Oops forgot that Astro::Telescope requires Lat and Long in radians:

#!/usr/bin/perl

use strict;
use warnings;
use Time::Piece;

use Astro::Coord::ECI::Utils 'deg2rad';
use Astro::Coords;
use Astro::Telescope;

print qq/Planet\tAzimuth\t\t\tElevation\n/;

for my $name (qw/Jupiter Saturn/) {

  my $planet = Astro::Coords->new(planet => $name);

  $planet->datetime(Time::Piece->new);

  $planet->telescope(Astro::Telescope->new(
    Name => '1600 Pennsylvania Ave, Washington DC',
    Long => deg2rad(-77),
    Lat  => deg2rad(38.9), 
    Alt  => 16.7));

  my $az = $planet->az(format => 'deg');
  my $el = $planet->el(format => 'deg');

  print qq/$name\t$az\t $el\n/
}
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