EXPTIME = The exposure time for this image given in seconds.

Note that for EXPMODE of type:

exp t and mexp t N

the exposure time is equal to the parameter t. For EXPMODE of the type:

frame t N

on the other hand the EXPTIME of the final image is equal to t x N.

NB! Note that since there is one and only one header for the resulting fits cube with all the N readouts from a frame command, the EXPTIME value is correct only for readout number N, as well as the final image. The correct EXPTIME for all the other readouts must be calculated and the headers updated if you wish to use the individual images separately.