what is rh on an indian sounding rocket

In the context of Indian sounding rockets, "RH" stands for "Rohini," which is the name of the rocket family developed by the Indian Space Research Organisation (ISRO) for meteorological and atmospheric studies. The rockets in the Rohini series are designated with the letters "RH," followed by a number corresponding to the diameter (in millimeters) of the rocket. The RH-75, RH-100, and RH-125 were the initial rockets in this series, with the RH-75 being the first truly Indian sounding rocket. The RH-200, RH-300 Mk-II, and RH-560 Mk-II are currently in operation.