Fixed Stephenson, Morrison & Hohenkerk solution for DeltaT

- This solution by F. R. Stephenson, L. V. Morrison and C. Y. Hohenkerk (2016) was published in "Measurement of the Earth’s rotation: 720 BC to AD 2015" (2016) and updated in "Addendum 2020 to 'Measurement of the Earth's Rotation: 720 BC to AD 2015'" (Morrison, L. V., Stephenson, F.R., Hohenkerk, C.Y. and Zawilski, M.; 2021). Outside of the named range (modelled with a spline fit) it provides values from an approximate parabola.
- The updated test data was obtained from http://astro.ukho.gov.uk/nao/lvm/
- Updated related unit tests

7 files changed, 288 insertions, 212 deletions

diff --git a/src/core/StelCore.cpp b/src/core/StelCore.cpp
index 382c8eb654..c240da6864 100644
--- a/src/core/StelCore.cpp
+++ b/src/core/StelCore.cpp
@@ -2226,7 +2226,7 @@ void StelCore::setCurrentDeltaTAlgorithm(DeltaTAlgorithm algorithm)
 			deltaTnDot = -25.82; // n.dot = -25.82 "/cy/cy
 			deltaTfunc=StelUtils::getDeltaTByStephensonMorrisonHohenkerk2016;
 			deltaTstart	= -720;
-			deltaTfinish	= 2015;
+			deltaTfinish	= 2019;
 			break;
 		case Henriksson2017:
 			// Henriksson solution (2017) for Schoch formula for DeltaT (1931)
@@ -2378,7 +2378,7 @@ QString StelCore::getCurrentDeltaTAlgorithmDescription(void) const
 			description = q_("This polynomial approximation with 0.6 seconds of accuracy by M. Khalid, Mariam Sultana and Faheem Zaidi was published in <em>Delta T: Polynomial Approximation of Time Period 1620-2013</em> (%1).").arg("<a href='https://doi.org/10.1155/2014/480964'>2014</a>").append(getCurrentDeltaTAlgorithmValidRangeDescription(jd, &marker));
 			break;
 		case StephensonMorrisonHohenkerk2016: // PRIMARY SOURCE, SEEMS VERY IMPORTANT
-			description = q_("This solution by F. R. Stephenson, L. V. Morrison and C. Y. Hohenkerk (2016) was published in <em>Measurement of the Earth’s rotation: 720 BC to AD 2015</em> (%1). Outside of the named range (modelled with a spline fit) it provides values from an approximate parabola.").arg("<a href='https://doi.org/10.1098/rspa.2016.0404'>2016</a>").append(getCurrentDeltaTAlgorithmValidRangeDescription(jd, &marker));
+			description = q_("This solution by F. R. Stephenson, L. V. Morrison and C. Y. Hohenkerk (2016) was published in <em>Measurement of the Earth’s rotation: 720 BC to AD 2015</em> (%1) and updated in <em>Addendum 2020 to 'Measurement of the Earth's Rotation: 720 BC to AD 2015'</em> (Morrison, L. V., Stephenson, F.R., Hohenkerk, C.Y. and Zawilski, M.; %2). Outside of the named range (modelled with a spline fit) it provides values from an approximate parabola.").arg("<a href='https://doi.org/10.1098/rspa.2016.0404'>2016</a>", "<a href='https://doi.org/10.1098/rspa.2020.0776'>2021</a>").append(getCurrentDeltaTAlgorithmValidRangeDescription(jd, &marker));
 			break;
 		case Henriksson2017:
 			description = q_("This solution by G. Henriksson was published in the article <em>The Acceleration of the Moon and the Universe - the Mass of the Graviton</em> (%1) and based on C. Schoch's formula (1931).").arg("<a href='https://doi.org/10.22606/adap.2017.23004'>2017</a>").append(getCurrentDeltaTAlgorithmValidRangeDescription(jd, &marker));
diff --git a/src/core/StelCore.hpp b/src/core/StelCore.hpp
index 4d782e38de..71ce035392 100644
--- a/src/core/StelCore.hpp
+++ b/src/core/StelCore.hpp
@@ -145,7 +145,7 @@ public:
 		Banjevic,					//!< Banjevic (2006) algorithm for DeltaT
 		IslamSadiqQureshi,			//!< Islam, Sadiq & Qureshi (2008 + revisited 2013) algorithm for DeltaT (6 polynomials)
 		KhalidSultanaZaidi,			//!< M. Khalid, Mariam Sultana and Faheem Zaidi polynomial approximation of time period 1620-2013 (2014)
-		StephensonMorrisonHohenkerk2016,    //!< Stephenson, Morrison, Hohenkerk (2016) RSPA paper provides spline fit to observations for -720..2016 and else parabolic fit.
+		StephensonMorrisonHohenkerk2016,    //!< Stephenson, Morrison, Hohenkerk (2016) RSPA paper provides spline fit to observations for -720..2019 and else parabolic fit.
