Observations of IS and IU Delphini

Our photographic observations of ISDel have been analysed. the two types of bursts have been discovered on the light curves of IS Del, those of the fist type reaching the magnitude 15.1m B and having a duration up to 6 days, and those of the second type being not so bright (15.6m - 16.0m B) and not so long (2d). The interval between bursts varies from 9d to > 1 month being on the average 10d. IS Del is shown to be a U Gem type variable. The photographic data for IU Del have shown that the star is an eclipsing variable of the EA/SD type. Its brightness changes between 15.0m - 17.4m B with the period 1.85999d.