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ACS Jupyter Notebooks

  • ACS CTE Forward Modeler

    This example provides guidelines for simulating the effects of CTE losses on synthetic images or existing CTE-corrected WFC images.

  • ACS Pixel Area Maps

    This example demonstrates how to create pixel area maps (PAMs) to account for the effects of geometric distortion in distorted images. This enables users to perform photometry on distorted images (FLTs or FLCs) if desired.

  • ACS SBC Dark Analysis

    This example demonstrates how to account for dark current in ACS/SBC observations. The temperature of the SBC detector increases steadily over time while it is in use, and the dark current is proportional to temperature. At temperatures above 25 ºC, the dark current is no longer negligible and must be subtracted.

  • ACS Subarrays

    This example demonstrates how to calibrate, de-stripe, and correct ACS subarray observations for charge transfer efficiency (CTE). Also included are instructions for updating the OCSNTAB reference file to subtract the bias level from the pre-scan columns in user-defined subarray observations.

  • ACS Saturation Trails

    The notebook demonstrates how to obtain accurate relative photometry of saturated sources using custom apertures.

  • ACS Reduction

    This example demonstrates how to use the CALACS pipeline to re-process raw ACS data retrieved from MAST.

  • ACS Polarization Tools

    This example demonstrates how to utilize polarization_tools in the acstools package to facilitate data analysis of ACS polarization data.

  • ACS Satellite Trails

    This notebook provides examples on how to find and create masks for satellite trails in ACS/WFC imaging data.

  • HST Exception Report

    This notebook explains how to check your ACS data and observing logs for possible data quality problems, indicated by an HST Exception Report and determine if a HOPR or Help Desk ticket needs to be filed.

  • HST Ephemeris and Related Data for an Observation

    This notebook walks through how to get various information about where HST is, and where it is pointing, in relation to Earth and the Sun, for a given observation.

  • Focus Diverse ePSFs for ACS/WFC

    This notebook highlights how to use the focus_diverse_psfs module within acstools to retrieve empirical, focus-diverse ePSFs for ACS/WFC data.

  • Planning WFC Imaging While Taking into Account CTE-related Losses

    This notebook assess the impact of degraded CTE and explains how to adjust exposure times to recover a desired signal-to-noise ratio (SNR).

  • Slitlessutils Cookbook: Spectral Extraction for ΑCS/WFC Full-Frame

    This notebook contains a step-by-step guide for performing spectral extractions with Slitlessutils for G800L full frame data from ACS/WFC.

  • Slitlessutils Cookbook: Spectral Extraction for ACS/WFC Subarrays

    This notebook contains a step-by-step guide for performing spectral extractions with Slitlessutils for G800L subarray data from ACS/WFC.

ACS Webtools and Software

Webtools

ACS Zeropoint Calculator

This webtool is designed to provide users with an interface for computing time-dependent zeropoint information (e.g PHOTFLAM, STmag, VEGAmag, etc..). It uses the most recent component and throughput files to compute the zeropoints for all filters or one specified by the user. The results are displayed in a table and if an extrapolation warning is raised by pysynphot, it is displayed beneath the table. For programmatic access to this webtool, please see the ACSZPT module in acstools.

ACS Zeropoint Calculator

 

ACS Photometric CTE Calculator

This webtool is designed to provide users with an interface for computing CTE corrections using the photometric CTE model described on the Photometric CTE Corrections webpage.

ACS Photometric CTE Calculator

 

ACS/WFC Focus-Diverse ePSF Generator

This tool allows easy access to focus-diverse, effective point-spread functions (ePSFs) for the Wide Field Channel on the ACS instrument. Uneven heating of the telescope's assembly is known to cause variations in the shape of the PSF, and the empirical ePSF models provided here take this into account. They are shown to be an improvement over the standard library PSFs. We strongly recommend you first read ACS ISR 2018-08   by A. Bellini et al. and ACS ISR 2023-06 by G. Anand et al. for more details on these ePSF models before using this tool. 

ACS/WFC Focus-Diverse ePSF Generator

Stand Alone Software

Slitlessutils

Slitlessutils is the new python package developed to support ACS grism/prism observations. It is the officially supported software package for working with wide‑field slitless data. A set of Jupyter notebooks are available in the hst_notebook repository. The tutorials are designed to both familiarize users with the slitlessutils framework and provide practical, end-to-end guidance that reflects common scientific use cases. 

Documentation and Installation Instructions

 

hst1pass

hst1pass is a software routine, written in Fortran, that has been optimized for PSF-fitting photometry on HST images. hst1pass currently supports WFPC2, ACS/HRC, ACS/WFC, WFC3/UVIS, and WFC3/IR images. For a user's manual, see ACS ISR 2022-02.

Download the hst1pass routine

Last Updated: 06/01/2026

HST Help Desk


Please contact the HST Help Desk with any questions.