Spin Period Evolution of SMC X-1




Time (MJD) Freq (Hz) Freq_ERR (Hz) F_dot (s^-2) F_dot_ERR (s^-2) Events Z2^2 Value
55141 1.4240083 1e-07 2.081e-11 4e-14 7696 181.8
55198 1.4241239 1e-07 2.429e-11 4e-14 12757 267.1
55255 1.424259 1e-07 2.382e-11 4e-14 13280 161.7
55310 1.4243534 1e-07 2.317e-11 5e-14 12065 170.2
55363 1.4244604 1e-07 2.517e-11 5e-14 8941 244.2
55421 1.4245835 1e-07 2.097e-11 3e-14 11838 168.4
55481 1.4246899 1e-07 2.013e-11 4e-14 12115 119
55540 1.4248189 1e-07 2.424e-11 4e-14 14009 158.2
55599 1.4249414 1e-07 2.403e-11 4e-14 15450 258.3
55656 1.4250781 1e-07 2.964e-11 4e-14 14739 182.4
55710 1.4251947 1e-07 2.761e-11 5e-14 6322 113.3
55764 1.4253197 1e-07 2.8e-11 4e-14 10986 91.1
55818 1.4254376 1e-07 2.509e-11 5e-14 14922 379
55871 1.4255514 1e-07 2.674e-11 5e-14 11469 188.2
55925 1.4256705 1e-07 2.36e-11 5e-14 10288 194.4
55976 1.4257661 1e-07 2.255e-11 6e-14 8411 142.4
56025 1.4258712 1e-07 2.714e-11 5e-14 10361 173.2
56078 1.4259987 1e-07 3.106e-11 4e-14 6732 74
56137 1.4261344 1e-07 2.796e-11 3e-14 6371 89
56197 1.4262785 1e-07 2.526e-11 4e-14 6568 68
56254 1.4263921 1e-07 2.7e-11 4e-14 6760 103.4
56311 1.4265115 1e-07 2.655e-11 4e-14 8966 98.4
56368 1.4266273 1e-07 2.563e-11 4e-14 5843 52.8
56426 1.4267431 1e-07 2.457e-11 4e-14 5623 51.3
56485 1.4268652 1e-07 2.074e-11 4e-14 5491 47.5
56544 1.4269959 1e-07 2.965e-11 4e-14 7488 86.5
56599 1.4271148 1e-07 2.335e-11 5e-14 6813 70.3
56649 1.4272283 1e-07 2.435e-11 5e-14 5271 87
56704 1.427356 1e-07 3.015e-11 4e-14 6170 77.2
56759 1.4274809 1e-07 2.605e-11 5e-14 7197 137.1
56812 1.4275901 1e-07 2.458e-11 4e-14 7259 101.8
56866 1.4276921 1e-07 2.229e-11 5e-14 5276 58.3
56915 1.4277966 1e-07 2.03e-11 6e-14 4541 46.2
56961 1.4278905 1e-07 2.476e-11 6e-14 6292 67.4
57006 1.4279816 1e-07 2.266e-11 7e-14 4415 82.3
57046 1.4280613 2e-07 2.494e-11 1e-13 3877 82.8
57085 1.4281527 1e-07 2.895e-11 8e-14 4321 72.1
57129 1.4282565 1e-07 2.392e-11 6e-14 5960 67.4
57180 1.4283766 1e-07 2.982e-11 4e-14 7755 124.1
57229 1.4284871 1e-07 2.399e-11 8e-14 4112 57.7
57272 1.4285729 1e-07 2.185e-11 7e-14 4712 68.5
57319 1.4286749 1e-07 2.523e-11 5e-14 6670 38.9
57369 1.4287774 1e-07 2.133e-11 5e-14 4798 100.6
57421 1.4288891 1e-07 2.783e-11 5e-14 5864 70.6
57474 1.4290248 1e-07 2.804e-11 5e-14 7793 71.4
57528 1.4291431 1e-07 2.556e-11 4e-14 7505 80.9
57583 1.4292693 1e-07 2.585e-11 5e-14 4966 68.2