 		Henriksson2017,			//!< Henriksson (2017) algorithm for DeltaT (The solution for Schoch formula for DeltaT (1931), but with ndot=-30.128"/cy^2)
 		Custom					//!< User defined coefficients for quadratic equation for DeltaT
 	};
diff --git a/src/core/StelUtils.cpp b/src/core/StelUtils.cpp
index ce60c57bb4..d2e8d04e51 100644
--- a/src/core/StelUtils.cpp
+++ b/src/core/StelUtils.cpp
@@ -1881,78 +1881,85 @@ double getDeltaTByKhalidSultanaZaidi(const double jDay)
 	return (((a4[i]*u + a3[i])*u + a2[i])*u + a1[i])*u + a0[i];
 }
 
-static const double StephensonMorrisonHohenkerk2016DeltaTtableS15[54][6]={
+static const double StephensonMorrisonHohenkerk2016DeltaTtableS15[58][6]={
+// Table S15: The Polynomial Coefficients for DT -720.0 to 2019.0   v. 2020
+// Source: http://astro.ukho.gov.uk/nao/lvm/Table-S15.2020.txt
 //	Row         Years                  Polynomial Coefficients
-//	  i      K_i    K_{i+1}        a_0         a_1         a_2         a_3
+//	  i      K_i     K_{i+1}        a_0         a_1         a_2         a_3
 //	- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-/*	  1 */  {-720.0,     400.0,   20550.593,  -21268.478,   11863.418,   -4541.129},
-/*	  2 */  { 400.0,    1000.0,    6604.404,   -5981.266,    -505.093,    1349.609},
-/*	  3 */  {1000.0,    1500.0,    1467.654,   -2452.187,    2460.927,   -1183.759},
-/*	  4 */  {1500.0,    1600.0,     292.635,    -216.322,     -43.614,      56.681},
-/*	  5 */  {1600.0,    1650.0,      89.380,     -66.754,      31.607,     -10.497},
-/*	  6 */  {1650.0,    1720.0,      43.736,     -49.043,       0.227,      15.811},
-/*	  7 */  {1720.0,    1800.0,      10.730,      -1.321,      62.250,     -52.946},
-/*	  8 */  {1800.0,    1810.0,      18.714,      -4.457,      -1.509,       2.507},
-/*	  9 */  {1810.0,    1820.0,      15.255,       0.046,       6.012,      -4.634},
-/*	 10 */  {1820.0,    1830.0,      16.679,      -1.831,      -7.889,       3.799},
-/*	 11 */  {1830.0,    1840.0,      10.758,      -6.211,       3.509,      -0.388},
-/*	 12 */  {1840.0,    1850.0,       7.668,      -0.357,       2.345,      -0.338},
-/*	 13 */  {1850.0,    1855.0,       9.317,       1.659,       0.332,      -0.932},
-/*	 14 */  {1855.0,    1860.0,      10.376,      -0.472,      -2.463,       1.596},
-/*	 15 */  {1860.0,    1865.0,       9.038,      -0.610,       2.325,      -2.497},
-/*	 16 */  {1865.0,    1870.0,       8.256,      -3.450,      -5.166,       2.729},
-/*	 17 */  {1870.0,    1875.0,       2.369,      -5.596,       3.020,      -0.919},
-/*	 18 */  {1875.0,    1880.0,      -1.126,      -2.312,       0.264,      -0.037},
-/*	 19 */  {1880.0,    1885.0,      -3.211,      -1.894,       0.154,       0.562},
-/*	 20 */  {1885.0,    1890.0,      -4.388,       0.101,       1.841,      -1.438},
-/*	 21 */  {1890.0,    1895.0,      -3.884,      -0.531,      -2.473,       1.870},
-/*	 22 */  {1895.0,    1900.0,      -5.017,       0.134,       3.138,      -0.232},
-/*	 23 */  {1900.0,    1905.0,      -1.977,       5.715,       2.443,      -1.257},
-/*	 24 */  {1905.0,    1910.0,       4.923,       6.828,      -1.329,       0.720},
-/*	 25 */  {1910.0,    1915.0,      11.142,       6.330,       0.831,      -0.825},
-/*	 26 */  {1915.0,    1920.0,      17.479,       5.518,      -1.643,       0.262},
-/*	 27 */  {1920.0,    1925.0,      21.617,       3.020,      -0.856,       0.008},
-/*	 28 */  {1925.0,    1930.0,      23.789,       1.333,      -0.831,       0.127},
-/*	 29 */  {1930.0,    1935.0,      24.418,       0.052,      -0.449,       0.142},
-/*	 30 */  {1935.0,    1940.0,      24.164,      -0.419,      -0.022,       0.702},
-/*	 31 */  {1940.0,    1945.0,      24.426,       1.645,       2.086,      -1.106},
-/*	 32 */  {1945.0,    1950.0,      27.050,       2.499,      -1.232,       0.614},
-/*	 33 */  {1950.0,    1953.0,      28.932,       1.127,       0.220,      -0.277},
-/*	 34 */  {1953.0,    1956.0,      30.002,       0.737,      -0.610,       0.631},
-/*	 35 */  {1956.0,    1959.0,      30.760,       1.409,       1.282,      -0.799},
-/*	 36 */  {1959.0,    1962.0,      32.652,       1.577,      -1.115,       0.507},
-/*	 37 */  {1962.0,    1965.0,      33.621,       0.868,       0.406,       0.199},
-/*	 38 */  {1965.0,    1968.0,      35.093,       2.275,       1.002,      -0.414},
-/*	 39 */  {1968.0,    1971.0,      37.956,       3.035,      -0.242,       0.202},
-/*	 40 */  {1971.0,    1974.0,      40.951,       3.157,       0.364,      -0.229},
-/*	 41 */  {1974.0,    1977.0,      44.244,       3.198,      -0.323,       0.172},
-/*	 42 */  {1977.0,    1980.0,      47.291,       3.069,       0.193,      -0.192},
-/*	 43 */  {1980.0,    1983.0,      50.361,       2.878,      -0.384,       0.081},
-/*	 44 */  {1983.0,    1986.0,      52.936,       2.354,      -0.140,      -0.166},
-/*	 45 */  {1986.0,    1989.0,      54.984,       1.577,      -0.637,       0.448},
-/*	 46 */  {1989.0,    1992.0,      56.373,       1.649,       0.709,      -0.277},
-/*	 47 */  {1992.0,    1995.0,      58.453,       2.235,      -0.122,       0.111},
-/*	 48 */  {1995.0,    1998.0,      60.677,       2.324,       0.212,      -0.315},
-/*	 49 */  {1998.0,    2001.0,      62.899,       1.804,      -0.732,       0.112},
-/*	 50 */  {2001.0,    2004.0,      64.082,       0.675,      -0.396,       0.193},
-/*	 51 */  {2004.0,    2007.0,      64.555,       0.463,       0.184,      -0.008},
