Sky Map Plotting (`ligo.skymap.plot.allsky`)¶

Axes subclasses for astronomical mapmaking.

This module adds several astropy.visualization.wcsaxes.WCSAxes subclasses to the Matplotlib projection registry. The projections have names of the form astro_or_geo_or_galactic [lon_units] projection.

astro_or_geo_or_galactic may be astro, geo, or galactic. It controls the reference frame, either celestial (ICRS), terrestrial (ITRS), or galactic.

lon_units may be hours or degrees. It controls the units of the longitude axis. If omitted, astro implies hours and geo implies degrees.

projection may be any of the following:

aitoff for the Aitoff all-sky projection
mollweide for the Mollweide all-sky projection
globe for an orthographic projection, like the three-dimensional view of the Earth from a distant satellite
zoom for a gnomonic projection suitable for visualizing small zoomed-in patches

All projections support the center argument, while some support additional arguments. The globe projections also support the rotate argument, and the zoom projections also supports the radius and rotate arguments.

Examples¶

import ligo.skymap.plot
from matplotlib import pyplot as plt
ax = plt.axes(projection='astro hours mollweide')
ax.grid()

(Source code, png, hires.png, pdf)

import ligo.skymap.plot
from matplotlib import pyplot as plt
ax = plt.axes(projection='geo aitoff')
ax.grid()

(Source code, png, hires.png, pdf)

import ligo.skymap.plot
from matplotlib import pyplot as plt
ax = plt.axes(projection='astro zoom',
              center='5h -32d', radius='5 deg', rotate='20 deg')
ax.grid()

(Source code, png, hires.png, pdf)

import ligo.skymap.plot
from matplotlib import pyplot as plt
ax = plt.axes(projection='geo globe', center='-50d +23d')
ax.grid()

(Source code, png, hires.png, pdf)

Insets¶

You can use insets to link zoom-in views between axes. There are two supported styles of insets: rectangular and circular (loupe). The example below shows both kinds of insets.

import ligo.skymap.plot
from matplotlib import pyplot as plt
fig = plt.figure(figsize=(9, 4), dpi=100)

ax_globe = plt.axes(
    [0.1, 0.1, 0.8, 0.8],
    projection='astro degrees globe',
    center='120d +23d')

ax_zoom_rect = plt.axes(
    [0.0, 0.2, 0.4, 0.4],
    projection='astro degrees zoom',
    center='150d +30d',
    radius='9 deg')

ax_zoom_circle = plt.axes(
    [0.55, 0.1, 0.6, 0.6],
    projection='astro degrees zoom',
    center='120d +10d',
    radius='5 deg')

ax_globe.mark_inset_axes(ax_zoom_rect)
ax_globe.connect_inset_axes(ax_zoom_rect, 'upper left')
ax_globe.connect_inset_axes(ax_zoom_rect, 'lower right')

ax_globe.mark_inset_circle(ax_zoom_circle, '120d +10d', '4 deg')
ax_globe.connect_inset_circle(ax_zoom_circle, '120d +10d', '4 deg')

ax_globe.grid()
ax_zoom_rect.grid()
ax_zoom_circle.grid()

for ax in [ax_globe, ax_zoom_rect, ax_zoom_circle]:
    ax.set_facecolor('none')
    for key in ['ra', 'dec']:
        ax.coords[key].set_auto_axislabel(False)

(Source code, png, hires.png, pdf)

Complete Example¶

The following example demonstrates most of the features of this module.

from astropy.coordinates import SkyCoord
from astropy.io import fits
from astropy import units as u
import ligo.skymap.plot
from matplotlib import pyplot as plt

url = 'https://dcc.ligo.org/public/0146/G1701985/001/bayestar_no_virgo.fits.gz'
center = SkyCoord.from_name('NGC 4993')

fig = plt.figure(figsize=(4, 4), dpi=100)

ax = plt.axes(
    [0.05, 0.05, 0.9, 0.9],
    projection='astro globe',
    center=center)

ax_inset = plt.axes(
    [0.59, 0.3, 0.4, 0.4],
    projection='astro zoom',
    center=center,
    radius=10*u.deg)

for key in ['ra', 'dec']:
    ax_inset.coords[key].set_ticklabel_visible(False)
    ax_inset.coords[key].set_ticks_visible(False)
ax.grid()
ax.mark_inset_axes(ax_inset)
ax.connect_inset_axes(ax_inset, 'upper left')
ax.connect_inset_axes(ax_inset, 'lower left')
ax_inset.scalebar((0.1, 0.1), 5 * u.deg).label()
ax_inset.compass(0.9, 0.1, 0.2)

ax.imshow_hpx(url, cmap='cylon')
ax_inset.imshow_hpx(url, cmap='cylon')
ax_inset.plot(
    center.ra.deg, center.dec.deg,
    transform=ax_inset.get_transform('world'),
    marker=ligo.skymap.plot.reticle(),
    markersize=30,
    markeredgewidth=3)

(Source code, png, hires.png, pdf)

class ligo.skymap.plot.allsky.AutoScaledWCSAxes(*args, header, obstime=None, center=None, **kwargs)[source]¶

Bases: WCSAxes

Axes base class. The pixel scale is adjusted to the DPI of the image, and there are a variety of convenience methods.

compass(x, y, size)[source]¶

Add a compass to indicate the north and east directions.

