# Dwarf/Irregular Galaxy HI Rotation Curve Corpus v1.0

**Author:** D. C. Flynn, EPS Research, Laurel MD, USA  
**ORCID:** 0000-0002-2768-6650  
**Email:** davidflynn@eps-research.com  
**Date:** 2026-05-19  
**Version:** 1.0  

---

## Overview

This corpus assembles HI rotation curve data for **129 dwarf and irregular galaxies**
from four complementary Local Volume surveys. It is the third in a series of
unified kinematic corpora by Flynn (2026), designed to support both machine learning
retrieval-augmented generation (RAG) applications and traditional astrophysical analysis.

The corpus focuses on the dwarf and irregular galaxy regime, extending and complementing
the Flynn (2026) SPARC/THINGS/LITTLE THINGS/WALLABY unified corpus (v7.0;
DOI: 10.5281/zenodo.19563417). While LITTLE THINGS was already present in v7.0,
this corpus significantly expands dwarf irregular coverage by adding LVHIS, VLA-ANGST,
and additional WALLABY dwarfs, with dedicated schema fields for Local Volume kinematics.

The corpus provides a natural testbed for the omega kinematic correction
(Flynn & Cannaliato 2025), with 24 omega-ready galaxies from LITTLE THINGS.
All 24 outer gaps V_adj(R2) - V_obs(R2) are negative, consistent with the
Flynn (2026) finding across 84 SPARC Q=1 spirals.

**Selection criteria:** All LVHIS, VLA-ANGST, and LITTLE THINGS galaxies with
published HI rotation curves. WALLABY dwarfs filtered from v7.0 WALLABY DR2 component.
Massive spirals and ellipticals excluded (Vrot > 150 km/s AND not classified Irr/Im/dIrr):
NGC 253, NGC 1313, NGC 4945, NGC 5128, NGC 5236, Circinus.

---

## Survey Coverage

| Survey | Galaxies | Telescope | Reference |
|--------|----------|-----------|-----------|
| LVHIS | 33 | ATCA | Koribalski et al. (2019), MNRAS 483, 4 |
| VLA-ANGST | 29 | VLA | Ott et al. (2012), AJ 144, 123 |
| LITTLE THINGS | 26 | VLA | Oh et al. (2015), AJ 149, 180 |
| WALLABY DR2 | 41 | ASKAP | Koribalski et al. (2020), Ap&SS 365, 118 |
| | | | *Note: HI mass, dynamical mass, rhi, hubble_type absent for all WALLABY entries* |
| **TOTAL** | **129** | | |

---

## Quality Tiers

| Tier | Count | Description |
|------|-------|-------------|
| 1 | 26 | Full tilted-ring rotation curve (LITTLE THINGS + WALLABY multi-point) |
| 2 | 103 | Single-ring or profile-width estimate (LVHIS seed, VLA-ANGST) |

**Omega-ready:** 24 galaxies (LITTLE THINGS Tier 1, n_points >= 5, excluding
IC 10 and NGC 3738 — see known_issues field for exclusion reasons).

---

## Omega Analysis Results

The omega kinematic correction (Flynn & Cannaliato 2025, Eq. 1) was applied to all
24 omega-ready galaxies. Key findings:

| Statistic | Dwarf corpus | SPARC (Flynn 2026) |
|-----------|-------------|-------------------|
| N galaxies | 24 | 84 |
| Mean omega (rad/Gyr) | 11.94 | 7.06 |
| Median omega (rad/Gyr) | 9.94 | ~7.0 |
| SD (rad/Gyr) | 6.84 | 3.26 |
| Outer gaps negative | 24/24 (100%) | 84/84 (100%) |
| Within 1-sigma of SPARC | 11/24 | — |

All outer gaps V_adj(R2) - V_obs(R2) are negative, ruling out dark-matter
re-importation in the dwarf irregular regime. The median omega (9.94 rad/Gyr)
overlaps the SPARC distribution within ~1 SD, suggesting the omega kinematic
regularity persists from spiral galaxies into the dark-matter-dominated dwarf regime.

Results are in: omega_results_dwarfs.csv
Script: compute_omega_dwarfs.py

---

## File Contents

| File | Description |
|------|-------------|
| dwarf_irregular_corpus_v1.json | Main corpus — 129 galaxies, full schema |
| dwarf_irregular_corpus_v1.jsonl | One galaxy per line — RAG-ready |
| dwarf_irregular_corpus_v1_flat.csv | Flat summary table (32 columns) |
| dwarf_irregular_corpus_v1_by_galaxy.zip | One JSON file per galaxy |
| rag_examples_v1.json | Three worked RAG examples |
| omega_results_dwarfs.csv | Per-galaxy omega results (24 galaxies) |
| fig_ddo154_omega.png | DDO 154 rotation curve decomposition figure |
| compute_omega_dwarfs.py | Omega computation script (Eqs 1-3) |
| formula_reference.py | All 6 paper equations with self-tests |
| build_corpus.py | Main corpus assembly script |
| schema_validator.py | Schema validation script |
| README.md | This file |

