OpticPlot

Optic plots simulate what you'll see through an optic (e.g. binoculars, telescope, camera) at a specific time and location. The simulated view will show you the true field of view for the optic, and it will even orient the stars based on the location you specify and the most logical position of your optic.

These plots use an azimuthal equidistant projection, with the projection's center set to the target's position (in azimuth, altitude coordinates). This projection was chosen because it preserves the correct proportional distances from the center point.

starplot.OpticPlot

OpticPlot(
    optic: Optic,
    ra: float,
    dec: float,
    lat: float,
    lon: float,
    dt: datetime = None,
    ephemeris: str = "de421_2001.bsp",
    style: PlotStyle = DEFAULT_OPTIC_STYLE,
    resolution: int = 2048,
    hide_colliding_labels: bool = True,
    raise_on_below_horizon: bool = True,
    *args,
    **kwargs
)

Creates a new optic plot.

Parameters:

• optic (Optic) –

  Optic instance that defines optical parameters

• ra (float) –

  Right ascension of target center, in hours (0...24)

• dec (float) –

  Declination of target center, in degrees (-90...90)

• lat (float) –

  Latitude of observer's location

• lon (float) –

  Longitude of observer's location

• dt (datetime, default: None ) –

  Date/time of observation (must be timezone-aware). Default = current UTC time.

• ephemeris (str, default: 'de421_2001.bsp' ) –

  Ephemeris to use for calculating planet positions (see Skyfield's documentation for details)

• style (PlotStyle, default: DEFAULT_OPTIC_STYLE ) –

  Styling for the plot (colors, sizes, fonts, etc)

• resolution (int, default: 2048 ) –

  Size (in pixels) of largest dimension of the map

• hide_colliding_labels (bool, default: True ) –

  If True, then labels will not be plotted if they collide with another existing label

• raise_on_below_horizon (bool, default: True ) –

  If True, then a ValueError will be raised if the target is below the horizon at the observing time/location

Returns:

• OpticPlot –

  A new instance of an OpticPlot

adjust_text

adjust_text(
    ensure_inside_axes: bool = False, **kwargs
) -> None

Adjust all the labels to avoid overlapping. This function uses the adjustText library.

Parameters:

• ensure_inside_axes (bool, default: False ) –

  If True, then labels will be forced to stay within the axes

• **kwargs –

  Any keyword arguments to pass through to adjustText

bino_fov

bino_fov(
    ra: float,
    dec: float,
    fov: float,
    magnification: float,
    style: PolygonStyle = DEFAULT_FOV_STYLE,
)

Draws a circle representing the field of view for binoculars.

Parameters:

• ra (float) –

  Right ascension of the center of view

• dec (float) –

  Declination of the center of view

• fov (float) –

  field of view (degrees) of the binoculars

• magnification (float) –

  magnification of the binoculars

• style (PolygonStyle, default: DEFAULT_FOV_STYLE ) –

  style of the polygon

celestial_equator

celestial_equator(
    style: PathStyle = None,
    label: str = "CELESTIAL EQUATOR",
)

Plots the celestial equator

Parameters:

• style (PathStyle, default: None ) –

  Styling of the celestial equator. If None, then the plot's style will be used

• label (str, default: 'CELESTIAL EQUATOR' ) –

  How the celestial equator will be labeled on the plot

circle

circle(
    center: tuple,
    radius_degrees: float,
    style: PolygonStyle,
    num_pts: int = 100,
)

Plots a circle

Parameters:

• center (tuple) –

  Center of circle (ra, dec)

• radius_degrees (float) –

  Radius of circle (degrees)

• style (PolygonStyle) –

  Style of circle

• num_pts (int, default: 100 ) –

  Number of points to calculate for the circle polygon

close_fig

close_fig() -> None

Closes the underlying matplotlib figure.

dsos

dsos(
    mag: float = 8.0,
    types: list[DsoType] = DEFAULT_DSO_TYPES,
    names: list[str] = None,
    null: bool = False,
    true_size: bool = True,
    labels: Mapping[str, str] = DSO_LABELS_DEFAULT,
    legend_labels: Mapping[
        DsoType, str
    ] = DSO_LEGEND_LABELS,
)

Plots Deep Sky Objects (DSOs), from OpenNGC

Parameters:

• mag (float, default: 8.0 ) –

  Limiting magnitude of DSOs to plot

• types (list[DsoType], default: DEFAULT_DSO_TYPES ) –

  List of DSO types to plot

• names (list[str], default: None ) –

  List of DSO names (as specified in OpenNGC) to filter by (case sensitive!). If None, then the DSOs will not be filtered by name.

