Defines available calendars and timescales for 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
with additional timescales defined as offsets to UTC:
Timescale Timescale Name Type Zone Par Zone
----------------------------------------------------------------------------------------
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
-
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.
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