Pro nvss_upfile,ra,dec,radius=radius,filename=filename,format=format

;+
;NAME:
;     nvss_upfile
;PURPOSE:
;     write a upfile for NVSS matched source
;CALLING SEQUENCE:
;     nvss_upfile,ra,dec,filename=filename
;
;INPUT:
;     ra    -----  RA for source in Unit:degree
;     dec   -----  DEC for source in Unit:degree
;OPTIONAL KEYWORD INPUT:
;     radius  ----  matched radius in Unit:arcsec
;                   default it,it will set it 15 arcsec
;     format  ----  if set it,it will output according to format
;OPTIONAL KEYWORD OUT:
;     filename  ----  upfile name
;EXAMPLE:
;     IDL>  nvss_upfile,ra,dec,filename='NVSS_update.dat'
;
;REVISION HISTORY:
;     Original by DL.Wang,Aug-30-2007
;-

    if ( N_PARAMS() lt 2 ) then begin
       message,'Syntax:nvss_upfile,ra,dec,[ radius=radius, .... ]'
       return
    endif

    if not keyword_set(radius) then radius=15

    openw,lun,filename,/get_lun
    n=n_elements(ra)
    for i=0L,n-1 do begin
        if not keyword_set(format) then begin
           printf,lun,adstring(ra[i],dec[i],1),' ',radius,' ','0'
        endif else begin
           printf,lun,adstring(ra[i],dec[i],1),radius,'0',format=format
        endelse
    endfor
    free_lun,lun

End