Level 3 FITS file : Extension 5 (Constants) - ITA-Solar/solo-spice-ql GitHub Wiki

Extension 5 - Constants

This extension is only saved if there are any non-default values in the cube, i.e. if at least one value is different from 0.

Data cube

This extension contains the 'constant' flags of each pixel and fit parameter. The flange determines whether a specific fit parameter is kept constant for a specific pixel. The dimensions are as follows:

  • Fit parameters, X, Y, Time

General Keywords

EXTNAME  = Extension name              
RESEXT   = Extension name of results extension
DATAEXT  = Extension name of data extension (this is a link to an external extension)
XDIMXT1  = Extension name of 1st dimension absorbed by analysis
WGTSEXT  = Extension name of weights extension
INCLEXT  = Extension name of include extension
CONSTEXT = Extension name of constant extension

World Coordinate System (WCS) keywords

WCSNAME = Name of coordinate system                                            
LONPOLE = Native longitude of the celestial pole                                             
SPECSYS = Spectral coord. not corrected for S/C velocity                                               
VELOSYS = [m/s] Default for SPECSYS='TOPOCENT'                                               

CTYPE1   = Type of 1st coordinate (fit parameter)                        
CNAME1   = Name of 1st coordinate                        
CUNIT1   = Units for 1st coordinate (for CRVAL1, CDELT1)  
CRVAL1   = [] 1st coordinate of reference point          
CDELT1   = [] Increment of 1st coord at ref point        
CRPIX1   = [pixel] 1st pixel index of reference point    
PC1_1    = Contribution of dim 1 to coord 1                    
                                                                            
CTYPE2   = Type of 2nd coordinate                        
CNAME2   = Name of 2nd coordinate  
CUNIT2   = Units for 2nd coordinate (for CRVAL2, CDELT2)  
CRVAL2   = [arcsec] 2nd coordinate of reference point    
CDELT2   = [arcsec] Increment of 2nd coord at ref point  
CRPIX2   = [pixel] 2nd pixel index of reference point    
PC2_2    = Contribution of dim 2 to coord 2   
PC2_3    = Contribution of dim 3 to coord 2  
                                                                            
CTYPE3   = Type of 3rd coordinate                        
CNAME3   = Name of 3rd coordinate  
CUNIT3   = Units for 3rd coordinate (for CRVAL3, CDELT3)  
CRVAL3   = [arcsec] 3rd coordinate of reference point    
CDELT3   = [arcsec] Increment of 3rd coord at ref point  
CRPIX3   = [pixel] 3rd pixel index of reference point    
PC3_2    = Contribution of dim 2 to coord 3 due to roll  
PC3_3    = Contribution of dim 3 to coord 3  
                                                                            
CTYPE4   = Type of 4th coordinate                         
CNAME4   = Description of 4th coordinate                  
CUNIT4   = Units for 4th coordinate (for CRVAL4, CDELT4)  
CRVAL4   = [s] 4th coord of ref point, relative to DATEREF  
CDELT4   = [s] Increment of 4th coord at ref point        
CRPIX4   = [pixel] 4th pixel index of reference point     
PC4_2    = Contribution of dim 2 to coord 4 due to roll  ; _optional, only for rasters_  
PC4_4    = Contribution of dim 4 to coord 4                    

BTYPE    = Type of data                                   
UCD      = Unified Content Descriptors v1.23           
BUNIT    = Physical units of calibrated data