In the Hanumatsahasranaama from Rudrayaamala one of the name is Gabhastigraasako. A few years ago I came across a stanza in sanskrit which roughly translated meant " ...At that time, in the constellation of Libra, a Sun named Gabhasti was giving birth to itself..." Anyone know the source?
Gabhasti or Gabhastika is mentioned as a form of the sun in chapter fifty-one of the Agni Purana:
(4). (The images of) Agni and other gods bearing the club, trident, disc and lotus should be placed in different directions (around). (The images of) the forms of Sun, commencing with Aryamā are represented as possessing four arms and placed in a diagram of twelve petals.
(5-6). Varuṇa, Sūrya, Sahasrāṃśu (one who has thousand rays), Dhātṛ, Tapana, Sāvitṛ, Gabhastika, Ravi, Parjanya, Tvaṣṭṛ, Mitra (and) Viṣṇu are his different names as he moves over the zodiacal signs commencing with the Aries in the course of months commencing with Mārgaśīrṣa and ending with Kārttika.
(7-9). Their female energies known by the names—Iḍā, Suṣumnā, Viśvārcis, Indu, Pramardinī, Praharṣaṇī, Mahākālī, Kapilā, Prabodhanī, Nīlambarā, Ghanāntasthā and Amṛtā, and placed at the ends of petals are of black, red, pale red, yellow, pale yellow, white, brown, yellow, green, white, grey and blue.
According to the Puranic Encyclopaedia, this specific form does indeed correspond to Libra.
On a side-note, Gabhastika is mentioned in the Skanda Purana as the tirtha (sacred place) associated with Sūrya: the 63rd of the 68 names of the sun. (source)