---

## JSON Schema

Each galaxy entry contains the following fields:

  galaxy           : string  - identifier
  survey           : string  - LVHIS | VLA_ANGST | LITTLE_THINGS | WALLABY
  telescope        : string  - ATCA | VLA | ASKAP
  ra_deg           : float   - J2000 right ascension
  dec_deg          : float   - J2000 declination
  hubble_type      : string  - morphological type (absent for WALLABY blind survey)
  morph_class      : string  - simplified morphological class
  group_member     : string  - group/association membership
  distance_mpc     : float   - distance in Mpc
  distance_method  : string  - TRGB | Cepheid | flow | SBF | etc.
  vsys_kms         : float   - systemic velocity km/s (absent for all 33 LVHIS galaxies; ingest from Koribalski et al. 2019 Table 4 for future versions)
  inc_deg          : float   - inclination in degrees
  pa_deg           : float   - position angle in degrees
  kinematic_model  : string  - tilted_ring | profile_width | tilted_ring_manual
  mhi_log_msun     : float   - log HI mass in solar masses (absent for WALLABY)
  log_mdyn         : float   - log dynamical mass in solar masses (absent for WALLABY)
  mhi_mdyn_ratio   : float   - HI-to-dynamical mass ratio (absent for WALLABY)
  rhi_kpc          : float   - HI radius in kpc (absent for WALLABY; LVHIS/VLA-ANGST only)
  rhi_arcsec       : float   - HI radius in arcseconds (from published catalog)
  vrot_max_kms     : float   - peak rotation velocity km/s
  vrot_mean_kms    : float   - mean rotation velocity km/s
  n_points         : int     - number of rotation curve points
  r_min_kpc        : float   - innermost radius in kpc
  r_max_kpc        : float   - outermost radius in kpc
  quality_tier     : int     - 1 (full RC) or 2 (seed/estimate)
  beam_arcsec      : float   - synthesised beam size in arcseconds
  n_beams_across   : float   - number of beams across HI disk
  omega_ready      : bool    - True if suitable for omega correction (Eq 1-3)
  has_vgas_profile : bool    - True if Vgas column present in data array
  has_stellar_mass : bool    - True if stellar mass estimate available
  ingest_mode      : string  - seed_table9 | v7_transfer | wallaby_filter
  ingested_date    : string  - ISO date of ingestion
  quality_notes    : string  - quality assessment details
  reference        : string  - primary data reference
  known_issues     : array   - data quality flags and exclusion reasons
  v7_source        : string  - source record ID from v7 corpus (WALLABY only)
  citation         : string  - [deprecated; renamed to reference in v1.0]
  data             : array   - rotation curve points [Rad(kpc), Vrot(km/s), errV(km/s)]
  columns          : dict    - column metadata and units

---

## Excluded Galaxies

**Excluded as non-dwarfs** (Vrot > 150 km/s AND not Irr/Im/dIrr):
  NGC 253 (SABc, 200 km/s), NGC 1313 (SBd, 220 km/s), NGC 4945 (SBcd, 174 km/s),
  NGC 5128/Cen A (S0, 260 km/s), NGC 5236/M83 (Sc, 150 km/s), Circinus (Sb, 161 km/s)

**Excluded from omega analysis** (omega_ready=False):
  IC 10: V1=1.95 km/s with errV=12.71 km/s at R1=0.060 kpc — error exceeds signal.
         Negative Vrot at R=0.080 kpc. R_max=0.54 kpc insufficient for reliable fit.
  NGC 3738: inc=22.6 deg below reliable threshold. Duplicate radii at boundaries.
            Vrot_max=132.7 km/s anomalous for dIrr classification.

---

## RAG Examples

Three worked examples are provided in rag_examples_v1.json:

1. Kinematic classification — IC 5152 (LVHIS): inclination, PA, peak velocity, group
2. Population filter — Centaurus A group dwarfs with Vrot < 80 km/s
3. Omega correction — DDO 154 (LITTLE THINGS + SPARC rotmod):
   omega = 6.162 rad/Gyr (LITTLE THINGS boundaries),
   omega = 6.864 rad/Gyr (SPARC rotmod boundaries),
   consistent with SPARC population mean 7.06 rad/Gyr (Flynn 2026).
   Figure: fig_ddo154_omega.png

---

## Research Context

This corpus is part of a documented research arc:

1. Flynn & Cannaliato (2025) — Introduced the omega kinematic correction.
   Frontiers in Astronomy and Space Sciences 12.
   DOI: 10.3389/fspas.2025.1680387

2. Flynn (2026) — Baryonic validation of omega across 84 SPARC Q=1 galaxies.
   Submitted to New Astronomy (NEWAST-D-26-00207).
   Preprint: DOI: 10.5281/zenodo.20132805

3. Flynn (2026) — Unified HI Rotation Curve Corpus v7.0 (438 galaxies).
   Astronomy and Computing (ASCOM-D-26-00129).
   Zenodo DOI: 10.5281/zenodo.19563417
   arXiv: 2604.13489

4. This corpus — Dwarf/Irregular Corpus v1.0 (129 galaxies).
   Target venue: Publications of the Astronomical Society of the Pacific (PASP).

---

## Reproduction

  pip install numpy scipy matplotlib
  python3 build_corpus.py \
      --v7-corpus /path/to/rotation_curve_corpus_v7.json \
      --output-dir ./dwarf_corpus_output
  python3 schema_validator.py ./dwarf_corpus_output/dwarf_irregular_corpus_v1.json
  python3 compute_omega_dwarfs.py --corpus ./dwarf_corpus_output/dwarf_irregular_corpus_v1.json
  python3 formula_reference.py   # verify all 6 equations with self-tests

LITTLE THINGS data transferred from v7 corpus (DOI: 10.5281/zenodo.19563417).
LVHIS and VLA-ANGST ingested from published catalog tables (seed mode).
WALLABY dwarfs filtered from v7 WALLABY DR2 component.
SPARC rotmod files for DDO 154 figure: http://astroweb.cwru.edu/SPARC/

---

## Citation

  Flynn, D.C. (2026). Dwarf/Irregular Galaxy HI Rotation Curve Corpus v1.0.
  Zenodo. https://doi.org/10.5281/zenodo.[DOI_TO_BE_ASSIGNED]

Please also cite the primary survey references in the Survey Coverage table.

---

## License

Data: Creative Commons CC BY 4.0
Code: MIT License