Instrument Configuration Parameters

Instrument dictionaries use Pandeia’s lowercase configuration values. Load a template with jdi.load_mode_dict('NIRSpec G395H'), then edit its configuration keys. The values below describe the 2026.7 PandExo release and the combinations exposed by its web interface; confirm final timing and detector settings in the current APT.

NIRSpec

Disperser/filter combinations

  • g140m or g140h with f070lp or f100lp

  • g235m or g235h with f170lp

  • g395m or g395h with f290lp

  • prism with clear

All grating modes support sub2048, sub1024a, sub1024b, and sub512. PRISM/CLEAR does not support sub1024a; it additionally supports the multistripe subarrays s256m2_prm, s128m4_prm, s64m8_prm, and s32m16_prm. Multistripe subarrays are valid only with PRISM/CLEAR.

NIRISS

NIRISS SOSS supports substrip256, substrip96, sub17stripe_soss, sub60stripe_soss, sub204stripe_soss, and sub680stripe_soss. Order 1 is the default; order 2 extraction is available with substrip256 by setting inst_dict['strategy']['order'] = 2.

NIRCam

Long-wave grism time series use grismr with f322w2 or f444w and subgrism64, subgrism128, or subgrism256. One- and four-output variants are available.

The NIRCam DHS template pairs one short-wave filter (f070w, f090w, f115w, f150w2, or f200w) with f322w2 or f444w. Supported DHS subarrays are sub41s1_2-spectra, sub82s2_4-spectra, sub164s4_8-spectra, and sub260s4_8-spectra. Short- and long-wave channels are observed simultaneously but returned one channel per calculation.

MIRI

MIRI slitless LRS uses p750l and slitlessprism, slitlessprism_ip, or slitlessprism_ips. MIRI LRS slit mode can be simulated with subslit or full, but it is not currently offered for JWST time-series observations and PandExo reports a warning.

Groups and readouts

Set inst_dict['configuration']['detector']['ngroup'] = 'optimize' to let PandExo select a group count, or enter an integer valid for the selected Pandeia detector configuration. optimize is a PandExo convenience value, not a native Pandeia detector value. NIRCam and DHS templates also accept readout_pattern = 'optimize' to account for saturation and estimated data excess when choosing a readout.

Use jdi.subarrays(), jdi.dispersers(), and jdi.filters() to inspect the values known to the installed PandExo release.