STIPS - Space Telescope Imaging Product Simulator
The Space Telescope Imaging Product Simulator for the Nancy Grace Roman Space Telescope, or STIPS , is used to simulate realistic post-pipeline astronomical scenes for WFI corresponding to Level 2 (L2) data products, which are also described in Data Levels and Products.
What is STIPS?
STIPS is the Space Telescope Imaging Product Simulator and is designed to create image simulations for the Nancy Grace Roman Space Telescope's Wide Field Instrument (WFI). It produces post-pipeline astronomical scenes for any number of sensor chip assembly (SCA) detectors, including the entire 18-SCA WFI. STIPS has the ability to add instrumental distortion (if available) as well as calibration residuals from flatfields, dark currents, and cosmic rays. Additionally, it includes an estimate of Poisson and readout noise to the simulations, but does not include instrument saturation or non-linearity effects.
Figure of STIPS M13 Demo
Top – Simulated color image of the globular cluster, M13, of all 18 SCAs in WFI generated with STIPS using the properties of individual stars from literature catalogs of positions and brightness. The simulated color image is a combination of the F106, F129, and F158 filters for WFI. Bottom – Zoom into the the M13 simulation to show a single SCA.
Current Software Version
This documentation is written for STIPS version 2.1.0 (released on November 15, 2023). The software can be obtained from the STScI-STIPS Github repository. Up-to-date development documentation is available in the detailed development documentation on the STIPS readthedocs.
Why Use STIPS?
STIPS is intended to produce quick image simulations similar to the anticipated Level 2 (L2) data products from the WFI. This software is useful for cases where Pandeia , the Exposure Time Calculator software for the WFI, does not provide a large enough simulation area. Thus, STIPS is required for both full-SCA or multiple-SCA image simulations. The software obtains instrument and filter parameters for the WFI directly from Pandeia , and it approximates point spread functions (PSFs) at a given pixel position by interpolating nine PSFs generated with WebbPSF , the PSF modeling software for the WFI, distributed uniformly across an individual SCA. The resulting flux measurements are expected to be within ~10% of those generated from Pandeia .
While STIPS has the ability to add error residuals (representing the remaining uncertainty after pipeline calibration), it does not start with Level 1 (L1) data products to propagate instrumental calibrations through the output images. In addition, the output residuals are not fully validated against the actual pipeline calibrations of L1 data products, therefore STIPS is not the ideal choice if high instrumental accuracy is needed. For applications that require high-accuracy simulations we recommend the use of Pandeia .
Warning
STIPS version 2.0 and above only support Roman. The last version to offer support for HST and JWST was 1.0.8.
Acknowledgements
STIPS was developed by Brian York (@york-stsci), Robel Geda (@robelgeda), and O. Justin Otor (@ojustino). Python ePSF code developed by Sebastian Gomez (@gmzsebastian) is based on Fortran code developed by Andrea Bellini (@AndreaBellini).
For additional questions not answered in this article, please contact the Roman Help Desk at STScI.