This online applet will convert a list of Barycentric Julian Dates in
Barycentric Dynamical Time (BJD_TDB) to JD in UTC to an accuracy of 20
ms or the accuracy of double precision (~few ms) if the observatory is
given. Its purpose is for precise scheduling of observations from
ephemerides given in BJD_TDB. The BJD_TDB will never differ from
JD_UTC by more than 10 minutes, so if your observing schedule is not
very tight, this calculator is probably unnecessary. For A brief,
non-technical explanation of BJD_TDB can be found here.
There is a programmatic interface to this applet. Here
is an example that converts a list of BJD_TDBs to JD_UTC for alpha
Centauri. The RA and Dec are always in decimal hours and the FUNCTION
can be utc2bjd, bjd2utc or hjd2bjd. It does not support any
observatories, so is only accurate to 20 ms.
**If specifying the space observatory, please note that it requires a
telnet session to HORIZONS, which will take at least 1 minute, and up
to 2 minutes if the date range is large (>~ 1 year). If you want
feedback during this time, check the verbose box. The telnet session
is somewhat flaky, and there is limited error checking -- in
particular, make sure the spacecraft was in flight during the dates
specified. If it fails and you cannot determine why, download the
source code and run it locally.
If you have made use of this calculator (or the source code) in a
scientific paper, please cite our paper, which contains a
more thorough explanation of the various corrections involved in this
Copyright © Jason Eastman () All Rights Reserved.
Last Updated: May 11, 2010