observer's meridian

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Noun

observer's meridian - a meridian that passes through the observer's zenith

line of longitude, meridian - an imaginary great circle on the surface of the earth passing through the north and south poles at right angles to the equator; "all points on the same meridian have the same longitude"

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References in periodicals archive ?

The algorithm for the time interval between rising and setting of a star and its transit over the observer's meridian for particular declinations is derived from spherical geometry (Kaler appendix 3) and is given by Ridpath (1989: 40).

Solar motion from Australia

Instead they corrected it to the Pole Star's position of minimum altitude on its orbit as it crossed the observer's meridian. At this point, the correction is zero.

The stars for which they do give information have widely differing declinations; and at equal altitudes they are far from being equidistant from the observer's meridian. It is inconceivable that they could have used the normal abdal method as already described above without some modification.(9) For with two stars at widely differing distances from the observer's meridian, they would show differences in altitude change per 1 |degree~ change in Pole Star or Pole altitude, so that their altitudes would not remain equal as the observer moved on the same meridian away from the initial reference latitude, whereas exact abdal stars retain their equal altitude relationship on the observer's meridian at all latitudes.

There is actually a very slow drift even for stars exactly abdal, and the further the stars are from the observer's meridian, the greater the variation and the smaller the range of latitude over which the method can be used.