a method of determining geographic latitude from observations of two stars at equal altitudes; it was proposed in 1887 by M. V. Pevtsov. The stars are selected so that at the time of observation the sum of their azimuths at equal altitudes or zenith distances is close to 180° or 54°; in addition, one star must be in the southern part of the sky from the zenith, and the other star in the northern part. Pairs of stars satisfying these conditions are selected by means of special ephemerides. The observations are made with a theodolite or a zenith telescope in the focal plane of whose objectives there is a reticle with several horizontal lines. The instrument must be equipped with a level that is securely attached to the instrument’s horizontal axis and that registers the slightest changes in the inclination of the tube. Calculations of the latitude ϕ can be made by the formula
where δS, tS, δN and tN are the declinations and hour angles of the southern and northern stars, respectively. Observations by the Pevtsov method are simple, and the results are highly accurate. The method is widely used in astronomical geodesy.
REFERENCESPevtsov, M. V. Ob opredelenii geograficheskoi shiroty po sootvetstvennym vysotam dvukh zvezd. St. Petersburg, 1887.
Tsvetkov, K. A. Prakticheskaia astronomiia, 2nd ed. Moscow, 1951.
Efemeridy dlia opredeleniia shiroty po sootvetstvennym vysotam zvezd (po sposobu Pevtsova), vols. 1-5. Moscow, 1946-49.