Keywords: Hydra Corvus et Crater - Mercator.jpeg Hydra Corvus and Crater constellations from the Mercator celestial globe The Mercator Globes at Harvard Map Collection http //hcl harvard edu/mercatorglobes/ 1551 Gerard Mercator 1512-1594 PD-old-100 Mercator celestial globe Hydra constellation Corvus constellation Crater constellation Antlia constellation Maps by Gerardus Mercator |