-/*	 52 */  {2007.0,    2010.0,      65.194,       0.809,       0.161,      -0.101},
-/*	 53 */  {2010.0,    2013.0,      66.063,       0.828,      -0.142,       0.168},
-/*	 54 */  {2013.0,    2016.0,      66.917,       1.046,       0.360,      -0.282}
+/*       1 */  { -720.0,    -100.0,   20371.848,   -9999.586,     776.247,     409.160 },
+/* 	 2 */  { -100.0,     400.0,   11557.668,   -5822.270,    1303.151,    -503.433 },
+/*	 3 */  {  400.0,    1000.0,    6535.116,   -5671.519,    -298.291,    1085.087 },
+/*	 4 */  { 1000.0,    1150.0,    1650.393,    -753.210,     184.811,     -25.346 },
+/*	 5 */  { 1150.0,    1300.0,    1056.647,    -459.628,     108.771,     -24.641 },
+/*	 6 */  { 1300.0,    1500.0,     681.149,    -421.345,      61.953,     -29.414 },
+/*	 7 */  { 1500.0,    1600.0,     292.343,    -192.841,      -6.572,      16.197 },
+/*	 8 */  { 1600.0,    1650.0,     109.127,     -78.697,      10.505,       3.018 },
+/*	 9 */  { 1650.0,    1720.0,      43.952,     -68.089,      38.333,      -2.127 },
+/*	10 */  { 1720.0,    1800.0,      12.068,       2.507,      41.731,     -37.939 },
+/*	11 */  { 1800.0,    1810.0,      18.367,      -3.481,      -1.126,       1.918 },
+/*	12 */  { 1810.0,    1820.0,      15.678,       0.021,       4.629,      -3.812 },
+/*	13 */  { 1820.0,    1830.0,      16.516,      -2.157,      -6.806,       3.250 },
+/*	14 */  { 1830.0,    1840.0,      10.804,      -6.018,       2.944,      -0.096 },
+/*	15 */  { 1840.0,    1850.0,       7.634,      -0.416,       2.658,      -0.539 },
+/*	16 */  { 1850.0,    1855.0,       9.338,       1.642,       0.261,      -0.883 },
+/*	17 */  { 1855.0,    1860.0,      10.357,      -0.486,      -2.389,       1.558 },
+/*	18 */  { 1860.0,    1865.0,       9.040,      -0.591,       2.284,      -2.477 },
+/*	19 */  { 1865.0,    1870.0,       8.255,      -3.456,      -5.148,       2.720 },
+/*	20 */  { 1870.0,    1875.0,       2.371,      -5.593,       3.011,      -0.914 },
+/*	21 */  { 1875.0,    1880.0,      -1.126,      -2.314,       0.269,      -0.039 },
+/*	22 */  { 1880.0,    1885.0,      -3.210,      -1.893,       0.152,       0.563 },
+/*	23 */  { 1885.0,    1890.0,      -4.388,       0.101,       1.842,      -1.438 },
+/*	24 */  { 1890.0,    1895.0,      -3.884,      -0.531,      -2.474,       1.871 },
+/*	25 */  { 1895.0,    1900.0,      -5.017,       0.134,       3.138,      -0.232 },
+/*	26 */  { 1900.0,    1905.0,      -1.977,       5.715,       2.443,      -1.257 },
+/*	27 */  { 1905.0,    1910.0,       4.923,       6.828,      -1.329,       0.720 },
+/*	28 */  { 1910.0,    1915.0,      11.142,       6.330,       0.831,      -0.825 },
+/*	29 */  { 1915.0,    1920.0,      17.479,       5.518,      -1.643,       0.262 },
+/*	30 */  { 1920.0,    1925.0,      21.617,       3.020,      -0.856,       0.008 },
+/*	31 */  { 1925.0,    1930.0,      23.789,       1.333,      -0.831,       0.127 },
+/*	32 */  { 1930.0,    1935.0,      24.418,       0.052,      -0.449,       0.142 },
+/*	33 */  { 1935.0,    1940.0,      24.164,      -0.419,      -0.022,       0.702 },
+/*	34 */  { 1940.0,    1945.0,      24.426,       1.645,       2.086,      -1.106 },
+/*	35 */  { 1945.0,    1950.0,      27.050,       2.499,      -1.232,       0.614 },
+/*	36 */  { 1950.0,    1953.0,      28.932,       1.127,       0.220,      -0.277 },
+/*	37 */  { 1953.0,    1956.0,      30.002,       0.737,      -0.610,       0.631 },
+/*	38 */  { 1956.0,    1959.0,      30.760,       1.409,       1.282,      -0.799 },
+/*	39 */  { 1959.0,    1962.0,      32.652,       1.577,      -1.115,       0.507 },
+/*	40 */  { 1962.0,    1965.0,      33.621,       0.868,       0.406,       0.199 },
+/*	41 */  { 1965.0,    1968.0,      35.093,       2.275,       1.002,      -0.414 },
+/*	42 */  { 1968.0,    1971.0,      37.956,       3.035,      -0.242,       0.202 },
+/*	43 */  { 1971.0,    1974.0,      40.951,       3.157,       0.364,      -0.229 },
+/*	44 */  { 1974.0,    1977.0,      44.244,       3.199,      -0.323,       0.172 },
+/*	45 */  { 1977.0,    1980.0,      47.291,       3.069,       0.193,      -0.192 },
+/*	46 */  { 1980.0,    1983.0,      50.361,       2.878,      -0.384,       0.081 },
+/*	47 */  { 1983.0,    1986.0,      52.936,       2.354,      -0.140,      -0.165 },
+/*	48 */  { 1986.0,    1989.0,      54.984,       1.577,      -0.637,       0.448 },
+/*	49 */  { 1989.0,    1992.0,      56.373,       1.648,       0.708,      -0.276 },
+/*	50 */  { 1992.0,    1995.0,      58.453,       2.235,      -0.121,       0.110 },
+/*	51 */  { 1995.0,    1998.0,      60.678,       2.324,       0.210,      -0.313 },
+/*	52 */  { 1998.0,    2001.0,      62.898,       1.804,      -0.729,       0.109 },
+/*	53 */  { 2001.0,    2004.0,      64.083,       0.674,      -0.402,       0.199 },
+/*	54 */  { 2004.0,    2007.0,      64.553,       0.466,       0.194,      -0.017 },
+/*	55 */  { 2007.0,    2010.0,      65.197,       0.804,       0.144,      -0.084 },
+/*	56 */  { 2010.0,    2013.0,      66.061,       0.839,      -0.109,       0.128 },
+/*	57 */  { 2013.0,    2016.0,      66.920,       1.007,       0.277,      -0.095 },
+/*	58 */  { 2016.0,    2019.0,      68.109,       1.277,      -0.007,      -0.139 }
 };
 double getDeltaTByStephensonMorrisonHohenkerk2016(const double jDay)
 {
 	int year, month, day;
 	getDateFromJulianDay(jDay, &year, &month, &day);
 	double y=yearFraction(year, month, day);
-	if ((y<-720.) || (y>2016.))
