time = Time.utc(2025, 10, 1)
instant = Astronoby::Instant.from_time(time)
ephem = Astronoby::Ephem.load("inpop19a.bsp")
equatorial_coordinates = Astronoby::Coordinates::Equatorial.new(
  right_ascension: Astronoby::Angle.from_hms(18, 36, 56.33635),
  declination: Astronoby::Angle.from_dms(38, 47, 1.2802),
  epoch: Astronoby::JulianDate::J2000
)
observer = Astronoby::Observer.new(
  latitude: Astronoby::Angle.from_degrees(48.856614),
  longitude: Astronoby::Angle.from_degrees(2.3522219)
)

dso = Astronoby::DeepSkyObject.new(
  instant: instant,
  equatorial_coordinates: equatorial_coordinates,
  ephem: ephem,
  proper_motion_ra: Astronoby::AngularVelocity
    .from_milliarcseconds_per_year(200.94),
  proper_motion_dec: Astronoby::AngularVelocity
    .from_milliarcseconds_per_year(286.23),
  parallax: Astronoby::Angle.from_degree_arcseconds(130.23 / 1000.0),
  radial_velocity: Astronoby::Velocity.from_kilometers_per_second(-13.5)
)
topocentric = dso.observed_by(observer)

topocentric.equatorial.right_ascension.str(:hms)
# => "18h 37m 48.7215s"

topocentric.equatorial.declination.str(:dms)
# => "+38° 48′ 41.4879″"

topocentric.horizontal.altitude.str(:dms)
# => "+26° 30′ 5.1834″"

topocentric.horizontal.azimuth.str(:dms)
# => "+299° 35′ 15.3519″"

time = Time.utc(2025, 10, 1)
instant = Astronoby::Instant.from_time(time)
equatorial_coordinates = Astronoby::Coordinates::Equatorial.new(
  right_ascension: Astronoby::Angle.from_hms(18, 36, 56.33635),
  declination: Astronoby::Angle.from_dms(38, 47, 1.2802),
  epoch: Astronoby::JulianDate::J2000
)
observer = Astronoby::Observer.new(
  latitude: Astronoby::Angle.from_degrees(48.856614),
  longitude: Astronoby::Angle.from_degrees(2.3522219)
)

dso = Astronoby::DeepSkyObject.new(
  instant: instant,
  equatorial_coordinates: equatorial_coordinates
)
topocentric = dso.observed_by(observer)

topocentric.equatorial.right_ascension.str(:hms)
# => "18h 37m 48.2804s"

topocentric.equatorial.declination.str(:dms)
# => "+38° 48′ 16.0412″"

topocentric.horizontal.altitude.str(:dms)
# => "+26° 29′ 44.1232″"

topocentric.horizontal.azimuth.str(:dms)
# => "+299° 34′ 58.3848″"