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SOHO Manual

 

These are general commands that are suitable for all data that is in FITS files; EIT, LASCO, TRACE, Yohkoh's SXT etc.

Generic Reading of Data

 
With generic reading you can read standard FITS files into arrays and structures. The operation can be done to any SOHO, TRACE or RHESSI data. The commands is:

mreadfits,'/path/filename',index,data

For example:

mreadfits,'/data/ssw/sswdata/eit/lz/1998/03/efz19980331.111216',index1,data1

 
You can replace index and data words with the variable names you want, but remember to use them in the following commands too. The real data is stored in the data variable and information of the data in the index variable.

To print the infromation stored in the variables, use commands:

print,index

or

print,data

 
By next command, you can plot the data:

tvscl,data

 
The colors of the images can be changed with this color palette (opens in a new window):

xpalette

 
You can load a new color in the palette by command:

loadct,n

For example:

loadct,5

 
There are 40 colors (n= 1,2,3,...,40)

Changing color can also be done in an Xloadct window that opens by command

xloadct

 
Third option is to press the Predefined button in the palette. This also opens the Xloadct window.

 
http://www.astro.washington.edu/deutsch-bin/getpro/library32.html?MRDFITS

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Making maps

 

General way to make map images from FITS data (not suitable for EIT data, see
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  • First you need to read the data from FITS form to array.

 

mreadfits,'/path/file',index,data
For example:
mreadfits,'/data/ssw/sswdata/hinode/XRT20061119_074308.1.fits',index1,data1

 

  • Next function reads the data into map variable.
map_nimi=make_map(data)
For example:
map1=make_map(data1)

 

  • The last step is to plot the map.
plot_map,map
For example:
plot_map,map1,/log
where /log orders to use the logarithmic coordinates.

 
Some FITS files need different way for mapping. This procedure both reads the file and makes the map.

fits2map,'/path/filename',map,header=header

For example:

fits2map,'/data/ssw/sswdata/hinode/eis_l0_20070327_030535.fits',map1,header=header

 
Then plot the map as usual by plot_map command.

Settings

 
To get color to map images, use xpalette. More information of xpalette is found under "Generic reading of data".

xpalette

 
If you want to get a more accurate image, use next function. It also scales the image. After using the function, you still need to use make_map and plot_map, to get the image (remember to use sdata1 instead of data1).

sdata=sobel_scale(index,data)

For example:

sdata1=sobel_scale(index,data1)

 
Keywords: http://www.astro.washington.edu/deutsch-bin/getpro/library32.html?SOBEL_SCALE

To plot sub-images of maps, use this prosedure. Here the name of the sub-map is smap and the values (limits) for x and y are chosen from the axes of the orginal map.

sub_map,map,smap,xrange=[x1,x2],yrange=[y1,y2]

For example:

sub_map,map1,smap1,xrange=[-200,200],yrange=[-100,200]

 
You still need to plot the map by command:

plot_map,smap

For example:

plot_map,smap1,/log

 
Multiple maps can be plotted over each other by next commands. Here, of course, you first have to reate those maps before plotting. In this example map2 is plotted over map1. You can also use the keywords you like in here.

plot_map,map1

 

plot_map,map2,over=over

 
Difference image of two maps. By default diff_map produces image map1-map2, but if you use keyword ratio it makes map1/map2. Keyword 'rotate' rotates maps to common time before differentiating. Also here map1 and map2 must first be created.

map1-map2

diff=diff_map(map1,map2,rotate=rotate)

 

plot_map,diff,/log

 
map1/map2

diff=diff_map(map1,map2,rotate=rotate,ratio=ratio)

 

plot_map,diff,/log

 
Function drot_map rotates image differentially. Duration is entered as hours by default (enter only value). Keyword 'days' or 'seconds' gives a chance to enter duration in the units of the keyword.

Basic command:

rmap=drot_map(map,duration)

 

plot_map,rmap

 
Example of using keyword days:

rmap=drot_map(map,duration,days=days)

or

rmap=drot_map(map,duration,/days)

 
Rotating the image clockwise about its center.

rmap=rot_map(map_name,nn.)

For example:

rmap1=rot_map(map1,60.)

 
Note that this (above) command rotates the image totally the amount you give. For example, if you enter value 60 degrees and the image is already rotated 20 degrees, it will now be rotated only 40 degrees. You can check the current roll angle by command "help,/st,map_name". This prints the information of the image, including "roll". If you wish to rotate the image regardless of the current roll angle use next command:

rmap=rot_map(map_name,roll=nn.)

For example:

rmap1=rot_map(map1,roll=100.)

 
Plot the rotated map:

plot_map,rmap_name,/log

For example:

plot_map,rmap1,/log

 
To plot the rotated and unrotated maps in different windows, use commands:

plot_map,map_name,/log

 

plot_map,rmap_name,/log,/new

 
For example:

plot_map,map1,/log

 

plot_map,rmap1,/log,/new

 

Changing coordinates of map image from SOHO view to Earth view.

earthmap=map2earth(map)

 

plot_map,earthmap,/log

 
And from Earth view to SOHO view

sohomap=map2soho(map)

 

plot_map,sohomap,/log

 
Plotting to white background:

!p.color=0
!p.background=255
plot_map,map,/log

 
To plot four maps in the same window use this command at the beginning. The next four maps you plot are plotted in the same window starting from upper left corner. The fifth map plotted will start a new series of images.

!p.multi=[0,2,2]

For example:

!p.multi=[0,2,2]

 
plot_map,map1,/log

plot_map,map2,/log

plot_map,map3,/log

plot_map,map4,/log

 
Getting back to plot only one map in one window:

!p.multi=[0,1,1]

 
This command plots the next two maps in parallel:

!p.multi=[0,2,1]

 
and this on top of each other:

!p.multi=[0,1,2]

 
In the last two cases the images stretch either in verticla or horizontal direction. This can be fixed by changing the size of the window.

For example:

xs=768

 
ys=256

wdef,0,xs,ys

 
Changing the size of the window can be done before or after plotting images. Default size (512x512) window is get back by command:

wdef,0

 
To make the window same size as the data, use command:

wdef,im=data

For example:

wdef,im=data1

 

Making Movies

 
You can make movies of map images by command movie_map. First you need to determine, which maps are included in the movie.

maps=[map1,map2,map3,...,mapn]

 

movie_map,maps

For example:

maps1=[map1,map2,map3]

 

movie_maps,maps1

 
Animation opens in a new window. The four buttons in the upper left corner are from left to right: backwards, pause, forwards, and "forwards and backwards". When the "forwards and backwards" is selested, images are run in order 0,1,2,...,n-1,n,n-1,...2,1,0,1,2,... By moving the Speed bar you can control the speed of which the images change. Pressing the Colors button opens Xloadct wndow where you can pick a color from a list. Notice that the colors are only seen in the image when the cursor is on top of Xloadct or animation window. End animation closes the animation window.

Saving Images

 
Map images can be saved in jpeg-form by the following command when they are open.

write_jpeg,'path/file_name.jpeg',tvrd()

For example:

write_jpeg,'/data/ssw/sswdata/eit/jpeg_image/sun1.jpeg',tvrd()

 
Opening jpeg-image can be done by reading the image and plotting it by tv command. Procedure read_jpeg reads the jpeg-file and stores the data in the variable image_name.

read_jpeg,'/path/file_name.jpeg',image_name

 

tv,image_name

 
For example:

read_jpeg,'/data/ssw/sswdata/eit/jpeg_image/sun1.jpeg',sun

 

tv,sun

 


Created by mevali. Last Modification: Thursday 17 of April, 2008 08:46:48 UTC by mevali.