SOONSPOT data information for the ISTP workshop  
From: Alan Kiplinger   kiplinge@sunray.colorado.edu 
 
 
In several of the "yymmmdd" labeled data directories there is 
a SOONSPOT subdirectory.  These subdirectories contain extended  
FITS image files containing up to 120 512x512 byte images of the  
Sun in H-alpha in a single file.  These files have been recorded  
by the 4 U.S. Air Force SOON observatories at Holloman, New Mexico; 
Learmonth, AU; San Vito, Italy and Ramey, Puerto Rico. 
 
More information about SOONSPOT can be found at:  
         http://www.sec.noaa.gov/solcoord/solcoord.html 
 
In each directory are data files which have been downloaded 
in compressed form *.*.Z   There also is an ascii file called  
"filetimes.list" which provides the time range, observing target, 
number of images per file and observing site.   
 
There are basically two types of files: 1) full disk; and 2) large scale   
images (about 6.5 X 6.5 arc-min).  Normally large scale H-alpha  
files are interleaved with white light images (broad-band B2) on  
a regular basis. Although the filenames.list files should help most in  
identifying files of interest, the filenames themselves reveal:  
1) the observing site with the first letter, 2) the target with the  
next four numbers (9999 means full disk), and the day of year in the 
last three digits of the prefix. 
 
The data is now readable by SOLARSOFT (ssw) software.  To read a single 
data file and display a movie under ther Interactive Data Language and 
ssw, one should first uncompress the data file (if it still has 
a *.*.Z extension) and then read the file into IDL structures 
in memory with a command like: 
  
  read_soon,'filename',-1,index,data      
 
At this point, one may display the data as a movie with: 
 
  xstepper,data,anytim(index,/ecs) 
 
An important concept to remember is that most datasets  
that are handled by ssw are represented by one image per file. 
The "read_soon" command allows one to read up to 120 images per 
file in each extended FITS file.  Moreover, read_soon can read 
multiple extended files and filter the output according to 
the second parameter (details are beyond the scope of this 
message). 
 
Time cadences are approximately 30m for full disk images 
and 5m or 30s for large scale images depending on the  
existence of a flare trigger.  Note that the 30s cadence is envoked 
5 minutes BEFORE the flare trigger and reverts back to 5 minute 
cadence at flare maximum. 
 
p.s. 
 
To upgrade your solarsoft software to read SOONSPOT data 
type (under IDL and ssw): 
 
   ssw_upgrade,/soon,/spawn 
 
and include the line: 
 
  ssw_path,'$SSW_SOON' 
 
in your "idl_setup.pro" file 
 
 
It is important to know that SOONSPOT images have celestial 
North at top, not solar.  Thus the images are rotated  
from most solar images by the P angle which is also given 
in the filetimes.list files. It is now possible to map  
SOONSPOT data onto other datasets using the absolute coordinates 
in the SOONSPOT headers.  This is accomplished by using the improved  
rot_map procedure developed by Dominic Zarro (NASA/GSFC) and the read_s on
procedure from Sam Freeland (LMSAL). 
 
An example of the recommended IDL/ssw syntax is: 
 
   read_soon,filename,-1,index,data 
   index2map,index,data,map 
   rmap=rot_map(map,roll=0,center=[0,0])  
   plot_map,rmap,grid=10,fov=10 
 
This should plot the image rotated onto a 10x10 arc-min 
field of view with a heliographic grid of 10 degree resolution. 
 
A final comment is that SOONSPOT data is a gift to the scientific 
community from an operational U.S. Air Force mission.  It is not 
always perfect in the sense that occasional images may differ from 
the header information due to the need for observers to tune and adjust 
the instruments for their needs.  The SOONSPOT archive program 
records blindly to these infrequent interruptions, but for the vast 
majority of the time, the data is of high or good quality.   
It is my hope that we can return this gift by using the data 
to help understand the nature of solar activity and to aid 
in the predictabilty of the activity and its effects.  
 
                                  - Alan Kiplinger