# Delta T

1. Oct 22, 2004

### 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

Last edited: Oct 22, 2004