Glossary

This page gives definition of some words commonly used in this Explanatory Supplement.

• ACMS : Attitude Control & Measurement Subsystem (AOCS)
• AHF : Attitude History File
• APID : Application Program Identifier
• APPL  : Augmented Preprogrammed Pointing List
• Calibration (absolute and relative) : for a single detector, the absolute calibration is gain factor between the measured signal (watts absorbed by the detector) and the sky signal (in astrophysical units); can vary with time. For a set of detectors, the relative calibration is the difference in the calibration between detector pairs. The latter can be measured very accurately from the observations of the same source by different detectors, and is only slightly affected by the differences in the detector spectral responses, which are similar; the former requires observations of sources with well modeled spectral energy distributions or well known spectra, and requires that the detector's spectral bandpass also be well known.
• CDMS : Command and Data Management System
• CDMU : Command and Data Management Unit
• CMB : Cosmic Microwave background
• CoP : Commissioning Phase
• CTR : Central Time Reference
• CUC : CCSDS Unsegmented Time Code
• DCE : Dilution Cooler Electronics
• DDS : MOC's Data Distribution System
• detector set [HFI meaning]: a detector set (aka detset aka quad) is a combinaison of two pairs of Polarization Sensitive Bolometers pairs at the proper orientations. The lists of detsets is given in here.
• DPC : Data Processing Center
• DPU : Data Processing Unit
• DQR  : Daily Quality Report
• DTCP : Daily Tele-Communication Period
• effective beam [HFI meaning]: the effective beam at the map level is the overall angular response to the sky in a map pixel, which results from the combined effect of the instrumental response, the scanning strategy and the data processing.
• EOL : End Of Life
• ERCSC : Early Release Compact Source Catalog
• ESA : European Space Agency
• ESOC : European Space Operations Centre (Darmstadt)
• ESTEC : European Space TEchnology and Research Centre
• FITS  : Flexible Image Transfer Specification
• focal plane geometry [HFI meaning]
• FOG : Fiber Optic Gyroscope
• FOV : Field-Of-View
• FPU : Focal Plane Unit
• FWHM  : Full-Width-at-Half-Maximum
• half ring difference : difference between the map built using the first half of each pointing period (typically 20 minutes of contiguous data) and the one built with the second half. This difference effectively removes the sky signal and most of the correlated noise, leaving only the noise components that have time scales of < ~ 20 min.
• HCM : Angular momentum Control Mode
• HEMT : High Electron Mobility Transistor
• HFI : High Frequency Instrument
• HPFTS : Herschel/Planck File Transfer System
• HPMCS : Herschel/Planck Mission Control System
• HPR [HFI meaning]: HEALPix Rings are introduced to avoid any additional binning of the data. We choose a sky pixelization as a basis for this ring making (HEALPix, Górski et al. 2005). HPR are therefore partial sky maps produced via a projection onto the sky of each single pointing period separately.
• HSK : House-Keeping data
• ICD : Interface Control Document
• IMO [HFI meaning]: the HFI Instrument MOdel is a central repository containing the models (or a link to them) and sets of fixed parameters used in these models describing for example how photons are gathered and transformed into data. IMO is oriented toward the data reduction and data processing. IMO is also used to monitor the instrument health. IMO represents at any time the official knowledge of the instrument response. It is intended to represent its best current knowledge agreed on by the project and applicable to the data processing. IMO does not represent the knowledge of the instrument. It is a knowledge of its response, (e.g. how photons are gathered and transformed into data). It is a simplified fraction of this knowledge directly useful to reduce the data. The IMO is restricted to the sole parameters used in the DPC. IMO does not contain timelines, nor maps, although it can provide links to calibration timelines (e.g. gain evolution) and calibration maps (e.g. beam maps). Models do not need to be unique (not a single model for a single process). Depending on the purpose for which they are used, they can be more or less sophisticated. (e.g. bolometer models, beam representations, very simplified for first assessment of pointing parameters, ...). IMO does not choose between them : it contains the parameters for each of them at the same time. See HFI RIMO.
