Results of PMM scans of Schmidt survey plates - USNA2.0 has 550 million stars on 10 CDs. SA2.0 is more manageable -55 million stars. UCAC1 is the best astrometrically (covers dec -90° to -5°, accuracy = 70 mas at R = 16) http://ad.usno.navy. mil/star/star cats rec.html
Regular publication of measures. Advice on observing. There is a comparison between the RETEL and van Slyke micrometers on the website. www.webbsociety.freeserve.co.uk/notes/ doublest01.html.
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