Make '' writable by PHP for this script to operate properly.
<pre>
WU-satellite-animate.php - V1.01 - 11-Jan-2024
using 'https://s.w-x.co/staticmaps/wu/wu/satir1200_cur/usasw/regionalIR.json' for query
now='2025-09-17 10:53:03 UTC' page cached='2025-09-17 10:53:03 UTC' (0 seconds ago)
forceRefresh=true
loading ./cache/WUregion-sw-IR.txt from
  'https://s.w-x.co/staticmaps/wu/wu/satir1200_cur/usasw/regionalIR.json'
curl fetching 'https://s.w-x.co/staticmaps/wu/wu/satir1200_cur/usasw/regionalIR.json'
HTTP stats:  RC=200 dest=151.101.2.133 port=443 (from sce=192.135.112.131)
      Times: dns=0.005 conn=0.006 pxfer=0.010 get=0.033 total=0.044 secs
unable to open ./cache/WUregion-sw-IR.txt for writing 1233 bytes.. cache not saved
html loading finished
--Sorry.  Unable to write ./cache/WUregion-sw-IR.txt to ''.
</pre>