Effective temperatures of hot white dwarfs.

ANS observations on hot DA white dwarfs in the ultraviolet (1500-3300 A) are compared with recently developed model atmospheres with helium and metal poor compositions, resulting in the determination of effective temperatures for these objects. The new temperatures are comparable to but more accurate than earlier determinations. It is specifically found that HZ 43 and Feige 24 have effective temperatures of 61,000 (+ or - 5000) K and 63,000 (+ or - 10,000) K, respectively, while n(He)/n(H) has values of about 0.00001 and 0.001.