Catalogued in RISM as “Semiramis (Excerpts); Manuscript copy; S-L Saml.Engelhart 571” by Anonymus. RISM 190001606
Probable
The aria 'Rigida sei' has the music of an aria (violin incipit 1.27.1) in Hasse's Cajo Fabricio, transposed: Hasse reusing it, if this Semiramis is his setting.
Attributed copies compared (1 of 1 encoded incipit match):
1.1.1 Andante · S · “Rigida sei” · 23 of 27 pitches agree
=6/2-'q6A8G6FG{AF}{ED}/8B4A8B''q8DC'6BA''q6C'8B{6AG}/{AF}8G-BA''DD{6C'B}/q6''G{8F6EF}{GEDC}8A4G8A/q6'''C{8''B6AG}qB{8A6GF}{GE}q8E4F8A/also RISM 270000644 1.27.2
Catalogue data and incipits come from RISM (Répertoire International des Sources Musicales), CC BY 4.0. Incipits are rendered with Verovio. Source and data: https://github.com/aaymeloglu/rism-attributions.