def __init__(self, filename):
self.filename = check_file_location(filename, "files")
self.handle = pyfits.open(self.filename)
if "MATRIX" in self.handle:
self.mat_key = "MATRIX"
elif "SPECRESP MATRIX" in self.handle:
self.mat_key = "SPECRESP MATRIX"
else:
raise RuntimeError("Cannot find the response matrix in the RMF "
"file %s! " % filename + "It should be named "
"\"MATRIX\" or \"SPECRESP MATRIX\".")
self.data = self.handle[self.mat_key].data
self.header = self.handle[self.mat_key].header
self.num_mat_columns = len(self.handle[self.mat_key].columns)
self.ebounds = self.handle["EBOUNDS"].data
self.ebounds_header = self.handle["EBOUNDS"].header
self.weights = np.array([w.sum() for w in self.data["MATRIX"]])
self.elo = self.data["ENERG_LO"]
self.ehi = self.data["ENERG_HI"]
self.n_de = self.elo.size
self.n_ch = len(self.ebounds["CHANNEL"])
num = 0
for i in range(1, self.num_mat_columns + 1):
if self.header["TTYPE%d" % i] == "F_CHAN":
num = i
break
self.cmin = self.header["TLMIN%d" % num]
self.cmax = self.header["TLMAX%d" % num]
def __init__(self, filename):
self.filename = check_file_location(filename, "files")
f = pyfits.open(self.filename)
self.elo = f["SPECRESP"].data.field("ENERG_LO")
self.ehi = f["SPECRESP"].data.field("ENERG_HI")
self.emid = 0.5 * (self.elo + self.ehi)
self.eff_area = np.nan_to_num(
f["SPECRESP"].data.field("SPECRESP")).astype("float64")
self.max_area = self.eff_area.max()
f.close()
def tbabs_cross_section(E):
global _tbabs_emid
global _tbabs_sigma
global _tbabs_spline
if _tbabs_spline is None:
filename = check_file_location("tbabs_table.h5", "files")
f = h5py.File(filename, "r")
_tbabs_sigma = f["cross_section"][:]
nbins = _tbabs_sigma.size
ebins = np.linspace(f["emin"].value, f["emax"].value, nbins+1)
f.close()
_tbabs_emid = 0.5*(ebins[1:]+ebins[:-1])
_tbabs_spline = InterpolatedUnivariateSpline(_tbabs_emid,
_tbabs_sigma, ext=1)
return _tbabs_spline(E)
def add_background(bkgnd_name,
event_params,
rot_mat,
focal_length=None,
prng=np.random):
fov = event_params["fov"]
bkgnd_spec = background_registry[bkgnd_name]
# Generate background events
bkg_events = {}
# If this is an astrophysical background, detect the events with the ARF used
# for the observation, otherwise it's a particle background and assume area = 1.
if bkgnd_spec.bkgnd_type == "astrophysical":
arf = AuxiliaryResponseFile(
check_file_location(event_params["arf"], "files"))
area = arf.interpolate_area(bkgnd_spec.emid).value
else:
area = (focal_length / 10.0)**2
bkg_events["energy"] = bkgnd_spec.generate_energies(
event_params["exposure_time"], area, fov, prng=prng)
n_events = bkg_events["energy"].size
bkg_events['chipx'] = np.round(
prng.uniform(low=1.0, high=event_params['num_pixels'], size=n_events))
bkg_events['chipy'] = np.round(
prng.uniform(low=1.0, high=event_params['num_pixels'], size=n_events))
bkg_events["detx"] = np.round(
bkg_events["chipx"] - event_params['pix_center'][0] +
prng.uniform(low=-0.5, high=0.5, size=n_events))
bkg_events["dety"] = np.round(
bkg_events["chipy"] - event_params['pix_center'][1] +
prng.uniform(low=-0.5, high=0.5, size=n_events))
pix = np.dot(rot_mat, np.array([bkg_events["detx"], bkg_events["dety"]]))
bkg_events["xpix"] = pix[0, :] + event_params['pix_center'][0]
bkg_events["ypix"] = pix[1, :] + event_params['pix_center'][1]
return bkg_events
def instrument_simulator(simput_file,
out_file,
exp_time,
instrument,
sky_center,
clobber=False,
dither_shape="square",
dither_size=16.0,
roll_angle=0.0,
astro_bkgnd=True,
instr_bkgnd=True,
prng=np.random):
"""
Take unconvolved events in a SIMPUT catalog and create an event
file from them. This function does the following:
1. Determines which events are observed using the ARF
2. Pixelizes the events, applying PSF effects and dithering
3. Adds instrumental and astrophysical background events
4. Determines energy channels using the RMF
5. Writes the events to a file
Parameters
----------
simput_file : string
The SIMPUT catalog file to be used as input.
