It was discovered in the Palomar-Green survey of ultraviolet-excess stellar objects[6] and, like the other PG 1159 stars, is in transition between being the central star of a planetary nebula and being a white dwarf.

[7] The luminosity of PG 1159-035 was observed to vary in 1979,[8] and it was given the variable star designation GW Vir in 1985.

[9] Variable PG 1159 stars may be called GW Vir stars, or the class may be split into DOV and PNNV stars.

[10][11] The variability of PG 1139-035, like that of other GW Vir stars, arises from non-radial gravity wave pulsations within itself.

[12] Its light curve has been observed intensively by the Whole Earth Telescope over a 264-hour period in March 1989, and over 100 of its vibrational modes have been found in the resulting vibrational spectrum, with periods ranging from 300 to 1,000 seconds.