+	if ((y<-720.) || (y>2019.))
 	{
 		double fact=(y-1825.0)/100.;
-		return -320.0+32.5*fact*fact;
+		//return -320.0+32.5*fact*fact;
+		return -10+31.4*fact*fact;
 	}
 	int i=0;
 	while (StephensonMorrisonHohenkerk2016DeltaTtableS15[i][1]<y) i++;
-	Q_ASSERT(i<54);
+	Q_ASSERT(i<58);
 	double t=(y-StephensonMorrisonHohenkerk2016DeltaTtableS15[i][0]) / (StephensonMorrisonHohenkerk2016DeltaTtableS15[i][1]-StephensonMorrisonHohenkerk2016DeltaTtableS15[i][0]);
 	return ((StephensonMorrisonHohenkerk2016DeltaTtableS15[i][5]*t + StephensonMorrisonHohenkerk2016DeltaTtableS15[i][4])*t
 		+ StephensonMorrisonHohenkerk2016DeltaTtableS15[i][3])*t + StephensonMorrisonHohenkerk2016DeltaTtableS15[i][2];
diff --git a/src/core/StelUtils.hpp b/src/core/StelUtils.hpp
index c32035cbbb..fe215b67d2 100644
--- a/src/core/StelUtils.hpp
+++ b/src/core/StelUtils.hpp
@@ -795,10 +795,15 @@ namespace StelUtils
 	double getDeltaTByKhalidSultanaZaidi(const double jDay);
 
 	//! Get Delta-T estimation for a given date.
-	//! Implementation of a spline approximation for time period -720-2016.0 for DeltaT by Stephenson, Morrison and Hohenkerk (2016).
-	//! Source: Measurement of the Earth’s rotation: 720 BC to AD 2015
-	//! Proc. R. Soc. A 472: 20160404.
+	//! Implementation of a spline approximation for time period -720-2019.0 for DeltaT by Stephenson, Morrison and Hohenkerk (2016).
+	//! Source: Measurement of the Earth's rotation: 720 BC to AD 2015, published in 2016 in the Royal Society's
+	//! Proceedings A 472, and made freely available via Open Access, by Stephenson, F.R., Morrison, L.V. and
+	//! Hohenkerk, C.Y..
 	//! https://doi.org/10.1098/rspa.2016.0404
+	//! Addendum 2020 to "Measurement of the Earth's Rotation: 720 BC to AD 2015", published in 2021 February
+	//! in the Royal Society's Proceedings A 478, by Morrison, L. V., Stephenson, F.R., Hohenkerk, C.Y. and
+	//! M. Zawilski, M..
+	//! https://doi.org/10.1098/rspa.2020.0776
 	//! @param jDay the date and time expressed as a Julian day
 	//! @return Delta-T in seconds. For times outside the limits, return result from the fitting parabola.
 	double getDeltaTByStephensonMorrisonHohenkerk2016(const double jDay);
diff --git a/src/gui/ConfigurationDialog.cpp b/src/gui/ConfigurationDialog.cpp
index 9762e7b54c..0ae75418bc 100644
--- a/src/gui/ConfigurationDialog.cpp
+++ b/src/gui/ConfigurationDialog.cpp
@@ -1822,7 +1822,7 @@ void ConfigurationDialog::populateDeltaTAlgorithmsList()
 	algorithms->addItem(q_("JPL Horizons"), "JPLHorizons");	
 	algorithms->addItem(q_("Meeus & Simons (2000)"), "MeeusSimons");
 	algorithms->addItem(q_("Morrison & Stephenson (2004, 2005)"), "MorrisonStephenson2004");
-	algorithms->addItem(q_("Stephenson, Morrison & Hohenkerk (2016)"), "StephensonMorrisonHohenkerk2016");
+	algorithms->addItem(q_("Stephenson, Morrison & Hohenkerk (2016, 2021)"), "StephensonMorrisonHohenkerk2016");
 	// Espenak & Meeus (2006) used by default
 	algorithms->addItem(q_("Espenak & Meeus (2006)").append(" *"), "EspenakMeeus");
 	// GZ: I want to try out some things. Something is still wrong with eclipses, see lp:1275092.
