Swiss Ephemeris Sideral Mode with Lahiri Ayanamsha gives wrong values

Question

I'm trying to generate the longitudes of planets. I've used the swiss ephemeris dll to do all my hard work. However to my misfortune the values generated by swiss ephemeris for the sidereal mode Lahiri Ayanamsha is way off (by around 25 minutes, especially for moon) from what I'm getting out of other vedic software or online portals including JuniorJyothsh

I've downloaded the .se1 files(for planets and moon) and am using the very accurate Swiss Ephemeris mode. Further I've set the Sidereal mode, the Lahiri Ayanmsha Flag, Topocentric Flag. I've also set the topolgy latitude and longitude location.

What bothers me most is that the values from all other online vedic natal chart generators including Jumior Jyothish seem to match with each other. I'm not sure what it is that I'm doing wrong. Here's a link to my code Swiss ephemeris used in .NET on git with a sample code snippet

[Test]
    public void ShouldGetAllPlanetValues()
    {
        var errorMessage = new StringBuilder(1000);
        var longitudeAndLatitude = new Double[6];
        var cusps = new Double[13];
        var ascentantAndMore = new Double[10];
        var julianDayNumbersInEtAndUt = new double[2];
        TimeZoneInfo indiaTimeZone = TimeZoneInfo.FindSystemTimeZoneById(IndiaStandardTimeZoneId);
        var ephemerisTablesPath = new StringBuilder(@"../../../EphemerisFiles/");

        swe_set_ephe_path(ephemerisTablesPath);
        var birthTimeInIndianZone = new DateTime(1989, 8, 21, 10, 29, 0);
        DateTime birthTimeInUtc = TimeZoneInfo.ConvertTimeToUtc(birthTimeInIndianZone, indiaTimeZone);

        int errorCOde = swe_utc_to_jd(birthTimeInUtc.Year, birthTimeInUtc.Month, birthTimeInUtc.Day,
                                      birthTimeInUtc.Hour, birthTimeInUtc.Minute, birthTimeInUtc.Second, 1,
                                      julianDayNumbersInEtAndUt, errorMessage);
        if (errorCOde != 0)
        {
            Assert.Fail("Error ho gaya julian date conversion par !!");
        }
        Console.WriteLine("Julian Day Number from UTC: " + julianDayNumbersInEtAndUt[1]);
        Console.WriteLine(swe_sidtime(julianDayNumbersInEtAndUt[1]));
        var computationFlag = EphemerisModes.Sidereal | EphemerisModes.SwissEphemeris
                                                                        | EphemerisModes.Topocentric;
        var longitude = ConvertDegreeAngleToDouble(80, 15, 0);
        var latitude = ConvertDegreeAngleToDouble(13, 4, 0);
        swe_set_topo(12.9667, 77.5667, 0);
        swe_set_sid_mode(SiderealFlag.Lahiri, 0, 0);
        foreach (var planet in Planets.AllPlanets)
        {
            int sweCalcUt = swe_calc_ut(julianDayNumbersInEtAndUt[1], planet, computationFlag, longitudeAndLatitude, errorMessage);
            Console.WriteLine("Planet Number " + planet + ": " + GetDegreesMinutesSeconds(longitudeAndLatitude[0]));
        }
        swe_houses_ex(julianDayNumbersInEtAndUt[1], EphemerisModes.Sidereal, 12.9667, 77.5667, 'A', cusps, ascentantAndMore);
        Console.WriteLine("Ascendant: " + GetDegreesMinutesSeconds(ascentantAndMore[0]));
    }

Here's a sample of how different the values are for my own birth date (21-August-1989 10:29 AM) Generated from Swiss ephemeris as per my code :

Planet Number 0: 124:24:30   SUN
Planet Number 1: 359:38:55   Moon
Planet Number 2: 150:20:40   Mercury
Planet Number 3: 160:0:11    Venus
Planet Number 4: 137:26:47   Mars
Planet Number 5: 70:20:45    Jupiter
Planet Number 6: 253:56:35   Satrun
Planet Number 10: 301:46:40  Rahu (Mean Node)
Ascendant:        187.27:46

Value form most other sources (JuniorJyothish, ProKerala, NadiAstrology, Astrosage):

Planet Number  0: 124:24:35    SUN
Planet Number  1: 0:6:21       Moon
Planet Number  2: 150:20:45    Mercury
Planet Number  3: 160:00:17    Venus
Planet Number  4: 137:26:56    Mars
Planet Number  5: 70:20:57     Jupiter
Planet Number  6: 253:56:48    Satrun
Planet Number 10: 301:46:52    Rahu
Ascendant       : 187:28:6     Ascendant   

Any help/hint/suggestion to point me in the right direction is deeply appreciated.

Thanks

Answer 1

After hours of googling and breaking my head I figured out that vedic horoscope traditionally uses geocentric values. I was using topocentric values for the moon's longitude. This doesn't make much difference for other planets due to their distance from earth unlike the moon. Once i generated the geocentric values the moon longitude matched as well.

Although it seems wrong that Vedic horoscope uses geocentric longitudes when a more accurate topocentric values are available, astrology has traditionally worked that way. Besides the astrological rules are built to give right predictions with wrong data :P

Answer 2

Swiss ephemeris is likely to give you more accurate results. For most planets difference exists in only seconds except for moon if you compare the value provided by you. For vedic horoscopy this difference is acceptable. Please proceed to use results obtained by you from swiss ephemeris.