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object_visibility.py
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object_visibility.py
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import numpy as np
import matplotlib.pyplot as plt
from labellines import labelLines
import astropy.units as u
from astropy.time import Time
from astropy.coordinates import SkyCoord, EarthLocation, AltAz, get_moon, get_sun
import pytz
from datetime import datetime
import logging as _log
from typing import Optional, Union, List
class ObjVisibility(object):
"""
A class to obtain the visibility of an astrophysical object in an specific date.
...
Attributes
----------
date-obs: str
Date in which the observations will take place.
location: str
Observatory location. One of those listed in astropy.coordinates.EarthLocation.get_site_names().
Methods
-------
staralt()
Plots the staralt visibility plot of the list of objects.
"""
def __init__(self, date_obs: str, location: str) -> None:
"""
Obtain all th enecessary data to construct the visibility plot of the desired objects at an specific date.
Parameters
----------
date-obs: str
Date in which the observations will take place.
location: str
Observatory location. One of those listed in astropy.coordinates.EarthLocation.get_site_names().
Returns
-------
None.
"""
self._i = 0
self.list_names = []
self.plot_handler = []
self.name_location = location
self.location = EarthLocation.of_site(location)
self.date_obs = Time(date_obs + " 00:00:00")
self.time_zone = self.location.info.meta["timezone"]
self.fig, self.ax = plt.subplots(tight_layout=True)
def __airmass_secz(self, degrees: np.ndarray) -> np.ndarray:
"""
Calculates the airmess assuming aplane-parallel atmosphere.
Formula: sec(z)
Parameters
----------
degrees: float
Degrees from the zenithal position.
Returns
-------
airmass: float
The airmass in a determined angle.
"""
return 1.0 / np.cos(np.deg2rad(degrees))
def _add_moon(self, delta_midnight, day_range, frame_date):
"""
Retrieves the moon Location.
"""
ax = self.ax
moon = get_moon(day_range)
moonaltz = moon.transform_to(frame_date)
ax.plot(delta_midnight, moonaltz.alt, color="k", ls="--", label="Moon")
return moon
def add_object(
self,
ra: float,
dec: float,
name: str,
color: Optional[str] = None,
moon_dist: bool = False,
) -> None:
"""
Adds an object to the plot.
"""
coords = SkyCoord(ra, dec, unit="deg", frame="icrs")
self._i += 1
self.list_names.append(f"{self._i} {name}")
ax = self.ax
tz = pytz.timezone(self.time_zone)
utcoffset = tz.utcoffset(datetime.now()).total_seconds() / 60.0 / 60.0 * u.hour
# Plotting interval
midnight = self.date_obs - utcoffset
delta_midnight = np.linspace(-8.0, 8.0, 100) * u.hour
day_range = midnight + delta_midnight
frame_date = AltAz(obstime=day_range, location=self.location)
objaltz = coords.transform_to(frame_date)
if moon_dist:
moon = get_moon(day_range)
moon_dist = moon.separation(objaltz)
objplot = ax.scatter(
delta_midnight,
objaltz.alt,
c=moon_dist,
label=name,
s=8,
cmap="viridis",
)
self.fig.colorbar(
objplot, ax=ax, label="Moon distance [deg]", pad=0.07
) # Only if there is one object
else:
(objplot,) = ax.plot(
delta_midnight,
objaltz.alt,
linestyle="-.",
label=f"{self._i}", # {self.names[i]}",
ms=8,
color=color,
lw=0.5,
)
self.plot_handler.append(objplot)
def staralt(
self,
ra: Union[List[float], float],
dec: Union[List[float], float],
names: Union[List[str], str],
color: Optional[str] = None,
linelabels: Optional[str] = False,
add_moon: Optional[str] = False,
) -> None:
"""
Function to plot the staralt visibility map with moon position.
Parameters
----------
color:
List[str] or str. List same size as object len.
Returns
-------
None.
