This page (revision-27) was last changed on 26-Oct-2022 21:57 by Peter Young

This page was created on 07-Jun-2010 19:35 by PeterYoung

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26 07-Dec-2016 14:14 6 KB Peter Young to previous | to last
25 05-Apr-2011 18:14 6 KB PeterYoung to previous | to last
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[{ALLOW edit EISMainUsers}]
[{ALLOW view Anonymous}]
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!!Exposure times and time routines
!!Time routines
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The exposure time for each exposure of the raster is given by
!Exposure time
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The exposure time (in seconds) for each exposure of the raster is given by
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There are a number of other potentially useful methods to time related phenomena:
Note that the exposure times generally vary between exposures, and will not be exactly equal to the requested exposure time.
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!The start and end times of an exposure
The start and end times of an exposure can be obtained through the shutter open and close times (ti1 and ti2):
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to find the shutter open (and close) times in 'TI' format.
The units are given in TI format, which is the Hinode spacecraft time. The TI format can be converted to standard time formats using:
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Convert 'TI' format time to atomic time units ('TAI') or UTC, if no 'ti' parameter is given, the shutter open (ti_1) times for the data object are converted. The final method 'SEC_FROM_OBS_START' computes the number of seconds from the start of observations given by the input array assumed to be in 'TI' format.
The last method gives the time in second since the start of the first exposure in the sequence.
NOTE: the difference between the shutter open and close times, and the exposure time returned by the getexp() method generally do not agree. The former being larger by a fraction of a second. There are various technical reasons for this including a latency between the Instrument Control Unit (ICU) communicating with the Mechanism & Heater Controller (MHC), and a delayed response time of the MHC. __Users are recommended to always use the exposure time returned by getexp().__
!Other time routines
The date of an observation can be obtained with various methods:
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Gives the date of obsvation in 'yyyy-mm-ddThh:mm:ss.sss' format ('GETDATE_OBS') or in 'yyyymmdd' format ('GETDATE'). The 'DATE_OBS2DATE' converts the former to the latter format, if no date_obs is given the data objects date_obs is converted. 'DAYS_SINCE_LAUNCH' gives the number of days since launch, if no date is given, the data objects date is used.
getdate_obs() gives the date in 'yyyy-mm-ddThh:mm:ss.sss' format, and getdate() in 'yyyymmdd' format. The date_obs2date converts the former to the latter format, if no date_obs is given the data object's date_obs is converted. days_since_launch() gives the number of days since launch, if no date is given then the data object's date is used.
This page (revision-27) was last changed on 26-Oct-2022 21:57 by Peter YoungTop