pynrc.obs_hci

NIRCam coronagraphic observations

Subclass of the nrc_hci instrument class used to observe stars (plus exoplanets and disks) with either a coronagraph or direct imaging.

The main concept is to generate a science target of the primary source along with a simulated disk structure. Planets are further added to the astronomical scene. A separate reference source is also defined for PSF subtraction, which contains a specified WFE. A variety of methods exist to generate slope images and analyze the PSF-subtracted results via images and contrast curves.

Parameters

• sp_sci (pysynphot.spectrum) – A pysynphot spectrum of science target (e.g., central star). Should already be normalized to the apparent flux.

• sp_ref (pysynphot.spectrum or None) – A pysynphot spectrum of reference target. Should already be normalized to the apparent flux.

• distance (float) – Distance in parsecs to the science target. This is used for flux normalization of the planets and disk.

• wfe_ref_drift (float) – WFE drift in nm RMS between the science and reference targets. Expected values are between ~3-10 nm.

• wfe_roll_drift (float) – WFE drift in nm RMS between science roll angles. Default=0.

• wind_mode (str) – ‘FULL’, ‘STRIPE’, or ‘WINDOW’

• xpix (int) – Size of the detector readout along the x-axis. The detector is assumed to be in window mode unless the user explicitly sets wind_mode=’FULL’.

• ypix (int) – Size of the detector readout along the y-axis. The detector is assumed to be in window mode unless the user explicitly sets wind_mode=’FULL’.

• disk_params (dict) –

  Arguments describing disk model information for a given FITS file:

  • ‘file’ : Path to model file or an HDUList.

  • ‘pixscale’ : Pixel scale for model image (arcsec/pixel).

  • ‘dist’ : Assumed model distance in parsecs.

  • ‘wavelength’ : Wavelength of observation in microns.

  • ‘units’ : String of assumed flux units (ie., MJy/arcsec^2 or muJy/pixel)

  • ‘cen_star’ : True/False. Is a star already placed in the central pixel?

• autogen_coeffs (bool) – Automatically generate base PSF coefficients. Equivalent to performing self.gen_psf_coeff(). gen_wfedrift_coeff, and gen_wfemask_coeff. Default: True.

• use_ap_info (bool) – For subarray observations, the mask reference points are not actually in the center of the array. Set this to True to shift the sources to actual aperture reference location. Otherwise, default will place in center of array.

• sgd_type (str or None) – Small grid dither pattern. Valid types are ‘9circle’, ‘5box’, ‘5diamond’, ‘3bar’, or ‘5bar’. If ‘auto’, then defaults are ‘5diamond’ for round masks, ‘5bar’ for bar masks, and ‘5diamond’ for direct imaging. If None, then no FSM pointings, but there will be a single slew.

• fsm_std (float) – One-sigma accuracy per axis of fine steering mirror positions. This provides randomness to each position relative to the nominal central position. Ignored for central position. Values should be in units of mas.

• slew_std (float) – One-sigma accuracy per axis of the initial slew. This is applied to all positions and gives a baseline offset relative to the desired mask center. *Values should be in units of mas*

Module Attributes

LONG_WAVELENGTH_MAX
LONG_WAVELENGTH_MIN
ND_acq	Use Coronagraphic ND acquisition square?
SHORT_WAVELENGTH_MAX
SHORT_WAVELENGTH_MIN
aperturename	SIAF aperture name for detector pixel to sky coords transformations
bandpass	Return bandpass throughput
bar_offset	Offset position along bar mask (arcsec).
channel
coron_substrate	Include coronagraphic substrate material?
det_info	Dictionary housing detector info parameters and keywords.
detector	Detector selected for simulated PSF
detector_list	Detectors on which the simulated PSF could lie
detector_position	The pixel position in (X, Y) on the detector, relative to the currently-selected SIAF aperture subarray.
disk_params
fastaxis	Fast readout direction in sci coords
filter	Currently selected filter name (e.g.
filter_list	List of available filter names for this instrument
fov_pix
image_mask	Currently selected image plane mask, or None for direct imaging
is_coron	Observation with coronagraphic mask (incl Lyot stop)?
is_dark
is_grism
is_lyot	Is a Lyot mask in the pupil wheel?
module
multiaccum	multiaccum object
multiaccum_times	Exposure timings in dictionary
name
ndeg
npsf	Number of wavelengths/PSFs to fit
options	A dictionary capable of storing other arbitrary options, for extensibility.
oversample
pixelscale	Detector pixel scale, in arcsec/pixel
planets	Planet info (if any exists)
psf_info	PSF parameters
pupil	Filename or fits.HDUList for JWST pupil mask.
pupil_mask	Currently selected Lyot pupil mask, or None for direct imaging
pupilopd	Filename or fits.HDUList for JWST pupil OPD.
quick	Perform quicker coeff calculation over limited bandwidth?
save_dir	Coefficient save directory
save_name	Coefficient file name
scaid	SCA ID (481, 482, .
siaf_ap	SIAF Aperture object
siaf_ap_names	Give all possible SIAF aperture names
slowaxis	Slow readout direction in sci coords
telescope
wave_fit	Wavelength range to fit
well_level	Detector well level in units of electrons
wfe_ref_drift	WFE drift (nm) of ref obs relative to sci obs
wfe_roll_drift	WFE drift (nm) of Roll2 obs relative to Roll1 obs