  The SPECtrophotometer for TRansmission spectroscopy of exoplanets (SPECTR) is
a new low-resolution optical (3800 {\AA} - 6850 {\AA}) spectrophotometer
installed at the Bohyunsan Optical Astronomy Observatory (BOAO) 1.8 m
telescope. SPECTR is designed for observing the transmission spectra of
transiting exoplanets. Unique features of SPECTR are its long slit length of 10
arcminutes which facilitates observing the target and the comparison star
simultaneously, and its wide slit width to minimize slit losses. SPECTR will be
used to survey exoplanets, such as those identified by the Transiting Exoplanet
Survey Satellite (TESS), providing information about their radii across the
wavelength range. In this paper, we present the design of SPECTR and the
observational results of the partial transit of HD 189733 b and a full transit
of Qatar-8 b. Analyses show the SPECTR's capability on the white light curves
with an accuracy of one ppt. The transmission spectrum of HD 189733 b shows
general agreement with previous studies.
