Galaxy groups in the 2MASS Redshift Survey
  A galaxy group catalog is constructed from the 2MASS Redshift Survey (2MRS)
with the use of a halo-based group finder. The halo mass associated with a
group is estimated using a `GAP' method based on the luminosity of the central
galaxy and its gap with other member galaxies. Tests using mock samples shows
that this method is reliable, particularly for poor systems containing only a
few members. On average 80% of all the groups have completeness >0.8, and about
65% of the groups have zero contamination. Halo masses are estimated with a
typical uncertainty $\sim 0.35\,{\rm dex}$. The application of the group finder
to the 2MRS gives 29,904 groups from a total of 43,246 galaxies at $z \leq
0.08$, with 5,286 groups having two or more members. Some basic properties of
this group catalog is presented, and comparisons are made with other groups
catalogs in overlap regions. With a depth to $z\sim 0.08$ and uniformly
covering about 91% of the whole sky, this group catalog provides a useful data
base to study galaxies in the local cosmic web, and to reconstruct the mass
distribution in the local Universe.
