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Ultraviolet images of NGC1851 at 2490 and 1520 Angstroms which were obtained on the Astro-1 Spacelab mission are presented. We discuss 46 blue horizontal branch (HB) stars which are detected in both UV passbands and are sufficiently uncrowded to allow accurate photometry. Supporting V and B band observations show excellent correlation with a model ZAHB of Z=0.001, Y=0.23, and M-m=15.49. In the UV the same stars fall approximately 0.6 mag fainter than the model. Instrument calibration, anomalous UV extinction, and errors in the theoretical models are discussed as sources of this discrepancy. A new hot subdwarf of Teff~26000K is discovered and compared with ground-based spectroscopy reported on by Landsman, et al in these proceedings. The PAGB star UV5, originally identified by Vidal and Freeman (1975) is also discussed.
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