Parameters:

x, yfloat: Position of compass vertex in axes coordinates.
sizefloat: Size of compass in axes coordinates.

connect_inset_axes(ax, loc, *args, **kwargs)[source]¶

Connect a corner of another WCSAxes to the matching point inside this one.

Parameters:

axastropy.visualization.wcsaxes.WCSAxes: The other axes.
locint, str: Which corner to connect. For valid values, see matplotlib.offsetbox.AnchoredOffsetbox.

Returns:

patchmatplotlib.patches.ConnectionPatch

Other Parameters:

args: Extra arguments for matplotlib.patches.ConnectionPatch
kwargs: Extra keyword arguments for matplotlib.patches.ConnectionPatch

connect_inset_circle(ax, center, radius, *args, **kwargs)[source]¶

Connect a circle in this and another Axes to create a loupe.

Parameters:

axastropy.visualization.wcsaxes.WCSAxes: The other axes.
coordastropy.coordinates.SkyCoord: The center of the circle.
radiusastropy.units.Quantity: The radius of the circle in units that are compatible with degrees.

Returns:

patch1, patch2matplotlib.patches.ConnectionPatch: The two connecting patches.

Other Parameters:

args: Extra arguments for matplotlib.patches.PathPatch
kwargs: Extra keyword arguments for matplotlib.patches.PathPatch

contour_hpx(data, hdu_in=None, order='bilinear', nested=False, field=0, smooth=None, **kwargs)[source]¶

Add contour levels for a HEALPix data set.

Parameters:

datanumpy.ndarray or str or TableHDU or BinTableHDU or tuple: The HEALPix data set. If this is a numpy.ndarray, then it is interpreted as the HEALPix array in the same coordinate system as the axes. Otherwise, the input data can be any type that is understood by reproject.reproject_from_healpix.
smoothastropy.units.Quantity, optional: An optional smoothing length in angle-compatible units.

Returns:

contoursmatplotlib.contour.QuadContourSet

Other Parameters:

hdu_in, order, nested, field, smooth: Extra arguments for reproject.reproject_from_healpix
kwargs: Extra keyword arguments for matplotlib.axes.Axes.contour

contourf_hpx(data, hdu_in=None, order='bilinear', nested=False, field=0, smooth=None, **kwargs)[source]¶

Add filled contour levels for a HEALPix data set.

Parameters:

datanumpy.ndarray or str or TableHDU or BinTableHDU or tuple: The HEALPix data set. If this is a numpy.ndarray, then it is interpreted as the HEALPix array in the same coordinate system as the axes. Otherwise, the input data can be any type that is understood by reproject.reproject_from_healpix.
smoothastropy.units.Quantity, optional: An optional smoothing length in angle-compatible units.

Returns:

contoursmatplotlib.contour.QuadContourSet

Other Parameters:

hdu_in, order, nested, field, smooth: Extra arguments for reproject.reproject_from_healpix
kwargs: Extra keyword arguments for matplotlib.axes.Axes.contour

imshow_hpx(data, hdu_in=None, order='bilinear', nested=False, field=0, smooth=None, **kwargs)[source]¶

Add an image for a HEALPix data set.

Parameters:

datanumpy.ndarray or str or TableHDU or BinTableHDU or tuple: The HEALPix data set. If this is a numpy.ndarray, then it is interpreted as the HEALPix array in the same coordinate system as the axes. Otherwise, the input data can be any type that is understood by reproject.reproject_from_healpix.
smoothastropy.units.Quantity, optional: An optional smoothing length in angle-compatible units.

Returns:

imagematplotlib.image.AxesImage

Other Parameters:

hdu_in, order, nested, field, smooth: Extra arguments for reproject.reproject_from_healpix
kwargs: Extra keyword arguments for matplotlib.axes.Axes.contour

mark_inset_axes(ax, *args, **kwargs)[source]¶

Outline the footprint of another WCSAxes inside this one.

Parameters:

axastropy.visualization.wcsaxes.WCSAxes: The other axes.

