This page (revision-9) was last changed on 27-Mar-2020 14:38 by Peter Young

This page was created on 24-Feb-2010 18:22 by PeterYoung

Only authorized users are allowed to rename pages.

Only authorized users are allowed to delete pages.

Page revision history

Version Date Modified Size Author Changes ... Change note
9 27-Mar-2020 14:38 1 KB Peter Young to previous
8 07-Dec-2016 14:14 1 KB Peter Young to previous | to last
7 04-Aug-2010 21:41 2 KB PeterYoung to previous | to last
6 07-Jul-2010 20:01 2 KB PeterYoung to previous | to last
5 07-Jul-2010 19:47 1 KB PeterYoung to previous | to last
4 07-Jul-2010 19:36 1 KB PeterYoung to previous | to last
3 24-Feb-2010 22:20 1 KB PeterYoung to previous | to last
2 24-Feb-2010 18:22 1 KB PeterYoung to previous | to last
1 24-Feb-2010 18:22 2 bytes PeterYoung to last

Page References

Incoming links Outgoing links
NarrowWorksheet3
NarrowWorksheet3

Version management

Difference between version and

At line 1 added 3 lines
[{ALLOW edit EISMainUsers}]
[{ALLOW view Anonymous}]
!!!Worksheet 3 - Reading and browsing data
At line 2 removed one line
!!!Worksheet 2 - Reading and browsing data
At line 4 changed one line
The EIS FITS file to be used in all the worksheets is from 9-Dec-2007, 11:30 UT:
Following on from Worksheet 2, you can now read the EIS FITS file from the command line:
At line 6 changed one line
filename=’eis_l0_20061209_113031.fits’
{{{
IDL> data=obj_new(‘eis_data’,filename)
}}}
At line 8 changed one line
(NOTE: you may need to add the path name, depending on where the file is located.)
data is an IDL object. Information is extracted from the object through a large number of ''methods'' and some examples are given below.
At line 10 changed one line
To read an EIS FITS file from the command line, type:
To determine the coordinates of the center of the raster, do:
At line 12 changed one line
IDL> data=obj_new(‘eis_data’,filename)
{{{
IDL> xcen=data->getxcen(/raster)
IDL> ycen=data->getycen(/raster)
}}}
At line 14 changed one line
data is an IDL object. You can extract information from the object using various methods. E.g.,
To find the exposure time for each exposure of the raster, do:
At line 16 changed 3 lines
IDL> exp=data->getexp()\\
IDL> xpos=data->getxpos()\\
IDL> wd0=data->getvar(0)\\
{{{
IDL> exp=data->getexp()
}}}
At line 20 changed one line
wd0 is a 3D array containing the window data for the specified window (0 in this case). You can get a list of all methods by doing:
A single data window can be extracted by doing:
At line 22 changed one line
IDL> data->display_methods
{{{
IDL> wd=data->getvar(195.12)
}}}
At line 24 changed one line
To extract the header into a string array, do:
where the specified wavelength is used to pick out the data window containing that particular wavelength. The first dimension of WD is always wavelength, the second is always solar-Y, and the third can be either solar-X or time depending if the observation was a raster or a sit-and-stare observation.
At line 26 changed 2 lines
IDL> hdr_obj=data->gethdr()\\
IDL> text=hdr_obj->getbte_hdr()
A complete list of methods is obtained by doing
At line 29 changed one line
A number of useful header tags can be sent to a structure by doing:
{{{
IDL> data->display_methods
}}}
At line 31 changed one line
IDL> eis_get_hdr_struc,data,hdrstr
while more [detailed information on some methods|EISmethods] is given elsewhere on the EIS wiki.
At line 33 removed one line
To find which wavelength windows are contained in data, do:
At line 35 changed one line
IDL> wininfo=eis_get_wininfo(filename,/list)
!Exercises
At line 37 changed one line
!Exercise
For these exercises you will need to refer to the [EIS object methods page|EISmethods].
At line 39 changed 2 lines
#Using eis_get_wininfo and the getvar() object method, extract an image in Fe XII 195 by summing all wavelength pixels in the window. Plot the image. What do you have to do to the image to orient it correctly? (You may need to refer to XRT images from Day 1 of the workshop.)
#Using the following commands:
#Create and plot an IDL map for the Fe XII 195.12 line by taking the moments of the line.
#Now use the getvar() method to extract the 195.12 wavelength window. Sum the 3D window over the wavelength direction (use the IDL total() routine), and plot the resulting image. How does it compare to the map image plotted above? See the object methods page for why it is different.
#Using the following commands, can you work out the direction that EIS rasters? (east-west, or west-east)
At line 42 changed 5 lines
IDL> aux_data=data->getaux_data()\\
IDL> exptimes=data->sec_from_obs_start(*(aux_data.ti_1))\\
IDL> xpos=data->getxpos()\\
work out in which direction EIS rasters (east-west, or west-east).
{{{
IDL> ti=data->getti_1()
IDL> sec=data->sec_from_obs_start(ti)
IDL> xpos=data->getxpos()
}}}
This page (revision-9) was last changed on 27-Mar-2020 14:38 by Peter YoungTop