• null (bool, default: False ) –

  If True, then DSOs without a defined magnitude will be plotted

• true_size (bool, default: True ) –

  If True, then each DSO will be plotted as its true apparent size in the sky (note: this increases plotting time). If False, then the style's marker size will be used. Also, keep in mind not all DSOs have a defined size (according to OpenNGC) -- so these will use the style's marker size.

• labels (Mapping[str, str], default: DSO_LABELS_DEFAULT ) –

  A dictionary that maps DSO names (as specified in OpenNGC) to the label that'll be plotted for that object. By default, the DSO's name in OpenNGC will be used as the label. If you want to hide all labels, then set this arg to None.

• legend_labels (Mapping[DsoType, str], default: DSO_LEGEND_LABELS ) –

  A dictionary that maps a DsoType to the legend label that'll be plotted for that type of DSO. If you want to hide all DSO legend labels, then set this arg to None.

ecliptic

ecliptic(style: PathStyle = None, label: str = 'ECLIPTIC')

Plots the ecliptic

Parameters:

• style (PathStyle, default: None ) –

  Styling of the ecliptic. If None, then the plot's style will be used

• label (str, default: 'ECLIPTIC' ) –

  How the ecliptic will be labeled on the plot

ellipse

ellipse(
    center: tuple,
    height_degrees: float,
    width_degrees: float,
    style: PolygonStyle,
    angle: float = 0,
    num_pts: int = 100,
)

Plots an ellipse

Parameters:

• center (tuple) –

  Center of ellipse (ra, dec)

• height_degrees (float) –

  Height of ellipse (degrees)

• width_degrees (float) –

  Width of ellipse (degrees)

• style (PolygonStyle) –

  Style of ellipse

• angle (float, default: 0 ) –

  Angle of rotation clockwise (degrees)

• num_pts (int, default: 100 ) –

  Number of points to calculate for the ellipse polygon

export

export(
    filename: str,
    format: str = "png",
    padding: float = 0,
    **kwargs
)

Exports the plot to an image file.

Parameters:

• filename (str) –

  Filename of exported file

• format (str, default: 'png' ) –

  Format of file: "png" or "svg"

• padding (float, default: 0 ) –

  Padding (in inches) around the image

• **kwargs –

  Any keyword arguments to pass through to matplotlib's savefig method

galaxies

galaxies(*args, **kwargs)

Plots galaxy DSO types

This is just a small wrapper around the dsos() function, so any kwargs will be passed through.

in_bounds

in_bounds(ra, dec) -> bool

Determine if a coordinate is within the bounds of the plot.

Parameters:

• ra –

  Right ascension, in hours (0...24)

• dec –

  Declination, in degrees (-90...90)

Returns:

• bool –

  True if the coordinate is in bounds, otherwise False

in_bounds_altaz

in_bounds_altaz(alt, az, scale: float = 1) -> bool

Determine if a coordinate is within the bounds of the plot.

Parameters:

• alt –

  Altitude angle in degrees (0...90)

• az –

  Azimuth angle in degrees (0...360)

Returns:

• bool –

  True if the coordinate is in bounds, otherwise False

info

info(style: LabelStyle = None)

Plots a table with info about the plot, including:

• Target's position (alt/az and ra/dec)
• Observer's position (lat/lon and date/time)
• Optic details (type, magnification, FOV)

Parameters:

• style (LabelStyle, default: None ) –

  If None, then the plot's style for info text will be used

legend

legend(style: LegendStyle = None)

Plots the legend.

If the legend is already plotted, then it'll be removed first and then plotted again. So, it's safe to call this function multiple times if you need to 'refresh' the legend.

