The plate scale of a

telescope A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to obse ...

connects the angular separation of an object with the linear separation of its image at the focal plane If focal length

f

is measured in mm, the plate scale in radians per mm is given by angular separation ''θ'' and the linear separation of the image at the focal plane ''s'', or by simply the focal length ''f'': :

p =\frac =\frac\ ,

since :

s =f \theta\ .

Plate scale is usually expressed in arc-seconds per mm: :

p \approx\frac,

where ''f'' is in mm, or expressed in arc-seconds per pixel after further division through the pixel scale.

Plate scale on JWST FGS/NIRISS

The plate scale of the

James Webb Space Telescope The James Webb Space Telescope (JWST) is a space telescope which conducts infrared astronomy. As the largest optical telescope in space, its high resolution and sensitivity allow it to view objects too old, distant, or faint for the Hubble ...

component Fine Guidance Sensor and Near Infrared Imager and Slitless Spectrograph is about 0.065 arcsec/pixel. It uses a 2048 x 2048 pixel array with a pixel size of 18 microns a side with a field of view of 2.2' x 2.2' http://www.stsci.edu/jwst/instruments/niriss/instrumentdesign

Notes

Astrophotography {{astronomy-stub

Plate scale on JWST FGS/NIRISS

See also

Notes