One should never perform a Shraddha under the constellation of his nativity. No Shraddha should be performed under any of the Bhadrapadas (prior or later), nor under the constellation Krittika, O Bharata.
नक्षत्रे न च कुर्वीत यस्मिन् जातो भवेन्नरः। न प्रोष्ठपदयोः कार्यं तथाग्नेये च भारत॥