Returns:

patchmatplotlib.patches.PathPatch

Other Parameters:

args: Extra arguments for matplotlib.patches.PathPatch
kwargs: Extra keyword arguments for matplotlib.patches.PathPatch

mark_inset_circle(ax, center, radius, *args, **kwargs)[source]¶

Outline a circle in this and another Axes to create a loupe.

Parameters:

axastropy.visualization.wcsaxes.WCSAxes: The other axes.
coordastropy.coordinates.SkyCoord: The center of the circle.
radiusastropy.units.Quantity: The radius of the circle in units that are compatible with degrees.

Returns:

patch1matplotlib.patches.PathPatch: The outline of the circle in these Axes.
patch2matplotlib.patches.PathPatch: The outline of the circle in the other Axes.

Other Parameters:

args: Extra arguments for matplotlib.patches.PathPatch
kwargs: Extra keyword arguments for matplotlib.patches.PathPatch

scalebar(*args, **kwargs)[source]¶

Add scale bar.

Parameters:

xytuple: The axes coordinates of the scale bar.
lengthastropy.units.Quantity: The length of the scale bar in angle-compatible units.

Returns:

patchmatplotlib.patches.FancyArrowPatch

Other Parameters:

args: Extra arguments for matplotlib.patches.FancyArrowPatch
kwargs: Extra keyword arguments for matplotlib.patches.FancyArrowPatch

set(*, adjustable=<UNSET>, agg_filter=<UNSET>, alpha=<UNSET>, anchor=<UNSET>, animated=<UNSET>, aspect=<UNSET>, autoscale_on=<UNSET>, autoscalex_on=<UNSET>, autoscaley_on=<UNSET>, axes_locator=<UNSET>, axisbelow=<UNSET>, box_aspect=<UNSET>, clip_box=<UNSET>, clip_on=<UNSET>, clip_path=<UNSET>, facecolor=<UNSET>, forward_navigation_events=<UNSET>, frame_on=<UNSET>, gid=<UNSET>, in_layout=<UNSET>, label=<UNSET>, mouseover=<UNSET>, navigate=<UNSET>, path_effects=<UNSET>, picker=<UNSET>, position=<UNSET>, prop_cycle=<UNSET>, rasterization_zorder=<UNSET>, rasterized=<UNSET>, sketch_params=<UNSET>, snap=<UNSET>, subplotspec=<UNSET>, title=<UNSET>, transform=<UNSET>, url=<UNSET>, visible=<UNSET>, xbound=<UNSET>, xlabel=<UNSET>, xlim=<UNSET>, xmargin=<UNSET>, xscale=<UNSET>, xticklabels=<UNSET>, xticks=<UNSET>, ybound=<UNSET>, ylabel=<UNSET>, ylim=<UNSET>, ymargin=<UNSET>, yscale=<UNSET>, yticklabels=<UNSET>, yticks=<UNSET>, zorder=<UNSET>)¶

Set multiple properties at once.

Supported properties are

Properties:: adjustable: {‘box’, ‘datalim’} agg_filter: a filter function, which takes a (m, n, 3) float array and a dpi value, and returns a (m, n, 3) array and two offsets from the bottom left corner of the image alpha: float or None anchor: (float, float) or {‘C’, ‘SW’, ‘S’, ‘SE’, ‘E’, ‘NE’, …} animated: bool aspect: {‘auto’, ‘equal’} or float autoscale_on: bool autoscalex_on: unknown autoscaley_on: unknown axes_locator: Callable[[Axes, Renderer], Bbox] axisbelow: bool or ‘line’ box_aspect: float or None clip_box: BboxBase or None clip_on: bool clip_path: Patch or (Path, Transform) or None facecolor or fc: color figure: Figure or SubFigure forward_navigation_events: bool or “auto” frame_on: bool gid: str in_layout: bool label: object mouseover: bool navigate: bool navigate_mode: unknown path_effects: list of AbstractPathEffect picker: None or bool or float or callable position: [left, bottom, width, height] or Bbox prop_cycle: Cycler rasterization_zorder: float or None rasterized: bool sketch_params: (scale: float, length: float, randomness: float) snap: bool or None subplotspec: unknown title: str transform: Transform url: str visible: bool xbound: (lower: float, upper: float) xlabel: unknown xlim: (left: float, right: float) xmargin: float greater than -0.5 xscale: unknown xticklabels: unknown xticks: unknown ybound: (lower: float, upper: float) ylabel: unknown ylim: (bottom: float, top: float) ymargin: float greater than -0.5 yscale: unknown yticklabels: unknown yticks: unknown zorder: float

Navigation

Sky Map Plotting (ligo.skymap.plot.allsky)¶

Examples¶

Insets¶

Complete Example¶

Sky Map Plotting (`ligo.skymap.plot.allsky`)¶