Quick start

A two-minute tour. Assumes you’ve already run pip install jwst-vmpt (see Installation).

1. Launch the app

vmpt
# browser opens at http://localhost:5006/app

If a tab doesn’t open automatically, visit the URL yourself.

2. Load an example

In the Input tab (left sidebar), click one of the two example buttons:

  • Load Abell 370 example — JWST/NIRCam F182M + F200W + F210M three-band FITS (~42 MB). Includes a target catalog and an APT MPT plan from GTO-1208.

  • Load RXCJ0600 example — JPG + WCS-sidecar pair (~17 MB). Demonstrates the JPG + WCS workflow. Includes a 28k-source target catalog.

If you haven’t downloaded the examples yet, run

vmpt examples download

from a directory of your choice (the tarball is fetched from the matching GitHub release).

3. Aim the MSA

Switch to the Pointing tab. The pointing centre auto-fills to the image centre. Drag the V3 PA slider (or type into the APA box) to rotate the MSA quadrants on the image.

Pick a Disperser / Filter combo — e.g. PRISM/CLEAR for low-res, G395H/F290LP for high-res near-IR.

4. Pick shutters

Switch to the Settings tab → choose N-shutter slitlet (default 3). Then on the image:

  • Click → opens an N-shutter slitlet at the nearest operable shutter.

  • Click an open shutter → closes it (and its siblings).

  • Double-click → toggles a cyan visual highlight (not exported).

  • Shift-click → moves the pointing centre to that location.

  • Mouse wheel → zoom.

Loaded a catalog? vMPT auto-tags every opened slitlet with the catalog source ID whose footprint falls inside any opened shutter. The status bar (bottom of the page) names the matched source.

5. Or run the optimizer

In the Pointing tab, click Open optimizer…. Choose a method (Democracy / Meritocracy / Hierarchy — see MSA pointing optimizer), set your search radius and optional collision protection, then Run optimization. The top-10 solutions appear in a results table; click Apply #N to set the pointing and auto-open slitlets for the matched targets.

6. Save / share

In the MPT tab:

  • Save session → writes a self-contained bundle (MPT_plan.json + vMPT_workspace.json + the eMPT three CSVs) to a directory you choose. Mail or git that directory; the recipient does Load session and gets your exact picks.

  • Export eMPT bundle → same writer, into a fresh timestamped exports/ subfolder.

See Exporting & sharing for the on-disk format.