G. Glossary

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.