Her Wikipedia article is here. Her husband, Duke Wilhelm Heinrich von Sachsen-Eisenach-Jena, died childless in 1741.
From the Lempertz Web site; a white dot in the lower center was removed with Photoshop and shadows were somewhat filled in.
Anna Sophia Charlotte is dressed for mourning in almost all black with attifet and veil in this 1742 de Gasc portrait.
Keywords: 1742, de Gasc, Anna Sophia Charlotte von Brandenburg-Schwedt, Hohenzollern family, Wettin family, Duchess, German, curly coiffure, attifet, veil, partlet, vee neckline, bodice, off shoulder scoop neckline, fur bertha, elbow length close sleeves, lace forward-back flared engageantes, vee waistline, train, fur trim, under-skirt, earrings, bracelets