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February 26, 2024

About This Article

In this STAN we announce the delivery of the Hubble Advanced Spectral Products (HASP) program, as well as summarize the STIS presentations given at the 243rd American Astronomical Society (AAS) meeting in New Orleans.


HASP: Unlocking the full potential of Hubble's spectral data


The Hubble Advanced Spectral Products (HASP) program is set to transform the way the MAST community accesses and utilizes Hubble Space Telescope (HST) spectroscopic data. HASP offers an innovative and automated approach to coadding and combining data to obtain high-quality one-dimensional spectra from HST's Cosmic Origins Spectrograph (COS) and Space Telescope Imaging Spectrograph (STIS). Products are automatically updated when new data come in or new calibrations are made available, ensuring users always have access to the latest insights.

HASP's mission is clear: simplify and enhance access to HST spectroscopic data. By default, HST data often require users to manually coadd spectra for scientific analysis. HASP generates two crucial data products: coadds and abutments, created at both the visit and program levels. Coadded spectra result from combining data from a common grating, while abutments involve merging spectra from different gratings and/or instruments (Fig 1). 

Figure 1: The two key techniques from the Hubble Advanced Spectral Products for a white dwarf star, WD 0308-565. On the left, we see combined data from multiple CENWAVES using the G160M grating, detailing the coadded spectrum, exposure times, and signal-to-noise ratios. The right shows data from three different gratings abutted together, highlighting the smoothness of the compiled spectrum and the corresponding exposure and signal quality metrics. This visual comparison showcases HASP's ability to refine and enhance astronomical data.

HASP also provides users with tools to create custom coadds, granting unprecedented flexibility and control over the coaddition process. This versatility is accessible through user-friendly Jupyter Notebooks, designed to assist users in setting up and running the coadd script, catering to specific use cases not covered by automatic coadds (Fig 2).

Figure 2: The HASP website has links, shown above, to interactive Jupyter notebooks that provide step-by-step guides on creating custom coadded/abutted datasets, enabling users to tailor spectral data combination to fit their unique research needs.

HASP is now seamlessly integrated into the Hubble MAST search form (Figure 3) as a standard component of data downloads from the archive. Users looking for HASP data can access them through new cspec.fits files, which have become a default MAST product.

Figure 3: A snapshot from the Hubble MAST download window showcasing the integration of Hubble Advanced Spectral Products (HASP). Users will now find new cspec.fits (combined spectrum) data as default download products.

For comprehensive details, please refer to the HASP webpage or HASP Instrument Science Report.

STIS at the 243rd American Astronomical Society Meeting

The STIS team presented three iPosters at the 243rd Meeting of the American Astronomical Society (AAS) in New Orleans, LA, during the week of Jan. 7 - 11, 2024.


"Updating the 20 year old HST STIS NUV MAMA Pixel-to-Pixel Flat Field” (Emily Wright + STIS team)
The Near-Ultraviolet Multi-Anode Microchannel Array (NUV MAMA) detector on the Space Telescope Imaging Spectrograph (STIS) onboard the Hubble Space Telescope (HST) is subject to pixel-to-pixel variations in sensitivity. These variations are corrected by a pixel-to-pixel flat field image, known as the p-flat. The pipeline currently uses a p-flat with data from 1998 to 2002 corresponding to HST Cycles 7 to 10. The code to create the p-flats was recently updated to remove all IRAF dependencies, which are no longer supported. It is now written only in IDL and can run on a modern operating system. We have tested and verified the updated code by comparing the intermediate and final outputs of the new and previous versions. With the updated code, we created and analyzed new p-flats for HST Cycles 17 and onwards with data taken every other Cycle. We show how the p-flats evolve with time and the improvements on the reduced data products with the new NUV MAMA p-flats.


"Performance and Calibration Updates for the Space Telescope Imaging Spectrograph” (Jackie Brown + STIS team)
The Space Telescope Imaging Spectrograph (STIS) has been a part of the Hubble Space Telescope (HST) for over 25 years. STIS is a versatile instrument providing spectroscopy and imaging with three detectors and a wavelength range from the near-infrared (NIR) to far-ultraviolet (FUV). The STIS instrument team presents several updates relevant to the instrument’s user base. We have updated the NUV MAMA dark reference files and dark correction table (TDCTAB) and have released a new cosmic ray monitor for CCD observations and updated suggestions for redundancy in non-repeatable observations. In addition, we note that STIS notebooks have migrated to a new GitHub repository under HST notebooks where they will be continually integrated. The STIS team is also investigating a recent change in behavior of the time dependent sensitivity in the NUV between 1800-2100 Angstroms. Lastly, in view of the fading of the onboard Pt/Cr-Ne lamps used for wavelength calibration, the STIS team has developed recommendations for increasing the wavelength calibration (wavecal) exposure times for the most affected FUV settings.

This poster also highlights an upcoming instrument science report which has since been published and which can be found here: ISR STIS 2024-01 Safety Acquisitions: Redundancy for non-repeatable multi-orbit STIS visits.


"Absolute Flux Recalibration of HST/STIS Spectroscopic and Imaging Modes: New Updates” (TalaWanda Monroe + STIS team)
The HST Space Telescope Imaging Spectrograph (STIS) team has been working to update the absolute flux calibration of STIS spectroscopic and imaging modes to benefit from improved stellar atmospheric models of the primary HST standard stars published in CALSPEC v11. Recent releases of updated CalSTIS pipeline reference files included improved photometric throughputs and blaze shift coefficients for many FUV and NUV echelle modes, improved characterization of the spectral traces of select secondary echelle modes, updated throughputs for NUV imaging modes, and a new sensitivity curve for the G750L first order mode. These updates will be presented along with recent progress on the recalibration of first order medium-resolution spectroscopic modes, FUV imaging modes, and the creation of a new type of pipeline reference file for echelle blaze shift coefficients.


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