Ok, great, thanks, I had forgotten the critical word ::Coords:: here.

I'm trying to get my head around that. If I gave you:

, could this locate it without having to hard code the position?

Yeah, so this looks very nice and clean. I've just lopped it into the beginning of what I had before mixing the sources:

fritz@laptop:~/Documents/gitlab1$ ./2.betelgeuse.pl 
Betelgeuse
RA : 05:55:10.305
DEC: 07:24:25.43

NOW: Sun Dec 18 22:39:20 2022
OBS: 43 -116 830

AZ: 131.819209124284°
EL: 44.4163511693206°
./2.betelgeuse.pl 
Name    Right Ascension        Declination 
Mars    1.22046550975414    0.432956445569288 
Moon    3.66020589860573    -0.191580119364385 
Aldeb    1.20392811802569    0.288139315093836  
Time is Sun Dec 18 22:39:20 2022 
Julian day is 2459932.73564815 
fritz@laptop:~/Documents/gitlab1$
[download]

Source:

#!/usr/bin/perl 

use strict;
use warnings;

use Time::Piece;
use Astro::Coord::ECI::Utils 'deg2rad';
use Astro::Coords;
use Log::Log4perl;
use Astro::Telescope;

# Observer latitude, longitude and altitude
# in decimal degrees and meters:
my ( $lat, $lon, $alt ) = ( 43.0, -116.0, 830 );

my $star = Astro::Coords->new(
  name => 'Betelgeuse',
  ra   => '05h 55m 10.30536s',
  dec  => '07 24 25.4304',
  type => 'j2000',
);

my $scope = Astro::Telescope->new(
  Name => "$lat $lon $alt",
  Lat  => deg2rad($lat),
  Long => deg2rad($lon),
  Alt  => $alt
);

$star->telescope($scope);
$star->datetime( Time::Piece->new );

print $star->name, "\n", "RA : ", $star->ra, "\n", "DEC:", $star->dec,
+ "\n\n",

  "NOW: ", scalar localtime, "\n", "OBS: ", $scope->name, "\n\n",

  "AZ: ", $star->az( format => 'deg' ), "°\n",    # Azimuth
  "EL: ", $star->el( format => 'deg' ), "°\n";    # Elevation

my $file = '/home/fritz/Documents/gitlab1/1.aldeb.txt';

# unlink $file or warn "Could not unlink $file: $!";
my $log_conf4 = "/home/fritz/Documents/gitlab1/conf_files/3.conf";
Log::Log4perl::init($log_conf4);                  #info
my $logger = Log::Log4perl->get_logger();
$logger->info("$0");

$logger->info("Name\tRight Ascension\t\tDeclination");

for my $name (qw/Mars Moon/) {

  my $planet2 = Astro::Coords->new( planet => $name );

  $planet2->datetime( Time::Piece->new );

  my $ra  = $planet2->ra( format => q/rad/ );
  my $dec = $planet2->dec( format => q/rad/ );

  $logger->info("$name\t$ra\t$dec");

}

my $aldeb_ra_degrees          = 68.98;
my $aldeb_ra_radians          = deg2rad($aldeb_ra_degrees);
my $aldeb_declination_degrees = 16.509166666667;
my $aldeb_dec_radians         = deg2rad($aldeb_declination_degrees);
$logger->info("Aldeb\t$aldeb_ra_radians\t$aldeb_dec_radians ");
my $t  = localtime;
my $jd = $t->julian_day;

$logger->info("Time is $t");
$logger->info("Julian day is $jd");

__END__
[download]

This is great progress, so I'm really pleased, and thanks for posting. I want to get away from as much hard-coding of values as possible. Let me ask this question:

How might we represent Orion as a perl data structure with as little cooking from scratch as possible? What about the Plieades?

Lots happening tonight, in the vicinity of Aldebaran....