  Over the past decade, time-domain astronomy in optical bands has developed
rapidly with the operations of some wide-field survey facilities. However, most
of these surveys are conducted with only a single band, and simultaneous color
information is usually unavailable for the objects monitored during the survey.
Here we present introductions to the system of Tsinghua University-Ma Huateng
Telescopes for Survey (TMTS), which consists of an array of four optical
telescopes installed on a single equatorial mount. Such a system is designed to
get multiband photometry simultaneously for stars and transients discovered
during the survey. The optics of each telescope is a modified
Hamilton-Newtonian system, covering the wavelengths from 400 to 900 nm, with a
field of view (FoV) of about 4.5 deg2 and a plate scale of 1.86"/pixel when
combining with a 4K*4K QHY4040 CMOS detector. The TMTS system can have a FoV of
about 9 deg2 when monitoring the sky with two bands (i.e., SDSS g and r
filters) at the same time, and a maximum FoV of ~18 deg2 when four telescopes
monitor different sky areas in monochromatic filter mode. For an exposure time
of 60 s, the average 3{\sigma} detection limit of the TMTS system can reach at
~19.4 mag in Luminous filter and at ~18.7 mag in SDSS r filter. The preliminary
discovery obtained during the first few months' survey is briefly discussed. As
this telescope array is located at the Xinglong Observatory of NAOC, it can
have an excellent synergy with the spectroscopic survey by the LAMOST (with a
FoV of about 20 deg2) at the same site, which will benefit the studies of
stellar and binary physics besides the transient sciences.
