Re: perl in the stars

Disclaimer: though I'm anonymous here, I'm the author of both Astro::Coord::ECI and Astro::SIMBAD::Client.

Astro::Coord::ECI and friends are a bit heavyweight if all you want to do is convert degrees to radians. The actual code to do this is two lines:

use constant PI => atan2 (0, -1);
sub deg2rad { return defined $_[0] ? $_[0] * PI / 180 : undef }

As for computing angles, I will not recommend a specific module. I will say the initial implementation of Astro::Coord::ECI->angle() naively used the law of cosines, but I had to switch to the law of haversines after trying to compute the closest passage of a satellite to a star and having the law of cosines blow up.

All I can say about Astro::SIMBAD::Client is that it is a mess. Sorry. There are a number of ways to get the data, the SIMBAD API changed over time, and, well, what can I say? It badly needs a simpler interface. It takes me 30-some lines of code just to get the position and proper motion of a star. If you decide you want to wrestle with it, you can contact me at wyant at cpan dot org.

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Re^2: perl in the stars
by Anonymous Monk on Dec 23, 2022 at 16:50 UTC

all your good work for Perl on CPAN

perl -MAstro::SIMBAD::Client -MData::Dumper -le '$s=Astro::SIMBAD::Cli
+ent->new;@s=split/\n/,$s->url_query(id => Ident => "$ARGV[0]", NbIden
+t => 1);splice(@s,0,7);splice(@s,20,$#s+1);%s=map{/([^:]+\S)\s?:\s+(\
+S.*)/;$1=>$2}@s;@s=grep/^Coord/,keys%s;print"$_: $s{$_}"for@s;print q
+q[\n$s{"Proper motions"}\n];print Dumper\%s;' sirius
[download]

Coordinates(Gal,ep=J2000,eq=2000): 227.23029126  -08.89028121 
Coordinates(ICRS,ep=J2000,eq=2000): 06 45 08.91728  -16 42 58.0171 (Op
+t ) A [11.70 10.90 90] 2007A&A...474..653V
Coordinates(FK4,ep=B1950,eq=1950): 06 42 56.72452  -16 38 45.4080

-546.01 -1223.07 [1.33 1.24 0] A 2007A&A...474..653V

$VAR1 = {
          'Angular size' => '~     ~   ~ (~)  ~ ~',
          'Coordinates(Gal,ep=J2000,eq=2000)' => '227.23029126  -08.89
+028121 ',
          'Spectral type' => 'A0mA1Va C 2003AJ....126.2048G',
          'Parallax' => '379.21 [1.58] A 2007A&A...474..653V',
          'Flux V' => '-1.46 [~] C 2002yCat.2237....0D',
          'Flux I' => '-1.43 [~] C 2002yCat.2237....0D',
          'Flux J' => '-1.36 [~] C 2002yCat.2237....0D',
          'Flux R' => '-1.46 [~] C 2002yCat.2237....0D',
          'Redshift' => '-0.000018 [0.000001] A 2006AstL...32..759G',
          'Proper motions' => '-546.01 -1223.07 [1.33 1.24 0] A 2007A&
+A...474..653V',
          'Flux K' => '-1.35 [~] C 2002yCat.2237....0D',
          'Morphological type' => '~ ~ ~',
          'Flux H' => '-1.33 [~] C 2002yCat.2237....0D',
          'cz' => '-5.50 [0.40] A 2006AstL...32..759G',
          'Flux U' => '-1.51 [~] C 2002yCat.2237....0D',
          'Radial Velocity' => '-5.50 [0.4] A 2006AstL...32..759G',
          'Flux B' => '-1.46 [~] C 2002yCat.2237....0D',
          'Coordinates(ICRS,ep=J2000,eq=2000)' => '06 45 08.91728  -16
+ 42 58.0171 (Opt ) A [11.70 10.90 90] 2007A&A...474..653V',
          'Coordinates(FK4,ep=B1950,eq=1950)' => '06 42 56.72452  -16 
+38 45.4080',
          'hierarchy counts' => '#parents=0, #children=0, #siblings=0'
        };
[download]

use Math::Trig 'deg2rad';
[download]

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