57635 1.4293987 1e-07 2.426e-11 5e-14 5920 37.5
57687 1.4295118 1e-07 2.318e-11 5e-14 8006 113.9
57743 1.4296318 1e-07 2.561e-11 4e-14 7912 82.8
57798 1.4297494 1e-07 2.4e-11 5e-14 5408 91.1
57852 1.4298754 1e-07 3.038e-11 4e-14 6858 74.1
57905 1.4299971 1e-07 2.18e-11 5e-14 7958 68.5
57962 1.4301205 1e-07 2.325e-11 3e-14 9474 130.4
58022 1.430241 1e-07 2.246e-11 4e-14 5901 59.6
58077 1.4303309 1e-07 1.78e-11 5e-14 6083 54.4
58126 1.430446 1e-07 2.507e-11 7e-14 9429 69.1
58174 1.4305565 1e-07 2.843e-11 5e-14 6975 69.7
58226 1.4306662 1e-07 2.656e-11 5e-14 5792 51.2
58280 1.4307847 1e-07 2.605e-11 4e-14 9010 79
58333 1.4308939 1e-07 2.589e-11 5e-14 8908 136.6
58382 1.4310074 1e-07 2.778e-11 6e-14 4971 55.1
58427 1.431112 1e-07 2.663e-11 8e-14 6863 75.7
58473 1.4312158 1e-07 2.834e-11 5e-14 7916 77.7
58526 1.4313410 1e-07 2.970e-11 4e-14 5524 132.1
58586 1.4314959 1e-07 2.931e-11 4e-14 6830 61.11
58639 1.4316334 1e-07 3.262e-11 5e-14 10519 137.9
58692 1.4317726 1e-07 3.342e-11 4e-14 10599 150.1
58745 1.4319160 1e-07 3.134e-11 5e-14 6895 148.5
58793 1.4320363 1e-07 2.839e-11 7e-14 7005 92.0
58834 1.4321353 1e-07 2.670e-11 7e-14 8842 101.2
58884 1.4322533 1e-07 2.827e-11 5e-14 6549 125.2
58934 1.4323730 1e-07 2.589e-11 6e-14 8386 97.4
58982 1.4324797 1e-07 2.579e-11 6e-14 8774 130.1
59057 1.4326459 2e-07 2.501e-11 9e-14 6853 133.0
59094 1.4327270 1e-07 2.803e-11 8e-14 3981 60.7
59139 1.4328296 1e-07 2.690e-11 5e-14 10802 108.8
59185 1.4329339 1e-07 2.760e-11 6e-14 4998 62.8
59232 1.4330281 1e-07 2.177e-11 7e-14 6282 75.2
59276 1.4331219 1e-07 2.873e-11 7e-14 9789 79.3
59323 1.4332338 1e-07 2.800e-11 5e-14 5805 49.7
59368 1.4333402 1e-07 2.597e-11 5e-14 5805 84.0
59414 1.4334424 1e-07 1.997e-11 5e-14 5548 45.0
59465 1.4335354 1e-07 2.514e-11 5e-14 5287 56.4
59518 1.4336532 1e-07 2.453e-11 5e-14 8617 78.2
59572 1.4337745 1e-07 2.876e-11 4e-14 14596 150.3
59628 1.4339109 1e-07 2.509e-11 4e-14 10170 89.7
59685 1.4340353 1e-07 2.279e-11 4e-14 5207 63.6
59743 1.4341704 1e-07 2.980e-11 4e-14 5869 89.9


Orbital parameters
Orbital Frequency (day) 0.25694194948
Orbital Frequency Deriv. (day^-2) 2.37935828467E-9
T_pi/2 (MJD) 52846.6912486
a sin(i) (lt-s) 53.48
Eccentricity 0.0009
Periastron Angle 10


Note1: Historical measurements before MAXI are obtained from Inam et al. (2010) and reference therein.
Note2: Please cite Hu et al. (2019) and Hu et al. (2023) when using this in your work.