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We report on the detection at $>$98% confidence of an optical counterpart toAGC 249525, an Ultra-Compact High Velocity Cloud (UCHVC) discovered by theALFALFA blind neutral hydrogen survey. UCHVCs are compact, isolated HI cloudswith properties consistent with their being nearby low-mass galaxies, butwithout identified counterparts in extant optical surveys. Analysis of theresolved stellar sources in deep $g$- and $i$-band imaging from the WIYN pODIcamera reveals a clustering of possible Red Giant Branch stars associated withAGC 249525 at a distance of 1.64$\pm$0.45 Mpc. Matching our optical detectionwith the HI synthesis map of AGC 249525 from Adams et al. (2016) shows that thestellar overdensity is exactly coincident with the highest-density HI contourfrom that study. Combining our optical photometry and the HI properties of thisobject yields an absolute magnitude of $-7.1 \leq M_V \leq -4.5$, a stellarmass between $2.2\pm0.6\times10^4 M_{\odot}$ and $3.6\pm1.0\times10^5M_{\odot}$, and an HI to stellar mass ratio between 9 and 144. This object hasstellar properties within the observed range of gas-poor Ultra-Faint Dwarfs inthe Local Group, but is gas-dominated.

Detection of an Optical Counterpart to the ALFALFA Ultra-compact High Velocity Cloud AGC 249525