HAT-P-13 c: a transiting exoplanet for amateurs

A hot jupiter transiting in the HAT-P-13's system was discovered last year. By measuring its mass by radial velocity, the American team discovered another very massive planet in the system, with a period of 428 days.The question is to know whether this second companion is a planet, formed in the same disc as the hot Jupiter, and therefore in transit also. It would be an incredible chance to discover this transit, because the planet the planet is close to it's star's habitable zone, and one of it's satellites could shelter life. If it conveys in transit, we will be able in the future to conduct a thorough study with space telescopes


The call of the professional astronomers towards the amateurs is now international, because the transit we seek is visible only once in 2010 (if transit there is!), is going to last 15 hours, everyone can observe it for only a few hours, and we have a 2 days uncertainty on it's precise date! With a network of observers in all degrees of longitude, we will be able to rebuild the light's curve on all lenght! I am in contact with an American astronomer who co-ordinates observations across the Atlantic.

if observing exoplanets interests you, if you have an adapted equipment, and some available nights between 8 and on April 24th, 2010, could you try to make this observation ?

You would need:
- to use a filter, red if possible
- to centre the star HAT-P-13 (V=10.6) in a clean area of your ccd and not to change the position during the whole sequence
- a 3 to 5 pixels image spread is optimum.
- observe as long as possible from the 8th to the 24th of April (included), with a highest probability around the 15th, 16th and 17th.
- to have a good quality flatfield with the same filter, if possible measured on the sky.

The co-ordinates of the star: RA = 8:39:32 AM DEC = +47:21:07 It is observable every night in april, during the first half of the night from the northern hemisphere

the awaited transit is deep (well, it's all relative: it's 1%), it is therefore accessible to your equipment, but for more security you can practise on the transit of the hot jupiter in the same system, which takes place on March 28th in 21:37 UT and on March 31st in 21:36 UT.
We can analyse and reduce the pictures for you if needed

The system
http://exoplanet.eu/star.php?st=HAT-P-13
French contact:
Claire Moutou claire.moutou@oamp.fr
US contact:
Ben Nelson benelson@astro.ufl.edu and Scott Fleming scfleming@astro.ufl.edu

Many of you have to respond to the request of the System
HAT-P-13, to determine whether an extrasolar planet outside of this system showed
transit. Thank you for your interest! There are new data on
system DATE CHANGE EXPECTED FOR EVENT! It is more than
ever important to observe, especially since the uncertainty on this date is
diminished.
The transit center is now expected to 17h UT April 28, 2010,
with an accuracy of 2 days.
It should therefore be observed as much as possible, FROM 24 APRIL TO 2 May 2010.
Yes, it's the full moon, it will do with ...
I will certainly tell you if a new update.

See here for full info on photometric observations of this star:
http://brucegary.net/AXA/HATP13/hatp13.html
Good comment!
Claire Moutou

That's a pretty darned cool webpage, Stalker.

Well the transit window for HAT-P-13c has probably passed (I guess), wonder if anyone saw anything.

Alex31 (Alexandre Santerne) from Webastro (translated)

Quote :

Some insoled detections were made from Europe, but obviously nothing very convincing or significant. We try now to put different events together to see if some are compatible, but I am afraid that nothing is seen!

Transit had to last fifteen hours, perhaps on the side of the United States they have something more convincing!

No detection of the transit of HAT-P-13 c.

HAT-P-13: a multi-site campaign to detect the transit of the second planet in the system
http://arxiv.org/abs/1009.3598

Abstract wrote:

A possible transit of HAT-P-13c has been predicted to occur on 2010 April 28. Here we report on the results of a multi-site campaign that has been organised to detect the event. CCD photometric observations have been carried out at five observatories in five countries. We reached 30% time coverage in a 5 days interval centered on the suspected transit of HAT-P-13c. Two transits of HAT-P-13b were also observed. No transit of HAT-P-13c has been detected while the campaign was on. By a numerical experiment with 10^5 model systems we conclude that HAT-P-13c is not a transiting exoplanet with a significance level from 65% to 72%, depending on the planet parameters and the prior assumptions. We present two times of transit of HAT-P-13b ocurring at BJD 2455141.5522 +- 0.0010 and BJD 2455249.4508 +- 0.0020. The TTV of HAT-P-13b is consistent with zero within 0.001 days. The refined orbital period of HAT-P-13b is 2.916293 +- 0.000010 days.

Ah well, would have been neat. Wonder how conveniently placed the HAT-P-13 star will be next time around, and whether the significance level could be improved.