# THE SPOT SATELLITES

The SPOT payload

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The SPOT payload comprises two identical HRV (High Resolution Visible) imaging instruments, two tape recorders for image data, and a payload telemetry package for image transmission to ground receiving stations. The position of each HRV entrance mirror can be commanded by ground control to observe a region of interest not necessarily vertically beneath the satellite. Thus, each HRV offers an oblique viewing capability, the viewing angle being adjustable through +/- 27deg. relative to the vertical.
Two imaging modes are employed,panchromatic (P) and multispectral (XS). Both HRVs can operate in either mode, either simultaneously or individually.

HRV telescope

### "P" panchromatic mode

Imaging is performed in a single spectral band, corresponding to the visible part of the spectrum without the blue. The band covers 0.51 to 0.73 µm. This single channel imaging mode supplies only black and white images with a pixel of 10 m. This band is intended primarily for applications calling for fine geometrical detail.

### "XS" multispectral mode

Imaging is performed in three spectral bands. The bands used are band XS1 covering 0.50 to 0.59 µm (green), band XS2 covering 0.61 to 0.68 µ m (red) and band XS3 covering 0.79 to 0.89 µm (near infrared).
By combining the data recorded in these channels, colour composite images can be produced with a pixel size of 20 meters.

Spot multispectral bands and typical spectral signatures