Coronagraph (esc_etc.coronagraph)

Coronagraph-specific physics for the ESC ETC.

Owns raw dark-hole contrast, post-processing gain, planet separation, and the off-axis (FPM) lambda/D throughput curve. The FPM throughput is a flat scalar applied by Simulation to every count rate (plan physics-fact #1).

Definitions (issue #10):

  • off_axis_throughput k: fraction of an off-axis point source’s photons transmitted by the FPM at that separation, relative to the same source with no coronagraph. Simulation multiplies point sources by k and, separately, by the aperture’s encircled energy Sensor.ee_fraction. The FPM FITS table does not record whether it is core, peak, or total throughput (issue #30).

  • raw_dh_contrast C: residual stellar intensity in the dark hole divided by the off-axis PSF at the same separation, so stellar leakage in the aperture is R_host * C * k * EE.

  • ppgain: an ASSUMED/calibrated residual-speckle suppression factor. The systematic floor is R_speckle / ppgain. It is not a prediction of what a post-processing algorithm will achieve, and it carries no random-noise cost; that cost is modeled by the subtraction strategy below (issue #12).

  • subtraction: "none" (one science image, the default) or "rdi" (reference-differential imaging). For RDI a reference star ref_brightness_ratio times brighter than the host is observed for ref_time_ratio times the science time, scaled to the target, and subtracted; its scaled random variance is added to the science variance (Nemati et al. 2023, JATIS 9, 034007). Roll/ADI self-subtraction is not modeled. total_time is always on-target science time; the noise model reports the charged time total_time * (1 + ref_time_ratio) for RDI.

class esc_etc.coronagraph.Coronagraph(raw_dh_contrast, ppgain, separation, primary_filter, diameter_primary, lamD, throughput, subtraction='none', ref_brightness_ratio=1.0, ref_time_ratio=1.0)[source]

Bases: _MetaHolder_

Raw dark-hole contrast, post-processing gain, planet separation, the FPM off-axis throughput curve, and the reference-subtraction strategy.

classmethod from_config(instrument_config, instrument_support_path, telescope, raw_dh_contrast=1e-08, ppgain=10, separation=0.2, arm='arm_a')[source]
classmethod from_default(telescope, raw_dh_contrast=1e-08, ppgain=10, separation=0.2, arm='arm_a')[source]
off_axis_throughput(separation=None)[source]
plot_offaxis_throughput(**kw)[source]

See esc_etc.plotting.plot_offaxis_throughput().

speckle_scale()[source]

Stellar-leakage rate in the extraction aperture per unit host rate.

noise_floor_factor()[source]