astro-legacy-archive/cobe-firas-beam-profile

COBE/FIRAS Instantaneous Beam Profile

[image]

This dataset gives the representative instantaneous radial beam profile of COBE/FIRAS. The profile was determined from multiple on-orbit observations of the Moon. Its 21 samples relate angular distance from the beam centroid to normalized response.

How to use

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

Data

from datasets import load_dataset
dataset = load_dataset("astro-legacy-archive/cobe-firas-beam-profile", "firas_beam_radial_profile", split="train[:1]", columns=["Column 1", "Column 2"])
row = dataset[0]
print(row["Column 1"], row["Column 2"])

0.0 1.0

Metadata

from huggingface_hub import hf_hub_download
import json
import pyarrow.parquet as pq
path = hf_hub_download(repo_id="astro-legacy-archive/cobe-firas-beam-profile", repo_type="dataset", filename="firas_beam_radial_profile.parquet")
print(json.loads(pq.read_metadata(path).metadata[b"statistical_product"])["fields"]["Column 1"]["unit"]["value"])

degrees

Dataset structure

The source calls the two fields Column 1 and Column 2. Column 1 is the radial distance from the beam centroid; its source unit spelling is degrees. Column 2 is the normalized beam response and has no stated unit. Both are float64 values in source row order.

The table samples the released relationship only. Interpolation, a fitted beam width, and a solid-angle integral are left to the analysis appropriate to the reader's application.

Scientific context

LAMBDA's detailed product description qualifies this as a representative instantaneous profile. The finite dwell time of each interferogram elongates the effective beam in the scan direction, and that in-scan elongation is not incorporated in this table. Analyses of survey maps therefore should not treat the tabulated radial profile as a full effective scanning beam. The Explanatory Supplement additionally states that Moon observations show radial and azimuthal departures from the nominal beam, and that the sky horn is imperfect, especially at higher frequencies. For a survey pixel, the effective profile averages profiles at many orientations and positions; this archive does not derive a correction from those statements.

The direct documentation is Chapter 7, “Errors and Uncertainty Estimation,” of the FIRAS Explanatory Supplement. The detailed product description cites Fixsen et al. (1997) in the contextual role of an inter-instrument calibration comparison that treats the beam.

Provenance

The canonical source is `firas_beam_radial_profile.txt`, listed on the download page. It is 855 bytes with SHA-256 4e06ec22fe7f93b6fc7a0dc56c12c1d6105c290dd37aa415d49257e33a6b7544. LAMBDA records the delivery date as 2010-08-24. The complete source comments and structured evidence for the stated degree unit and for documentary silence on Column 2's unit are embedded with the table.

Licensing, credit, and citation

HEASARC's policy states, verbatim: “HEASARC materials are all available freely for your use.” It requests this acknowledgement when the service makes a significant contribution: “This research has made use of data and/or software provided by the High Energy Astrophysics Science Archive Research Center (HEASARC), which is a service of the Astrophysics Science Division at NASA/GSFC.” heasarc-free-use is the archive's local catalogue label; the checked source pages publish this policy and acknowledgement but no source-issued named licence.

LAMBDA's COBE credit is, verbatim: “The COBE datasets were developed by the NASA Goddard Space Flight Center under the guidance of the COBE Science Working Group.”

@article{Fixsen1997,
  author = {Fixsen, D. J. and others},
  title = {Comparison of the COBE FIRAS and DIRBE Calibrations},
  journal = {The Astrophysical Journal},
  volume = {490},
  pages = {482},
  year = {1997}
}

Citation

Please cite this dataset:

@misc{https://doi.org/10.57967/hf/10431,
  doi = {10.57967/hf/10431},
  url = {https://huggingface.co/datasets/astro-legacy-archive/cobe-firas-beam-profile},
  author = {{Astro Legacy Archive}},
  title = {cobe-firas-beam-profile},
  publisher = {Hugging Face},
  year = {2026}
}

The initial public release is Hub revision `5e14f4871e93bc11f4737985fa0e49ac06a3773c`.

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 Community tab of any dataset. Confirmed corrections are made in the source conversion tools and published by rebuilding the dataset.