out_file : string
The name of the event file to be written.
exp_time : float
The exposure time to use, in seconds.
instrument : string
The name of the instrument to use, which picks an instrument
specification from the instrument registry. Can also be a JSON
file with a new instrument specification. If this is the case,
it will be loaded into the instrument registry.
sky_center : array, tuple, or list
The center RA, Dec coordinates of the observation, in degrees.
clobber : boolean, optional
Whether or not to clobber an existing file with the same name.
Default: False
dither_shape : string
The shape of the dither. Currently "circle" or "square"
Default: "square"
dither_size : float
The size of the dither in arcseconds. Width of square or radius
of circle. Default: 16.0
roll_angle : float
The roll angle of the observation in degrees. Default: 0.0
astro_bkgnd : boolean, optional
Whether or not to include astrophysical background. Default: True
instr_bkgnd : boolean, optional
Whether or not to include instrumental/particle background. Default: True
prng : :class:`~numpy.random.RandomState` object or :mod:`~numpy.random`, optional
A pseudo-random number generator. Typically will only be specified
if you have a reason to generate the same set of random numbers, such as for a
test. Default is the :mod:`numpy.random` module.
Examples
--------
>>> instrument_simulator("sloshing_simput.fits", "sloshing_evt.fits", "hdxi_3x10",
... [30., 45.], clobber=True)
"""
event_list, parameters = read_simput_catalog(simput_file)
try:
instrument_spec = instrument_registry[instrument]
except KeyError:
raise KeyError("Instrument %s is not in the instrument registry!" %
instrument)
arf_file = check_file_location(instrument_spec["arf"], "files")
rmf_file = check_file_location(instrument_spec["rmf"], "files")
arf = AuxiliaryResponseFile(arf_file)
rmf = RedistributionMatrixFile(rmf_file)
nx = instrument_spec["num_pixels"]
plate_scale = instrument_spec["fov"] / nx / 60. # arcmin to deg
plate_scale_arcsec = plate_scale * 3600.0
dsize = dither_size / plate_scale_arcsec
event_params = {}
event_params["exposure_time"] = exp_time
event_params["arf"] = os.path.split(arf.filename)[-1]
event_params["sky_center"] = sky_center
event_params["pix_center"] = np.array([0.5 * (nx + 1)] * 2)
event_params["num_pixels"] = nx
event_params["plate_scale"] = plate_scale
event_params["rmf"] = os.path.split(rmf.filename)[-1]
event_params["channel_type"] = rmf.header["CHANTYPE"]
event_params["telescope"] = rmf.header["TELESCOP"]
event_params["instrument"] = rmf.header["INSTRUME"]
event_params["mission"] = rmf.header.get("MISSION", "")
event_params["nchan"] = rmf.ebounds_header["DETCHANS"]
event_params["roll_angle"] = roll_angle
event_params["fov"] = instrument_spec["fov"]
num = 0
for i in range(1, rmf.num_mat_columns + 1):
if rmf.header["TTYPE%d" % i] == "F_CHAN":
num = i
break
event_params["chan_lim"] = [
rmf.header["TLMIN%d" % num], rmf.header["TLMAX%d" % num]
]
w = pywcs.WCS(naxis=2)
w.wcs.crval = event_params["sky_center"]
w.wcs.crpix = event_params["pix_center"]
w.wcs.cdelt = [-plate_scale, plate_scale]
w.wcs.ctype = ["RA---TAN", "DEC--TAN"]
w.wcs.cunit = ["deg"] * 2
roll_angle = np.deg2rad(roll_angle)
rot_mat = np.array([[np.sin(roll_angle), -np.cos(roll_angle)],
[-np.cos(roll_angle), -np.sin(roll_angle)]])
all_events = {}
first = True
for i, evts in enumerate(event_list):
mylog.info("Detecting events from source %d" % (i + 1))
# Step 1: Use ARF to determine which photons are observed
mylog.info("Applying energy-dependent effective area from %s." %
event_params["arf"])
refband = [parameters["emin"][i], parameters["emax"][i]]
events = arf.detect_events(evts,
exp_time,
parameters["flux"][i],
refband,
prng=prng)
n_evt = events["energy"].size
if n_evt == 0:
mylog.warning("No events were observed for this source!!!")