diff --git a/src/tests/testDeltaT.cpp b/src/tests/testDeltaT.cpp
index 3c2ccd13ea..c19da5a8dc 100644
--- a/src/tests/testDeltaT.cpp
+++ b/src/tests/testDeltaT.cpp
@@ -32,152 +32,185 @@ QTEST_GUILESS_MAIN(TestDeltaT)
 void TestDeltaT::initTestCase()
 {
 	// source: http://astro.ukho.gov.uk/nao/lvm/
+	// the data obtainded 13 Jan. 2021
 
-	//                            Year               ΔT              ε (seconds)
+	//              Year         ΔT         ε (seconds)
 	// ΔT (s) : −2000 to −800 (convert from hours)
-	genericData << -2000.0  <<  1123200 <<  25920;
-	genericData << -1900.0  <<  1062720 <<  25920;
-	genericData << -1800.0  <<  1010880 <<  25920;
-	genericData << -1700.0  <<    950400 <<  25920;
-	genericData << -1600.0  <<    907200 <<  17280;
-	genericData << -1500.0  <<    855360 <<  17280;
-	genericData << -1400.0  <<    803520 <<  17280;
-	genericData << -1300.0  <<    760320 <<  17280;
-	genericData << -1200.0  <<    708480 <<  17280;
-	genericData << -1100.0  <<    665280 <<  17280;
-	genericData << -1000.0  <<    622080 <<  17280;
-	genericData <<   -900.0  <<    570240 <<    8640;
-	genericData <<   -800.0  <<    527040 <<    8640;
+	genericData << -2000.0  << 46080.00 << 1080.00;
+	genericData << -1900.0  << 43560.00 << 1080.00;
+	genericData << -1800.0  << 41040.00 << 1080.00;
+	genericData << -1700.0  << 38880.00 << 1080.00;
+	genericData << -1600.0  << 36720.00 <<  720.00;
+	genericData << -1500.0  << 34920.00 <<  720.00;
+	genericData << -1400.0  << 32760.00 <<  720.00;
+	genericData << -1300.0  << 30960.00 <<  720.00;
+	genericData << -1200.0  << 29160.00 <<  720.00;
+	genericData << -1100.0  << 27360.00 <<  720.00;
+	genericData << -1000.0  << 25560.00 <<  720.00;
+	genericData <<  -900.0  << 23760.00 <<  360.00;
+	genericData <<  -800.0  << 21960.00 <<  360.00;
 	// ΔT (s) : −720 to +1600
-	genericData <<   -720.0  << 20480.00 << 180.00;
-	genericData <<   -700.0  << 20120.00 << 170.00;
-	genericData <<   -600.0  << 18400.00 << 160.00;
-	genericData <<   -500.0  << 16820.00 << 150.00;
-	genericData <<   -400.0  << 15370.00 << 130.00;
-	genericData <<   -300.0  << 14030.00 << 120.00;
-	genericData <<   -200.0  << 12800.00 << 110.00;
-	genericData <<   -100.0  << 11640.00 << 100.00;
-	genericData <<        0.0  << 10550.00 <<   90.00;
-	genericData <<    100.0  <<   9510.00 <<   80.00;
-	genericData <<    200.0  <<   8500.00 <<   70.00;
-	genericData <<    300.0  <<   7510.00 <<   60.00;
-	genericData <<    400.0  <<   6520.00 <<   50.00;
-	genericData <<    500.0  <<   5520.00 <<   40.00;
-	genericData <<    600.0  <<   4550.00 <<   40.00;
-	genericData <<    700.0  <<   3630.00 <<   30.00;
-	genericData <<    800.0  <<   2800.00 <<   25.00;
-	genericData <<    900.0  <<   2090.00 <<   20.00;
-	genericData <<  1000.0  <<   1540.00 <<   15.00;
-	genericData <<  1100.0  <<   1170.00 <<   15.00;
-	genericData <<  1200.0  <<     900.00 <<   15.00;
-	genericData <<  1300.0  <<     660.00 <<   15.00;
-	genericData <<  1400.0  <<     400.00 <<   15.00;
-	genericData <<  1500.0  <<     200.00 <<   15.00;
-	genericData <<  1600.0  <<     110.00 <<   15.00;
+	genericData <<  -720.0  << 20370.00 <<  180.00;
+	genericData <<  -700.0  << 20050.00 <<  170.00;
+	genericData <<  -600.0  << 18470.00 <<  160.00;
+	genericData <<  -500.0  << 16940.00 <<  150.00;
+	genericData <<  -400.0  << 15470.00 <<  130.00;
+	genericData <<  -300.0  << 14080.00 <<  120.00;
+	genericData <<  -200.0  << 12770.00 <<  110.00;
+	genericData <<  -100.0  << 11560.00 <<  100.00;
+	genericData <<     0.0  << 10440.00 <<   90.00;
+	genericData <<   100.0  <<  9410.00 <<   80.00;
+	genericData <<   200.0  <<  8420.00 <<   70.00;
+	genericData <<   300.0  <<  7480.00 <<   60.00;
+	genericData <<   400.0  <<  6540.00 <<   50.00;
+	genericData <<   500.0  <<  5590.00 <<   40.00;
+	genericData <<   600.0  <<  4650.00 <<   40.00;
+	genericData <<   700.0  <<  3760.00 <<   30.00;
+	genericData <<   800.0  <<  2940.00 <<   25.00;
+	genericData <<   900.0  <<  2230.00 <<   20.00;
+	genericData <<  1000.0  <<  1650.00 <<   15.00;
+	genericData <<  1100.0  <<  1220.00 <<   15.00;
+	genericData <<  1200.0  <<   910.00 <<   15.00;
+	genericData <<  1300.0  <<   680.00 <<   15.00;
+	genericData <<  1400.0  <<   480.00 <<   15.00;
+	genericData <<  1500.0  <<   290.00 <<   15.00;
+	genericData <<  1600.0  <<   110.00 <<   15.00;
 	// ΔT (s) : +1600 to +1800
-	genericData <<  1600.0  <<     113.00 <<   15.00;
-	genericData <<  1610.0  <<     100.00 <<   15.00;
-	genericData <<  1620.0  <<       86.00 <<   20.00;
-	genericData <<  1630.0  <<       72.00 <<   20.00;
-	genericData <<  1640.0  <<       58.00 <<   20.00;
-	genericData <<  1650.0  <<       45.00 <<   20.00;
-	genericData <<  1660.0  <<       35.00 <<   15.00;
-	genericData <<  1670.0  <<       26.00 <<   10.00;
-	genericData <<  1680.0  <<       21.00 <<     5.00;
