By doing it under the constellation Abhijit, one acquires great knowledge. By doing it under Shravana, one, after death, attains to a very high end.
श्राद्धं त्वभिजिता कुर्वन् भिषक्सिद्धिमवाप्नुयात्। श्रवणेषु ददच्छ्राद्धं प्रेत्य गच्छेत् स सद्गतिम्॥