NOVAS User Updates and FAQ
Known Issues
NOVAS F3.1 NOVAS_F3.1.f: WOBBLE has incorrect sign in rotation matrix
A previously reported sign error in the YY (middle) element of the rotation matrix
in subroutine WOBBLE (Eq. 6.15 in Kaplan 2005) was corrected in the C version of NOVAS,
but not the Fortran version.
This sign omission, in the first term of that element, in many cases is of negligible
concern. The angles used are extremely small and YY will be dominated by the 2nd term,
which for practical concerns reduces to YY = 1. The calculation error introduced by
this sign flip is of the order 10-21 radians.
This mistake will be corrected in the next version of NOVAS. However, if desired, the
following correction to the WOBBLE subroutine in the Fortran source code
(NOVAS_F3.1.f) can be made.
Line 3222 (in subroutine WOBBLE) as released reads
YY = SINX * SINY * SINL + COSY * COSL
However, it should read
YY = -SINX * SINY * SINL + COSY * COSL
Reference
Kaplan, George H. United States Naval
Observatory Circular No. 179: The IAU Resolutions on Astronomical Reference Systems,
Time Scales, and Earth Rotation Models. US Naval Observatory, Washington: 2005
NOVAS C3.1 novas.c: sidereal_time units bug
When NOVAS C3.1 computes Greenwich Mean Sidereal Time (GMST; gst_type = 0)
using the method based on the Celestial Intermediate Origin (CIO; method = 0),
the units for the equation of the equinox are calculated incorrectly.
In sidereal_time, the line
ha_eq -= (eqeq / 240.0);
should read
ha_eq -= (eqeq / 3600.0);
since the eqeq variable has been previously converted to arcseconds
instead of seconds in time.
NOVAS C3.1 eph_manager.c: ephem_close does not reset the EPHFILE pointer
The check to see if an ephemeris file is already open will always be true if an ephemeris
file was open at any point in the program, even if ephem_close was called. ephem_close
does not reset the EPHFILE pointer to NULL.
This bug will be addressed during the next overhaul of the ephemeris-access software.
Memory errors occur when a call to ephem_close occurs between two calls to ephem_open.
The second time ephem_open is called, if (EPHFILE) is
TRUE because EPHFILE is still the address
that was assigned the first time.
Two calls to ephem_open without an intervening call to ephem_close will work
because the EPHFILE still is open when if (EPHFILE)
checks during the second ephem_open call.
Users who open multiple ephemeris files within a particular program may wish to edit the
ephem_close function as follows:
if (EPHFILE)
{
error = (short int) fclose (EPHFILE);
EPHFILE = NULL; // new line, reset pointer
free (BUFFER);
}
return error;
FAQ
Is my NOVAS documentation up-to-date?
No revisions have been issued for the NOVAS 3.1 user's guides to date. USNO Circular
180 contains the user's guides for NOVAS F3.0 and C3.0; Rev. C is the current, and final
version, of USNO Circular 180 and its component user's guides. No updates have been
issued for USNO Circular 181, which applies to both versions 3.0 and 3.1. Click below to
download the most recent version of each.
Python users should consult the docstrings included in their download or the C User's guide for
additional information.
How do I cite NOVAS 3.1?
If you use NOVAS, please send us an email
that outlines your application. This information helps justify further improvements to NOVAS. Your
comments and suggestions are also welcome.
The official references for NOVAS F3.1 and C3.1 are the corresponding user's guides, which
may be cited as follows:
- Kaplan, G., Bartlett, J., Monet, A., Bangert, J., & Puatua, W. (2011)
User's Guide to NOVAS Version F3.1
(Washington, DC: USNO).
- Bangert, J., Puatua, W., Kaplan, G., Bartlett, J., Harris, W., Fredericks, A., & Monet, A. (2011)
User's Guide to NOVAS Version C3.1
(Washington, DC: USNO).
NOVAS Python may be cited as follows:
- Barron, E. G., Kaplan, G. H., Bangert, J., Bartlett, J. L., Puatua, W., Harris, W., & Barrett, P. (2011)
"Naval Observatory Vector Astrometry Software (NOVAS) Version 3.1,
Introducing a Python Edition," Bull. AAS, 43, 2011.
(
Abstract
)
In addition, we ask that you also direct your readers to the NOVAS page.
How do I cite earlier versions of NOVAS?
NOVAS 3.0 may be cited as follows:
- Kaplan, G., Bangert, J., Bartlett, J., Puatua, W., & Monet, A. (2009)
User's Guide to NOVAS 3.0, USNO Circular 180
(Washington, DC: USNO).
The official reference for all previous versions of NOVAS is the 1990 software report
announcing its release, which is
