If δ is the declination of the star and φ is the latitude of the observer then the hour angle of the star at elongation is given by
sin H = tan φ . cot δ
cos H = tan φ . cot δ
tan H = tan φ . cot δ
None of these
Correct Answer :
B. cos H = tan φ . cot δ
Related Questions
The altitudes of a circumpolar star at culminations are 70° and 10°, both culminations being north of zenith. The declination of the star, is
80°
70°
60°
50°
Accidental errors
Do not follow any definite mathematical law
Cannot be removed by applying corrections to the observed values
Are generally small
All the above
The great circle along which the sun appears to trace on the celestial sphere with earth as centre during the year, is called
Equator
Celestial equator
Ecliptic
None of these
The most convenient co-ordinate system for specifying the relative positions of heavenly bodies on the celestial sphere, is
Altitude and azimuth system
Declination and hour angle system
Declination and right ascension system
Declination and altitude system
α and β are the angles subtended by a point of elevation h at their air station with respective plumb points. Photo scale and focal length of the lens being S and f respectively. Parallax displacement of the point due to relief, is
h tan α/S
h tan β/S
h (tan α + tan β)/S
h (tan α - tan β)/S
The altitudes of a circumpolar star at culminations are 70° and 10°, both culminations being north of zenith. The latitude of the place, is
80°
70°
60°
40°
If the altitudes of a star at its upper and lower transits are 60° 30' and 19° 30' respectively, the latitude of the place, is
30°
35°
40°
45°
The Polaris remains below horizon at
10° N
50° N Latitude
Equator
5° S latitude
Rotation of the camera at exposure about its vertical axis, is known as
Swing
Tilt
Tip
None of these
Pick up the correct statement from the following:
The vertical plane containing the zenith, the station of observation and the celestial pole is the observer's meridian plane
The angle between the direction of star in vertical plane and the direction of the star in horizontal plane is called the altitude of the star
The complement of the altitude of star is called the zenith distance of the star
All the above
A star in northern sphere is said to transit
When its altitude is maximum
When its azimuth is 180°
When it is in south
All the above
The declination and right ascension of the sun becomes 23° 27' N and 90° respectively on
March 21
June 21
September 21
December 22
The position of the sun when its north declination is maximum is known as
Vernal equinox
Autumnal equinox
Summer solstice
Winter solstice
Pick up the correct statement from the following:
The principal point coincides with plumb point on a true vertical photograph
The top of a hill appears on a truly vertical photograph at greater distance than its bottom from the principal point
The top of a hill is represented on a vertical photograph at larger scale than the area of a nearby valley
All the above
An aerial photograph may be assumed as
Parallel projection
Orthogonal projection
Central projection
None of these
A plate parallel is the line on the plane of the negative
Parallel to the principal line
Perpendicular to the principal line
Along the bisector of the angle between the principal line and a perpendicular line through principal plane
None of these
The solar tidal force divided by lunar tidal force is
1/3
1/2
3/4
5/4
The rate of change of parallax dp/dh with respect to change in h, may be expressed as
fB/(H - h)
fB/(H - h)2
fB/(H + h)
fB/(H + h)2
If two points differing by 1° of latitude and of the same longitude is 110 km apart on the earth, then two astronomical positions on the moon is about
10 km
25 km
30 km
50 km
The true and mean suns occupy the same meridian at the same time on
April 15
June 14
September 1
All the above
The nautical mile is the length of
1 minute of latitude
1 minute of longitude
1 degree of latitude
1 degree of longitude
Pick up the correct statement from the following:
North end of the polar axis is known as North Pole
South end of the polar axis is known as South Pole
Point where polar axis when produced northward intersects the celestial sphere, is known as north celestial pole
All the above
The meridian of a place is
A great circle passing through the place and the poles
A great circle whose plane is perpendicular to the axis of rotation and it also passes through the place
A semi-circle which passes through the place and is terminated at the poles
An arc of the great circle which passes through the place and is perpendicular to the equator
The scale of a tilted photograph of focal length f, taken from an altitude H, along the plate parallel through plumb point, is
f/H sec θ
f sec θ/H
f/H
f/H cos ½θ
The principal plane contains
Nadir point
Iso centre
Principal point
All the above
Pick up the correct statement from the following. The difference between the longitudes of the places is obtained.
By subtracting their longitudes if places are in the same hemisphere
By adding their longitudes if places are in the different hemispheres
By subtracting the sum of their longitudes exceeding 180° from 360° if places are in different hemispheres
All the above
The First Point of Aeries
Is the point in the celestial sphere where zero meridian crosses the celestial equator
Is usually denoted by the Greek letter γ
Is located near the very conspicuous rectangle of stars in the constellations of Pegasus and Andromeda
All the above
The point on the celestial sphere vertically below the observer's position, is called
Zenith
Celestial point
Nadir
Pole
The distance between the projection centre and the photograph, is called
Principal distance
Principal line
Isocentric distance
Focal length
The point on the photograph where bisector between the vertical line through optical centre of the camera lens and the plate perpendicular meets, is known as
Principal point
Isocenter
Plumb point
Perspective centre