#zdat (zcalib by M.Zolliker 2018)
#time since midnight, R ref, R meas, sigma
44075.44	35612.98	11467.38	0.500159974
46205.43	31228.29	10373.52	0.645879246
52400.44	26845.82	9228.4	0.402492236
55974.32	22002.05	7916.19	0.684755431
57937.32	17885.1	6748.13	0.254578082
59899.33	14615.56	5776.21	0.155209536
61875.46	11938.91	4937.685	0.138486461
70603.40	78.8533	76.6798	0.00170762994
75123.39	71.4354	70.1416	0.000885437745
79462.46	65.0644	64.4673	0.00122515305
82992.46	61.9986	61.7145	0.000992471662
86035.44	60.3502	60.2281	0.000830060239