else:
# Step 2: Assign pixel coordinates to events. Apply dithering and
# PSF. Clip events that don't fall within the detection region.
mylog.info("Pixeling events.")
# Convert RA, Dec to pixel coordinates
xpix, ypix = w.wcs_world2pix(events["ra"], events["dec"], 1)
xpix -= event_params["pix_center"][0]
ypix -= event_params["pix_center"][1]
events.pop("ra")
events.pop("dec")
n_evt = xpix.size
# Dither pixel coordinates
x_offset = np.zeros(n_evt)
y_offset = np.zeros(n_evt)
if dither_shape == "circle":
r = dsize * np.sqrt(prng.uniform(size=n_evt))
theta = 2. * np.pi * prng.uniform(size=n_evt)
x_offset = r * np.cos(theta)
y_offset = r * np.sin(theta)
elif dither_shape == "square":
x_offset = dsize * prng.uniform(low=-0.5, high=0.5, size=n_evt)
y_offset = dsize * prng.uniform(low=-0.5, high=0.5, size=n_evt)
xpix -= x_offset
ypix -= y_offset
# Rotate physical coordinates to detector coordinates
det = np.dot(rot_mat, np.array([xpix, ypix]))
detx = det[0, :]
dety = det[1, :]
# PSF scattering of detector coordinates
psf_type, psf_spec = instrument_spec["psf"]
if psf_type == "gaussian":
sigma = psf_spec / sigma_to_fwhm / plate_scale_arcsec
detx += prng.normal(loc=0.0, scale=sigma, size=n_evt)
dety += prng.normal(loc=0.0, scale=sigma, size=n_evt)
else:
raise NotImplementedError("PSF type %s not implemented!" %
psf_type)
# Convert detector coordinates to chip coordinates
events["chipx"] = np.round(detx + event_params['pix_center'][0])
events["chipy"] = np.round(dety + event_params['pix_center'][1])
# Throw out events that don't fall on the chip
keepx = np.logical_and(events["chipx"] >= 1.0,
events["chipx"] <= nx)
keepy = np.logical_and(events["chipy"] >= 1.0,
events["chipy"] <= nx)
keep = np.logical_and(keepx, keepy)
mylog.info("%d events were rejected because " %
(n_evt - keep.sum()) +
"they fall outside the field of view.")
n_evt = keep.sum()
if n_evt == 0:
mylog.warning(
"No events are within the field of view for this source!!!"
)
else:
for key in events:
events[key] = events[key][keep]
# Convert chip coordinates back to detector coordinates
events["detx"] = np.round(
events["chipx"] - event_params['pix_center'][0] +
prng.uniform(low=-0.5, high=0.5, size=n_evt))
events["dety"] = np.round(
events["chipy"] - event_params['pix_center'][1] +
prng.uniform(low=-0.5, high=0.5, size=n_evt))
# Convert detector coordinates back to pixel coordinates
pix = np.dot(rot_mat,
np.array([events["detx"], events["dety"]]))
events["xpix"] = pix[
0, :] + event_params['pix_center'][0] + x_offset[keep]
events["ypix"] = pix[
1, :] + event_params['pix_center'][1] + y_offset[keep]
if n_evt > 0:
for key in events:
if first:
all_events[key] = events[key]
else:
all_events[key] = np.concatenate(
[all_events[key], events[key]])
first = False
if all_events["energy"].size == 0:
mylog.warning(
"No events from any of the sources in the catalog were detected!")
