, please see www.perseus.gr/Astro-Photometry-HAT-P-12-20090513.htm .

Anthony.

Anthony, that's amazing work. I didn't even realise you could get so much detailed information like that. Wow. You are officially a cool dude

nectarine wrote:

Anthony, that's amazing work. I didn't even realise you could get so much detailed information like that. Wow.

Thanks. To be totally honest, I had some apprehension since the parent star is mag 12.84 and which is dim for a 6.4 refractor and where the signal/noise ratio is critical for such work.

You are officially a cool dude

Oh, when and where do I get my OFFICIAL certificate?

Anthony.

Oh, and when and where do I get my OFFICIAL certificate

Isn't it about time you visited Ireland then? Mind you, if you could see the weather we're having at the moment, you would stay FAR FAR away.....:dry:

Anthony

That is a really good data capture. Can I suggest that you plot the data in a spreadsheet and find a regression line (polynomial order 4 or 5) that best fits the data. This represents a mathematical approximation of the "underlying" curve if there wasn't random variation. You then can (I believe) have an attempt at predicting the relative sizes of star and planet?

I haven't done this sort of thing but its the kind of stuff that interests me.

When you have the minumum (bottom of regression curve at mid-transit) you can compare with one or both maxima. Convert magnitudes to flux values and the ratio of these should equal the ratio of unobscurred disc of star area to obscrurred star area minus area of disc of planet and from which the ratio of sizes could be approximated.

It may be, however, that you are a little short of data to make a good estimate of the maxima - but it would still be interesting to try.

Mark

Mark,

I understand fully what you describe but how about the following scenario:

(1) get the mean flux for midtransit +/- five measurements
(2) get the mean flux for pre-ingress
(3) get the mean flux for post-egress
(4) average (2) and (3) for non-transit mean flux

Proceed using (1) and (4) ....

Anthony.