January 6, 2023

About This Article

1. WFC3 at AAS 241!

We invite all interested users at the AAS to stop by the WFC3 iPosters at the upcoming AAS meeting. Below, we provide abstracts and session information, and link to the presentations listing in the AAS meeting itinerary. For a full listing of STScI Workshops, Events, and Sessions planned for the AAS, please see the recent STScI Newsletter article. Times are given in Pacific Time (PT). 

462.03. Machine Learning and HST/WFC3: An Update for 2023 - F. Dauphin, J. Medina, M. Montes, V. Bajaj, N. Easmin, P. McCullough, S. Baggett and the WFC3 team
Thursday, January 12, 1:00 - 2:00 PM PT

Hubble's Wide Field Camera 3 (WFC3) is the workhorse instrument for HST, providing direct (staring) and scanning modes using filters and grisms, covering from the near-IR to near-UV. Installed during the most recent HST servicing mission in 2009, WFC3 has logged almost 300,000 observations resulting in exciting scientific discoveries over the past 14 years. With this abundance of data and growing accessibility to artificial intelligence, we utilize machine learning for detecting anomalies in our images, specifically WFC3/IR Blobs and WFC3/UVIS Figure-8 Ghosts. We discuss our models' performances and future projects, such as utilizing dimensionality reduction and clustering to further explore the WFC3 database. In addition, we highlight items of particular interest to proposers in Cycle 31 and observers with data in hand.

205.06. Constructing Additional PSF Models for WFC3 - Z. Mancuso de Lopez, V. Bajaj
Tuesday, January 10, 9:00 - 10:00 AM PT

The library of HST Wide Field Camera 3 (WFC3) point spread function (PSF) models developed by J. Anderson are a valuable resource for image analysis, providing the ability to fit stellar fluxes and positions to extremely high precision. Because the PSF varies with wavelength as well as other properties of the optical elements, the models must be created with spatial and filter dependence. While the current models have good spatial coverage, they cover only some of the most used, wide-band filters. Leveraging the database of star cutouts in the MAST Archive and modern PSF construction tools, we will develop models for the next-most-often-used WFC3 infrared filters, to further the applicability of the existing PSF fitting and analysis tools.


2. STENV Released to Replace Astroconda

N. Dencheva, M. Rafelski, J. Carlberg

The Space Telescope Science Institute has released stenv to supersede Astroconda for its software distribution. stenv provides a common environment for both the Hubble Space Telescope (HST) and the James Webb Space Telescope (JWST) pipelines and includes most of the packages in Astroconda.

While Astroconda has served our community well for many years, more recently the vast number of versions with an ever increasing number of software packages would often result in Astroconda taking a very long time to resolve dependencies. Moreover, some Astroconda dependencies are fundamentally incompatible with Python versions > 3.7.

To better support our users, stenv employs pre-determined Conda environments that are verified to be compatible with Python versions from 3.8 to 3.11. Additionally, while Astroconda primarily uses Conda recipes to build and serve packages, which need to be updated separately from PyPI releases, stenv draws most of its packages directly from PyPI with pip (though it still requires use of a Conda environment for hstcal and fitsverify, which are provided by conda-forge). Support for Astroconda will end on February 1st, 2023.

Instructions for installing and using stenv can be found at https://stenv.readthedocs.io/. Questions can be directed to the HST help desk.

A screenshot of the stenv documentation page


3. WFC3/UVIS Postflash: Change to Time-Dependent Reference Files

C. Martlin, J. Green

We are announcing an update of all WFC3/UVIS postflash reference files. An in-depth WFC3 Instrument Science Report (ISR 2023-01, in review) will be available shortly. This study has determined that using calwf3 with reference files from the same year as the data results in a slight improvement in data quality (compared with the current reference file averaged over all years).

The 40 new postflash reference files were delivered to the MAST automated calibration pipeline in December 2022 and all affected UVIS data are being reprocessed. Users wishing to have their science data calibrated with the new reference files can re-download their data from MAST or, alternatively, manually recalibrate their data with the new postflash reference files. See the CRDS website for the reference filenames and the WFC3 Software Library for a Jupyter notebook on manual recalibration of WFC3 data.


4. New Version of HSTaXe Released!

D. Som, A. Pidgeon, B. Kuhn, N. Hathi, R. O'Steen, D. Nguyen

We are announcing the release of HSTaXe v.1.0.3 featuring several major bug-fixes and improvements. HSTaXe is the official STScI provided software package for the extraction and calibration of slitless spectroscopic data from the HST, and replaces the IRAF/PyRAF based aXe software (no longer supported). This new release adds several functionalities to HSTaXe including:

  • Extraction and calibration of G280 (WFC3/UVIS) full frame data
  • Extraction and calibration of G280 (WFC3/UVIS) sub array data
  • Option to perform local background subtraction

Other major improvements provided by the latest version are:

  • Streamlined installation process
  • Improved documentation, including the creation of a new documentation page

Please visit the HSTaXe GitHub repository and the documentation page for instructions on how to install and use the software.

In addition, the WFC3 team would like to announce the availability of several new or updated Jupyter notebooks demonstrating example extraction workflows for WFC3 slitless spectroscopic data. These notebooks are located (with several additions coming soon) in the HSTaXe repository.

5. New Documentation

ISR 2022-08: WFC3/UVIS Gain Stability Results for Cycles 26 - 29 - K. Huynh & B. Kuhn

ISR 2022-09: TrExoLiSTS: Transiting Exoplanets List of Space Telescope Spectroscopy - N.K. Nikolov, A. Kovacs, C. Martlin

The complete WFC3 ISR archive is available here. Additional information about WFC3 calibration, performance, data analysis, software tools, and more can be found online.

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