If θ and δ be the latitude of an observer and declination of a heavenly body respectively, the upper culmination of the body will be south of zenith if its zenith distance, is
Spring tides are caused when
A star may culminate at zenith if its declination is
A star has a declination of 55°N its upper culmination is in the zenith of the place. The altitude of the lower culmination is
When star’s upper culmination is in zenith, polar distance = latitude and declination = latitude
At lower culmination, Zenith distance
= 180°- (latitude + delineation)
= 180°- 2 x 55° = 70°
Hence altitude = 90° - 70° = 20°
A vertical photograph was taken from an aircraft flying at an altitude of 2000 m above mean sea level. The focal length of the camera is 175 mm. The scale of the photograph for a hill of an elevation of 250 m is
In an aerial photograph, if the photograph has a tilt of 3° and the focal length is 100 mm, then the distance between the perspective centre and the plumb point will be
In an aerial photograph, if the photograph has a tiit of 4° and the focal length is 200 mm, then the distance between, the principal point and plumb point will be
An aircraft is flying at a ground speed of 200 km/h. The focal length of the camera is 200 mm. The ground distance covered is 200 mm. The ground distance covered along the flight line between exposures is 2 km. The time interval between exposures is given by
Time interval betw een exposures (sec) = 3600L/V where L is ground distance covered between exposures along the flight line is km and V is the ground speed of the aircraft in km/h.
Which one of the following surveys is required in observations of stars?
Cadastral survey is used to plot the details such as boundaries of fields, houses and property lines in rural and urban areas. These are also known as public land surveys.
Photogrammetry is used to produce a mosaic or map by compiling the photographs. Aerial survey covers photogrammetry and photo-interpretation both.