Parameters:

• style (LegendStyle, default: None ) –

  Styling of the legend. If None, then the plot's style (specified when creating the plot) will be used

marker

marker(
    ra: float,
    dec: float,
    label: str,
    style: Union[dict, ObjectStyle],
    legend_label: str = None,
) -> None

Plots a marker

Parameters:

• ra (float) –

  Right ascension of the marker

• dec (float) –

  Declination of the marker

• label (str) –

  Label for the marker

• style (Union[dict, ObjectStyle]) –

  Styling for the marker

• legend_label (str, default: None ) –

  How to label the marker in the legend. If None, then the marker will not be added to the legend

moon

moon(
    style: ObjectStyle = None,
    true_size: bool = False,
    label: str = "Moon",
    legend_label: str = "Moon",
) -> None

Plots the Moon

Parameters:

• style (ObjectStyle, default: None ) –

  Styling of the Moon. If None, then the plot's style (specified when creating the plot) will be used

• true_size (bool, default: False ) –

  If True, then the Moon's true apparent size in the sky will be plotted. If False, then the style's marker size will be used.

• label (str, default: 'Moon' ) –

  How the Moon will be labeled on the plot and legend

nebula

nebula(*args, **kwargs)

Plots nebula DSO types

This is just a small wrapper around the dsos() function, so any kwargs will be passed through.

planets

planets(
    style: ObjectStyle = None,
    true_size: bool = False,
    labels: Dict[Planet, str] = PLANET_LABELS_DEFAULT,
    legend_label: str = "Planet",
) -> None

Plots the planets

Parameters:

• style (ObjectStyle, default: None ) –

  Styling of the planets. If None, then the plot's style (specified when creating the plot) will be used

• true_size (bool, default: False ) –

  If True, then each planet's true apparent size in the sky will be plotted. If False, then the style's marker size will be used.

• labels (Dict[Planet, str], default: PLANET_LABELS_DEFAULT ) –

  How the planets will be labeled on the plot and legend. If not specified, then the planet's name will be used (see Planet)

• legend_label (str, default: 'Planet' ) –

  How to label the planets in the legend. If None, then the planets will not be added to the legend

polygon

polygon(points: list, style: PolygonStyle)

Plots a polygon of points

Parameters:

• points (list) –

  List of polygon points [(ra, dec), ...]

• style (PolygonStyle) –

  Style of polygon

rectangle

rectangle(
    center: tuple,
    height_degrees: float,
    width_degrees: float,
    style: PolygonStyle,
    angle: float = 0,
    *args,
    **kwargs
)

Plots a rectangle

Parameters:

• center (tuple) –

  Center of rectangle (ra, dec)

• height_degrees (float) –

  Height of rectangle (degrees)

• width_degrees (float) –

  Width of rectangle (degrees)

• angle (float, default: 0 ) –

  Angle of rotation clockwise (degrees)

• style (PolygonStyle) –

  Style of rectangle

scope_fov

scope_fov(
    ra: float,
    dec: float,
    scope_focal_length: float,
    eyepiece_focal_length: float,
    eyepiece_fov: float,
    style: PolygonStyle = DEFAULT_FOV_STYLE,
)

Draws a circle representing the field of view for a telescope and eyepiece.

Parameters:

• ra (float) –

  Right ascension of the center of view

• dec (float) –

  Declination of the center of view

• scope_focal_length (float) –

  focal length (mm) of the scope

• eyepiece_focal_length (float) –

  focal length (mm) of the eyepiece

• eyepiece_fov (float) –

  field of view (degrees) of the eyepiece

• style (PolygonStyle, default: DEFAULT_FOV_STYLE ) –

  style of the polygon

stars

stars(
    mag: float = 8.0,
    mag_labels: float = 6.0,
    catalog: StarCatalog = StarCatalog.TYCHO_1,
    style: MarkerStyle = None,
    rasterize: bool = False,
    size_fn: Callable[
        [Star], float
    ] = callables.size_by_magnitude_for_optic,
    alpha_fn: Callable[
        [Star], float
    ] = callables.alpha_by_magnitude,
    color_fn: Callable[[Star], str] = None,
    legend_label: str = "Star",
    *args,
    **kwargs
)

Plots stars

Parameters:

• mag (float, default: 8.0 ) –

  Limiting magnitude of stars to plot

• mag_labels (float, default: 6.0 ) –

  Limiting magnitude of stars to label on the plot

• catalog (StarCatalog, default: TYCHO_1 ) –

  The catalog of stars to use: "hipparcos" or "tycho-1"

• style (MarkerStyle, default: None ) –

  If None, then the plot's style for stars will be used

• rasterize (bool, default: False ) –

  If True, then the stars will be rasterized when plotted, which can speed up exporting to SVG and reduce the file size but with a loss of image quality

• size_fn (Callable[[Star], float], default: size_by_magnitude_for_optic ) –

  Callable for calculating the marker size of each star. If None, then the marker style's size will be used.

