In sunposa.php the code $graph->xaxis->title->Set("Sun AZ: $az2[0]° Zenith: $zen Sun EL: $he2[0]°");
just displays '°' instead of ''°" when changed to $graph->xaxis->title->Set("Sun AZ: $az2[0]° Zenith: $zen Sun EL: $he2[0]°");
I tried it on PHP 8.2 with JPgraph 4.4.2 and that's what I saw.
The same happened with $txt3 =new Text("Moon EL: $he5[0]°");
for the moon elevation.
I know the underlying GD library doesn't have HTML support as I discovered years ago with the degree sign in thermometer.php .. for that, I ended up using $cnt = chr(176) . $UOM; // chr(176) = degree sign in ISO-8859-1
imagestring( $image, $font+2, ($width/2)-((strlen($cnt)/2)*ImageFontWidth($font+2)),
(10-(integer)(ImageFontHeight($font+2) / 2)),
$cnt, $tx);
to draw the '°F' or '°C' at the top.
The sunposa.php is encoded in ANSI (ISO-8859-1)