Документ взят из кэша поисковой машины. Адрес
оригинального документа
: http://www.naic.edu/~phil/pnt/chkverifymodel.html
Дата изменения: Mon May 17 00:16:29 2004 Дата индексирования: Tue Oct 2 06:39:01 2012 Кодировка: Поисковые слова: п п п п п п п п п п п п п п п п п п |
The table below has the rms pointing error for each receiver on CTA21
and the rms of the difference in pointing error between the receiver
and sband narrow:
|
|
|
|
rms azDif | rms zaDif |
|
|
|
|
- | - |
|
|
|
|
4.4 | 4.0 |
|
|
|
|
8.5 | 4.8 |
|
|
|
|
7.5 | 4.4 |
The model rms was 6.7 asecs so this source was not fit very well by the model. To speed up the verification you could track only a portion of the source on each receiver, and get all the recievers done in one night. Looking at the curves shows the perils in doing this. A single point can be up to 15 asecs from the median value. There are also trends that last for a long time: lbn-lbw azerr difference change at sample 40 when the source transits. This could happen if the platform tilt changed north/south between the two days. I'm starting to wonder whether the large, fast jumps in azimuth and then slow recovery is the wheels driving off the rolling surface and then jumping back when the rollers finally hit the limit. Remember that 1/8" is 5 arcseconds at 435 feet...
If the offsets between receivers remained constant
then we could use that to compute the new offset for each model. Unfortunatley,
most models have had the horns repositioned (via a survey) before building
the model. The offsets
between model 11 and model12 (.ps) (.pdf)
are shown in the figure. Sband narrow offsets changed by -6 and 2 asecs.
Lbw had the largest variation changing by -8,+5.5. This differs from lbn
by about 3 asecs. For a more complete history of the turret positions
and the pointing errors see: turret
positions and pointing errors.
home_~phil