next up previous contents
Up: OBSERVER'S MANUAL FOR ISOCAM Previous: Acronyms

Glossary

AOT - Astronomical Observation Template: Representation of an observing mode in the proposal generation software (PGA).
Background: Sky emission towards the direction of the source. The contributors are: Zodiacal Light, diffuse galactic emission and local diffuse emission in the vicinity of the source.
Drift: Time evolution of detector response.
Instrument mode: A mode in which the instrument can be operated.
Exposure: a 32x32 pixel frame obtained after a readout of the array following an integration of the signal of one elementary integration time
Exposure time: Time during which the target is observed plus, in the case of beam-switching observations, the time for measurements at a reference position.
Image: a 32x32 pixel frame obtained after processing the exposures of one observation.
Integration time: The time during which the target is observed. Time for observing a reference field is not included (cf. Exposure time).
Micro-scan: A scan which involves short spacecraft slews, within a raster.
Observing mode: An instrument mode dedicated to a specific type of astronomical observation.The representation of an observing mode vis-a-vis the observer is an AOT.
Orientation: Angular distance of direction of a scan line. Counted anticlockwise from North.
Overhead: Time to prepare the spacecraft and instrument for an observation, e.g. array stabilization, wheel positioning and spacecraft slews.
Point spread function: The flux distribution due to diffraction in the image of an ideal point-like source as seen by the telescope optics at a specific wavelength.
Pointing: Positioning of spacecraft at a required sky position.
Proposal Generation Aids - PGA: The ISO software system to enter proposals in submission phase II. It consists of a data base management system with a user interface of panels.
Raster: A series of regularly spaced pointed observations, where at each position the observation is repeated. It is defined by the centre position and the step sizes in R.A. and Dec.
Readout: One measurement of the current output voltage before resetting a pixel or after integrating the signal.
Reference beam or Reference field: A position adjacent to the source usually to determine the background emission.
Scan, Scan line or Scan leg: A series of spacecraft pointings in one dimension, where the positions between two spacecraft pointings are obtained by chopping. A scan is defined by the orientation and the tolerance angle.
Sky bin: A portion of the sky which is 10 by 10 degrees. The division of the sky in finite bins facilitates the calculation of visibility of the sky.
Step size: Distance between two points in a raster and between scan lines to define the size of the raster.
Target dedicated time: The time spent for the observation of a source in an observing mode including integration time and overhead times.



next up previous contents
Up: OBSERVER'S MANUAL FOR ISOCAM Previous: Acronyms



ISOCAM Observer's Manual - V1.0
Tue Oct 31 12:06:23 MET 1995