astro-legacy-archive/wise-12um-dust-sample

WSSA 12 Micron Low-Resolution Sample

This dataset contains the authors' NSIDE-1024 low-resolution exploratory sample of the WISE 12 micron dust map (WSSA), as hosted by NASA LAMBDA. The native WSSA release is a separate set of 430 high-resolution sky tiles.

Source product	wssa_sample_1024-bintable.fits
Sample role	Initial exploration rather than production-stage science
Pixelisation	HEALPix NSIDE 1024; 12,582,912 pixels
Ordering	RING
Coordinate frame	Galactic
Sample resolution	12 arcmin
Source field	I12
Source unit	MJy/sr from the table BUNIT keyword

The source has one scalar float32 row per HEALPix pixel. The I12 spelling, row order, shape, dtype, and every value are unchanged.

How to use

python -m venv .venv && .venv/bin/pip install datasets huggingface_hub pyarrow

from datasets import load_dataset
dataset = load_dataset("astro-legacy-archive/wise-12um-dust-sample", "wssa_sample_1024-bintable", split="train[:1]", columns=["I12"])
row = dataset[0]
print(row["I12"])

0.02364903688430786

import json
from huggingface_hub import hf_hub_download
import pyarrow.parquet as pq
path = hf_hub_download("astro-legacy-archive/wise-12um-dust-sample", "wssa_sample_1024-bintable.parquet", repo_type="dataset")
print(json.loads(pq.read_schema(path).metadata[b"healpix_map"])["schema"])

astro-legacy-archive/healpix-map

The embedded document records geometry, unit, and coverage for the mirrored scalar field. Coordinate lookup uses the recorded NSIDE and ordering.

Source structure

The FITS file contains an empty primary HDU and one bintable named clean. The table contains 12,582,912 rows and one scalar field:

source field	source format	source TUNIT	unit source
I12	E	absent	table BUNIT = 'MJy/sr'

Every value is finite. The source contains 94,499 negative values, no zero values, and no documented coverage code. The negative values are retained as ordinary source measurements without an assigned meaning.

Relationship to the WSSA release

Meisner and Finkbeiner release WSSA principally as 430 multi-extension 12.5-degree-square tiles, smoothed to 15 arcsec FWHM. Each tile contains the eight source extensions documented in their Table 3:

extension	source name	content
0	clean	cleaned co-add
1	dirt	dirty co-add
2	cov	integer coverage
3	min	minimum value image
4	max	maximum value image
5	amsk	AND bit-mask
6	omsk	OR bit-mask
7	art	transient artifact image

The authors also provide low-resolution HEALPix samples at NSIDE 1024, 2048, 4096, and 8192, each as an image and as a binary table. This dataset contains only the NSIDE-1024 binary-table sample.

Considerations for use

• The authors describe the HEALPix products as quick exploratory samples and encourage production analyses to use the full-resolution tiles.
• Sample values incorporate interpolation based on WSSA bit-masks. The authors note that optimal mask use depends on the scientific application and sky location.
• The sample's pixels are much larger than the 15 arcsec resolution of the native WSSA tiles.
• The sample contains only the clean extension. The authors omit the masks because their rebinning is ambiguous.
• Meisner and Finkbeiner report Moon-contamination stripes over about 5% of the sky, with diffuse W3 emission badly contaminated by Moon glow and/or Solar System planets in about 5% of the sky.
• Bright-source processing can leave dark 1--2 arcmin latent “divots,” which are a dominant residual imperfection in many low-dust-signal regions.
• The WISE All-Sky Release “dynamic calibration sky offset correction” can produce those acausal latent divots and assign up to about 4% of pixels in an L1b image exactly the frame's median value; the initial WSSA tile release did not address these effects.
• Separately, WSSA sets its large-scale zero point by comparison with Planck 857 GHz emission using a spatially varying 12 micron/857 GHz ratio.

Provenance

The source file wssa_sample_1024-bintable.fits has SHA-256 e60d878ea2bc9e3c6be85bcce40183bb1922571360e63d757fb2139dce930e72. The complete source headers, URL, hash, retrieval timestamp, document pins, and regeneration command are embedded in the Parquet file. Rebuild with python tools/make_wise_12um_dust.py data/wise-12um-dust-sample.

Licensing, credit and citation

The product pages do not publish a named licence. HEASARC's data-use page states: “HEASARC materials are all available freely for your use.”

LAMBDA requests:

We acknowledge the use of the Legacy Archive for Microwave Background Data Analysis (LAMBDA), part of the High Energy Astrophysics Science Archive Center (HEASARC). HEASARC/LAMBDA is a service of the Astrophysics Science Division at the NASA Goddard Space Flight Center.

Please cite Meisner and Finkbeiner (2014), “A Full-sky, High-resolution Atlas of Galactic 12 um Dust Emission with WISE,” The Astrophysical Journal, 781, 5, doi:10.1088/0004-637X/781/1/5.

The sample description and download are available from NASA LAMBDA, and the native release, sample siblings, extension definitions, and warnings are on the authors' WSSA site.

Errata and requests

To report an erratum, propose a correction, or ask a question about this dataset, open a Discussion or Pull Request in its Community tab; posting requires a free Hugging Face account. Dataset requests and archive-wide questions may be posted in the README space's Community tab or the Community tab of any dataset. Confirmed corrections are made in the source conversion tools and published by rebuilding the dataset.