• IOT : Instrument Operation Team
• JFET : Junction Field Elect Transistor
• LEOP : Launch & Early Orbit Phase
• LFI : (Planck) Low Frequency Instrument
• LOBT : Local On Board Time
• LOS : Line Of Sight
• mission [HFI meaning]
• MOC : [ESA's] Mission Operation Center [Darmstadt, Germany]
• NET  : Noise Equivalent Temperature
• OBT  : On-Board Time
• OD : Operation Day definition is geometric visibility driven as it runs from the start of a DTCP (satellite Acquisition Of Signal) to the start of the next DTCP. Given the different ground stations and spacecraft will takes which station for how long, the OD duration varies but it is basically once a day.
• optical beam [HFI meaning]
• P/L : Payload
• PAU : Pre_Amplification Unit
• PBR [HFI meaning]: Phase Bin Rings provide a compressed and higher signal-to-noise ratio rendition of the original Time Order Data
• PI : Principal Investigator
• PLA  : Planck Legacy Archive
• PLM : Payload Module
• POI : Phase-Ordered Information (DMC group/object)
• polarization leakage [HFI meaning]: in general, systematic effects mix the I,Q,U signals. Given the amplitudes of the sky signals, leakage from temperature to polarisation can be dramatic for polarisation analysis.
• PPL  : Pre-programmed Pointing List
• PPLM : Planck Payload Module
• PSM  : Planck Sky Model
• PSO : Planck Science Office
• PUS : Packet Utilisation Standard
• RAF : Raw Attitude history File
• REBA : LFI Radiometer Electronics Box Assembly
• REU : Readout Electronic Unit
• ring [HFI meaning]: at the HFI DPC level the ring is the time intervalle between two First Thurster Firings as defined in AHF description document. It thus starts with a satellite slew and thus an unstable pointing period and continue with a satellite dwell and thus stable pointing period.
• RIMO [HFI meaning]: The RIMO, or Reduced Instrument Model is a FITS file containing selected instrument characteristics that are needed by users who work with the released data products.
• ROI : Ring-Ordered Information (DMC group/object)
• rpm : revolutions per minute
• RSSD : Research Space Science Division of ESA [ESTEC, Netherlands]
• S/C : Spacecraft
• SAA : Solar Aspect Angle
• sample [HFI meaning]
• scanning beam [HFI meaning]: the scanning is defined as the beam measured from the response to a point source of the full optical and electronic system, after the filtering.
• SCS : Sorption Cooler Subsystem (Planck)
• SEV  : Sun Earth Vector
• SGR  : Small Gap Recovery
• SGS  : Science Ground Segment
• SIAM  : Spacecraft Instrument Alignment Matrix
• SOVT  : System Operation and Validation Test
• spectral response (or bandpass): steady state response of a detector system (i.e., detector and its electronics + horn + filter) as a function of frequency. It does not consider the temporal response and associated transfer function.
• SPPT : Survey Performance and Planning Tool
• SREM : Space Radiation Environment Monitor
• SRP  : Solar Radiation Pressure
• SSCE : Sun-SpaceCraft-Earth angle max= 15°
• SSO : Solar System Object
• STR  : Star TRacker
• survey [HFI meaning]: sky surveys (aka Scan #)are defined in terms of the direction of the satellite's spin axis. Survey periods are given here.
• SVM : Service Module
• SZ  : Sunyaev-Zel'dovich effect
• TBC : To Be Confirmed
• TBD : To Be Determined
• TC : Tele-Command
• THF : Telecommand History File
• TOD  : Time-Ordered Data
• TOI : Time Ordered Information
• ToS : Time of Sample
• UTC : Universal Time Coordinate(d)
• warm units : JFET, Bellow, PAU et REU
• WHR : Weekly Health Report