Getting started
Planning an imaging observation? PyDIET helps you estimate the exposure time needed to reach a target SNR, or the SNR you can expect from a given exposure. CFHT runs it at pydiet.cfht.hawaii.edu. You can also run it on your computer, host it for other observers, or adapt it to your own imaging system. Its complete web API lets you bring the calculator into your scripts and observing tools, with a Python client included.
Try it in your browser
The quickest way to get a feel for the calculator is to open the CFHT service. Choose MegaCam or WIRCam, select a filter, and enter your source brightness and observing conditions. Then ask for an exposure time or SNR and explore how the result changes with seeing, sky brightness, or the number of exposures. The Using the web interface chapter walks through the form and results.
Run it on your computer
For a local copy, install Python 3.10 or later, Git, and Python's virtual-environment support. In a terminal, download the source and install it with pip in a virtual environment:
git clone https://github.com/astromatic/pydiet.git
cd pydiet
python3 -m venv .venv
. .venv/bin/activate
python -m pip install .
With the environment active, start the calculator and open your browser with:
pydiet -b
The -b option opens the web interface once the local server is ready.
You can also visit http://localhost:8010/ yourself.
Keep the terminal open while using the calculator, and press Ctrl-C when you are finished.
The supplied instrument data and web client are included; Deploying the ETC explains how to build the local manual and configure the server.