-	genericData <<  1690.0  <<       17.00 <<     5.00;
-	genericData <<  1700.0  <<       14.00 <<     5.00;
-	genericData <<  1710.0  <<       12.00 <<     5.00;
-	genericData <<  1720.0  <<       12.00 <<     5.00;
-	genericData <<  1730.0  <<       13.00 <<     2.00;
-	genericData <<  1740.0  <<       15.00 <<     2.00;
-	genericData <<  1750.0  <<       17.00 <<     2.00;
-	genericData <<  1760.0  <<       19.00 <<     2.00;
-	genericData <<  1770.0  <<       21.00 <<     1.00;
-	genericData <<  1780.0  <<       21.00 <<     1.00;
-	genericData <<  1790.0  <<       21.00 <<     1.00;
-	genericData <<  1800.0  <<       18.00 <<     0.50;
-	genericData <<  1810.0  <<       16.00 <<     0.50;
-	// ΔT (s) : +1950 to +2016
-	genericData <<  1950.0  <<       28.93 <<     0.05;
-	genericData <<  1951.0  <<       29.32 <<     0.05;
-	genericData <<  1952.0  <<       29.70 <<     0.05;
-	genericData <<  1953.0  <<       30.00 <<     0.05;
-	genericData <<  1954.0  <<       30.20 <<     0.05;
-	genericData <<  1955.0  <<       30.41 <<     0.05;
-	genericData <<  1956.0  <<       30.76 <<     0.05;
-	genericData <<  1957.0  <<       31.34 <<     0.05;
-	genericData <<  1958.0  <<       32.03 <<     0.05;
-	genericData <<  1959.0  <<       32.65 <<     0.05;
-	genericData <<  1960.0  <<       33.07 <<     0.05;
-	genericData <<  1961.0  <<       33.36 <<     0.05;
-	genericData <<  1962.0  <<       33.62 <<     0.05;
-	genericData <<  1963.0  <<       33.96 <<     0.05;
-	genericData <<  1964.0  <<       34.44 <<     0.05;
-	genericData <<  1965.0  <<       35.09 <<     0.05;
-	genericData <<  1966.0  <<       35.95 <<     0.05;
-	genericData <<  1967.0  <<       36.93 <<     0.05;
-	genericData <<  1968.0  <<       37.96 <<     0.05;
-	genericData <<  1969.0  <<       38.95 <<     0.05;
-	genericData <<  1970.0  <<       39.93 <<     0.05;
-	genericData <<  1971.0  <<       40.95 <<     0.05;
-	genericData <<  1972.0  <<       42.04 <<     0.05;
-	genericData <<  1973.0  <<       43.15 <<     0.05;
-	genericData <<  1974.0  <<       44.24 <<     0.05;
-	genericData <<  1975.0  <<       45.28 <<     0.05;
-	genericData <<  1976.0  <<       46.28 <<     0.05;
-	genericData <<  1977.0  <<       47.29 <<     0.05;
-	genericData <<  1978.0  <<       48.33 <<     0.05;
-	genericData <<  1979.0  <<       49.37 <<     0.05;
-	genericData <<  1980.0  <<       50.36 <<     0.05;
-	genericData <<  1981.0  <<       51.28 <<     0.05;
-	genericData <<  1982.0  <<       52.13 <<     0.05;
-	genericData <<  1983.0  <<       52.94 <<     0.05;
-	genericData <<  1984.0  <<       53.70 <<     0.05;
-	genericData <<  1985.0  <<       54.39 <<     0.05;
-	genericData <<  1986.0  <<       54.98 <<     0.05;
-	genericData <<  1987.0  <<       55.46 <<     0.05;
-	genericData <<  1988.0  <<       55.89 <<     0.05;
-	genericData <<  1989.0  <<       56.37 <<     0.05;
-	genericData <<  1990.0  <<       56.99 <<     0.05;
-	genericData <<  1991.0  <<       57.70 <<     0.05;
-	genericData <<  1992.0  <<       58.45 <<     0.05;
-	genericData <<  1993.0  <<       59.19 <<     0.05;
-	genericData <<  1994.0  <<       59.92 <<     0.05;
-	genericData <<  1995.0  <<       60.68 <<     0.05;
-	genericData <<  1996.0  <<       61.46 <<     0.05;
-	genericData <<  1997.0  <<       62.23 <<     0.05;
-	genericData <<  1998.0  <<       62.90 <<     0.05;
-	genericData <<  1999.0  <<       63.42 <<     0.05;
-	genericData <<  2000.0  <<       63.81 <<     0.05;
-	genericData <<  2001.0  <<       64.08 <<     0.05;
-	genericData <<  2002.0  <<       64.27 <<     0.05;
-	genericData <<  2003.0  <<       64.41 <<     0.05;
-	genericData <<  2004.0  <<       64.55 <<     0.05;
-	genericData <<  2005.0  <<       64.73 <<     0.05;
-	genericData <<  2006.0  <<       64.94 <<     0.05;
-	genericData <<  2007.0  <<       65.19 <<     0.05;
-	genericData <<  2008.0  <<       65.48 <<     0.05;
-	genericData <<  2009.0  <<       65.78 <<     0.05;
-	genericData <<  2010.0  <<       66.06 <<     0.05;
-	genericData <<  2011.0  <<       66.33 <<     0.05;
-	genericData <<  2012.0  <<       66.60 <<     0.05;
-	genericData <<  2013.0  <<       66.92 <<     0.05;
-	genericData <<  2014.0  <<       67.30 <<     0.05;
-	genericData <<  2015.0  <<       67.69 <<     0.05;
-	genericData <<  2016.0  <<       68.04 <<     0.05;
-	// ΔT (seconds) : +2017 to +2500
-	genericData <<  2017.0  <<       68.60 <<     0.10;
-	genericData <<  2018.0  <<       69.00 <<     0.10;
-	genericData <<  2019.0  <<       69.20 <<     0.10;
-	genericData <<  2020.0  <<       69.50 <<     0.10;
-	genericData <<  2030.0  <<       70.00 <<     2.00;
-	genericData <<  2040.0  <<       72.00 <<     4.00;
-	genericData <<  2050.0  <<       75.00 <<     6.00;
-	genericData <<  2100.0  <<       93.00 <<   10.00;
-	genericData <<  2200.0  <<     163.00 <<   20.00;
-	genericData <<  2300.0  <<     297.00 <<   30.00;
