The photographic observations of 51 Peg with the known planetary companion which has been discovered on the basis of radial velocities (Mayor and Quelos 1995), are being performed at Pulkovo since 1995 by means of 65 cm refractor. So far 46 plates with 170 individual positions have been obtained. The mean error of one exposure is $0.^{\prime\prime}031$ and the error of one plate is $0.^{\prime\prime}020$. The external error of one plate or the error of unit weight is $0.^{\prime\prime}033$, while the error of one yearly position equals to $0.^{\prime\prime}010$. The aim of our observations is to investigate whether this star has some satellites of low mass (stellar or substellar) with periods of rotation from some years to a decade, or more. At present we have the possibility to study its motion over a time span of 8 years and to learn of probable perturbations due to the presence of possible satellites with the periods 0.5–6.0 years and with masses more than $0.2M_\odot$. The absence of satellites with such periods and masses has been shown by means of our observations. The results are compared with the Pulkovo series of the star Gliese 623, whose satellite with the period of $3.76$ yr and mass of $0.09M_\odot$, has been confirmed by observations.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html