Ṛgveda & Vedāṅga Jyotiṣa · c. 1200–900 BCE
No e-text of the Kāṭhaka Saṃhitā is online; the name is attested here through Macdonell & Keith's comparative table of the nakṣatra lists.
[Attested only via the secondary comparative table] '21. Srona .. Srona. .. Asvattha' — A.A. Macdonell & A.B. Keith, Vedic Index of Names and Subjects (1912), i.413
A name unique to the Kāṭhaka Saṃhitā, standing in slot 21 where the Taittirīya and Maitrāyaṇī lists both read Śroṇā. Attested in Macdonell & Keith's comparative table of the three Yajurveda lists, Vedic Index (1912) i.413: '21. Srona .. Srona. .. Asvattha' for TS | MS | KS. The word otherwise means the pipal tree (Ficus religiosa). NOT verified against a primary Kāṭhaka e-text — GRETIL does not host it and the TITUS URL returned only a frame stub — so confidence is marked disputed on that ground alone, not because the scholarly attestation is weak.
Pāṇini & Patañjali · c. 500–350 BCE (Pāṇini)
४.२.२२ आग्रहायणी अश्वत्थात् ठक् ।
Devanāgarī from Sanskrit Wikisource, which de-sandhis the compound; GRETIL's texts give 'āgrahāyaṇy-aśvatthāṭ ṭhak' and 'āgrahāyaṇī=aśvatth-āt=ṭhak'. See also 4.2.5 quoted in the shravana entry.
22. The affix [ṭhak] comes in the sense of the locative case after the words 'agrahayani' and 'asvattha' ending in the first case-affix in construction and being the name of a full-moon night. — Śrīśa Chandra Vasu (1896)
A useful strengthening of a thin entry. Pāṇini names Aśvattha three times: 4.2.5 saṃjñāyāṃ śravaṇa-aśvatthābhyām (paired directly with Śravaṇā, under the rule for asterism-derived TIME names), 4.2.22 āgrahāyaṇy-aśvatthāṭ ṭhak (paired with Āgrahāyaṇī, deriving a month-name from a full-moon night), and 4.3.48 kalāpy-aśvattha-yavabusād vun. The first two put Aśvattha squarely in the calendrical/asterism series, which supports — without proving — the database's identification of it as a name for the Śravaṇa region; Vasu's Kāśikā gloss calls the product 'the Muhūrta called Aśvattha', i.e. a unit of time, and 4.2.22 treats it exactly as it treats Āgrahāyaṇī, a genuine full-moon name. Pāṇini himself never says which asterism it is, so this stays disputed. Confounder: aśvattha is also the ordinary word for the pipal tree, and 4.3.48 (with kalāpin, yava, busa) is probably botanical.