Orbital Analysis for matched events on 20210929_223145.364_UK

Summary for Event
-----------------
shower ID 17 NTA
Lg 22.37° Bg 7.02° Vg 32.56km/s
mass 0.00982g, abs. mag 1.6
Path Details
------------
start -0.08° 51.81° 94.63km
end   -0.16° 51.85° 87.21km

Orbit Details
-------------
Semimajor axis 2.81A.U., eccentricity 0.90, inclination 10.72°, Period 4.70Y, LA Sun 186.70°, last Perihelion 2017-02-25

Full details below
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Input measurement type: Azimuth +east of due north for meas1, Elevation angle above the horizon for meas2

Uncertainties type:
 Purely geometric uncertainties

Reference JD: 2459487.438719500322
Time: 2021-09-29 22:31:45.364828 UTC


Plane intersections
-------------------
Intersection 1 - Stations: UK002C and UK002F
 Convergence angle = 5.26749 deg
 R.A. =  23.43664  Dec = +21.31791 deg
Intersection 2 - Stations: UK002C and UK0035
 Convergence angle = 28.52889 deg
 R.A. =  16.56092  Dec = +15.91251 deg
Intersection 3 - Stations: UK002F and UK0035
 Convergence angle = 33.74717 deg
 R.A. =  17.97947  Dec = +16.20248 deg

Best intersection: Stations UK002F and UK0035 with Qconv = 33.75 deg


Least squares solution
----------------------
State vector (ECI, epoch of date):
 X =   3903475.48 +/- 90.86 m
 Y =   -918732.24 +/- 72.73 m
 Z =   5064131.97 +/- 71.63 m
 Vx =    31438.84 +/- 394.06 m/s
 Vy =    10019.52 +/- 344.05 m/s
 Vz =     9724.25 +/- 348.28 m/s

State vector covariance matrix (X, Y, Z, Vx, Vy, Vz):
+7.505317e+03, +5.599145e+03, +5.708957e+03, -1.384273e+04, +1.206102e+04, +1.740006e+04
+5.599145e+03, +4.849426e+03, +4.244596e+03, -9.010700e+03, +1.148320e+04, +1.272918e+04
+5.708957e+03, +4.244596e+03, +4.769373e+03, -8.081987e+03, +9.026949e+03, +1.568018e+04
-1.384273e+04, -9.010700e+03, -8.081987e+03, +8.273847e+04, -1.646038e+04, -9.774116e+03
+1.206102e+04, +1.148320e+04, +9.026949e+03, -1.646038e+04, +6.152772e+04, +4.312643e+04
+1.740006e+04, +1.272918e+04, +1.568018e+04, -9.774116e+03, +4.312643e+04, +6.658024e+04

Timing offsets (from input data):
    UK000F: 0.000000 s
    UK002C: -0.000483 s
    UK002F: 0.000000 s
    UK0035: -0.000880 s

Reference point on the trajectory:
  Time: 2021-09-29 22:31:45.364828 UTC
  Lon     = +-0.083724 +/- 0.0013 deg
  Lat     = +51.809760 +/- 0.0002 deg
  Lat geo = +51.625342 +/- 0.0002 deg
  Ht      =   94599.76 +/- 100.13 m

