Data Sources

Public spectral-line surveys we can use to develop and benchmark PHSpectra. The primary reference dataset comes from the GaussPy+ paper (Riener et al. 2019), which provides both raw data and a full Gaussian decomposition catalog for comparison.

GRS --Galactic Ring Survey

The Galactic Ring Survey mapped ${}^{13}\mathrm{CO}$ ($J = 1 \to 0$) emission at 110.2 GHz across the inner Milky Way.

Property	Value
Tracer	${}^{13}\mathrm{CO}$ ($J = 1 \to 0$), 110.201 GHz
Coverage	$18\degree \leq \ell \leq 55.7\degree$, $\lvert b \rvert \leq 1\degree$
Angular resolution	46"
Velocity range	$-5$ to 135 km/s (VLSR)
Channel width	0.21 km/s
Channels per spectrum	~670
RMS noise	~0.13 K ($T_A^*$)
Reference	Jackson et al. 2006

Public access: Full FITS cubes are available from the BU GRS archive.

Downloading the full survey

The survey is distributed as 22 FITS tiles (2° × 2° each, ~5.5 GB total) from the BU archive. Each tile is named grs-{LL}-cube.fits where LL is the central galactic longitude.

# Download all 22 tiles into a local directory
mkdir -p /tmp/phspectra/grs-full
for l in 15 17 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56; do
  curl -ksL -o "/tmp/phspectra/grs-full/grs-${l}-cube.fits" \
    "https://grunt.bu.edu/grs-stitch/source/grs-${l}-cube.fits"
done

Tile range	Tiles	Velocity range	Size per tile
$\ell = 15$--40°	14 tiles (~290 MB each)	$-5$ to 135 km/s	~290 MB
$\ell = 42$--54°	7 tiles (~190 MB each)	$-5$ to 85 km/s	~190 MB
$\ell = 56$°	1 tile	$-5$ to 85 km/s	~67 MB

GaussPy+ test field

The GaussPy+ repository bundles a small FITS cube covering a test field from the GRS. This is the easiest way to get started -- no large downloads required.

Direct download:

https://github.com/mriener/gausspyplus/raw/master/gausspyplus/data/grs-test_field.fits

The cube is ~4 MB and covers a $60 \times 70$ pixel spatial region (4,200 spectra) with 424 velocity channels. The GaussPy+ tutorial uses pixel (y=31, x=40) as a representative spectrum.

Property	Value
File	grs-test_field.fits
Dimensions	424 $\times$ 60 $\times$ 70 (vel $\times$ lat $\times$ lon)
Size	~4 MB
Coverage	$\ell = [55.27, 55.69]\degree$, $b = [0.01, 0.37]\degree$
Parent tile	grs-56-cube.fits ($\ell = [55.00, 55.71]\degree$) -- a sub-region of tile 56

Reference: Riener et al. 2019, A&A 628, A78 (arXiv:1906.10506)

GaussPy+ full decomposition catalog

Riener et al. (2020) published a complete Gaussian decomposition of the GRS using GaussPy+. This catalog provides ground-truth component parameters (amplitude, velocity, FWHM) for every spectrum in the survey -- ideal for benchmarking.

Property	Value
Catalog	GRS GaussPy+ decomposition
Format	FITS tables via CDS/VizieR
Reference	Riener et al. 2020, A&A 633, A14

Access: CDS VizieR catalog J/A+A/633/A14

Downloading with the CLI

The benchmarks CLI downloads both the GRS test field FITS cube and the VizieR decomposition catalog in a single command:

uv run benchmarks download

Files are cached in /tmp/phspectra/ by default (configurable with --cache-dir). Use --force to re-download. See Reproducing results for the full benchmark workflow.

Other public surveys

These surveys use different tracers and resolutions. They are useful for testing generalization beyond ${}^{13}\mathrm{CO}$:

• GALFA-HI -- HI 21-cm emission from Arecibo. High spectral resolution (0.18 km/s), covers the full Arecibo sky. Peek et al. 2018

• THOR -- The HI/OH/Recombination line survey of the inner Milky Way (VLA). Beuther et al. 2016

• SEDIGISM -- ${}^{13}\mathrm{CO}$/$\mathrm{C}{}^{18}\mathrm{O}$ ($J = 2 \to 1$) from the APEX telescope, covering $\ell = -60\degree$ to $+18\degree$. Schuller et al. 2021

References

1. Jackson, J. M. et al. 2006, ApJS 163, 145 --DOI
2. Riener, M. et al. 2019, A&A 628, A78 --DOI / arXiv:1906.10506
3. Riener, M. et al. 2020, A&A 633, A14 --DOI
4. Peek, J. E. G. et al. 2018, ApJS 234, 2 --DOI
5. Beuther, H. et al. 2016, A&A 595, A32 --DOI
6. Schuller, F. et al. 2021, MNRAS 500, 3064 --DOI