The Sizes of $z\sim9-10$ Galaxies Identified in the BoRG Survey
  Redshift $z=9--10$ object selection is the effective limit of Hubble Space
Telescope imaging capability, even when confirmed with Spitzer. If only a few
photometry data points are available, it becomes attractive to add criteria
based on their morphology in these J- and H-band images.
  One could do so through visual inspection, a size criterion, or alternate
morphometrics. We explore a vetted sample of BoRG $z\sim9$ and $z\sim10$
candidate galaxies and the object rejected by Morishita+ (2018) to explore the
utility of a size criterion in z=9-10 candidate selection. A stringent,
PSF-corrected effective radius criterion ($r_e<0\farcs3$) would result in the
rejection of 65-70\% of the interlopers visually rejected by Morishita+. It may
also remove up to $\sim20$\% of bona-fide brightest ($L>>L^*$) z=9 or 10
candidates from a BoRG selected sample based on the Mason+ (2015) luminosity
functions, assuming the Holwerda+ (2015) $z\sim9$ size-luminosity relation. We
argue that including a size constraint in lieu of a visual inspection may serve
in wide-field searches for these objects in e.g. EUCLID or HST archival imaging
with the understanding that some brightest ($L>>L^*$) candidates may be missed.
  The sizes of the candidates found by Morishita+ (2018) follow the expected
size distribution of $z\sim9$ for bright galaxies, consistent with the
lognormal in Shibuya+ (2015) and single objects. Two candidates show high
star-formation surface density ($\Sigma_{SFR} > 25 M_\odot/kpc^2$) and all
merit further investigation and follow-up observations.
