ASTTIMES: Using daylight savings time

Frank Valdes wrote on Aug 12, 1998

Q: A simple question about asttimes in the astutil package: if the input
parameters day, month, year and time are local time and date, as
described in the help file, should the time always be given with or
without the daylight savings correction if you select observatory=
some standard in a timezone which has daylight savings (e.g. APO)? 
my gut tells me always use standard time, but i want to make sure.


A: Yes you will get standard times normally.  The observatory entry contains
the number of hours from UT for the site.  It is possible to set this
to give daylight time or have two entries, etc.  But to avoid confusion
it should just give standard time.  Just in case you are interested,
to get daylight time you could do the following:

as> observat
Command (set|list|images) (set|list|images) (set): set
Observatory to set, list, or image default (apo): apo 
Using default observatory database: noao$lib/obsdb.dat
Using observatory parameters for database entry: apo
# Observatory parameters for Apache Point Observatory
        observatory = apo
        timezone = 7
        altitude = 2798.
        latitude = 32:46.8
        longitude = 105:49.2
        name = 'Apache Point Observatory'
as> asttime observ=obspars
# ASTTIMES: Observatory parameters for Apache Point Observatory
#       timezone = 7.
#       longitude = 105.82
Year: 1998
Month (1:12): 8
Day (1:31): 12
Local zone time
 (0.:24.): 9:21
##YR MON   DAY          ZT         UT      EPOCH           JD       LMST
1998   8 12 WED  9:21:00.0 16:21:00.0 1998.61241 2451038.1813  6:41:23.1
as> observat.time=6
as> ^astt
asttime observ=obspars
# ASTTIMES: Observatory parameters for Apache Point Observatory
#       timezone = 6.
#       longitude = 105.82
Year: 1998
Month (1:12): 8
Day (1:31): 12
Local zone time
 (0.:24.): 10:21
##YR MON   DAY          ZT         UT      EPOCH           JD       LMST
1998   8 12 WED 10:21:00.0 16:21:00.0 1998.61241 2451038.1813  6:41:23.1

The first case used standard time and the second used daylight time.

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Last post on Aug 12, 1998