Open utilities for planning JWST NIRSpec multi-object spectroscopy (MSA) observations.
This package collects methods for steps most MSA programs need: shutter geometry, source throughput as a function of position within a shutter, spectral trace and detector-gap prediction, dither and sub-shutter stepping, and lensed survey-area estimation. Many groups re-implement these privately. The goal here is one tested, documented, permissively licensed place to share them.
Early-stage (v0.0.1). This repository is the start of open-sourcing planning tooling developed for the VENUS JWST program. The first public module covers shutter geometry and source throughput; other modules are planned (see ROADMAP.md). Default instrument dimensions are approximate, widely-quoted public values and should be verified against current NIRSpec documentation before use in real observation planning.
git clone https://github.com/sfseiji/msa-planning-toolkit
cd msa-planning-toolkit
pip install -e .Requires Python 3.9 or newer. The first module uses only the standard library.
from msa_planning_toolkit import Shutter, gaussian_throughput
s = Shutter() # approximate public NIRSpec MSA shutter, dimensions in arcsec
# Fraction of a compact (FWHM = 0.1") source passing through the open shutter
# when its centroid sits 0.09" off-center along the dispersion axis:
print(gaussian_throughput(0.09, 0.0, fwhm=0.1, shutter=s))See examples/throughput_vs_offset.py for throughput across a dither.
This repository contains only generic, public methodology and approximate public instrument values. It does not include proprietary data, calibration products, or unpublished results.
Issues and pull requests are welcome. The aim is a small, well-tested toolkit, so new modules should come with tests and a short example.
MIT. See LICENSE.
Seiji Fujimoto, Department of Astronomy and Astrophysics, University of Toronto.