  JD dynamic   = 2459487.439520241227 
  LST apparent = 346.7557608529 deg
Radiant (apparent in ECI which includes Earth's rotation, epoch of date):
  R.A.      =  17.67702 +/- 0.5125 deg
  Dec       = +16.42038 +/- 0.4724 deg
  Azimuth   = 133.75792 +/- 0.9076 deg
  Elevation = +46.96580 +/- 0.2810 deg
  Vavg      =  32.29685 +/- 0.2509 km/s
  Vinit     =  34.39990 +/- 0.2665 km/s
Radiant (apparent ground-fixed, epoch of date):
  R.A.      =  18.11064 +/- 0.5125 deg
  Dec       = +16.34948 +/- 0.4724 deg
  Azimuth   = 133.26873 +/- 0.9076 deg
  Elevation = +46.70869 +/- 0.2810 deg
  Vavg      =  32.44193 +/- 0.2509 km/s
  Vinit     =  34.54497 +/- 0.2665 km/s
Radiant (geocentric, J2000):
  R.A.   =  17.99029 +/- 0.5231 deg
  Dec    = +15.20945 +/- 0.4845 deg
  Vg     =  32.55677 +/- 0.2817 km/s
  Vinf   =  34.39990 +/- 0.2665 km/s
  Zc     =  42.90682 +/- 0.2798 deg
  Zg     =  44.14636 +/- 0.2910 deg
Radiant (ecliptic geocentric, J2000):
  Lg     =  22.37381 +/- 0.6282 deg
  Bg     =  +7.01666 +/- 0.3193 deg
  Vh     =  38.14819 +/- 0.3378 km/s
Radiant (ecliptic heliocentric, J2000):
  Lh     = 333.07935 +/- 0.4285 deg
  Bh     =  +5.98738 +/- 0.2965 deg
  Vh_x   = -33.82869 +/- 0.3063 km/s
  Vh_y   =  17.17761 +/- 0.3275 km/s
  Vh_z   =  -3.97921 +/- 0.1851 km/s
Orbit:
  La Sun = 186.698138 +/- 0.0000 deg
  a      =   2.806096 +/- 0.2709 AU
  e      =   0.903214 +/- 0.0071
  i      =  10.724596 +/- 0.5850 deg
  peri   = 302.390406 +/- 1.2827 deg
  node   = 186.705133 +/- 0.0004 deg
  Pi     = 129.095539 +/- 1.2824 deg
  q      =   0.271590 +/- 0.0077 AU
  f      = 237.602747 +/- 1.2824 deg
  M      = 351.735128 +/- 1.0180 deg
  Q      =   5.340602 +/- 0.5370 AU
  n      =   0.209677 +/- 0.0249 deg/day
  T      =   4.700612 +/- 0.7102 years
  Last perihelion JD = 2457809.928381 (2017-02-25 10:16:52.143441) +/- 259.5908 days
  Tj     =   2.473925 +/- 0.1456
Shower association:
  IAU No.  =   17
  IAU code =  NTA

Orbit covariance matrix:
             e     ,     q (AU)   ,      Tp (JD) ,   node (rad) ,   peri (rad) ,    i (rad)
e   , +4.508360e-05, +1.314995e-05, -1.529715e+00, +5.888585e-09, -7.742344e-05, -7.348364e-06
q   , +1.314995e-05, +4.962987e-05, -9.241926e-01, +3.357389e-08, -1.341173e-04, -4.472680e-05
Tp  , -1.529715e+00, -9.241926e-01, +5.699203e+04, -5.466855e-04, +3.791632e+00, +7.161318e-01
node, +5.888585e-09, +3.357389e-08, -5.466855e-04, +5.188196e-11, -8.731241e-08, -7.039735e-08
peri, -7.742344e-05, -1.341173e-04, +3.791632e+00, -8.731241e-08, +4.046371e-04, +1.158489e-04
i   , -7.348364e-06, -4.472680e-05, +7.161318e-01, -7.039735e-08, +1.158489e-04, +9.582645e-05

Jacchia fit on lag = -|a1|*exp(|a2|*t):
 a1 = 3.451342
 a2 = 17.914273

Mean time residuals from time vs. length:
  Station with reference time: UK002F
  Avg. res. = 7.183e-06 s
  Stddev    = 2.68e-03 s

Begin point on the trajectory:
  Lon =    -0.083478 +/- 0.0013 deg
  Lat =    51.809614 +/- 0.0001 deg
  Ht  = 94625.32 +/- 97.60 m
End point on the trajectory:
  Lon =    -0.156442 +/- 0.0015 deg
  Lat =    51.852063 +/- 0.0001 deg
  Ht  = 87209.94 +/- 99.80 m

