Near-infrared (0.8-2.5 micron) spectroscopy of Nova Sagittarius 1998=v4633Sagittarii

The 0.8-2.4 km spectroscopy of the moderately fast Nova Sgr 1998 = V4633 Sg r, obtained approximately 525 and 850 days after peak brightness, revealed an expanding, hydrogen-deficient shell of medium excitation level that incr eased with time. The strongest lines were He I and He II and the coronal li ne of [Si VI] 1.9641 mum. Also prominent were the lines of H I, and coronal [Ca VIII] 2.3205 mum and [Si VII] 2.4807 mum. Other lines included the [S III] lines at 0.9069 and 0.9532 mum and the coronal lines of [Al IX] 2.0444 mum and [Ti VI] 1.7155 mum. Five lines that frequently appear in novae spe ctra remain unidentified: 0.8926, 1.1114, 1.1900, 1.5545, and 2.1000 +/- 0. 005 mum. All the observed lines were roughly 1800 km s(-1) wide (FWHM), and no asymmetries or underlying plateaus were seen. The continuum was signifi cantly shallower than a 1/lambda (4) blackbody emission (approximately stel lar photosphere) and steepened with age.