from datetime import datetime

from zoneinfo import ZoneInfo

from starplot import Observer, HorizonPlot, styles, callables, DSO, _

tz = ZoneInfo("America/Los_Angeles")

dt = datetime(2025, 11, 18, 21, 30, 0, tzinfo=tz)

observer = Observer(

dt=dt,

lat=32.97,

lon=-117.038611,

)

style = styles.PlotStyle().extend(

styles.extensions.GRAYSCALE_DARK,

styles.extensions.HORIZON,

)

style.axes.background.fill = {

"stops": styles.gradients.NIGHT,

"type": "linear",

}

style.figure.background.fill = "#000"

p = HorizonPlot(

altitude=(0, 70),

azimuth=(30, 150),

observer=observer,

style=style,

resolution=2000,

autoscale=True,

)

p.ground(min_altitude=5, max_altitude=8)

p.stars(

where=[_.magnitude < 3.6],

where_labels=[_.magnitude < 1.6],

# callable to color the stars based on their BV index:

color_fn=callables.color_by_bv_gradient,

# callable to make dimmer stars semi-transparent:

opacity_fn=lambda s: 1 if s.magnitude < 2 else 0.5,

)

style.gridlines.label.font_size *= 1.2 # make the labels 20% bigger

style.gridlines.label.fill = "#e5ecf3"

style.gridlines.line.width = 0 # hide the gridlines, we just want the labels

p.gridlines(alt_label_locations=[])

# Plot a dotted circle around the Pleiades (M45) and an arrow pointing to it

m45 = DSO.get(m="45")

p.polygon(

geometry=m45.geometry,

style={

"fill": None,

"stroke": "#fffb0e",

"stroke_width": 6,

"dash_array": "dotted",

},

)

p.arrow(target=(m45.ra, m45.dec))

p.export("tutorial_08.svg")