GSC 02652-01324

The designation GSC 02652-01324 comes from the Guide Star Catalog. The star is sometimes called TrES-1, in reference to its planet discovered by the Trans-Atlantic Exoplanet Survey (TrES). The discovery paper and the SIMBAD database use this designation for the planet itself, but other sources call the star TrES-1 and the planet TrES-1b, following the standard exoplanet naming convention. Since the planet transits the star, the star is classified as a planetary transit variable and has received the variable star designation V672 Lyrae. The transits last a little over an hour, about 4% of the orbital period, and the brightness diminishes by a few hundredths of a magnitude. ==Planetary system==

In 2004, the exoplanet TrES-1b was found to be orbiting this star by the Trans-Atlantic Exoplanet Survey using the transit method. The planet was detected crossing its parent star using a small telescope. The discovery was confirmed by the Keck Observatory using the radial velocity method, allowing its mass to be determined. The planet is a hot Jupiter, with a mass and size similar to those of Jupiter but an orbital period of only three days. Evidence of a candidate second planet, designated TrES-1c, was found in 2025 by the radial velocity method. If existing, this planet would have a minimum mass about that of Saturn, and an eccentric orbit with a 1,200-day period. An additional planet in the system is suspected due to transit-timing variations (TTVs) of TrES-1b, but has not been detected. For a planet causing the observed TTVs to remain undetected, it would need to have a mass less than ~ and an orbital period less than ~7 days. Other than the TTVs, there is as yet no evidence of such a planet, but the observed TTVs cannot be explained by other known effects. ==See also==