jayrock 0.0.2

JWST observations planning for asteroids.

Features - Install - Documentation

JWST observation planning and simulation for minor bodies across the Solar System. You define the target and instrument(s) – jayrock does the rest.

>>> import jayrock

Features

Computation of target ephemeris

Define a solar system target by name and then compute and display its JWST-observable ephemeris for a specified cycle, including visibility windows, magnitude changes, and thermal flux estimates.

>>> achilles = jayrock.Target("achilles") # define target by name or designation
>>> achilles.compute_ephemeris(cycle=6)   # compute ephemeris for JWST Cycle 6
>>> achilles.print_ephemeris()
(588) Achilles: Ephemeris from 2027-07-01 to 2028-06-30
├── Window 1: 2027-07-02 -> 2027-08-10
│   ├── Duration         40 days
│   ├── Vmag             16.18 -> 16.48
│   └── Thermal @ 15um   393.39 -> 308.31 mJy
├── Window 2: 2028-03-02 -> 2028-04-21
│   ├── Duration         51 days
│   ├── Vmag             16.54 -> 16.15
│   └── Thermal @ 15um   279.80 -> 360.74 mJy
└── errRA/errDec in arcsec: 0.027 / 0.005

Modelling of reflectance spectrum and thermal emission

Identify the dates of maximum and minimum thermal emission within the visibility window and then plot the target's modelled reflectance and thermal spectrum for a direct comparison between the two observation dates.

>>> # compare spectra at dates of max/min thermal emission
>>> date_thermal_max = achilles.get_date_obs(at="thermal_max")
>>> date_thermal_min = achilles.get_date_obs(at="thermal_min")
>>> achilles.plot_spectrum(date_obs=[date_thermal_max, date_thermal_min])

Compute instrument configuration to reach SNR target

Configure a JWST instrument and calculate the required exposure time parameters (groups and integrations) to achieve a specified Signal-to-Noise Ratio (SNR) at a particular wavelength.

>>> miri_lrs = jayrock.Instrument('MIRI', mode='LRSSLIT')
>>> miri_lrs.detector.nexp = 2  # 2-pt dither
>>> miri_lrs.detector.readout_pattern = 'fastr1'  # recommended for LRS
>>> # Compute exposure times for SNR target of 300 at 10 micron
>>> miri_lrs.set_snr_target(300, target, date_thermal_min, wave=10)
>>> # -> jayrock defines ngroup and nint for you

Visualise SNR across detector configurations and possible saturation issues

Simulate multiple observations using manually set exposure parameters across different detector configurations (apertures/filters/dispersers). Plot the resulting simulated SNR over the full wavelength range for all defined observations.

# Simulate observation of Achilles on date of minimum Vmag
date_obs = achilles.get_date_obs(at="vmag_min")

observations = []  # list to store observations

inst = jayrock.Instrument("NIRSpec", mode="IFU")

for disp, filt in [("G235M", "F170LP"), ("G395M", "F290LP")]:

    # Set filter and disperser
    inst.disperser = disp
    inst.filter = filt

    # Set ngroup, nint, nexp directly
    inst.detector.ngroup = 10  # number of groups per integration
    inst.detector.nint = 1     # number of integrations per exposure
    inst.detector.nexp = 4     # number of exposures -> number of dithers

    obs = jayrock.observe(achilles, inst, date_obs=date_obs)
    observations.append(obs)

# Plot SNR over wavelength
jayrock.plot_snr(observations)

Install

Install from PyPi using pip:

 $ pip install jayrock

The minimum required python version is 3.11. jayrock relies on pandeia, the python engine behind the JWST ETC. Detailed install instructions for this dependency can be found here.

Documentation

Check out the documentation at jayrock.readthedocs.io.