About This Article
In this STAN, the STIS team presents new Jupyter Notebooks on Hubble Advanced Spectral Products (HASP) for data diagnostics and wavelength adjustments, as well as a tool to test coronagraphic observation feasibility. The STIS team also presents a new Instrument Science Report on STIS Cycle 30 Calibration Programs and summarizes the STIS presentations given at the 245th American Astronomical Society (AAS) meeting in National Harbor.
New HASP Jupyter Notebooks for Data Diagnostics and Wavelength Adjustments
The Hubble Advanced Spectral Products (HASP) program provides the MAST community with high-quality, automated coadded and combined spectra from the Hubble Space Telescope's Cosmic Origins Spectrograph (COS) and Space Telescope Imaging Spectrograph (STIS). HASP products are continually updated with the latest data and calibrations, offering reliable and up-to-date resources for scientific analysis.
To support users in maximizing the utility of these products, two new Jupyter Notebooks are now available:
- Wavelength Adjustment Notebook: This notebook guides users through applying custom wavelength shifts to COS and STIS spectra when running the HASP coadd script.
- Data Diagnostics Notebook: This notebook helps users inspect input spectra and assess what data were included or excluded in the coadded product output.
These tools provide enhanced flexibility for data diagnostics and customization, ensuring users can tailor HASP outputs to their specific scientific needs.
New Coronagraphic Observation Feasibility Tool
Some of the most important steps in planning and preparing coronagraphic high-contrast observations with STIS involve assessing the feasibility of a detection of the high-contrast imaging science target (either a point source or a disk) within the capabilities of the predicted contrast sensitivity. In order to estimate the contrast sensitivity of a given observation, the STIS team has developed a Jupyter notebook that users may find beneficial in assessing the feasibility of high-contrast imaging observations of point sources (i.e. exoplanets, brown dwarf companions) and/or disks around stars for a given expected contrast at the 1, 3 and 5 σ level with STIS coronagraphy.
The purpose of this notebook is to provide a function to estimate the direct imaging detectability of point sources and/or disks around stars with given exposure and sub-exposure times, target properties, and noise parameters. The predicted noise that is estimated for the contrast sensitivity calculation is based on Debes et al. 2019, which contains the full explanation of the treatment of each of the noise parameters used in this notebook. The tool is available through the STIS/HST Github Jupyter notebook repository, as well as through the STIS website software tools page.
Instrument Science Report on STIS Cycle 30 Calibration Programs
ISR 2025-01: STIS Cycle 30 Calibration Programs
D. Welty, R. Bohlin, J. Carlberg, M. Dallas, S. Hernandez, A. Jones, S. Lockwood, S. Medallon, E. Rickman, D. Stapleton, T. Wheeler
We discuss the suite of STIS calibration programs executed during HST Cycle 30, covering the period 2022 Nov 07 through 2023 Nov 05. For each of the 19 current regular calibration programs, we provide brief descriptions of the objectives, observations, analysis procedures, and results – with comparisons to the results from previous cycles and to desired accuracies, as well as references to more detailed analyses of the calibration data. Many of these calibration programs produce routine reference file deliveries or demonstrate the continuing applicability of existing reference files for processing STIS observations. This ISR provides a brief snapshot of the current instrument performance, similar to those given in annual reports for Cycles 7–10 and 17–21. Two Appendices briefly discuss the state of the onboard calibration lamps and the ongoing major effort to revise the flux calibration for the many STIS spectroscopic and imaging modes.
STIS Presentations at the 245th Meeting of the American Astronomical Society
The STIS team presented two iPosters at the 245th Meeting of the American Astronomical Society (AAS) in National Harbor, MD, during the week of Jan. 12 - 16, 2025.
HST/STIS General Performance and Calibration Updates (Daniel Stapleton and the STIS team)
The Space Telescope Imaging Spectrograph (STIS) instrument onboard the Hubble Space Telescope (HST), with wavelength coverage from the far-ultraviolet to the near-infrared, is an essential tool for astronomers. Starting in 2023, STIS has undergone some alterations to calibration brought about by rapid changes in sensitivity, while the observatory operations and visit planning have been impacted by reduced gyro mode. In this poster, we present a general overview of STIS monitoring and calibration projects, with a focus on the STIS time dependent sensitivity (TDS) monitor. The TDS monitor ensures that optimal sensitivity corrections are performed based on the changes of the throughput of each observing mode with time. Over the past year, the STIS TDS has been undergoing much more rapid changes than is typical. The NUV-MAMA and CCD have seen an ~5% decrease in sensitivity since 2022 between 1800-2100 angstroms, while the FUV-MAMA shows a slight increase in sensitivity over much of its wavelength range. We will discuss our recent work on the TDS to account for these changes. Finally, we will provide a general overview of the status of STIS, including performance in reduced gyro mode and updates on both the absolute flux calibration effort and the STIS Jupyter notebook repository.
STIS ETC Validation for Lesser Used STIS Modes (Shannon Markward, Daniel Stapleton, Joleen Carlberg)
The Hubble Space Telescope (HST) Exposure Time Calculators (ETCs) are online tools designed for astronomers to accurately plan their observations. Annual calibration programs for the Space Telescope Imaging Spectrograph (STIS) provide corrections that keep the ETC outputs accurate for the most commonly used observing modes of the instrument. These corrections are then also applied to the lesser used STIS observing modes. We will discuss an initial investigation into the continued validity of those corrections by comparing the signal-to-noise ratios of time-dependent sensitivity data to those simulated by the ETC. We will also discuss the development of a method to automate the comparisons between the ETC outputs with science exposures, with a goal of applying that method to lesser used STIS observing modes to validate the continued precision of the ETC’s calibration.