Документ взят из кэша поисковой машины. Адрес
оригинального документа
: http://www.atnf.csiro.au/computing/software/miriad/userguide/node138.html
Дата изменения: Unknown Дата индексирования: Mon Apr 11 02:18:15 2016 Кодировка: Поисковые слова: п п п п п |
You can either allow fits
to retrieve the needed velocity information from the FITS file, or you
can give this
information explicitly using the velocity
keyword. The default
behaviour (if you do not set the velocity
keyword at all) is to
use the information in the FITS file. You will need to explicitly enter the
velocity information to fits
if the information in the FITS file
is incorrect.
The velocity
keyword gives three values: the velocity definition and rest frame,
the velocity of a particular channel, and the channel velocity in km/s. Possible
values for the velocity definition and rest frame are lsr (LSR
velocity, radio definition), bary (barycentric velocity, radio
definition), optlsr (LSR velocity, optical definition),
optbary (barycentric velocity, optical definition) and obs (velocity
relative to the observatory - not of much use). For example, to indicate
that channel 257 has an LSR velocity (radio definition) of 4310 km/s, use
velocity=lsr,4310,257Specifying the velocity of a channel for a multi-source FITS file is not a particular meaningful thing to do (unless you are interested in only one source).
velocity
keyword (either lsr, bary, optlsr, optbary or
obs, as before), but the velocity and reference channel are omitted. For
example, fits
will use its Earth model to determine the observatory's
radial velocity with respect to the LSR if given:
velocity=lsr
Miriad manager