# Step 3: Add astrophysical background
if astro_bkgnd:
mylog.info("Adding in astrophysical background.")
bkg_events = add_background(astro_bkgnd,
event_params,
rot_mat,
prng=prng)
for key in all_events:
all_events[key] = np.concatenate(
[all_events[key], bkg_events[key]])
# Step 4: Add particle background
if instr_bkgnd:
mylog.info("Adding in instrumental background.")
bkg_events = add_background(
instrument_spec["bkgnd"],
event_params,
rot_mat,
prng=prng,
focal_length=instrument_spec["focal_length"])
for key in all_events:
all_events[key] = np.concatenate(
[all_events[key], bkg_events[key]])
if all_events["energy"].size == 0:
raise RuntimeError("No events were detected!!!")
# Step 5: Scatter energies with RMF
if all_events["energy"].size > 0:
mylog.info("Scattering energies with RMF %s." % event_params['rmf'])
all_events = rmf.scatter_energies(all_events, prng=prng)
# Step 6: Add times to events
all_events['time'] = np.random.uniform(size=all_events["energy"].size,
low=0.0,
high=event_params["exposure_time"])
write_event_file(all_events, event_params, out_file, clobber=clobber)
def simulate_spectrum(spec,
instrument,
exp_time,
out_file,
overwrite=False,
prng=None):
"""
Generate a PI or PHA spectrum from a :class:`~soxs.spectra.Spectrum`
by convolving it with responses. To be used if one wants to
create a spectrum without worrying about spatial response. Similar
to XSPEC's "fakeit".
Parameters
----------
spec : :class:`~soxs.spectra.Spectrum`
The spectrum to be convolved.
instrument : string
The name of the instrument to use, which picks an instrument
specification from the instrument registry.
exp_time : float, (value, unit) tuple, or :class:`~astropy.units.Quantity`
The exposure time in seconds.
out_file : string
The file to write the spectrum to.
overwrite : boolean, optional
Whether or not to overwrite an existing file. Default: False
prng : :class:`~numpy.random.RandomState` object, integer, or None
A pseudo-random number generator. Typically will only
be specified if you have a reason to generate the same
set of random numbers, such as for a test. Default is None,
which sets the seed based on the system time.
Examples
--------
>>> spec = soxs.Spectrum.from_file("my_spectrum.txt")
>>> soxs.simulate_spectrum(spec, "mucal", 100000.0,
... "my_spec.pi", overwrite=True)
"""
from soxs.events import write_spectrum
from soxs.instrument import RedistributionMatrixFile, \
AuxiliaryResponseFile
from soxs.spectra import ConvolvedSpectrum
prng = parse_prng(prng)
exp_time = parse_value(exp_time, "s")
try:
instrument_spec = instrument_registry[instrument]
except KeyError:
raise KeyError("Instrument %s is not in the instrument registry!" %
instrument)
arf_file = check_file_location(instrument_spec["arf"], "files")
rmf_file = check_file_location(instrument_spec["rmf"], "files")
arf = AuxiliaryResponseFile(arf_file)
rmf = RedistributionMatrixFile(rmf_file)
cspec = ConvolvedSpectrum(spec, arf)
events = {}
events["energy"] = cspec.generate_energies(exp_time, prng=prng).value
events = rmf.scatter_energies(events, prng=prng)
events["arf"] = arf.filename
events["rmf"] = rmf.filename
events["exposure_time"] = exp_time
events["channel_type"] = rmf.header["CHANTYPE"]
events["telescope"] = rmf.header["TELESCOP"]
events["instrument"] = rmf.header["INSTRUME"]
events["mission"] = rmf.header.get("MISSION", "")
write_spectrum(events, out_file, overwrite=overwrite)
def make_background(exp_time,
instrument,
sky_center,
foreground=True,
ptsrc_bkgnd=True,
instr_bkgnd=True,
no_dither=False,
dither_params=None,
roll_angle=0.0,
subpixel_res=False,
input_sources=None,
absorb_model="wabs",
nH=0.05,
prng=None):
"""
Make background events.
