#zdat (zcalib by M.Zolliker 2018)
#time since midnight, R ref, R meas, sigma
43742.37	35636.98	46958.95	38.7498935
45872.41	31270.09	40948.93	7.55712975
52067.31	26804.28	34824.47	3.72934445
55641.47	21995.97	28266.33	9.47822821
57604.32	17888.38	22759.57	3.22998607
59566.33	14613.6	18428.56	1.75118246
61542.37	11937.87	14913.07	1.58335403
70270.44	78.9836	91.4431	0.00185714835
74790.45	71.5259	82.847	0.0014832397
79129.31	65.138	75.4783	0.00103004854
82659.31	62.0709	71.9378	0.00144775689
85702.40	60.4077	70.0165	0.00136565003