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We present the fourth catalog of serendipitously discovered compactextragalactic emission-line sources -- H$\alpha$ Dots. A total of 454 newlydiscovered objects are included in the current survey list. These objects havebeen detected in searches of moderately deep narrow-band images acquired forthe ALFALFA H$\alpha$ project (Van Sistine et al. 2016). The catalog of H-alphaDots presented in the current paper was derived from searches carried out usingALFALFA H$\alpha$ images obtained with the KPNO 2.1 m telescope. This resultsin a substantially deeper sample of Dots compared to our previous lists, whichwere all discovered in images taken with the WIYN 0.9 m telescope. The medianR-band magnitude of the current catalog is 21.59, more than 1.6 magnitudesfainter than the median for the 0.9~m sample (factor of 4.4x fainter).Likewise, the median emission-line flux of the detected sources is a factor of4.3x fainter. The line-flux completeness limit of the current sample isapproximately 3 x 10$^{-16}$ erg/s/cm$^2$. We present accurate coordinates,apparent magnitudes and narrow-band line fluxes for each object in the sample.Unlike our previous lists of H$\alpha$ Dots, the current sample does notinclude follow-up spectroscopy.

The H$\alpha$ Dots Survey. IV. A Fourth List of Faint Emission-Line Objects