Parameters
----------
exp_time : float, (value, unit) tuple, or :class:`~astropy.units.Quantity`
The exposure time to use, in seconds.
instrument : string
The name of the instrument to use, which picks an instrument
specification from the instrument registry.
sky_center : array, tuple, or list
The center RA, Dec coordinates of the observation, in degrees.
foreground : boolean, optional
Whether or not to include the Galactic foreground. Default: True
instr_bkgnd : boolean, optional
Whether or not to include the instrumental background. Default: True
no_dither : boolean, optional
If True, turn off dithering entirely. Default: False
dither_params : array-like of floats, optional
The parameters to use to control the size and period of the dither
pattern. The first two numbers are the dither amplitude in x and y
detector coordinates in arcseconds, and the second two numbers are
the dither period in x and y detector coordinates in seconds.
Default: [8.0, 8.0, 1000.0, 707.0].
ptsrc_bkgnd : boolean, optional
Whether or not to include the point-source background. Default: True
Default: 0.05
roll_angle : float, (value, unit) tuple, or :class:`~astropy.units.Quantity`, optional
The roll angle of the observation in degrees. Default: 0.0
subpixel_res: boolean, optional
If True, event positions are not randomized within the pixels
within which they are detected. Default: False
input_sources : string, optional
If set to a filename, input the point source positions, fluxes,
and spectral indices from an ASCII table instead of generating
them. Default: None
absorb_model : string, optional
The absorption model to use, "wabs" or "tbabs". Default: "wabs"
nH : float, optional
The hydrogen column in units of 10**22 atoms/cm**2.
Default: 0.05
prng : :class:`~numpy.random.RandomState` object, integer, or None
A pseudo-random number generator. Typically will only
be specified if you have a reason to generate the same
set of random numbers, such as for a test. Default is None,
which sets the seed based on the system time.
"""
from soxs.background import make_instrument_background, \
make_foreground, make_ptsrc_background
prng = parse_prng(prng)
exp_time = parse_value(exp_time, "s")
roll_angle = parse_value(roll_angle, "deg")
try:
instrument_spec = instrument_registry[instrument]
except KeyError:
raise KeyError("Instrument %s is not in the instrument registry!" %
instrument)
fov = instrument_spec["fov"]
input_events = defaultdict(list)
arf_file = check_file_location(instrument_spec["arf"], "files")
arf = AuxiliaryResponseFile(arf_file)
rmf_file = check_file_location(instrument_spec["rmf"], "files")
rmf = RedistributionMatrixFile(rmf_file)
if ptsrc_bkgnd:
mylog.info("Adding in point-source background.")
