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.
@article{arxiv.1009.3598,
title = {HAT-P-13: a multi-site campaign to detect the transit of the second planet in the system},
author = {Gy. M. Szabó and L. L. Kiss and J. M. Benkő and Gy. Mező and J. Nuspl and Zs. Regály and K. Sárneczky and A. E. Simon and G. Leto and R. Zanmar Sanchez and C. -C. Ngeow and Zs. Kővári and R. Szabó},
journal= {arXiv preprint arXiv:1009.3598},
year = {2015}
}