Stations
--------
        ID, Ignored, Lon +E (deg), Lat +N (deg),  Ht (m), Jacchia a1, Jacchia a2,  Beg Ht (m),  End Ht (m), +/- Obs ang (deg), +/- V (m), +/- H (m), Persp. angle (deg), Weight, FOV Beg, FOV End, Comment
    UK000F,    True,    -1.306160,    51.883100,   80.00,  21.297528,  10.894514,    93210.28,    86706.43,          0.444915,       nan,       nan,              25.95, 0.0000,    True,    True, {"ff_name": "FF_UK000F_20210929_223138_408_0377344.fits"}
    UK002C,   False,    -1.801980,    51.351940,  130.00,   0.089717,  33.761205,    94165.89,    88485.97,          0.016657,     43.71,     13.44,              49.78, 0.5830,    True,    True, {"ff_name": "FF_UK002C_20210929_223138_772_0374272.fits"}
    UK002F,   False,    -1.306160,    51.883100,   80.00,   6.806158,  15.729203,    94625.32,    87209.94,          0.010055,     20.31,      6.83,              25.95, 0.1915,    True,    True, {"ff_name": "FF_UK002F_20210929_223145_139_0360704.fits"}
    UK0035,   False,     1.010397,    52.949859,   25.00,   0.000000,   0.000000,    92361.70,    88482.91,          0.010470,     31.34,      2.91,              57.22, 0.7068,    True,    True, {"ff_name": "FF_UK0035_20210929_223138_327_0389120.fits"}

