deshima_sensitivity.simulator module#

Calculate the sensitivity of a spectrometer.

Parameters which are functions of frequency can be a vector (see Parameters). Output is a pandas DataFrame which containts results of simulation (see Returns).

Parameters:

F (ndarray | List[float] | List[int] | float | int) – Frequency of the astronomical signal. Units: Hz.
pwv (float) – Precipitable water vapour. Units: mm.
EL (float) – Telescope elevation angle. Units: degrees.
R (ndarray | List[float] | List[int] | float | int) – Spectral resolving power in F/W_F where W_F is equivalent bandwidth. Units: None. See also: http://www.astrosurf.com/buil/us/spe2/hresol7.htm
eta_M1_spill (ndarray | List[float] | List[int] | float | int) – Spillover efficiency at the telescope primary mirror. Units: None.
eta_M2_spill (ndarray | List[float] | List[int] | float | int) – Spillover efficiency at the telescope secondary mirror. Units: None.
eta_wo_spill (ndarray | List[float] | List[int] | float | int) – Product of all spillover losses in the warm optics in the cabin. Units: None.
n_wo_mirrors (int) – Number of cabin optics excluding telescope M1 and M2. Units: None.
window_AR (bool) – Whether the window is supposed to be coated by Ar (True) or not (False).
eta_co (ndarray | List[float] | List[int] | float | int) – Product of following. Units: None. (1) Cold spillover. (2) Cold ohmic losses. (3) Filter transmission loss.
eta_lens_antenna_rad (ndarray | List[float] | List[int] | float | int) – The loss at chip temperature, that is not in the circuit. Product of the following. Units: None. (1) Front-to-back ratio of the lens-antenna on the chip (defalut: 0.93). (2) Reflection efficiency at the surface of the lens (default: 0.9). (3) Matching efficiency, due to the mismatch (default: 0.98). (4) Spillover efficiency of the lens-antenna (default: 0.993). These values can be found in D2_2V3.pdf, p14.
eta_circuit (ndarray | List[float] | List[int] | float | int) – The loss at chip temperature, in the circuit.. Units: None.
eta_IBF (ndarray | List[float] | List[int] | float | int) – Fraction of the filter power transmission that is within the filter channel bandwidth. Units: None. The rest of the power is cross talk, picking up power that is in the bands of neighboring channels. This efficiency applies to the coupling to astronomical line signals. This efficiency does not apply to the coupling to continuum, including the the coupling to the atmosphere for calculating the NEP.
KID_excess_noise_factor (float) – Need to be documented. Units: None.
theta_maj (ndarray | List[float] | List[int] | float | int) – The HPBW along the major axis, assuming a Gaussian beam. Units: radians.
theta_min (ndarray | List[float] | List[int] | float | int) – The HPBW along the minor axis, assuming a Gaussian beam. Units: radians.
eta_mb (ndarray | List[float] | List[int] | float | int) – Main beam efficiency. Units: None. Note that eta_mb includes the following terms from D2_2V3.pdf from Shahab’s report. because a decrease in these will launch the beam to the sky but not couple it to the point source (See also FAQ.). (1) eta_Phi. (2) eta_amp.
telescope_diameter (float) – Diameter of the telescope. Units: m.
Tb_cmb (ndarray | List[float] | List[int] | float | int) – Brightness temperature of the CMB. Units: K.
Tp_amb (ndarray | List[float] | List[int] | float | int) – Physical temperature of the atmosphere and ambient environment around the telescope. Units: K.
Tp_cabin (ndarray | List[float] | List[int] | float | int) – Physical temperature of the telescope cabin. Units: K.
Tp_co (ndarray | List[float] | List[int] | float | int) – Physical temperature of the cold optics inside the cryostat. Units: K.
Tp_chip (ndarray | List[float] | List[int] | float | int) – Physical temperature of the chip. Units: K.
snr (float) – Target signal to noise to be reached (for calculating the MDLF). Units: None.
obs_hours (float) – Observing hours, including off-source time and the slew overhead between on- and off-source. Units: hours.
on_source_fraction (float) – Fraction of the time on source (between 0. and 1.). Units: None.
on_off (bool) – If the observation involves on_off chopping, then the SNR degrades by sqrt(2) because the signal difference includes the noise twice.

Returns:

F – Same as input.
pwv – Same as input.
EL – Same as input
eta_atm – Atmospheric transmission. Units: None.
R – Same as input.
W_F_spec – Equivalent bandwidth within the bandwidth of F/R. Units: Hz.
W_F_cont – Equivalent bandwidth of 1 channel including the power coupled outside of the filter channel band. Units: Hz.
theta_maj – Same as input.
theta_min – Same as input.
eta_a – Aperture efficiency. Units: None. See also: https://deshima.kibe.la/notes/324
eta_mb – Main beam efficiency. Units: None.
eta_forward – Forward efficiency. Units: None. See also: https://deshima.kibe.la/notes/324
eta_sw – Coupling efficiency from a point source to the cryostat window. Units: None.
eta_window – Transmission of the cryostat window. Units: None.
eta_inst – Instrument optical efficiency. Units: None. See also: https://arxiv.org/abs/1901.06934
eta_circuit – Same as input.
Tb_sky – Planck brightness temperature of the sky. Units: K.
Tb_M1 – Planck brightness temperature looking into the telescope primary. Units: K.
Tb_M2 – Planck brightness temperature looking into the telescope secondary, including the spillover to the cold sky. Units: K.
Tb_wo – Planck brightness temperature looking into the warm optics. Units: K.
Tb_window – Planck brightness temperature looking into the window. Units: K.
Tb_co – Planck brightness temperature looking into the cold optis. Units: K.
Tb_KID – Planck brightness temperature looking into the filter from the KID. Units: K.
Pkid – Power absorbed by the KID. Units: W.
n_ph – Photon occupation number. Units: None. See also: http://adsabs.harvard.edu/abs/1999ASPC..180..671R
NEPkid – Noise equivalent power at the KID with respect to the absorbed power. Units: W Hz^0.5.
NEPinst – Instrumnet NEP. Units: W Hz^0.5. See also: https://arxiv.org/abs/1901.06934
NEFD_line – Noise Equivalent Flux Density for couploing to a line that is not wider than the filter bandwidth. Units: W/m^2/Hz * s^0.5.
NEFD_continuum – Noise Equivalent Flux Density for couploing to a countinuum source. Units: W/m^2/Hz * s^0.5.
NEF – Noise Equivalent Flux. Units: W/m^2 * s^0.5.
MDLF – Minimum Detectable Line Flux. Units: W/m^2.
MS – Mapping Speed. Units: arcmin^2 mJy^-2 h^-1.
snr – Same as input.
obs_hours – Same as input.
on_source_fraction – Same as input.
on_source_hours – Observing hours on source. Units: hours.
equivalent_Trx – Equivalent receiver noise temperature. Units: K. at the moment this assumes Rayleigh-Jeans!

Notes

The parameters to calculate the window transmission / reflection is hard-coded in the function window_trans().