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Last modified: December 2009

AHELP for CIAO 4.2


Context: proposaltools


Defines available calendars and timescales for command line versions of Chandra Proposal Tools


The default timescale types in DATES are:

Timescale     Timescale Type
 TT         Terrestrial Time
 UTC        Civil Time
 TDB        Dynamical Time
 TAI        Atomic Time
 UT1        UT1 Time
 GMST       Sidereal Time
 LST        Local Siderial Time
with additional timescales defined as offsets to UTC:

Timescale    Timescale Name          Type      Zone Par   Zone
 Local  Zone +0000                 Civil Time         0   +0000
  MST   Moscow Summer Time         Civil Time     14400   +0400
  DMV   Moscow Decree Time         Civil Time     10800   +0300
  BST   British Summer Time        Civil Time      3600   +0100
  GMT   Greenwich Mean Time        Civil Time         0   +0000
  EDT   Eastern Daylight Time      Civil Time    -14400   -0400
  EST   Eastern Standard Time      Civil Time    -18000   -0500
  CDT   Central Daylight Time      Civil Time    -18000   -0500
  CST   Central Standard Time      Civil Time    -21600   -0600
  MDT   Mountain Daylight Time     Civil Time    -21600   -0600
  MST   Mountain Standard Time     Civil Time    -25200   -0700
  PDT   Pacific Daylight Time      Civil Time    -25200   -0700
  PST   Pacific Standard Time      Civil Time    -28800   -0800
The supported calendar types are:
  Calendar   Calendar Name              Type
  GREG	     Gregorian date             Gregorian Calendar
  JD	     Julian Day                 Julian Day Number
  MJD	     Modified Julian Day        Julian Day Number
  DAYS	     JD - 2450814.5             Julian Day Number
  DATE	     Date		        Gregorian Calendar  
  PACK	     Packed date                Gregorian Calendar
  DOY	     Day of year                Gregorian Calendar
  OS	     Julian Calendar            Julian Calendar
  ROMAN	     Roman calendar             Roman Calendar
  RF	     French Rev. Calendar       French Revolutionary Cal
  GSD	     Greenwich Sidereal Date    Greenwich Sidereal Date
  GST	     Greenwich Sidereal Time    Greenwich Sidereal Date
  TIME	     TIME(JD 2450814.5)         Elapsed Seconds
  JEPOCH     Julian Epoch               Epoch
  BEPOCH     Besselian Epoch            Epoch
  • JD/MJD/DAYS: For the JD, MJD and days calendars, enter a numeric value. Only Julian days between -2 x 10^9 and 2 x 10^9 are supported.
  • GREG: There are a variety of formats for the GREG calendar. The standard is the words AD or BC followed by the year, month name, day, time of day. For example: AD 1993 Jun 30 23:59:50.234. The BC is mandatory, AD may be left off. Day 0 is the last day of the preceding month. Month numbers may be used instead of names. Colons may be omitted, replaced by spaces, or the letters h, m, s. Trailing information may be omitted, in such case, the earliest date is assumed. Further forms of imprecise and uncertain dates are supported: example: 1993 Jun 30 23:59? or 1990s?. Day of Year format is supported also: 1997 Day 104 14:20:32.
  • DOY: Last three digits of the integral part is the day of the year, earlier digits are assumed to be the year.
  • PACK: Last four digits are MM and DD, earlier digits assumed to be the year, if less then 100, 1900 automatically added.
  • TIME: Elapsed time calendar, gives seconds since the zero point defined by the zero command. The default is Chandra time: the time tag on events in the Chandra data files, measured in seconds since 1998 Jan 1 00:00:0.0.
  • GSD/GST: GSD is essentially JD(GMST). Calendar GSD outputs the result as JD and fraction of day. GST outputs the result as an integer day number and hh:mm:ss.sss of sidereal time.

See Also

colden, dates, obsvis, pimms, precess, prop-coords, prop-tools

Last modified: December 2009