We present the results of an extendeded multi-site observing campaign for the search for 
extrasolar planetary transits in two super metal-rich, old open clusters: NGC6791 and 
NGC6253.  The purpose of our investigation is to infer the frequency of planets in open 
cluster environment, and to compare it with that of field stars.

In the case of NGC6791, using the data from four telescopes (CFHT 3.6m, NOT 2.5m, San Pedro 
Martir 2.2m, and Loiano 1.5m) spanning about 15 nights in two observing seasons (July 2001 
for the NOT, and July 2002 for the other, multisite campaign), we achieved millimag 
photometric precision in more than 3300 cluster stars. Our photometric sequences are fully 
adequate to detect "hot jupiters", i.e. planets with periods of a few days, transit duration 
of the order of a few hours, and radii of the order of one jovian radius.

The main result of the investigation is that no significant planetary transits were 
identified.
This null result contrast with the number of transits we expected from our observing 
campaign. 

In fact, a set of detailed simulations show that with reasonable assumptions on planet 
radii, cluster metallicity, planet frequencies, and for our photometric accuracy and total 
number of monitored stars,  the expected number of detectable transiting planets with at 
least one transit inside our observing window is 3+-1.

Our simulations also show that the probability to obtain a null result by chance is from 3% 
to 10%, depending on the adopted metallicity for NGC6791.

We will discuss the implication of our results, and we will present a possible new observing 
campaign which could definitively solve the problem of the presence or absence of hot 
jupiters in NGC 6791.


The analysis of NGC 6253, observed with a 10 day long multisite campaign at ESO using 
WFI@2.2 and at the AAT, is in progress, and will be presented at the conference.