3 Piscis Austrini

3 Piscis Austrini, also known as HD 201901 or simply 3 PsA, is an astrometric binary (100% chance ) located in the southern constellation Microscopium. It was once part of Piscis Austrinus, the southern fish. The system has a combined apparent magnitude of 5.39, making it faintly visible to the naked eye under ideal conditions. Gaia DR3 parallax measurements imply a distance of 404 light years and it is currently approaching the Solar System with a heliocentric radial velocity of $$. At its current distance, 3 PsA's brightness is diminished by 0.12 magnitudes due to extinction from interstellar dust and it has an absolute magnitude of +0.19.

The visible component is an evolved red giant with a stellar classification of K3 III. The interferometry-measured angular diameter of the star, after correcting for limb darkening, is $$, which, at its estimated distance, equates to a physical radius of about 20 times the radius of the Sun. However, its actual empirical radius is. It has 1.58 times the mass of the Sun and is radiating 184 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of $$. 3 PsA is metal deficient with an iron abundance 68% that of the Sun ([Fe/H] = −0.17) and it spins too slowly for its projected rotational velocity to be measured accurately. It is estimated to be 2.59 billion years old based on Gaia DR3 models.