SDSS SpecViewer

authors: Dr. Jennifer Li (UIUC) and Meg Davis (UConn, megan.c.davis@uconn.edu), 2021
authors: Pat Hall, Zezhou Zhu, and Kevin Welch (YorkU, phall@yorku.ca, zzz@my.yorku.ca), 2023-2024

This is a demo for a multi-epoch spectral viewer for SDSSV-BHM using plotly/dash. The ultimate goal is to build a web application that allows quick spectral visualization for SDSSV BHM data. The current version will access the data via url and it takes 1-2 seconds to load each spectra.

Usage: Please see the Getting Started section, below, before launching the tool. To launch the web app, you run the script sdssv_spec_appREMOTE.py as a regular python file. The web app will be at http://127.0.0.1:8050/, which you can open with any web browser.

Getting Started

Authentication

You must have the proper SDSS-V Proprietary Data username and password in the authentication.txt (created upon first run) to use this tool, the program will prompt you to input required authentication if the file does not exist yet. The code will immediately check the authentication upon start up.

Dependencies

Please install the following Python packages to use this tool.

dash
plotly
astropy
requests
numpy

If you use conda, you may run (preferably, within a separate environment):

conda install astropy dash numpy plotly requests

If you use pip, you may run (preferably, within a separate environment):

pip install astropy dash numpy plotly requests

Then, run this to start the tool:

python sdssv_spec_appREMOTE.py

Keeping up-to-date

The dictionaries.txt file is the backbone to this tool. By running the update_dictionaries.jl file, it will look for FITS file(s) (e.g., spAll-lite-master.fits) on your local machine and update said dictionary file. Runtime was ~50s on AMD Zen 1, or ~30s on AMD Zen 3, FWIW. The file provided here is up-to-date for BHM targets for GOOD fields ONLY as of 2024-04-30.

To update dictionaries.txt, please first install latest version of Julia, and set environment variable JULIA_NUM_THREADS=auto (read more).

Next, run this to install/update the dependencies for you:

julia update.jl

Then, having the FITS files or archive files (each archive should contain only one FITS file, and would be used only if the filename to be extracted does not exist) accessible in the same directory (either copies or via symbolic links), run:

julia update_dictionaries.jl

Alternatively, provide paths as arguments:

julia update_dictionaries.jl <path/to/file1> <path/to/file2> ...

PS: The filename(s) shall match the pattern /\bspall\b.*\.fits(\.tmp)?$/i and not match /\ballepoch\b/i.

User's guide

To change the x-axis and/or y-axis range and keep it changed as you adjust the smoothing or redshift, use the Y-axis range and X-axis range buttons below the plot.
You can also select the x-axis and/or y-axis range by clicking and dragging; HOWEVER, this method does not update the Y-axis range or X-axis range buttons and your selection will be reset if the smoothing or redshift is changed.
Rest-frame wavelengths appear along the top of the plot and observed-frame wavelengths along the bottom of the plot.
Emission-line labels appear above the top of the plot, and their wavelengths are shown with solid vertical lines. Absorption-line labels appear at the bottom of the plot, and their wavelengths are shown with dotted vertical lines. In both cases, the wavelength(s) of the line(s) associated with that label are shown when the cursor hovers over the label.

Features to be added

include previous spectra from SDSS I-IV, provide downloadable links to all data
include quick links to other databases (Simbad, Ned, etc...)
include source information summary (RA, Dec, z, source types...)
search with RA/Dec for objects
renormalization of spectra (based on specific wavelength or line)
DONE smoothing of spectra
show the residual spectra in greyscale (could add as a second figure)
DONE optimize the loading speed
add session history
S/N selection slider bar
Fix colors

Heptazhou / SDSS-SpecViewer