On March 9, Eduardo Baca, Yjeguel Camasa, and I climbed Nevado Bonanta (ca 5,300m a.k.a. Bonomia), a large, rounded glacial summit on the ridge extending west from Nevado Veronica (5,893m). Our route up the east ramp had a short, easy, but very exposed 5th-class rock section to gain the glacier. Here, I found an old Charlet Moser ice axe; I believe it is from the 1958 Italian expedition that made the first ascents of Bonanta, Huakeihuilqui, Marconi, and the Chicon peaks farther east (AAJ 1959).
The climb onto the summit plateau was straightforward on 120m of 50° ice, after which we post-holed up knee-deep snow until the summit (300m, PD+). There were no views, as it was still the wet season, but they would be spectacular on a clear day.
– Nathan Heald, Peru
Update (12/17/17), per information from Sevi Bohorquez: "Nathan Heald sent me two photos and he says that the photo of the 'top' of Nevado Bononia (5,110m), where the Italian expedition of 1958 planted its flag (this photo is in Mario Fantin's book, Yucay, 1958, p.87), was taken about 400m below the top of Nevado Bonanta. If the Italian expedition only got there, then the first ascent to the summit of the Bonanta must be attributed to the Argentine expedition of 1959 (AAJ 1960). It is still difficult to know if the Japanese expedition of 1967 was the second to reach the summit of Bonanta, because in its sketch (Sangaku Vol. 63, 1969, p.13 and p.55–56) it was pointed out as 'Nevado Bononia 5,110m' , which may be a different summit, and, therefore, we can not assure yet if the ascension of Heald et al. to Bonanta was the second or the third."