CIRSI - Observing Practicalities
Data rates and volumes:
The total read out time for the 4 arrays is around 10seconds. It
is intended in the long term that
a series of around 10 exposures will be coadded to produce a single
image OR if photon rate is sufficiently low longer exposures will
be used. Assuming only one image is stored evry 100seconds,
the typical data-rate is 8MB every two minutes
at 16bits per pixel (0 to 65536).
In a typical 8 hr night the
maximum data volume will therefore be 1.92GB. Within IRAF this
will double to 3.84GB when the images are stored as floating
A fully reduced contiguous image produced from 4 interleaved
exposures will result in a 4096 x 4096 pixel 64MB image plus ancillary
exposure and bad pixel maps.
In an ideal world, there would be UBVRIZJHK photometry of a set
of closelt spaced faint standards so that colours terms and
extinction could be derived with observations of a single field.
Maybe we will set some up. In the mean time there is little overlap
between optical and NIR calibration fields.
The primary source of NIR standard stars will be:
The UKIRT Faint standards
UKIRT original ]
local copy ]
Information about the NICMOS ground based calibartion program is
University of Arizona original ]
local copy ]
The arrays may have to be windowed down for some of the brighter standards so that
so that array does not saturate. The windowed arrays will have a faster read out time
then the whole array
Published by Richard McMahon
Last modified: Sun Nov 15 09:00:47 1998