LU  fname          write          read                write thread
--------------------------------------------------------------------------
10  *.tf2                         getfile2
11  prefixes.txt   pfxdump        GUI                 GUI     (once only)
11  decoded.txt    map65a         GUI                 decoder (60 s)
12
13  tsky.dat                      astro0.F
14  azel.dat       astro0.F                           GUI     (1 s)
15
16
17  *.tf2          savetf2                            decoder
18  TxData                        wsjtgen
19  messages.txt   display.txt    GUI                 decoder
20  bandmap.txt    display.txt    GUI                 decoder
21  ALL65.TXT      map65a                             decoder
22  kvasd.dat      extract        KVASD               decoder
23  CALL3.TXT                     deep65              decoder
24  meas24.txt     savetf2                            decoder
25  meas25.txt     savetf2                            decoder
26  tmp26.txt      map65a,display display             decoder
27  dphi.txt       map65a                             decoder
28
29  debug.txt
77                 deep65                             decoder
--------------------------------------------------------------------------

So ... the problem may be writing to azel.dat from the GUI thread?
(Could put astro data into a common, and write to file from decode1.F90.)

Also: look at write(line,...) forms ...

  unpackgrid unpackmsg symspec display savetf2 (all in decoder thread)

read(char,...) 

  packcall packgrid astro0 display getfile2