  The temporal heating and subsequent cooling of the crusts of transiently
accreting neutron stars carries unique information about their structure and a
variety of nuclear reaction processes. We report on a new Chandra Director's
Discretionary Time observation of the globular cluster Terzan 5, aimed to
monitor the transiently accreting 11-Hz X-ray pulsar IGR J17480-2446 after the
cessation of its recent 10-week long accretion outburst. During the
observation, which was performed ~125 days into quiescence, the source displays
a thermal spectrum that fits to a neutron star atmosphere model with a
temperature for an observer at infinity of kT~92 eV. This is ~10% lower than
found ~75 days earlier, yet ~20% higher than the quiescent base level measured
prior to the recent outburst. This can be interpreted as cooling of the
accretion-heated neutron star crust, and implies that crust cooling is
observable after short accretion episodes. Comparison with neutron star thermal
evolution simulations indicates that substantial heat must be released at
shallow depth inside the neutron star, which is not accounted for in current
nuclear heating models.
