def backprojection(calibrated_event_list, pixel_size=(1.0, 1.0), image_dim=(64, 64)):
"""Given a stacked calibrated event list fits file create a back projection image."""
import sunpy.sun.constants as sun
from sunpy.sun.sun import angular_size
from sunpy.sun.sun import sunearth_distance
from sunpy.time.util import TimeRange
calibrated_event_list = sunpy.RHESSI_EVENT_LIST
fits = pyfits.open(calibrated_event_list)
info_parameters = fits[2]
xyoffset = info_parameters.data.field("USED_XYOFFSET")[0]
time_range = TimeRange(info_parameters.data.field("ABSOLUTE_TIME_RANGE")[0])
image = np.zeros(image_dim)
# find out what detectors were used
det_index_mask = fits[1].data.field("det_index_mask")[0]
detector_list = (np.arange(9) + 1) * np.array(det_index_mask)
for detector in detector_list:
if detector > 0:
image = image + _backproject(
calibrated_event_list, detector=detector, pixel_size=pixel_size, image_dim=image_dim
)
dict_header = {
"DATE-OBS": time_range.center().strftime("%Y-%m-%d %H:%M:%S"),
"CDELT1": pixel_size[0],
"NAXIS1": image_dim[0],
"CRVAL1": xyoffset[0],
"CRPIX1": image_dim[0] / 2 + 0.5,
"CUNIT1": "arcsec",
"CTYPE1": "HPLN-TAN",
"CDELT2": pixel_size[1],
"NAXIS2": image_dim[1],
"CRVAL2": xyoffset[1],
"CRPIX2": image_dim[0] / 2 + 0.5,
"CUNIT2": "arcsec",
"CTYPE2": "HPLT-TAN",
"HGLT_OBS": 0,
"HGLN_OBS": 0,
"RSUN_OBS": angular_size(time_range.center()),
"RSUN_REF": sun.radius,
"DSUN_OBS": sunearth_distance(time_range.center()) * sunpy.sun.constants.au,
}
header = sunpy.map.MapHeader(dict_header)
result_map = sunpy.map.BaseMap(image, header)
return result_map
def backprojection(calibrated_event_list, pixel_size=(1.,1.), image_dim=(64,64)):
"""Given a stacked calibrated event list fits file create a back
projection image.
.. warning:: The image is not in the right orientation!
Parameters
----------
calibrated_event_list : string
filename of a RHESSI calibrated event list
detector : int
the detector number
pixel_size : 2-tuple
the size of the pixels in arcseconds. Default is (1,1).
image_dim : 2-tuple
the size of the output image in number of pixels
Returns
-------
map : RHESSImap
Return a backprojection map.
See Also
--------
Examples
--------
>>> import sunpy.instr.rhessi as rhessi
>>> map = rhessi.backprojection(sunpy.RHESSI_EVENT_LIST)
>>> map.show()
Reference
---------
|
"""
import sunpy.sun.constants as sun
from sunpy.sun.sun import angular_size
from sunpy.sun.sun import sunearth_distance
from sunpy.time.util import TimeRange
calibrated_event_list = sunpy.RHESSI_EVENT_LIST
fits = pyfits.open(calibrated_event_list)
info_parameters = fits[2]
xyoffset = info_parameters.data.field('USED_XYOFFSET')[0]
time_range = TimeRange(info_parameters.data.field('ABSOLUTE_TIME_RANGE')[0])
image = np.zeros(image_dim)
#find out what detectors were used
det_index_mask = fits[1].data.field('det_index_mask')[0]
detector_list = (np.arange(9)+1) * np.array(det_index_mask)
for detector in detector_list:
if detector > 0:
image = image + _backproject(calibrated_event_list, detector=detector, pixel_size=pixel_size, image_dim=image_dim)
dict_header = {
"DATE-OBS": time_range.center().strftime("%Y-%m-%d %H:%M:%S"),
"CDELT1": pixel_size[0],
"NAXIS1": image_dim[0],
"CRVAL1": xyoffset[0],
"CRPIX1": image_dim[0]/2 + 0.5,
"CUNIT1": "arcsec",
"CTYPE1": "HPLN-TAN",
"CDELT2": pixel_size[1],
"NAXIS2": image_dim[1],
"CRVAL2": xyoffset[1],
"CRPIX2": image_dim[0]/2 + 0.5,
"CUNIT2": "arcsec",
"CTYPE2": "HPLT-TAN",
"HGLT_OBS": 0,
"HGLN_OBS": 0,
"RSUN_OBS": angular_size(time_range.center()),
"RSUN_REF": sun.radius,
"DSUN_OBS": sunearth_distance(time_range.center()) * sunpy.sun.constants.au
}
header = sunpy.map.MapHeader(dict_header)
result_map = sunpy.map.BaseMap(image, header)
return result_map