-	genericData <<  2400.0  <<     521.00 <<   50.00;
-	genericData <<  2500.0  <<     855.00 << 100.00;
+	genericData <<  1600.0  <<   109.00 <<   15.00;
+	genericData <<  1610.0  <<    94.00 <<   15.00;
+	genericData <<  1620.0  <<    80.00 <<   20.00;
+	genericData <<  1630.0  <<    66.00 <<   20.00;
+	genericData <<  1640.0  <<    54.00 <<   20.00;
+	genericData <<  1650.0  <<    44.00 <<   20.00;
+	genericData <<  1660.0  <<    35.00 <<   15.00;
+	genericData <<  1670.0  <<    28.00 <<   10.00;
+	genericData <<  1680.0  <<    22.00 <<    5.00;
+	genericData <<  1690.0  <<    17.00 <<    5.00;
+	genericData <<  1700.0  <<    14.00 <<    5.00;
+	genericData <<  1710.0  <<    12.00 <<    5.00;
+	genericData <<  1720.0  <<    12.00 <<    5.00;
+	genericData <<  1730.0  <<    13.00 <<    2.00;
+	genericData <<  1740.0  <<    15.00 <<    2.00;
+	genericData <<  1750.0  <<    17.00 <<    2.00;
+	genericData <<  1760.0  <<    19.00 <<    2.00;
+	genericData <<  1770.0  <<    21.00 <<    1.00;
+	genericData <<  1780.0  <<    21.00 <<    1.00;
+	genericData <<  1790.0  <<    21.00 <<    1.00;
+	genericData <<  1800.0  <<    18.00 <<    0.50;
+	genericData <<  1810.0  <<    16.00 <<    0.50;
+	// ΔT (s) : +1800 to +1950
+	genericData <<  1800.0  <<    18.40 <<    0.50;
+	genericData <<  1805.0  <<    16.60 <<    0.30;
+	genericData <<  1810.0  <<    15.70 <<    0.20;
+	genericData <<  1815.0  <<    16.40 <<    0.20;
+	genericData <<  1820.0  <<    16.50 <<    0.20;
+	genericData <<  1825.0  <<    14.10 <<    0.20;
+	genericData <<  1830.0  <<    10.80 <<    0.20;
+	genericData <<  1835.0  <<     8.50 <<    0.10;
+	genericData <<  1840.0  <<     7.60 <<    0.10;
+	genericData <<  1845.0  <<     8.00 <<    0.10;
+	genericData <<  1850.0  <<     9.30 <<    0.10;
+	genericData <<  1855.0  <<    10.36 <<    0.10;
+	genericData <<  1860.0  <<     9.04 <<    0.10;
+	genericData <<  1865.0  <<     8.25 <<    0.10;
+	genericData <<  1870.0  <<     2.37 <<    0.05;
+	genericData <<  1875.0  <<    -1.13 <<    0.05;
+	genericData <<  1880.0  <<    -3.21 <<    0.05;
+	genericData <<  1885.0  <<    -4.39 <<    0.05;
+	genericData <<  1890.0  <<    -3.88 <<    0.05;
+	genericData <<  1895.0  <<    -5.02 <<    0.05;
+	genericData <<  1900.0  <<    -1.98 <<    0.05;
+	genericData <<  1905.0  <<     4.92 <<    0.05;
+	genericData <<  1910.0  <<    11.14 <<    0.05;
+	genericData <<  1915.0  <<    17.48 <<    0.05;
+	genericData <<  1920.0  <<    21.62 <<    0.05;
+	genericData <<  1925.0  <<    23.79 <<    0.05;
+	genericData <<  1930.0  <<    24.42 <<    0.05;
+	genericData <<  1935.0  <<    24.16 <<    0.05;
+	genericData <<  1940.0  <<    24.43 <<    0.05;
+	genericData <<  1945.0  <<    27.05 <<    0.05;
+	genericData <<  1950.0  <<    28.93 <<    0.05;
+	// ΔT (s) : +1950 to +2019
+	genericData <<  1950.0  <<    28.93 <<    0.05;
+	genericData <<  1951.0  <<    29.32 <<    0.05;
+	genericData <<  1952.0  <<    29.70 <<    0.05;
+	genericData <<  1953.0  <<    30.00 <<    0.05;
+	genericData <<  1954.0  <<    30.20 <<    0.05;
+	genericData <<  1955.0  <<    30.41 <<    0.05;
+	genericData <<  1956.0  <<    30.76 <<    0.05;
+	genericData <<  1957.0  <<    31.34 <<    0.05;
+	genericData <<  1958.0  <<    32.03 <<    0.05;
+	genericData <<  1959.0  <<    32.65 <<    0.05;
+	genericData <<  1960.0  <<    33.07 <<    0.05;
+	genericData <<  1961.0  <<    33.36 <<    0.05;
+	genericData <<  1962.0  <<    33.62 <<    0.05;
+	genericData <<  1963.0  <<    33.96 <<    0.05;
+	genericData <<  1964.0  <<    34.44 <<    0.05;
+	genericData <<  1965.0  <<    35.09 <<    0.05;
+	genericData <<  1966.0  <<    35.95 <<    0.05;
+	genericData <<  1967.0  <<    36.93 <<    0.05;
+	genericData <<  1968.0  <<    37.96 <<    0.05;
+	genericData <<  1969.0  <<    38.95 <<    0.05;
+	genericData <<  1970.0  <<    39.93 <<    0.05;
+	genericData <<  1971.0  <<    40.95 <<    0.05;
+	genericData <<  1972.0  <<    42.04 <<    0.05;
+	genericData <<  1973.0  <<    43.15 <<    0.05;
+	genericData <<  1974.0  <<    44.24 <<    0.05;
+	genericData <<  1975.0  <<    45.28 <<    0.05;
+	genericData <<  1976.0  <<    46.28 <<    0.05;
+	genericData <<  1977.0  <<    47.29 <<    0.05;
+	genericData <<  1978.0  <<    48.33 <<    0.05;
+	genericData <<  1979.0  <<    49.37 <<    0.05;
+	genericData <<  1980.0  <<    50.36 <<    0.05;
+	genericData <<  1981.0  <<    51.28 <<    0.05;
+	genericData <<  1982.0  <<    52.13 <<    0.05;
+	genericData <<  1983.0  <<    52.94 <<    0.05;
+	genericData <<  1984.0  <<    53.70 <<    0.05;
+	genericData <<  1985.0  <<    54.39 <<    0.05;
+	genericData <<  1986.0  <<    54.98 <<    0.05;
+	genericData <<  1987.0  <<    55.46 <<    0.05;
+	genericData <<  1988.0  <<    55.89 <<    0.05;
+	genericData <<  1989.0  <<    56.37 <<    0.05;
+	genericData <<  1990.0  <<    56.99 <<    0.05;
+	genericData <<  1991.0  <<    57.70 <<    0.05;