Points
------
 No, Station ID,  Ignore,  Time (s),                   JD,     meas1,     meas2, Azim +E of due N (deg), Alt (deg), Azim line (deg), Alt line (deg), RA obs (deg), Dec obs (deg), RA line (deg), Dec line (deg),       X (m),       Y (m),       Z (m), Latitude (deg), Longitude (deg), Height (m),  Range (m), Length (m), State vect dist (m),  Lag (m), Vel (m/s), Vel prev avg (m/s), H res (m), V res (m), Ang res (asec), AppMag, AbsMag
  0,     UK000F,       1,  0.056212, 2459487.438720150851,  38.81679,  33.50584,               94.40242,  47.90373,        94.51685,       47.49982,     38.81679,     +33.50584,      39.11084,      +33.17596,  3901738.05,  -919285.95,  5063594.57,      51.817707,       -0.097353,   93210.28,  125561.92,       0.00,             1901.07,   -86.71,      0.00,           33693.87,   -291.95,    852.48,        1480.25,  +2.59,  +2.10
  1,     UK000F,       1,  0.096092, 2459487.438720612321,  39.08628,  33.71329,               93.94832,  47.87753,        94.07488,       47.44144,     39.08628,     +33.71329,      39.40424,      +33.35638,  3900335.54,  -919732.93,  5063160.76,      51.824124,       -0.108338,   92088.80,  124171.68,    1534.61,             3435.68,    76.03,  38480.69,           33693.87,   -312.40,    910.90,        1599.65,  +2.38,  +1.91
  2,     UK000F,       1,  0.136028, 2459487.438721074723,  39.33803,  33.85095,               93.58697,  47.81491,        93.71266,       47.39300,     39.33803,     +33.85095,      39.64544,      +33.50455,  3899206.35,  -920092.80,  5062811.50,      51.829291,       -0.117221,   91185.99,  123053.44,    2770.15,             4671.21,   -62.23,  30937.92,           33693.87,   -299.66,    874.30,        1549.23,  +2.28,  +1.83
  3,     UK000F,       1,  0.175924, 2459487.438721536659,  39.57904,  34.03053,               93.18909,  47.78664,        93.32505,       47.33958,     39.57904,     +34.03053,      39.90515,      +33.66276,  3898018.12,  -920471.49,  5062443.97,      51.834729,       -0.126564,   90236.08,  121879.70,    4070.29,             5971.36,  -134.50,  32588.38,           33693.87,   -315.07,    918.26,        1642.97,  +1.68,  +1.25
  4,     UK000F,       1,  0.215852, 2459487.438721998595,  39.84152,  34.17938,               92.80842,  47.72422,        92.94509,       47.28598,     39.84152,     +34.17938,      40.16105,      +33.81771,  3896872.77,  -920836.51,  5062089.71,      51.839972,       -0.135580,   89320.54,  120750.61,    5323.51,             7224.58,  -254.80,  31387.03,           33029.87,   -306.21,    892.80,        1612.30,  +1.77,  +1.36
  5,     UK000F,       1,  0.255772, 2459487.438722460531,  40.10512,  34.33772,               92.41736,  47.66712,        92.55701,       47.22981,     40.10512,     +34.33772,      40.42393,      +33.97575,  3895722.28,  -921203.17,  5061733.85,      51.845239,       -0.144641,   88400.99,  119619.08,    6582.37,             8483.43,  -369.19,  31534.37,           32626.51,   -303.01,    883.51,        1610.60,  +1.75,  +1.36
  6,     UK000F,       1,  0.295704, 2459487.438722922932,  40.36449,  34.47747,               92.05142,  47.59995,        92.19015,       47.17568,     40.36449,     +34.47747,      40.67362,      +34.12513,  3894652.00,  -921544.27,  5061402.81,      51.850140,       -0.153086,   87545.64,  118568.30,    7753.44,             9654.51,  -571.77,  29326.77,           32128.76,   -291.59,    850.66,        1564.37,  +2.77,  +2.40
  7,     UK000F,       1,  0.335588, 2459487.438723384403,  40.57921,  34.66628,               91.66801,  47.59253,        91.82456,       47.12052,     40.57921,     +34.66628,      40.92376,      +34.27384,  3893601.82,  -921878.96,  5061077.98,      51.854949,       -0.161379,   86706.43,  117539.42,    8902.54,            10803.60,  -794.68,  28810.88,           31645.16,   -322.39,    938.61,        1741.59,  +4.26,  +3.91
  0,     UK002C,       0,  0.015688, 2459487.438719687052,  67.33374,  41.15322,               66.00313,  35.23921,        66.01054,       35.23033,     67.33374,     +41.15322,      67.33750,      +41.14284,  3902932.99,  -918905.13,  5063964.17,      51.812241,       -0.087973,   94165.89,  160704.82,       0.00,              593.58,    -0.20,      0.00,           34808.87,     -8.87,    -28.82,          38.70,  +3.51,  +2.48
  1,     UK002C,       0,  0.055804, 2459487.438720151316,  67.79909,  41.21381,               65.66731,  35.01364,        65.65131,       35.03270,     67.79909,     +41.21381,      67.79154,      +41.23619,  3901740.36,  -919285.22,  5063595.29,      51.817697,       -0.097335,   93212.13,  159846.26,    1304.95,             1898.54,   -75.24,  32529.51,           34808.87,     18.96,     61.67,          83.26,  +3.08,  +2.06
