A New Cold Stream near the Southern Galactic Pole

We report the discovery of a cold stream near the southern Galactic pole (dubbed as SGP-S) detected in $Gaia$ Early Data Release 3. The stream is at a heliocentric distance of $\sim$ 9.5 kpc and spans nearly 58${}^{\circ }$ by 0.6${}^{\circ }$ on sky. The colour-magnitude diagram of SGP-S indicates an old and metal-poor (age $\sim$ 12 Gyr, [M/H] $\sim$ -2.0 dex) stellar population. The stream’s surface brightness reaches an exceedingly low level of ${\mathrm{\Sigma }}_G\simeq$ 36.2 mag arcsec${}^{-2}$. Neither extant globular clusters nor other known streams are associated with SGP-S.