+	genericData <<  1992.0  <<    58.45 <<    0.05;
+	genericData <<  1993.0  <<    59.19 <<    0.05;
+	genericData <<  1994.0  <<    59.92 <<    0.05;
+	genericData <<  1995.0  <<    60.68 <<    0.05;
+	genericData <<  1996.0  <<    61.46 <<    0.05;
+	genericData <<  1997.0  <<    62.23 <<    0.05;
+	genericData <<  1998.0  <<    62.90 <<    0.05;
+	genericData <<  1999.0  <<    63.42 <<    0.05;
+	genericData <<  2000.0  <<    63.81 <<    0.05;
+	genericData <<  2001.0  <<    64.08 <<    0.05;
+	genericData <<  2002.0  <<    64.27 <<    0.05;
+	genericData <<  2003.0  <<    64.41 <<    0.05;
+	genericData <<  2004.0  <<    64.55 <<    0.05;
+	genericData <<  2005.0  <<    64.73 <<    0.05;
+	genericData <<  2006.0  <<    64.95 <<    0.05;
+	genericData <<  2007.0  <<    65.20 <<    0.05;
+	genericData <<  2008.0  <<    65.48 <<    0.05;
+	genericData <<  2009.0  <<    65.77 <<    0.05;
+	genericData <<  2010.0  <<    66.06 <<    0.05;
+	genericData <<  2011.0  <<    66.33 <<    0.05;
+	genericData <<  2012.0  <<    66.61 <<    0.05;
+	genericData <<  2013.0  <<    66.92 <<    0.05;
+	genericData <<  2014.0  <<    67.28 <<    0.05;
+	genericData <<  2015.0  <<    67.69 <<    0.05;
+	genericData <<  2016.0  <<    68.11 <<    0.05;
+	genericData <<  2017.0  <<    68.53 <<    0.05;
+	genericData <<  2018.0  <<    68.92 <<    0.05;
+	genericData <<  2019.0  <<    69.24 <<    0.05;
+	// ΔT (seconds) : +2020 to +2500
+	//genericData <<  2020.0  <<       69.50 <<     0.10;
+	genericData <<  2030.0  <<    67.00 <<    2.00;
+	genericData <<  2040.0  <<    68.00 <<    4.00;
+	genericData <<  2050.0  <<    70.00 <<    6.00;
+	genericData <<  2100.0  <<    80.00 <<   10.00;
+	genericData <<  2200.0  <<   160.00 <<   20.00;
+	genericData <<  2300.0  <<   330.00 <<   30.00;
+	genericData <<  2400.0  <<   610.00 <<   50.00;
+	genericData <<  2500.0  <<  1000.00 <<  100.00;
 }
 
 void TestDeltaT::testDeltaTByEspenakMeeus()
@@ -737,7 +770,7 @@ void TestDeltaT::testDeltaTByStephensonMorrison2004WideDates()
 
 void TestDeltaT::testDeltaTByStephensonMorrisonHohenkerk2016GenericDates()
 {
-	// Valid range: 720 BC to AD 2015
+	// Valid range: 720 BC to AD 2019
 
 	double year, expectedResult, acceptableError, JD;
 	int yout, mout, dout;
@@ -751,9 +784,7 @@ void TestDeltaT::testDeltaTByStephensonMorrisonHohenkerk2016GenericDates()
 		if (year<0)  // https://github.com/Stellarium/stellarium/wiki/FAQ#There_is_no_year_0_or_BC_dates_are_a_year_out
 			year += 1;
 
-		// Unit tests failures ranges: 300-600, 900-1610, 1780, 1800-1810
-		// TODO: Check algorithm
-		if ((year>=-720. && year<300.) || (year>600. && year<900.) || (year>=1620. && year<=1770.) || (year>=1820. && year<=2015.))
+		if (year>=-720. && year<2019.)
 		{
 			StelUtils::getJDFromDate(&JD, static_cast<int>(year), 1, 1, 0, 0, 0);
 			double result = StelUtils::getDeltaTByStephensonMorrisonHohenkerk2016(JD);
@@ -832,6 +863,38 @@ void TestDeltaT::testDeltaTByStephensonMorrisonHohenkerk2016GenericDates()
 	*/
 }
 
+void TestDeltaT::testDeltaTByStephensonMorrisonHohenkerk2016SpecialDates()
+{
+	QVariantList data;
+	// From United States Naval Observatory table
+	// see details: https://github.com/Stellarium/stellarium-web-engine/blob/53906077226a735473023d4c5beb4adce6855903/src/algos/deltat.c#L108
+	data << 1980 <<  50.5387;
+	data << 2000 <<  63.8285;
+	data << 2010 <<  66.0699;
+
+	while(data.count() >= 2)
+	{
+		int year = data.takeFirst().toInt();
+		int yout, mout, dout;
+		double JD;
+		double expectedResult = data.takeFirst().toDouble();
+		double acceptableError = 0.2; // TODO: Increase accuracy to 0.1 seconds
+		StelUtils::getJDFromDate(&JD, year, 1, 1, 0, 0, 0);
+		double result = StelUtils::getDeltaTByStephensonMorrisonHohenkerk2016(JD);
+		double actualError = qAbs(qAbs(expectedResult) - qAbs(result));
+		StelUtils::getDateFromJulianDay(JD, &yout, &mout, &dout);
+		QVERIFY2(actualError <= acceptableError, QString("date=%2 year=%3 result=%4 expected=%5 error=%6 acceptable=%7")
+							.arg(QString("%1-%2-%3 00:00:00").arg(yout).arg(mout).arg(dout))
+							.arg(year)
+							.arg(result)
+							.arg(expectedResult)
+							.arg(actualError)
+							.arg(acceptableError)
+							.toUtf8());
+	}
+}
+
+
 void TestDeltaT::testDeltaTByMeeusSimons()
 {
 	// test data from Meeus, Jean, "The Effect of Delta T on Astronomical Calculations",
diff --git a/src/tests/testDeltaT.hpp b/src/tests/testDeltaT.hpp
index 772beea4b1..f078d79440 100644
--- a/src/tests/testDeltaT.hpp
+++ b/src/tests/testDeltaT.hpp
@@ -39,6 +39,7 @@ private slots:
 	void testDeltaTByStephensonMorrison1995WideDates();	
 	void testDeltaTByStephensonMorrison2004WideDates();	
 	void testDeltaTByStephensonMorrisonHohenkerk2016GenericDates();
+	void testDeltaTByStephensonMorrisonHohenkerk2016SpecialDates();
 	void testDeltaTByStephenson1997WideDates();	
 	void testDeltaTByMeeusSimons();	
 	void testDeltaTByKhalidSultanaZaidiWideDates();