AO jargon


     As in any well established discipline, we have generated a set of terms that guarantee that new users will have no idea what we are talking about... Here's a start at the list. I welcome any additions from the non jargon speaking majority.
terms description
Atlantic Standard Time. This is arecibo's local time zone (all year since puerto rico does not switch for daylight savings).


A single  integration is called a group. Groups can contain multiple records. Each record contains a header followed by data. Example:
  • A 5 minute scan using 4 correlator boards at different frequencies is written to disc using 1 second integrations. Each 1 second output is a group. There will be 300 groups in this scan. Each group contains 4 records (one for each correlator board). Each record will have a header followed by the data for that correlator board.
WARNING: the documentation has evolved and now often uses record in place of group. This is probably ok since the original distinction between group and record came from tape drives where the above group would have taken 4 physical records on the tape (at least with  9 track tapes). 
position switch  


a set of integrations (records) contiguous in time. Normally the configuration of the system will remain constant for a scan. Examples are:
  • an on/off position switch pattern with a cal on, off. This normally take 4 scans: tracking on src, tracking off src, calOn integration, calOff Integration.
  • mapping a region of the sky. Each strip of the map will be a scan.
scan number


scan numbers uniquely identify scans. They are  32 bit integers (which hold numbers up to 2 billion). The format is ydddxxxxx.
  • y is the last digit of the year (so scan numbers repeat every 10 years)
  • ddd is the daynumber of the year (AST).
  • xxxxx starts at 1 at the start of each AST day and gets  incremented each scan. If the computer reboots then xxxxx is set to the current seconds from midnight.
Data reduction routines usually use scan numbers to identify the data to process.
scan list