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astro-ph.EP · Earth and Planetary Astrophysicsastro-ph.IM · Instrumentation and Methods for Astrophysics

Band contrasts differ by more than three formal errors in 147 of 355 Gaia DR3 and SMASS II asteroid pairs when covariance is set to zero

We test a fixed, signed spectral contrast near 0.7 micrometres in public Gaia DR3 and SMASS II data. The sample has 355 numbered asteroids with Bus classes B, C, Cb, Cg, Ch, or Cgh. The Gaia score ranks Ch/Cgh against the other classes with area under the receiver operating characteristic curve 0.830. The 95% object bootstrap interval is 0.786 to 0.871. Gaia minus ground contrast has median +1.513 percentage points. Its 95% interval is +1.299 to +1.751. Differences exceed three combined formal errors in 147 of 355 pairs, or 41.4%. This calculation adds the reported marginal variances with covariance set to zero. After subtraction of the sample median difference, 104 pairs still exceed three errors. A separate fixed Gaussian score gives similar class ranking. A threshold set from development controls recovers 24 of 67 test Ch/Cgh objects and selects 7 of 116 test controls. The formal errors alone do not describe the survey differences. The result does not establish their cause, new mineral detections, or surface change. The selected sample does not give a main-belt hydration fraction. We preserve code, aggregate results, figures, the analysis plan, exact source requests, response checksums, and commands to rebuild the test from public downloads.

asteroids · Gaia DR3 · SMASS II · reflectance spectra · spectral classification · hydration · measurement errors · reproducible benchmark

Admitted 2 citing publications

References

10
  1. usesdoi:10.5270/esa-qa4lep3

    We use Gaia DR3 mean asteroid reflectance spectra, marginal errors, and quality flags.

  2. usesdoi:10.26033/fj1d-vb37

    We use the PDS SMASS II V1.0 ground spectra and their reported errors.

  3. usesdoi:10.26033/e1p3-xm59

    We use the Bus class field in the PDS Asteroid Taxonomy V6.0 table. Provenance records specify the PDS4 bundle bytes.

  4. doi:10.1051/0004-6361/202243791

    This work describes Gaia DR3 asteroid spectra, quality flags, and prior comparisons with ground spectra.

  5. doi:10.1051/0004-6361/202348752

    This prior work measures the 0.7 micrometre band in Gaia spectra. Our fixed signed scores test a different procedure.

  6. doi:10.1051/0004-6361/202245134

    This prior work corrects blue Gaia samples. Our scores use wavelengths at 550 nm and above.

  7. doi:10.1051/0004-6361/202556127

    This prior work classifies asteroids with Gaia spectra and other data. Its experiment differs from our fixed-score benchmark.

  8. doi:10.1051/0004-6361/202245311

    This prior Gaia and SDSS comparison reports survey color differences, including at high signal to noise.

  9. doi:10.1006/icar.2002.6857

    This paper describes the SMASS II observations and measurement limits.

  10. doi:10.1006/icar.2002.6856

    This paper defines the Bus classes used for the target and control groups.

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