"""
if not isinstance(ra, list):
ra = [ra]
dec = [dec]
if not isinstance(names, list):
names = [names]
tz = pytz.timezone(self.time_zone)
utcoffset = tz.utcoffset(datetime.now()).total_seconds() / 60.0 / 60.0 * u.hour
# Plotting interval
midnight = self.date_obs - utcoffset
delta_midnight = np.linspace(-8.0, 8.0, 100) * u.hour
day_range = midnight + delta_midnight
frame_date = AltAz(obstime=day_range, location=self.location)
if add_moon:
_ = self._add_moon(delta_midnight, day_range, frame_date)
# Get Sun
sun = get_sun(day_range)
sunaltz = sun.transform_to(frame_date)
# # Plotting
# plt.plot(delta_midnight, objairmass)
# plt.show()
ax = self.ax
ax.fill_between(
delta_midnight.value,
0,
90,
sunaltz.alt.value < -0,
color="0.8",
zorder=0,
)
ax.fill_between(
delta_midnight.value,
0.0,
90.0,
sunaltz.alt.value < -18,
color="0.5",
zorder=0,
)
ax.set_ylim(0.0, 90.0)
ax.set_xlim(-8.0, 8.0)
ax.set_xlabel("Local Time [h]")
ax.set_ylabel("Altitude [deg]")
ax.set_title(
f"Location: {self.name_location}. UTC offset: {utcoffset}. Date: {self.date_obs.fits.split('T')[0]}"
)
ax.grid()
## Check if multiple objects
if len(names) == 1:
self.add_object(
ra=ra[0], dec=dec[0], name=names[0], color=color, moon_dist=add_moon
)
else:
for i in range(len(names)):
c = color[i] if isinstance(color, list) else color
self.add_object(
ra=ra[i], dec=dec[i], name=names[i], color=c, moon_dist=False
)
if linelabels:
print(self.list_names, self._i, len(ax.get_lines()))
labelLines(ax.get_lines(), fontsize=5, drop_label=True)
def savePlot(self, show: bool = False, formatFig: str = "pdf") -> None:
"""
Saves the plot to a file.
"""
ax = self.ax
tz = pytz.timezone(self.time_zone)
utcoffset = tz.utcoffset(datetime.now()).total_seconds() / 60.0 / 60.0 * u.hour
# Legend
ax.legend(handles=self.plot_handler, labels=self.list_names, fontsize=5)
# Second axes
ax2 = ax.twinx()
ax2.set_ylabel(r"Airmass [sec$(z)$]", fontsize=8.0, rotation=270, labelpad=10.0)
yyl = np.asarray(ax.get_yticks())
new_ylabels = np.round(self.__airmass_secz(yyl[::-1]), 2)
new_ylabels = new_ylabels.tolist()
new_ylabels[0] = " "
ax2.set_yticks(yyl)
ax2.set_yticklabels(new_ylabels, rotation="vertical", fontsize=8.0)
ax3 = ax.twiny()
ax3.set_xlabel("UT [h]", fontsize=8.0)
xx1 = np.asarray(ax.get_xticks())
ax3.set_xticks(xx1)
new_upxlabels = xx1 - utcoffset.value + 24
for i in range(len(new_upxlabels)):
if new_upxlabels[i] > 24:
new_upxlabels[i] -= 24
ax3.set_xticklabels(new_upxlabels, fontsize=8.0)
# Changing xticks marks to local time
ll = ax.get_xticks()
new_xlabels = np.asarray(ll) + 24
for i in range(len(new_xlabels)):
if new_xlabels[i] > 24:
new_xlabels[i] -= 24
ax.set_xticklabels(new_xlabels)
if not show:
self.fig.savefig(
self.date_obs.fits.split("T")[0]
+ "_"
+ self.name_location
+ "_visibility."
+ formatFig
)
else:
plt.show()
if __name__ == "__main__":
c = SkyCoord.from_name("PN M 1-16")
c2 = SkyCoord.from_name("NGC 3242")
ra = [c.ra.value, c2.ra.value]
dec = [c.dec.value, c2.dec.value]
names = ["M 1-16", "N3242"]
ov = ObjVisibility(
date_obs="2021-4-10",
location="spm",
)
ov.staralt(ra=ra, dec=dec, names=names, color="C0", linelabels=True, add_moon=True)
ov.savePlot(show=False, formatFig="pdf")