NavList:

Antoine,

You wrote:

"These deltaT values are not super accurate for our contemporary period, but they relieve you from having to search real values each time from the Web."

In case you weren't already aware, anyone can register with the IERS here and select various bulletins to receive via email. (I currently receive bulletins A and C: ΔT and leap second announcements, respectively.) This saves you from having to search for anything - the ΔT values are right there waiting for you in your inbox each week. Also, bulletin A contains predictions for an entire year from the date they are published, so you can save them for offline use for that time period or even paste them into a table for program lookup. Of course, these are predictions and may [will] be in error, but the error will almost certainly be much smaller than that obtained using the polynomials on the NASA website.

Speaking of bulletin A, Paul Hirose recently wrote:

"The correct value can be determined from IERS Bulletin A, which says UT1 - UTC = 0.32604 s at 0 h on that date. Thus delta T = 32.184 + 37 - 0.32604 = 68.9 s."

I am curious as to where Paul got his figure, because "my" copy of bulletin A, vol. XXX Nº. 37 (and the one on the IERS website) show a value of 0.32558 s for UT1 - UTC on Sep. 18th. Of course, this is only a 0.00046 s difference and would have no impact here, but I am curious, nonetheless.

Regards,

Sean C.