Updated Configuration files for JWST NIRISS Slitless Spectroscopy
Description
We share the following new configuration files for JWST NIRISS Slitless Spectroscopy:
- F115W + GR150C
- F115W + GR150R
- F150W + GR150C
- F150W + GR150R
- F200W + GR150C
- F200W + GR150R
We use JWST comissioning data from program 1085, the NIRISS-FOCUS-FIELD, which are observations of the outer LMC. We optimise Grizli model fits to the grism spectra of stars in individual exposures with MAG_AUTO < 21.5 and 1 < FLUX_RADIUS < 2 that have the positions x_flt and y_flt in the associated direct image (in the rotated Grizli dispersed frame). In each case, we get best fits to DYDX_A_0 (trace centre in y) and DLDP_A_0 (wavelength zeropoint in x). These parameters are measured in the Grizli convention where all spectra have been rotated to have the dispersion roughly parallel to array rows and with wavelength increasing "toward the right". Only those fits with a chi-squared < 50000 are used.
The field dependence of these parameters across the detector are fit with a low-order 2D Polynomial model with astropy.modeling.models.Polynomial2D. Degree = 2 is used for the more sparsely sampled F200W and degree = 3 is used for the the bluer filters that better fill the detector frame. These fits are then iterated to remove outliers.
New coefficients for DYDX_{}_0 and DLDP_{}_0 are calculated and provided in the configuration files in this release. PNG files show the field dependence for each parameter in each filter + grism combination.
List of files available in the tar file
- GR150C.F115W.221215.conf
- GR150C.F150W.221215.conf
- GR150C.F200W.221215.conf
- GR150R.F115W.221215.conf
- GR150R.F150W.221215.conf
- GR150R.F200W.221215.conf
- f115w_gr150c_dldp_a_0.png
- f115w_gr150c_dydx_a_0.png
- f115w_gr150r_dldp_a_0.png
- f115w_gr150r_dydx_a_0.png
- f150w_gr150c_dldp_a_0.png
- f150w_gr150c_dydx_a_0.png
- f150w_gr150r_dldp_a_0.png
- f150w_gr150r_dydx_a_0.png
- f200w_gr150c_dldp_a_0.png
- f200w_gr150c_dydx_a_0.png
- f200w_gr150r_dldp_a_0.png
- f200w_gr150r_dydx_a_0.png
Installation
Download the tar file into the CONF directory of your Grizli installation and unpack. An example of how to do this in python is shown below.
import os
import grizli
os.chdir(os.path.join(grizli.GRIZLI_PATH, 'CONF'))
if not os.path.exists('GR150C.F115W.221215.conf'):
os.system('wget "https://zenodo.org/record/7447545/files/niriss_config_221215.tar.gz?download=1" -O niriss_config_221215.tar.gz')
os.system('tar xzvf niriss_config_221215.tar.gz')
