Package: pastasoss
Predicting Accurate Spectral Traces in Astrophysical SOSS Spectra(PASTASOSS)Author: Tyler BainesAffiliation: Science Support Analyst, NIRISS/SOSS Team, Space Telescope Science Institute (STScI)Email:tbaines@stsci.eduOverviewWhen JWST operates in the NIRISS/SOSS mode, the rotation of the pupil wheel, responsible for positioning the GR700XD grism into the optical path, does not consistently align with its expected position (i.e., there is a slight rotational offset). This variability, with shifts of just a few fractions of a degree from the commanded position, leads to noticeable changes in the positions of spectral traces (with the greatest changes observed at redder wavelength) for NIRISS/SOSS observations from one visit to another. These variations can result in differences in the wavelength solutions between visits, potentially impacting data accuracy.To address these challenges and ensure accurate data analysis and spectral extraction, we introducePASTASOSS, a robust tool to designed to predict the positions and associated wavelength values of the GR700XD spectral traces with sub-pixel precision. Currently, the tools supports spectral orders 1 and 2, with plans to extend support to order 3 in the future. PASTASOSS provides trace position models for both Order 1 and Order 2, which accurately represent the positions when the GR700XD is located in its commanded positions. Additionally, it offers a global wavelength solution based on the pupil wheel position, ensuring precise spectral calibration. It's worth noting that the reference files included in this package are not apart of the official JWST reference files system at this time. However, they serve as essential resources for achieving precise spectral trace predictions in the face of instrument variatation.As more NIRISS/SOSS observations become increasingly available, we are commited to continually updating the tool and reference data models to ensure its accuracy and relevance.Note: Please be aware that the spectral trace positions provided are based on theSUBSTRIP256subarray configuration. We have not conducted accuracy tests using theSUBSTRIP96subarray or analyzed/compared trace positions with theF277Wfilter. While we believe that the tool should function adequately with these configurations, we advise users to proceed with caution and use them at their own discretion, as thorough testing has not yet been completed.Supported Spectral Trace RangesSpectral OrderTrace Position Model (Pixels)Wavelength Solution Model ($\mu m$)PWCPOS (deg)Order 1[4, 2043][0.85, 2.83][245.656, 245.923]Order 2[600, 1750][0.60, 1.30][245.656, 245.918]Order 3UnsupportedUnsupportedUnsupportedInstallationTo install the package via pip, use the following command:pipinstallpastasossAltneratively, you can clone the repository and navigate to directory:pipinstall.UsageTo use the package:importpastasoss# predict gr700xd traces position for order 1pastasoss.get_soss_traces(245.84,order='1')# predict gr700xd traces position for order 2pastasoss.get_soss_traces(245.84,order='2')# predict gr700xd traces position for orders 1 and 2pastasoss.get_soss_traces(245.84,order='12')DemoA concise demonstrationnotebookis included with the package. We encourage users to explore it for a quick introduction toPASTASOSS.Get InvolvedWe welcome community feedback to improve and expand PASTASOSS.
Community feedback  and contribution is encouraged!If you make use of this code, please cite: TBD