• alpha_fn (Callable[[Star], float], default: alpha_by_magnitude ) –

  Callable for calculating the alpha value (aka "opacity") of each star. If None, then the marker style's alpha will be used.

• color_fn (Callable[[Star], str], default: None ) –

  Callable for calculating the color of each star. If None, then the marker style's color will be used.

• legend_label (str, default: 'Star' ) –

  Label for stars in the legend. If None, then they will not be in the legend.

title

title(text: str, style: LabelStyle = None)

Plots a title at the top of the plot

Parameters:

• text (str) –

  Title text to plot

• style (LabelStyle, default: None ) –

  Styling of the title. If None, then the plot's style (specified when creating the plot) will be used

starplot.optics.Optic

Abstract class for defining Optics.

starplot.optics.Binoculars

Binoculars(magnification: float, fov: float)

Creates a new Binoculars optic

Parameters:

• magnification (float) –

  Magnification of the binoculars

• fov (float) –

  Apparent field of view (FOV) of the binoculars in degrees. This isn't always easy to find for binoculars, so if you can't find it in your binocular's specs, then try using 60.

Returns:

• Binoculars –

  A new instance of a Binoculars optic

starplot.optics.Scope

Scope(
    focal_length: float,
    eyepiece_focal_length: float,
    eyepiece_fov: float,
)

Creates a new generic Scope optic.

Use this class to create custom scope optics or use it as a generic optic that does NOT apply any transforms to the view.

See subclasses of this optic for more specific use cases:

• Refractor - automatically inverts the view (i.e. assumes a star diagonal is used)

• Reflector - automatically rotates the view so it's upside-down

Parameters:

• focal_length (float) –

  Focal length (mm) of the telescope

• eyepiece_focal_length (float) –

  Focal length (mm) of the eyepiece

• eyepiece_fov (float) –

  Field of view (degrees) of the eyepiece

Returns:

• Scope –

  A new instance of a Scope optic

starplot.optics.Refractor

Refractor(
    focal_length: float,
    eyepiece_focal_length: float,
    eyepiece_fov: float,
)

Creates a new Refractor Telescope optic

Warning

This optic assumes a star diagonal is used, so it applies a transform that inverts the image.

If you don't want this transform applied, then use the generic Scope optic instead.

Parameters:

• focal_length (float) –

  Focal length (mm) of the telescope

• eyepiece_focal_length (float) –

  Focal length (mm) of the eyepiece

• eyepiece_fov (float) –

  Field of view (degrees) of the eyepiece

Returns:

• Refractor –

  A new instance of a Refractor optic

starplot.optics.Reflector

Reflector(
    focal_length: float,
    eyepiece_focal_length: float,
    eyepiece_fov: float,
)

Creates a new Reflector Telescope optic

Warning

This optic applies a transform that produces an "upside-down" image.

If you don't want this transform applied, then use the generic Scope optic instead.

Parameters:

• focal_length (float) –

  Focal length (mm) of the telescope

• eyepiece_focal_length (float) –

  Focal length (mm) of the eyepiece

• eyepiece_fov (float) –

  Field of view (degrees) of the eyepiece

Returns:

• Reflector –

  A new instance of a Reflector optic

starplot.optics.Camera

Camera(
    sensor_height: float,
    sensor_width: float,
    lens_focal_length: float,
    rotation: float = 0,
)

Creates a new Camera optic

Note

Field of view for each dimension is calculated using the following formula:

TFOV = 2 * arctan( d / (2 * f) )

Where:

d = sensor size (height or width)

f = focal length of lens

Parameters:

• sensor_height (float) –

  Height of camera sensor (mm)

• sensor_width (float) –

  Width of camera sensor (mm)

• lens_focal_length (float) –

  Focal length of camera lens (mm)

• rotation (float, default: 0 ) –

  Angle (degrees) to rotate camera

Returns:

• Camera –

  A new instance of a Camera optic