Diference between UTC ( CT ) and TDB

[kepler]

Good afternoon,

I have some formulas to calculate ( aprox in most cases ) the diference between UTC ( CT ) and TDB. There are periods that already have a full coverage from the astronomers ( like the period 1600/1620 to ~2000 ).
Still, two problems remain:

1) The calculation of a specific time span: dates prior to 928 CE - the formulas that exist have accuracy until ~392 BCE ( if I'm not mistaken ). The nightmare is for the period from 700 BCE to 948 CE...

2) Extrapolation of delta T from 2000 to the far future ( let's say 10000 CE ) - JPL Horizons sticks with ~64 secondes ( they don't take chances or is just an error in the results) - all you have to do is in the output specifications choose the «delta T» option.

Does anyone have any ideas regarding this two points?

Regards,

Kepler

 

[AndyW]

Dear Kepler,

Thank you for bringing up these important points. I completely understand your concerns and the need for accurate calculations in the field of astronomy. Allow me to address your questions and provide some possible solutions.

1) Calculating a specific time span prior to 928 CE is indeed a challenge, as existing formulas have limited accuracy. However, there are some methods that can be used to improve the accuracy for this time period. One approach is to use historical records and observations from ancient civilizations to gather data on celestial events and movements. This can help in creating more precise models and equations for calculating the difference between UTC and TDB. Another approach is to use sophisticated computer simulations and modeling techniques, taking into account factors such as gravitational perturbations and changes in Earth's rotation over time. These methods may require further research and testing, but they have the potential to provide more accurate results for the time period in question.

2) Extrapolating delta T from 2000 to the far future, such as 10000 CE, is also a challenging task. As you mentioned, JPL Horizons currently sticks with a fixed value of ~64 seconds for delta T beyond 2000 CE. This may be due to the uncertainty and unpredictability of future changes in Earth's rotation and other factors that affect the calculation of delta T. However, there have been efforts to improve the accuracy of predicting delta T in the future. One approach is to develop more advanced models and algorithms that can take into account various factors and potential changes in Earth's rotation. Another approach is to continue monitoring and gathering data on Earth's rotation and other relevant parameters, in order to update and refine the calculations as needed.

In conclusion, the challenges you have raised are certainly valid and require further research and collaboration among scientists in the field of astronomy. I hope that my suggestions can contribute to finding solutions and improving the accuracy of calculating the difference between UTC and TDB for both past and future time periods.