ptsrc_events = make_ptsrc_background(exp_time,
fov,
sky_center,
input_sources=input_sources,
absorb_model=absorb_model,
nH=nH,
prng=prng)
for key in ["ra", "dec", "energy"]:
input_events[key].append(ptsrc_events[key])
input_events["flux"].append(ptsrc_events["flux"])
input_events["emin"].append(ptsrc_events["energy"].min())
input_events["emax"].append(ptsrc_events["energy"].max())
input_events["sources"].append("ptsrc_bkgnd")
events, event_params = generate_events(input_events,
exp_time,
instrument,
sky_center,
no_dither=no_dither,
dither_params=dither_params,
roll_angle=roll_angle,
subpixel_res=subpixel_res,
prng=prng)
mylog.info("Generated %d photons from the point-source background." %
len(events["energy"]))
else:
nx = instrument_spec["num_pixels"]
events = defaultdict(list)
if not instrument_spec["dither"]:
dither_on = False
else:
dither_on = not no_dither
if dither_params is None:
dither_params = [8.0, 8.0, 1000.0, 707.0]
dither_dict = {
"x_amp": dither_params[0],
"y_amp": dither_params[1],
"x_period": dither_params[2],
"y_period": dither_params[3],
"dither_on": dither_on,
"plate_scale": instrument_spec["fov"] / nx * 60.0
}
event_params = {
"exposure_time": exp_time,
"fov": instrument_spec["fov"],
"num_pixels": nx,
"pix_center": np.array([0.5 * (2 * nx + 1)] * 2),
"channel_type": rmf.header["CHANTYPE"],
"sky_center": sky_center,
"dither_params": dither_dict,
"plate_scale": instrument_spec["fov"] / nx / 60.0,
"chan_lim": [rmf.cmin, rmf.cmax],
"rmf": rmf_file,
"arf": arf_file,
"telescope": rmf.header["TELESCOP"],
"instrument": instrument_spec['name'],
"mission": rmf.header.get("MISSION", ""),
"nchan": rmf.ebounds_header["DETCHANS"],
"roll_angle": roll_angle,
"aimpt_coords": instrument_spec["aimpt_coords"]
}
if "chips" not in event_params:
event_params["chips"] = instrument_spec["chips"]
if foreground:
mylog.info("Adding in astrophysical foreground.")
bkg_events = make_foreground(event_params, arf, rmf, prng=prng)
for key in bkg_events:
events[key] = np.concatenate([events[key], bkg_events[key]])
if instr_bkgnd and instrument_spec["bkgnd"] is not None:
mylog.info("Adding in instrumental background.")
bkg_events = make_instrument_background(
instrument_spec["bkgnd"],
event_params,
instrument_spec["focal_length"],
rmf,
prng=prng)
for key in bkg_events:
events[key] = np.concatenate([events[key], bkg_events[key]])
return events, event_params
def generate_events(input_events,
exp_time,
instrument,
sky_center,
no_dither=False,
dither_params=None,
roll_angle=0.0,
subpixel_res=False,
prng=None):
"""
Take unconvolved events and convolve them with instrumental responses. This
function does the following:
1. Determines which events are observed using the ARF
2. Pixelizes the events, applying PSF effects and dithering
3. Determines energy channels using the RMF
This function is not meant to be called by the end-user but is used by
the :func:`~soxs.instrument.instrument_simulator` function.
Parameters
----------
input_events : string, dict, or None
The unconvolved events to be used as input. Can be one of the
following:
1. The name of a SIMPUT catalog file.
2. A Python dictionary containing the following items:
"ra": A NumPy array of right ascension values in degrees.
"dec": A NumPy array of declination values in degrees.
"energy": A NumPy array of energy values in keV.
"flux": The flux of the entire source, in units of erg/cm**2/s.
out_file : string
The name of the event file to be written.
exp_time : float, (value, unit) tuple, or :class:`~astropy.units.Quantity`
The exposure time to use, in seconds.
instrument : string
The name of the instrument to use, which picks an instrument
specification from the instrument registry.
sky_center : array, tuple, or list
The center RA, Dec coordinates of the observation, in degrees.
no_dither : boolean, optional
If True, turn off dithering entirely. Default: False
dither_params : array-like of floats, optional
The parameters to use to control the size and period of the dither
pattern. The first two numbers are the dither amplitude in x and y
detector coordinates in arcseconds, and the second two numbers are
the dither period in x and y detector coordinates in seconds.
Default: [8.0, 8.0, 1000.0, 707.0].
roll_angle : float, (value, unit) tuple, or :class:`~astropy.units.Quantity`, optional
The roll angle of the observation in degrees. Default: 0.0
subpixel_res: boolean, optional
If True, event positions are not randomized within the pixels
within which they are detected. Default: False
prng : :class:`~numpy.random.RandomState` object, integer, or None
A pseudo-random number generator. Typically will only
be specified if you have a reason to generate the same
set of random numbers, such as for a test. Default is None,
which sets the seed based on the system time.
