Latitudinal structure of the equatorial F3 layer based on Intercosmos-19 topside sounding data

► Equatorial F3 layer from the Intercosmos-19 topside sounding data is studied. ► It is shown that F3 layer is usually observed at the afternoon and evening hours. ► Sometimes prominent F3 layer is seen at night and early morning hours. ► F3 layer is observed from −10° to 10° GMLAT around of the magnetic equator. ► F3 layer and equatorial anomaly crest are located near the same magnetic field line.