  2,     UK002C,       0,  0.095896, 2459487.438720615115,  68.35274,  41.34873,               65.21082,  34.78748,        65.21118,       34.78706,     68.35274,     +41.34873,      68.35331,      +41.34823,  3900287.10,  -919748.37,  5063145.78,      51.824346,       -0.108713,   92050.08,  158810.33,    2895.09,             3488.67,   135.74,  39662.18,           34808.87,     -0.42,     -1.37,           1.87,  +2.35,  +1.35
  3,     UK002C,       0,  0.135976, 2459487.438721079379,  68.78997,  41.44197,               64.86354,  34.60110,        64.86895,       34.59472,     68.78997,     +41.44197,      68.79305,      +41.43442,  3899165.60,  -920105.79,  5062798.89,      51.829478,       -0.117537,   91153.41,  158015.27,    4122.23,             4715.81,   -15.87,  30617.15,           34808.87,     -6.31,    -20.50,          28.00,  +1.99,  +1.00
  4,     UK002C,       0,  0.176100, 2459487.438721543644,  69.34124,  41.52758,               64.45592,  34.34622,        64.44839,       34.35504,     69.34124,     +41.52758,      69.33857,      +41.53807,  3897794.08,  -920542.89,  5062374.67,      51.835755,       -0.128297,   90056.99,  157052.58,    5622.92,             6216.50,   104.56,  37401.41,           35070.49,      8.70,     28.27,          38.84,  +2.26,  +1.28
  5,     UK002C,       0,  0.216176, 2459487.438722007442,  69.73157,  41.60391,               64.15360,  34.17686,        64.14815,       34.18322,     69.73157,     +41.60391,      69.73005,      +41.61151,  3896822.32,  -920852.59,  5062074.10,      51.840203,       -0.135974,   89280.22,  156373.15,    6686.21,             7279.79,  -210.77,  26531.74,           33926.14,      6.27,     20.36,          28.10,  +2.48,  +1.51
  6,     UK002C,       0,  0.256276, 2459487.438722471707,  70.14362,  41.65420,               63.86249,  33.97875,        63.83975,       34.00517,     70.14362,     +41.65420,      70.13483,      +41.68581,  3895828.62,  -921169.28,  5061766.74,      51.844752,       -0.143823,   88485.97,  155683.09,    7773.50,             8367.08,  -502.91,  27114.48,           32787.50,     25.92,     84.30,         116.85,  +5.39,  +4.43
  0,     UK002F,       0,  0.000000, 2459487.438719500322,  38.75488,  32.94942,               95.06301,  47.56477,        95.06184,       47.56874,     38.75488,     +32.94942,      38.75205,      +32.95270,  3903507.44,  -918722.05,  5064141.85,      51.809614,       -0.083478,   94625.32,  127321.88,       0.00,               34.97,   -19.14,      0.00,           35336.32,      2.86,      8.52,          14.56,  +2.66,  +2.14
  1,     UK002F,       0,  0.040128, 2459487.438719964586,  39.03903,  33.13535,               94.62119,  47.51632,        94.62224,       47.51285,     39.03903,     +33.13535,      39.04167,      +33.13247,  3902077.07,  -919177.91,  5063699.43,      51.816157,       -0.094671,   93481.39,  125899.75,    1565.08,             1530.11,    95.61,  39002.17,           35336.32,     -2.48,     -7.38,          12.75,  +2.42,  +1.92
  2,     UK002F,       0,  0.080248, 2459487.438720429316,  39.29993,  33.30070,               94.22236,  47.46777,        94.22440,       47.46116,     39.29993,     +33.30070,      39.30497,      +33.29522,  3900807.03,  -919582.67,  5063306.60,      51.821967,       -0.104634,   92465.80,  124639.12,    2954.75,             2919.78,   105.15,  34637.73,           35336.32,     -4.68,    -13.91,          24.29,  +1.85,  +1.37
  3,     UK002F,       0,  0.120356, 2459487.438720893115,  39.54661,  33.46407,               93.83849,  47.42623,        93.84346,       47.41050,     39.54661,     +33.46407,      39.55831,      +33.45098,  3899612.06,  -919963.50,  5062936.99,      51.827435,       -0.114024,   91510.36,  123455.21,    4262.26,             4227.29,    32.95,  32599.85,           35336.32,    -11.05,    -32.84,          57.89,  +1.61,  +1.15
  4,     UK002F,       0,  0.160468, 2459487.438721357379,  39.78906,  33.61505,               93.47251,  47.37857,        93.47822,       47.36088,     39.78906,     +33.61505,      39.80233,      +33.60028,  3898485.23,  -920322.62,  5062588.45,      51.832591,       -0.122891,   90609.49,  122340.75,    5495.22,             5460.26,  -113.93,  30738.06,           34119.94,    -12.34,    -36.66,          65.21,  +1.79,  +1.35
  5,     UK002F,       0,  0.200620, 2459487.438721822109,  40.11336,  33.79501,               93.00835,  47.29960,        93.01008,       47.29440,     40.11336,     +33.79501,      40.11790,      +33.79065,  3897067.70,  -920774.39,  5062150.00,      51.839080,       -0.134010,   89476.36,  120944.24,    7046.27,             7011.30,    55.88,  38629.21,           34417.10,     -3.59,    -10.67,          19.19,  +1.84,  +1.43
  6,     UK002F,       0,  0.240720, 2459487.438722286373,  40.32121,  33.91013,               92.71194,  47.24859,        92.71069,       47.25229,     40.32121,     +33.91013,      40.31959,      +33.91324,  3896175.56,  -921058.71,  5061874.05,      51.843164,       -0.141074,   88763.27,  120064.43,    8022.43,             7987.46,  -347.39,  24343.27,           33444.43,      2.54,      7.55,          13.69,  +2.18,  +1.78
