[ ESO ] La Silla

La Silla - Science Operation Department


CES CCD modes

CCD modes

Three CCD read-out (R/O) speeds are possible: normal (normal,100kps), fast (fast,225kps), and very fast (vfast,625kps). The only binning modes offered are 1x1 and 4x1, i.e. no binning in the dispersion direction is offered. Note that "X" is the direction perpendicular and "Y" is the direction parallel to the dispersion (in the CCD image "lambda goes up").

Recommended R/O spead for scientific exposures is normal. Programmes which require minimum overhead times (i.e. R/O time, data transfer, and storage) should use fast R/O. CCD binning also reduces the overheads. vfast R/O is not recommended for scientific applications.

The following table lists the temporal overheads for the various R/O speed and binning modes. They are precise to ±1 sec.

CCD modes and read-out/transfer time
Binning XxY Normal R/O Fast R/O Very fast R/O
1x1 51 sec 26 sec 15 sec
4x1 16 sec 11 sec 7 sec

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