position angle

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position angle

(PA; p.a.)

1. The direction in the sky of one celestial body with respect to another, measured from 0° to 360° in an easterly direction from north. It is used, for example, to give the position of the fainter component of a visual binary with respect to the brighter component.

2. The angle at which the axis of a planet or star, or some other line on a celestial body, is inclined to the hour circle passing through the center of the body; it is measured eastwards from 0° to 360° from north.

Position Angle

an angle on the celestial sphere between a direction given at some point and the hour circle through this point; it is measured counterclockwise from 0° to 360° from the northern sector of the hour circle. Position angles are used to determine the relative position of the components of binary stars and multiple systems and the directions of the proper motions of stars. They are measured with a position micrometer.

position angle

[pə′zish·ən ′aŋ·gəl]

(astronomy)

The angle formed by the great circle running through two celestial objects and the hour circle running through one of the objects.

In measuring double stars, the angle formed between the great circle running through both components and the hour circle going through the primary measured from the north through the east from 0 to 360°.

(navigation)

That angle of the navigational triangle at the celestial body having the hour circle and the vertical circle at its sides. Also known as parallactic angle.

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References in periodicals archive ?

Not only is the distance measurement prone to a larger percentage error than for a wider pair, but also the position angle (PA) is much more difficult to determine, as there is such a short baseline available for aligning the central scale for the PA measurement.

Measurements of nine southern double stars

As mentioned above, the change of plant leaf temperature with plant leaf position with respect to the radiation source changing also depends on plant leaf thickness [delta], leaf position angle [beta], duration of being in a certain position [tau] or oscillation frequency f, but expression (17) points to a considerable impact that the difference in temperatures between the leaf surface and the environment [t.

Theoretical modeling of temperature pulsations in plant leaf which are caused by leaf swing with respect to the sun/Lokaliu augalo temperaturos pulsaciju, kurias sukelia lapo svyravimai saules atzvilgiu, teorinis modeliavimas

The mean lateral component position angle and the SD were calculated for the series of radiographs of each hip (Fig.

Measuring acetabular component position on lateral radiographs: ischio-lateral method

Where R(z) is the flute radius at z, [phi] is the tool offset magnitude, [lambda] is the tool offset position angle, and [[psi].

Adjustable toolholder for tool runout analysis in peripheral milling

Cigar-shaped NGC 4085 is smaller and fainter than NGC 4088, but at 152x is even more elongated at 8:1 [Gottlieb 4:1] with a position angle of 78[degrees] (almost east to west).

A flotilla of edge-on galaxies: turn your scope toward this quintet of faint fuzzies floating in Ursa Major

Finally, in order to figure the difference among the three screw types out, variation of position angle under the maximum force of 4 N in z-direction is also considered and results of FCR for Model I and Model II are presented in Figures 9-12.

A new appliance for improving the miniscrew stability

Closer examination of the original image shows a faint extension in position angle (p.

Observations of Comet C/2012 F6 (Lemmon)

By combining both of our observations, Brian was able to estimate the position angle, separation and magnitude difference of the double star's components.

Lunar occultations of double stars--a plea for observations

Leaves change their position with respect to the Sun with the change of the leaf position angle [beta] (Fig.

Solar radiation energy pulsations in a plant leaf/Saules spinduliuotes energijos pulsacijos augalo lape

A new correction of the position angle values of the wheels brought the interference within acceptable values; also the penetration values are in good limits (table 1) considering the case of grinded teeth.

On the torsion gear tooth stiffness at helical gears

Three examiners measured joint position angle of -10[degrees], 0[degrees], 10[degrees], 20[degrees] and 30[degrees] of plantarflexion at 0[degrees] and 20[degrees] of the ankle inversion, respectively.

Position-specific deficit of joint position sense in ankles with chronic functional instability

Our database includes, for each timing, the corresponding position angle around the umbra, so in principle one could look for a topographic effect.