Temperature and heating-induced temperature differences were measured along a chain of thermistors. SIMBA 2018T51 (a.k.a. Awi_33r) is an autonomous instrument that was installed on drifting sea ice in the Arctic Ocean during the expedition Oden AO18 in 2018. The thermistor chain was 5 m long and included 240 sensors with a regular spacing of 2 cm. The resulting time series describes the evolution of temperature and temperature differences after two heating cycles of 30 and 120 s as a function of location, depth and time between 2018-08-23 and 2019-03-30. Sample intervals are commonly between 1 and 24 hours, but most frequently hit intervals of 6 hours for temperature and 24 hours for temperature differences. In addition to temperature and geographic position, barometric pressure, air temperature measured approximately 1m over the ice level, tilt and compass were measured. The data set has been processed as follows: obvious inconsistencies (missing values) and unrealistic values in position have been removed. This instrument was deployed as part of the project Sea Ice Physics @ AWI (AWI_SeaIce).