Inspector

It's for inspecting DESI spectra.

Overview

Inspector is a prototype DESI spectral viewer for use with jupyter notebooks at NERSC. It provides a fast interactive viewer for spectral data at NERSC without requiring users to download the data or install any code locally.

It is currently in a standalone package for exploratory development, but could be moved into desispec after it matures. This should be viewed as a technology demonstrator. Details about the interface and implementation can and probably will (should!) change. The main point of releasing this package is to provide a functionally useful demonstration that bokeh+jupyter+NERSC could work for viewing DESI spectra.

Getting Started

See https://desi.lbl.gov/trac/wiki/Computing/JupyterAtNERSC for instructions to configure a desi-18.6 jupyter kernel at NERSC. This only needs to be done once.

Checkout the Inspector code on cori.nersc.gov:

git clone https://github.com/sbailey/inspector

Generate the URL where you will be able to login to jupyter (this is unfortunately necessary for the next step):

cd inspector
echo https://jupyter-dev.nersc.gov/user/${USER}/tree${PWD}

Copy that URL into a browser window and login with your NERSC username/password. The URL should be something like https://jupyter-dev.nersc.gov/user/johndoe/tree/global/homes/j/johndoe/inspector).

Note: inspector is currently not compatible with the newer Jupyter Lab default interface at NERSC, thus requiring the URL messiness above; we're working with NERSC consulting to resolve that.

The URL generated above should show you a directory file browser of your inspector git checkout (if not, navigate to where you did check it out). Click inspector.ipynb to start the notebook and explore.

Note: Unfortunately jupyter does not save the generated plots in the notebook itself, so viewing the static notebook on github isn't so instructive; you'll really need to start it at NERSC yourself. There is a floppy disk (!) save icon on the plot that can be used to save the plot if you want to send it to someone else.

What it does

• Provides an interactive spectral viewer for DESI data at NERSC without needing to download or install anything locally.
• Interative zoom and pan
• Shows redrock results including the redshift, ZWARN flags, and the best fit model.
• Mouse over a region of the spectrum to get a real-time zoom in a sub-window; this is handy for inspecting narrow emission lines without zooming in and out on each one.
• Shows TARGETID and targeting bits from DESI_TARGET, MWS_TARGET, and BGS_TARGET.
• Imaging survey thumbnails and links.
• Highlight common emission / absorption lines.
• Buttons for navigating previous/next target
• Buttons for saving visual inspection results before moving to next target.

What it doesn't do (yet)

Any of these could be added later but don't yet exist. If you really want a feature, please consider contributing it.

• Show individual exposures (multiple exposures are coadded prior to display)
• Show errors and masks
• Show the Nth best fit instead of just the best fit
• Restframe wavelengths
• User-defined smoothing
• User-defined redshift
• More target info like mags and shapes
• Displaying model of 2D sky-subtracted raw data
• Viewing spectra that don't yet have redshift fits
• Filtering to individual exposures or tiles

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Stephen Bailey Lawrence Berkeley National Lab
Benjamin Weaver National Optical Astronomy Observatory
Summer 2018