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Indian Spy Satellites

Deatails of Cameras in cartoSat Series :

PAN Camera (Panchromatic Camera):

The objective is to provide imagery for cartographic applications. The optical system is designed with two mirror Ritchey-Chretien on-axis obscured reflective telescope system with a concave hyperboloidal primary mirror and convex hyperboloid secondary mirrors and the field correcting relay optics. The mirrors are made of special Zerodur glass and are light-weighted to about 60% as in CartoSat-1 series. The mirrors are mounted inside the telescope cylinder made of CFRP with special MFDs (Mirror Fixation Devices) and the whole telescope assembly is mounted to the spacecraft structure through a special suspension arrangement. The optical system is designed to provide < 1 m resolution across track. The along track GSD of 0.8 m is achieved by apparent velocity reduction by a factor of 2.5.

The spacecraft can be suitably biased to provide various modes of imaging:

1) Continuous strip monoscopic mode

2) Spot scene imaging (strips on either side of the ground track can be imaged)

3) Paint brush mode of imaging. This mode is used to increase the total swath. Both roll tilt and pitch tilt is employed.

The PAN Camera is a nadir-pointing pushbroom CCD instrument (detector line array of 12, 288 pixels), observing in the visible spectral range of 0.5-0.85 µm with a GSD (Ground Sample Distance) of < 1 m, and a swath width of 9.6 km at nadir.

Table 2: Summary of PAN Camera parameters

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Figure 10: Focal plane alignment of the panchromatic camera (image credit: ISRO)

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Table 3: Evolution of ISRO high-resolution imaging systems 21)

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Figure 11: Configuration of the electrooptical module assembly (image credit: ISRO)

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Figure 12: FOR (Field of Regard) of CartoSat-2 for various spacecraft pointing angles (image credit: ISRO) 22)

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Figure 13: Hyderabad (India) as seen by the Pan Camera of CartoSat-2 (image credit: ISRO)
 
Just to point out this is not full resolution. There are ways to blow up a picture but optical is loose less and this resolution is not the max resolution optical zoom image.
 
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