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SDSS F Star Spectra Project

Overview

This project downloads and visualizes SDSS DR18 spectra for F-type stars (Teff ~ 6500K).

Files

  • plot_spectra.py - Main plotting script
  • sky_map.py - Interactive sky map generator
  • spectra_metadata.json - Stellar parameters from SDSS
  • spectrum_plots/ - Generated PNG plots
  • spectrum_plots/index.html - Gallery view of all spectra
  • sky_map.html - Interactive sky map with spectrum popups

Running

# Generate spectrum plots
/opt/miniconda3/envs/py39/bin/python plot_spectra.py

# Generate interactive sky map
/opt/miniconda3/envs/py39/bin/python sky_map.py

Recent Changes

Interactive Sky Map (2026-02-05)

  • Added sky_map.py to generate interactive HTML visualization
  • Plotly scatter plot showing star positions (RA vs Dec)
  • RA axis reversed (East is left, astronomical convention)
  • Points colored by metallicity [Fe/H] with Viridis colorscale
  • Hover over any star to see spectrum popup with:
    • Full spectrum PNG image
    • Stellar parameters (Teff, log g, [Fe/H], S/N)
    • Plate-MJD-Fiber identifier
  • Popup auto-positions to stay on screen

Spectrum Plot Improvements (2026-02-05)

1. Fixed Label Collisions

  • Reduced spectral lines to 8 major features only:
    • Balmer series: Hα, Hβ, Hγ, Hδ
    • Calcium: Ca II H & K
    • Sodium: Na D
    • Magnesium: Mg I b
  • Moved info box from upper-left to upper-right (avoids Ca H&K region)
  • Labels placed at top of plot with staggered heights for close lines
  • Increased font size from 7pt to 11pt

2. Added Color

  • Spectrum line: blue (#2E86AB) instead of black
  • Subtle light blue fill under the curve (alpha=0.15)
  • Color-coded spectral line markers:
    • Blue: Balmer lines
    • Orange: Calcium lines
    • Gray: Other metals (Na, Mg)

3. Added Noise Panel

  • Two-panel layout with 4:1 height ratio
  • Bottom panel shows noise (σ = 1/√ivar) vs wavelength
  • Coral/light red line (#E07A5F) for noise
  • Dashed horizontal line at median noise level
  • Noise typically higher at blue/red ends, lower in middle