A High-amplitude Radial Velocity Variable in DESI DR1: Gaia DR3 3802130935635096832

Abstract I report a large-amplitude radial velocity (RV) variable, Gaia DR3 3802130935635096832, identified in the Dark Energy Spectroscopic Instrument (DESI) DR1 Milky Way Survey. The DESI catalog RVs span Δ RV max ≈ 146 km s −1 over 38.9 days. Gaia DR3 lists a neighbor at angular separation ρ ≃ 0 . ″ 688 (Δ G ≃ 2.21 mag), so contamination and background variability are plausible. Using per-exposure DESI cframe spectra, I find that sky-dominated wavelengths in the Z arm can bias the same-night pair; restricting to the Ca ii triplet window (8500–9000 Å) yields a trusted swing ΔRV ≈ 151 km s −1 . Relative spectrophotometric fluxes in this window are stable to ∼0.13 mag. The source merits resolved follow-up spectroscopy or imaging to distinguish a compact companion from a blended variable.