def test_dice9_bad():
with pytest.raises(ValueError):
dither.get_dither_positions(base_position=42,
n_positions=42,
pattern=dither.dice9,
pattern_offset=300 * u.arcsecond)
with pytest.raises(ValueError):
dither.get_dither_positions(base_position="16h52m42.2s -38d37m12s",
n_positions=42,
pattern=dither.dice9)
def test_dice9_string():
base = "16h52m42.2s -38d37m12s"
positions = dither.get_dither_positions(base_position=base,
n_positions=12,
pattern=dither.dice9,
pattern_offset=30 * u.arcminute)
base = SkyCoord(base)
assert isinstance(positions, SkyCoord)
assert len(positions) == 12
# postion 0 should be the base position
assert positions[0].separation(base) < Angle(1e12 * u.degree)
# With no random offset positions 9, 10, 11 should be the same as 0, 1, 2
assert positions[0:3].to_string() == positions[9:12].to_string()
# Position 1 should be 30 arcminute offset from base, in declination direction only
assert base.spherical_offsets_to(
positions[1])[0].radian == pytest.approx(Angle(0 * u.degree).radian)
assert base.spherical_offsets_to(
positions[1])[1].radian == pytest.approx(Angle(0.5 * u.degree).radian)
# Position 3 should be 30 arcminute offset from base in RA only.
assert base.spherical_offsets_to(
positions[3])[0].radian == pytest.approx(Angle(0.5 * u.degree).radian)
assert base.spherical_offsets_to(
positions[3])[1].radian == pytest.approx(Angle(0 * u.degree).radian)
def test_custom_pattern():
base = SkyCoord("16h52m42.2s -38d37m12s")
cross = ((0, 0),
(0, 1),
(1, 0),
(0, -1),
(-1, 0))
positions = dither.get_dither_positions(base_position=base,
n_positions=12,
pattern=cross,
pattern_offset=1800 * u.arcsecond)
assert isinstance(positions, SkyCoord)
assert len(positions) == 12
# postion 0 should be the base position
assert positions[0].separation(base) < Angle(1e12 * u.degree)
# With no random offset positions 5, 6, 7 should be the same as 0, 1, 2
assert positions[0:3].to_string() == positions[5:8].to_string()
# Position 3 should be 30 arcminute offset from base, in declination direction only
assert base.spherical_offsets_to(
positions[3])[0].radian == pytest.approx(Angle(0 * u.degree).radian)
assert base.spherical_offsets_to(positions[3])[1].radian == pytest.approx(
Angle(-0.5 * u.degree).radian)
# Position 4 should be 30 arcminute offset from base in RA only.
assert base.spherical_offsets_to(positions[4])[0].radian == pytest.approx(
Angle(-0.5 * u.degree).radian)
assert base.spherical_offsets_to(
positions[4])[1].radian == pytest.approx(Angle(0 * u.degree).radian)
def test_plot(tmpdir):
base = SkyCoord("16h52m42.2s -38d37m12s")
plot_path = tmpdir.join('dither_test.png')
positions = dither.get_dither_positions(base_position=base,
n_positions=12,
pattern=dither.dice9,
pattern_offset=30 * u.arcminute,
plot=plot_path.strpath)
assert plot_path.check()
def test_random():
base = SkyCoord("16h52m42.2s -38d37m12s")
positions = dither.get_dither_positions(base_position=base,
n_positions=12,
random_offset=30 * u.arcsecond)
assert isinstance(positions, SkyCoord)
assert len(positions) == 12
assert base.spherical_offsets_to(positions[0])[0].radian == pytest.approx(Angle(0 * u.degree).radian,
abs=Angle(30 * u.arcsecond).radian)
assert base.spherical_offsets_to(positions[0])[1].radian == pytest.approx(Angle(0 * u.degree).radian,
abs=Angle(30 * u.arcsecond).radian)
assert base.spherical_offsets_to(positions[1])[0].radian == pytest.approx(Angle(0 * u.degree).radian,
abs=Angle(30 * u.arcsecond).radian)
assert base.spherical_offsets_to(positions[1])[1].radian == pytest.approx(Angle(0 * u.degree).radian,
abs=Angle(30 * u.arcsecond).radian)
def test_dice9_random():
base = SkyCoord("16h52m42.2s -38d37m12s")
positions = dither.get_dither_positions(base_position=base,
n_positions=12,
pattern=dither.dice9,
pattern_offset=30 * u.arcminute,
random_offset=30 * u.arcsecond)
assert isinstance(positions, SkyCoord)
assert len(positions) == 12
# postion 0 should be the base position
assert positions[0].separation(base) < Angle(30 * 2**0.5 * u.arcsecond)
# Position 1 should be 30 arcminute offset from base, in declination direction only
assert base.spherical_offsets_to(positions[1])[0].radian == pytest.approx(Angle(0 * u.degree).radian,
abs=Angle(30 * u.arcsecond).radian)
assert base.spherical_offsets_to(positions[1])[1].radian == pytest.approx(Angle(0.5 * u.degree).radian,
abs=Angle(30 * u.arcsecond).radian)
# Position 3 should be 30 arcminute offset from base in RA only.
assert base.spherical_offsets_to(positions[3])[0].radian == pytest.approx(Angle(0.5 * u.degree).radian,
abs=Angle(30 * u.arcsecond).radian)
assert base.spherical_offsets_to(positions[3])[1].radian == pytest.approx(Angle(0 * u.degree).radian,
abs=Angle(30 * u.arcsecond).radian)
def get_target_list(target_name,
imagers,
primary_imager,
base_position,
exposure_parameters,
dither_parameters={'pattern': dither.dice9,
'pattern_offset': 30 * u.arcminute,
'random_offset': 3 * u.arcminute},
priority=100):
"""
Generates a list of dictionaries containing the details for a dithered,
HDR sequence of exposures.
Args:
target_name (str): name of the target objects
imagers (dictionary): dictionary of `gungala.imager.Imager` objects, as
returned from `gunagala.imager.create_imagers()`
primary_imager: name of the Imager object from imagers that should be
used to calculate the exposure times.
base_position (SkyCoord or compatible): base position for the dither
pattern, either a SkyCoord or an object that can be converted to one
by the SkyCoord constructor (e.g. string).
exposure_parameters (dict): dictionary of keyword parameters to pass to
`Imager.exp_time_sequence()`. See that method's docstring for
details of all the accepted parameters.
dither_parameters (dict): dictionary of keyword parameters to pass to
`dither.get_dither_positions()``. See that function's docstring for
details of all the accepted parameters.
priority (optional, default 100): scheduler priority to assign to the exposures.
Returns:
list: list of dictionaries, each containing the details for an individual exposure.
"""
try:
imager = imagers[primary_imager]
except KeyError:
raise ValueError(
"Could not find imager '{}' in imagers dictionary!".format(primary_imager))
if not isinstance(base_position, SkyCoord):
try:
base_position = SkyCoord(base_position)
except ValueError:
raise ValueError(
"Base position '{}' could not be converted to a SkyCoord object!", base_position)
explist = imager.exp_time_sequence(**exposure_parameters)
target_list = []
position_list = dither.get_dither_positions(base_position=base_position,
n_positions=len(explist),
**dither_parameters)
for i in range(0, len(explist)):
target = {}
if base_position.obstime is not None:
target['epoch'] = base_position.obstime
if base_position.equinox is not None:
target['equinox'] = base_position.equinox
target['frame'] = base_position.frame.name
target['name'] = target_name
target['position'] = position_list[i].to_string('hmsdms')
target['priority'] = priority
target['exp_time'] = explist[i].value,
target_list.append(target)
return target_list