  7,     UK002F,       0,  0.280800, 2459487.438722750172,  40.51269,  34.04667,               92.40605,  47.22180,        92.41035,       47.20924,     40.51269,     +34.04667,      40.52279,      +34.03610,  3895292.11,  -921340.27,  5061600.80,      51.847209,       -0.148072,   88057.18,  119194.69,    8989.08,             8954.11,  -759.48,  24118.03,           32262.80,     -8.56,    -25.43,          46.43,  +3.03,  +2.65
  8,     UK002F,       0,  0.320928, 2459487.438723214902,  40.77514,  34.17981,               92.04683,  47.14873,        92.04469,       47.15484,     40.77514,     +34.17981,      40.77215,      +34.18496,  3894231.96,  -921678.14,  5061272.88,      51.852063,       -0.156442,   87209.94,  118154.66,   10149.09,            10114.12,  -979.88,  28907.64,           31487.46,      4.13,     12.27,          22.61,  +3.21,  +2.85
  0,     UK0035,       1,  0.046757, 2459487.438720050268, 321.52699,  -1.21831,              211.34006,  31.53016,       211.35598,       31.54720,    321.52699,      -1.21831,     321.51965,       -1.19787,  3901708.47,  -919295.38,  5063585.42,      51.817843,       -0.097544,   93186.62,  174786.90,       0.00,             1933.44,   270.88,      0.00,           31929.21,      6.16,     66.17,          78.42,  +6.22,  +5.01
  1,     UK0035,       0,  0.086981, 2459487.438720515929, 321.22153,  -1.31081,              211.64566,  31.34622,       211.64872,       31.34947,    321.22153,      -1.31081,     321.22045,       -1.30689,  3900676.84,  -919624.16,  5063266.33,      51.822562,       -0.105670,   92361.70,  174198.39,    1128.79,             3062.22,    15.97,  28062.53,           31929.21,      1.17,     12.64,          15.03,  +2.48,  +1.27
  2,     UK0035,       0,  0.127225, 2459487.438720981590, 320.90039,  -1.42474,              211.95939,  31.13622,       211.96035,       31.13723,    320.90039,      -1.42474,     320.90048,       -1.42352,  3899580.60,  -919973.53,  5062927.26,      51.827579,       -0.114298,   91485.20,  173578.63,    2328.28,             4261.72,  -168.93,  29805.47,           31929.21,      0.36,      3.93,           4.69,  +2.02,  +0.82
  3,     UK0035,       0,  0.167553, 2459487.438721448183, 320.48553,  -1.58569,              212.35738,  30.85072,       212.36490,       30.85868,    320.48553,      -1.58569,     320.48269,       -1.57608,  3898157.68,  -920427.01,  5062487.14,      51.834091,       -0.125454,   90347.65,  172781.85,    3885.21,             5818.65,     0.72,  38606.76,           31929.21,      2.86,     30.77,          36.89,  +2.28,  +1.09
  4,     UK0035,       0,  0.207841, 2459487.438721914776, 320.08130,  -1.70154,              212.75831,  30.61007,       212.74409,       30.59508,    320.08130,      -1.70154,     320.08886,       -1.71971,  3896829.14,  -920850.42,  5062076.21,      51.840172,       -0.135887,   89285.69,  172047.75,    5338.88,             7272.32,    68.49,  36081.88,           33358.08,     -5.36,    -57.88,          69.68,  +2.65,  +1.47
  5,     UK0035,       0,  0.248077, 2459487.438722380437, 319.78458,  -1.82245,              213.03762,  30.39873,       213.03245,       30.39330,    319.78458,      -1.82245,     319.78805,       -1.82904,  3895824.76,  -921170.51,  5061765.55,      51.844770,       -0.143820,   88482.91,  171500.18,    6437.86,             8371.30,  -216.64,  27313.43,           32903.30,     -1.94,    -20.93,          25.29,  +4.47,  +3.30

Notes
-----
- Points that have not been taken into consideration when computing the trajectory have '1' in the 'Ignore' column.
- The time already has time offsets applied to it.
- 'meas1' and 'meas2' are given input points.
- X, Y, Z are ECI (Earth-Centered Inertial) positions of projected lines of sight on the radiant line.
- Zc is the observed zenith distance of the entry angle, while the Zg is the entry zenith distance corrected for Earth's gravity.
- Latitude (deg) and Longitude (deg) are in WGS84 coordinates, while Height (m) is in the EGM96 datum. There values are coordinates of each point on the radiant line.
- Jacchia (1955) deceleration equation fit was done on the lag.
- Right ascension and declination in the table are given in the epoch of date for the corresponding JD, per every point.
- 'RA and Dec obs' are the right ascension and declination calculated from the observed values, while the 'RA and Dec line' are coordinates of the lines of sight projected on the fitted radiant line. The coordinates are in the epoch of date, and NOT J2000!. 'Azim and alt line' are thus corresponding azimuthal coordinates.
- 'Vel prev avg' is the average velocity including all previous points up to the given point. For the first 4 points this velocity is computed as the average velocity of those 4 points.