The man with two resistors problem.
Which one is the reference? It is the NTC resistor, and then the 10K 'standard' drifted -1 ppm?
Or it is the 10K standard the reference resistor and then it is the NTC resistor which has drifted?
Or did actually both 10K and NTC resistors drifted? And then, which one is expected to drift more?
In other words ... Is that ESI SR104 a big case for an NTC resistor worth US $9,000 plus a 10K 'standard' resistor besides given as gift. Or the other way around?
You will definitely need that Fluke probe and thermometer !