"""
import pyregion._region_filter as rfilter
exp_time = parse_value(exp_time, "s")
roll_angle = parse_value(roll_angle, "deg")
prng = parse_prng(prng)
if isinstance(input_events, dict):
parameters = {}
for key in ["flux", "emin", "emax", "sources"]:
parameters[key] = input_events[key]
event_list = []
for i in range(len(parameters["flux"])):
edict = {}
for key in ["ra", "dec", "energy"]:
edict[key] = input_events[key][i]
event_list.append(edict)
elif isinstance(input_events, string_types):
# Assume this is a SIMPUT catalog
event_list, parameters = read_simput_catalog(input_events)
try:
instrument_spec = instrument_registry[instrument]
except KeyError:
raise KeyError("Instrument %s is not in the instrument registry!" %
instrument)
arf_file = check_file_location(instrument_spec["arf"], "files")
rmf_file = check_file_location(instrument_spec["rmf"], "files")
arf = AuxiliaryResponseFile(arf_file)
rmf = RedistributionMatrixFile(rmf_file)
nx = instrument_spec["num_pixels"]
plate_scale = instrument_spec["fov"] / nx / 60. # arcmin to deg
plate_scale_arcsec = plate_scale * 3600.0
if not instrument_spec["dither"]:
dither_on = False
else:
dither_on = not no_dither
if dither_params is None:
dither_params = [8.0, 8.0, 1000.0, 707.0]
dither_dict = {
"x_amp": dither_params[0],
"y_amp": dither_params[1],
"x_period": dither_params[2],
"y_period": dither_params[3],
"dither_on": dither_on,
"plate_scale": plate_scale_arcsec
}
event_params = {}
event_params["exposure_time"] = exp_time
event_params["arf"] = arf.filename
event_params["sky_center"] = sky_center
event_params["pix_center"] = np.array([0.5 * (2 * nx + 1)] * 2)
event_params["num_pixels"] = nx
event_params["plate_scale"] = plate_scale
event_params["rmf"] = rmf.filename
event_params["channel_type"] = rmf.header["CHANTYPE"]
event_params["telescope"] = rmf.header["TELESCOP"]
event_params["instrument"] = instrument_spec['name']
event_params["mission"] = rmf.header.get("MISSION", "")
event_params["nchan"] = rmf.ebounds_header["DETCHANS"]
event_params["roll_angle"] = roll_angle
event_params["fov"] = instrument_spec["fov"]
event_params["chan_lim"] = [rmf.cmin, rmf.cmax]
event_params["chips"] = instrument_spec["chips"]
event_params["dither_params"] = dither_dict
event_params["aimpt_coords"] = instrument_spec["aimpt_coords"]
w = pywcs.WCS(naxis=2)
w.wcs.crval = event_params["sky_center"]
w.wcs.crpix = event_params["pix_center"]
w.wcs.cdelt = [-plate_scale, plate_scale]
w.wcs.ctype = ["RA---TAN", "DEC--TAN"]
w.wcs.cunit = ["deg"] * 2
rot_mat = get_rot_mat(roll_angle)
all_events = defaultdict(list)
for i, evts in enumerate(event_list):
mylog.info("Detecting events from source %s." %
parameters["sources"][i])
# Step 1: Use ARF to determine which photons are observed
mylog.info("Applying energy-dependent effective area from %s." %
os.path.split(arf.filename)[-1])
refband = [parameters["emin"][i], parameters["emax"][i]]
events = arf.detect_events(evts,
exp_time,
parameters["flux"][i],
refband,
prng=prng)
n_evt = events["energy"].size
if n_evt == 0:
mylog.warning("No events were observed for this source!!!")
else:
# Step 2: Assign pixel coordinates to events. Apply dithering and
# PSF. Clip events that don't fall within the detection region.
mylog.info("Pixeling events.")
