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LASCO Manual

 
This section is about the special comamnds that are written for LASCO only. Because LASCO data are in FITS files (*fits, *fts), you can use basic soho commands to process the data. The basic commands are based on generic reading of data and can be found under SOHO.

Before starting

 
First check that environment variable NRL_LIB is set to point in right place. Open the .cshrc file with Emacs:

emacs .cshrc

 
This command is needed to be given in the home directory of pollux. After Emacs has started, click the screen to get to see the file and check that the next line is typed.

setenv NRL_LIB /data/ssw/soho/lasco

 
If you can't find this line, add it at the end of the file. If you need some other environment variables, you can find them at: http://lasco-www.nrl.navy.mil/index.php?p=content/team/usersguide

To use special commands of LASCO, you must make the path:

ssw_path,'/data/ssw/soho/lasco/idl/'

 
This should change the path number from 233 to 266.

Then after using the special commands, read the data:

mreadfits,'file',index,data,header=header

For example:

mreadfits,'/data/ssw/sswdata/lasco/22158046.fts',index1,data1,header=header1

 

Images

 
Make image. Bmin and bmax are the minimum and maximum DN for BYTSCL.

img = mk_img( 'file', bmin, bmax)

For example:

img = mk_img( '/data/ssw/sswdata/lasco/22158046.fts', -100, 100)

 
This function plots the image automatically, so you don't have to use any plotting procedure.

Make lasco image.

image = lasco_image('file',header)

For example:

image1 = lasco_image('/data/ssw/sswdata/lasco/22158046.fts',header1)

 
After making this, you can either plot or display it

plot,image

or

tvscl,image

 

Spectra

 
Plot LASCO spectra. Replace tel varable with the code of the telescope you want (c1, c2 or c3). In the example, the keyword /single tells to plot only one spectrum. The default is to plot all of the spectra.

plot_lasco_spectra,'Tel'

For example:

plot_lasco_spectra,'c1',/single

 

Others

 
Detemining the coordinates of the center of the Sun. Remember first to read the data to determine the header.

result = get_sun_center(header)

For example:

scenter = get_sun_center(header)

 
The coordinates are printed in the terminal.

Determine the angle from which Soho sees the radius of the Sun. The angle is given in arcseconds, and can be used to calculate the distance between Soho and the Sun. If you use the keyword distance=distance, the function will calculate it for you in kilometers (this may not work very well).

result = get_solar_radius(header)

For example:

angle = get_solar_radius(header)

 
You also have to print the result:

print,result

For example:

print,angle

 
Or

print,distance

 
Next function returns the center of the image relative to the sun center in arc seconds.

result = get_img_center(header)

For example:

icenter = get_img_center(header)

 






Created by mevali. Last Modification: Thursday 12 of June, 2008 08:39:14 UTC by mevali.