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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EISmethods
EISmethods

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At line 1 removed 2 lines
[{ALLOW edit EISMainUsers}]
[{ALLOW view Anonymous}]
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To get the 1D wavelength array for the window, do:
{{{IDL> wvl=data->getlam(iwin)
}}}
although bear in mind that the spectra shift in the detector-X direction during an orbit, and in the Y-direction due to the tilt of the EIS slit relative to the detector. These issues are discussed in [EIS Software Note 5|http://solarb.mssl.ucl.ac.uk/SolarB/eis_docs/eis_notes/05_WAVELENGTH_CORRECTION/eis_swnote_05.pdf] and [EIS Software Note 4|http://solarb.mssl.ucl.ac.uk/SolarB/eis_docs/eis_notes/04_SLIT_TILT/eis_swnote_04.pdf], respectively.
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More details about EIS pointing information are given on the wiki page [Obtaining pointing information from EIS data|EISPointing].
More details about EIS pointing information are given on the wiki page [Obtained pointing information from EIS data|EISPointing].
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!!Time routines
!!Exposure times and time routines
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!Exposure time
The exposure time for each exposure of the raster is given by
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The exposure time (in seconds) for each exposure of the raster is given by
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Note that the exposure times generally vary between exposures, and will not be exactly equal to the requested exposure time.
There are a number of other potentially useful methods to time related phenomena:
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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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The units are given in TI format, which is the Hinode spacecraft time. The TI format can be converted to standard time formats using:
to find the shutter open (and close) times in 'TI' format.
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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:
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.
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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.
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.
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!!Intensity units
To find the units for the intensity arrays in the data object, do
{{{IDL> units=data->getunit()}}}
which returns a 3-element string array, with the first element containing the intensity units. (The other elements are empty.)
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IDL> wp=cal->warm_pixels(data,iwin[0])}}}
IDL> wp=cal->warm_pixels(data,iwin)}}}
This page (revision-27) was last changed on 26-Oct-2022 21:57 by Peter YoungTop