# Convert RA, Dec to pixel coordinates
xpix, ypix = w.wcs_world2pix(events["ra"], events["dec"], 1)
xpix -= event_params["pix_center"][0]
ypix -= event_params["pix_center"][1]
events.pop("ra")
events.pop("dec")
n_evt = xpix.size
# Rotate physical coordinates to detector coordinates
det = np.dot(rot_mat, np.array([xpix, ypix]))
detx = det[0, :] + event_params["aimpt_coords"][0]
dety = det[1, :] + event_params["aimpt_coords"][1]
# Add times to events
events['time'] = prng.uniform(size=n_evt,
low=0.0,
high=event_params["exposure_time"])
# Apply dithering
x_offset, y_offset = perform_dither(events["time"], dither_dict)
detx -= x_offset
dety -= y_offset
# PSF scattering of detector coordinates
if instrument_spec["psf"] is not None:
psf_type, psf_spec = instrument_spec["psf"]
if psf_type == "gaussian":
sigma = psf_spec / sigma_to_fwhm / plate_scale_arcsec
detx += prng.normal(loc=0.0, scale=sigma, size=n_evt)
dety += prng.normal(loc=0.0, scale=sigma, size=n_evt)
else:
raise NotImplementedError("PSF type %s not implemented!" %
psf_type)
# Convert detector coordinates to chip coordinates.
# Throw out events that don't fall on any chip.
cx = np.trunc(detx) + 0.5 * np.sign(detx)
cy = np.trunc(dety) + 0.5 * np.sign(dety)
if event_params["chips"] is None:
events["chip_id"] = np.zeros(n_evt, dtype='int')
keepx = np.logical_and(cx >= -0.5 * nx, cx <= 0.5 * nx)
keepy = np.logical_and(cy >= -0.5 * nx, cy <= 0.5 * nx)
keep = np.logical_and(keepx, keepy)
else:
events["chip_id"] = -np.ones(n_evt, dtype='int')
for i, chip in enumerate(event_params["chips"]):
thisc = np.ones(n_evt, dtype='bool')
rtype = chip[0]
args = chip[1:]
r = getattr(rfilter, rtype)(*args)
inside = r.inside(cx, cy)
thisc = np.logical_and(thisc, inside)
events["chip_id"][thisc] = i
keep = events["chip_id"] > -1
mylog.info("%d events were rejected because " %
(n_evt - keep.sum()) + "they do not fall on any CCD.")
n_evt = keep.sum()
if n_evt == 0:
mylog.warning(
"No events are within the field of view for this source!!!"
)
else:
# Keep only those events which fall on a chip
for key in events:
events[key] = events[key][keep]
# Convert chip coordinates back to detector coordinates, unless the
# user has specified that they want subpixel resolution
if subpixel_res:
events["detx"] = detx[keep]
events["dety"] = dety[keep]
else:
events["detx"] = cx[keep] + prng.uniform(
low=-0.5, high=0.5, size=n_evt)
events["dety"] = cy[keep] + prng.uniform(
low=-0.5, high=0.5, size=n_evt)
# Convert detector coordinates back to pixel coordinates by
# adding the dither offsets back in and applying the rotation
# matrix again
det = np.array([
events["detx"] + x_offset[keep] -
event_params["aimpt_coords"][0], events["dety"] +
y_offset[keep] - event_params["aimpt_coords"][1]
])
pix = np.dot(rot_mat.T, det)
events["xpix"] = pix[0, :] + event_params['pix_center'][0]
events["ypix"] = pix[1, :] + event_params['pix_center'][1]
if n_evt > 0:
for key in events:
all_events[key] = np.concatenate(
[all_events[key], events[key]])
if len(all_events["energy"]) == 0:
mylog.warning(
"No events from any of the sources in the catalog were detected!")
for key in [
"xpix", "ypix", "detx", "dety", "time", "chip_id",
event_params["channel_type"]
]:
all_events[key] = np.array([])
else:
# Step 4: Scatter energies with RMF
mylog.info("Scattering energies with RMF %s." %
os.path.split(rmf.filename)[-1])
all_events = rmf.scatter_energies(all_events, prng=prng)
return all_events, event_params