The James Webb Space Telescope Coronagraph Visibility Tool (CVT) is a GUI-based target visibility tool for assessing target visibilities and available position angles versus time relative to MIRI[1] and NIRCam[2] coronagraphic masks. The CVT is available as a standalone gui-based python tool (AstroConda package) or as a macOS app bundle.
The allowed pointing of JWST leads to target visibility that depends on ecliptic latitude, and the range of roll angles allowed depends on solar elongation. The allowed position angles for a target can thus be a complicated function of time. As a result, it can be difficult to: (1) understand the possible orientations of a given target on the detector, especially in relation to any instrumental obscurations; (2) determine the ideal roll angle offsets for multi-roll observations; and (3) determine a group of targets that are simultaneously visible. The CVT was created to address these issues and assist in planning MIRI and NIRCam programs prior to entering targets and observations into the APT[3].
We stress that the CVT is designed to provide quick illustrations of the possible observable orientations for a given target. As such, the CVT rapidly approximates JWST’s pointing restrictions and does not query the official JWST Proposal Constraint Generator (PCG), nor include detailed pointing restrictions like Earth and Moon avoidance, etc. Therefore, CVT results should be treated as useful approximations that may differ from official APT constraints by a degree or so.
Documentation can be found online at JWST Coronagraph Visibility Tool Help.
Authors: Christopher Stark, Joseph Long, J. Brendan Hagan, Mees Fix and Bryony Nickson
CVT may be installed from the Python Package Index in the usual manner for Python packages.
$ pip install jwst_coronagraph_visibility
If you are running macOS and would like a double-clickable application, click on the following link:
Download for macOS (86.4 MB).
Simply extract the downloaded zip file to obtain the .app bundle, then double-click to run the JWST Coronagraph Visibility Tool.
For those wishing to contribute to the code base, you can install jwst_coronagraph_visibility by cloning and
installing the repository. This is only recommended for those looking to help with development. In general, those
wishing only to use the jwst_coronagraph_visibility tool should install the latest stable version from using Astroconda,
as described in the instructions above.
It is highly recommended that contributors have a working installation of Miniconda
or Anaconda for Python 3.6. Package requirements for contributing to jwst_coronagraph_visibility will be
provided by a setup.py script included in the repository.
Clone the jwst_coronagraph_visibility GitHub repository as follows:
$ git clone https://github.com/brynickson/jwst_coronagraph_visibility.git
$ cd jwst_coronagraph_visibility
Following the download of the jwst_coronagraph_visibility repository, create and activate a new
jwst_coronagraph_visibility environment:
$ conda create -n jwst_coronagraph_visibility-3.7 python=3.7
$ conda activate jwst_coronagraph_visibility-3.7
Next, you need to install the jwst_coronagraph_visibility package. This can be accomplished by running the setup.py
script:
(jwst_coronagraph_visibility-3.7)$ python setup.py develop
The package should now appear if you run conda list jwst_coronagraph_visibility.
If you use the CVT for work/research presented in a publication (whether directly, or as a dependency to another package), please consider citing the Zenodo record using the DOI page above. Please find additional instructions in CITATION.
Contributors should use a "forking workflow" when making contributions to the project.
Users and contributors to the jwst_coronagraph_visibility repository should adhere to the
Code of Conduct. Any issues or violations pertaining to the Code of Conduct should be brought to
the attention of a jwst_coronagraph_visibility team member or to [email protected].
For any questions about the jwst_coronagraph_visibility project or its software or documentation, please
open an Issue.
- The CVT does not (and will not) query the JWST Proposal Constraint Generator. The only constraint on the field of regard is the Sun and anti-Sun avoidance angle.
- Target name resolution depends on the availability of the SIMBAD service. If the service cannot be reached, you will have to enter coordinates yourself.
- The CVT does not currently provide a way to export the plotted points as text. Plots can be saved from the GUI using the save icon below the plot panel.
- The CVT has only been tested on Mac and Linux. Issue reports from Windows users are welcome, and we will do our best to address them, but we are not testing the tool on Windows.
See issue tracker at https://github.com/spacetelescope/jwst_coronagraph_visibility/issues.
- Mees Fix @mfixstsci
- Bryony Nickson @brynickson
[1] - Mid-Infrared Instrument (see documentation) ↩
[2] - Near-Infrared Instrument (see documentation) ↩
[3] - Astronomer's Proposal Tool (see documentation) ↩