auto analysis results (AAR) are the products from the auto-analysis processing
chopper Movable mirror positioned in the beam to enable differential
sky measurements or to deflect the beam to one of the FCSs
chopper dwell time The commanded time for a given position of the chopper.
chopper plateau The period during a fixed position of a chopper. In the case of
a staring measurement the chopper plateau is equal to the whole
measurement period.
data reduction The ISO telemetry fully supported only a maximum readout
rate, higher readout rates were achieved by transmitting
parts of the data flow. The ratio between the amount of
data read and the amount transmitted is called data reduction.
default aperture (Also standard aperture) the ISOPHOT photometric calibration
against celestial standards of a given PHT-P filter is only
performed in one selected aperture, the default or standard aperture.
default responsivity A mean detector responsivity value which is a function of orbital
phase. The default responsivity is used in case the FCS calibration
of an observation cannot be used.
destructive readout Last readout of an integration ramp.
generic pattern A sequence of 8 signals (4 off- and 4 on-source signals) representing
the repeated signal pattern of the chopper cycles in a chopped measurement.
glitch A glitch is a short duration anomaly in the data stream,
usually caused by an ionising particle.
illumination matrix A table which lists the relative illumination of an FCS to
the individual detector pixels of the PHT-C arrays.
in-band power The power (in W) falling on the detector for a filter,
aperture, and polariser combination
integration time The period a detector sees a specific position on the sky during
a measurement.
measurement See definition Section 2.5
meaurement time The period of a measurement
non-destructive readout Any CRE voltage sample along an integration ramp except for the last one.
performance verification The performance verification (PV) phase comprises the
first 80 days of the ISO mission and was exclusively
reserved for instruments check-out, calibrations, and AOT commissioning.
product (Or FITS product) is a FITS file with defined contents
and contains ISO data for official distribution.
observation An observation refers to the acquisition of the
scientifically useful data during one AOT by the prime
instrument requested by the proposer. The term
`observation' also loosely refers to the data products
created from the acquired data.
ramp A ramp is formed by the readouts collected during
one and the same reset interval
raster Regular and rectangular grid of pointings on the sky where the
distance between the pointings is the same in each of the
grid directions.
raster point A pointing in a raster.
raster point dwell time The commanded time the spacecraft spent while pointing
on a given raster point.
reset interval The time between two reset pulses while reading out the detector,
also referred to as fundamental integration time.
responsivity The detector responsivity (in A/W) is the ratio between
electrical current (in [A]) through a detector and the
illuminating power (in [W]) falling on the detector.
signal The rate of voltage increase of the CRE output, this is in general
equivalent to the slope of an integration ramp in V/s. The signal is
proportional to the photocurrent or power on the detector.
sparse map A map obtained with the sparse map AOTs.
standard aperture See default aperture
standard processed data (SPD) are products from the standard processing or Derive_SPD
step, Chapter 7
straylight Unwanted light from sources outside the central field of view
contributing to the detector signal.
target dedicated time A target dedicated time (TDT) is the entire contiguous
time period scheduled for performing the N observations of
a concatenated group. (N = 1 if no concatenation). All
overheads, including slewing, are included (TDT = observation
time plus overheads time). The start of a TDT is defined as
the time of the first AOCS command to point at the new target.
The end of the TDT is defined as the time at which all
instrument activities connected with the (N) observation(s) have
been completed. Note that the above restrictions on concatenation
imply that one TDT can belong to only one proposer.
telemetry Data send by the spacecraft to the ground station
transient A systematic variation of the detector output signal in time
after an illumination change.