old stars, and their rotations should appear in the NSD. The dynamical (rotational) time scale in the NSD is several Myr; hence, these stars may have orbited several times since their birth. Such tracers would provide important insight into the formation and dynamical evolution of stars in the NSD. The pulsations of Cepheids cause red- and blue-shifts of their stellar absorption lines, and spectra should preferably be taken at different pulsation epochs [see, for instance, @Marconi-2013]. In addition, the severe interstellar extinction toward the NSD demands infrared observations, although little research exists on the infrared spectroscopy of Cepheids [@Sasselov-1990; @Sabbey-1995; @Nardetto-2011]. The present work utilizes the $H$-band spectra between [15680 Å]{} and [17870 Å]{}; in this wavelength range the extinction for the Cepheids found near the NSD is around 4.5 mag in contrast to more than 30 mag in the optical. These infrared spectra are used for measuring the radial velocities in order to confirm the membership to the NSD and to study the kinematics within the NSD.

Observations
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Targets
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Our targets are the three Cepheids reported in @Matsunaga-2011 [@Matsunaga-2013], named [GCC-a]{}, -b, and -c, and a similar newly-discovered Cepheid, named [GCC-d]{} (Table \[tab:obj\]). Our recent survey of 