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: http://www.naic.edu/~emuller/EALFA/
Дата изменения: Thu Oct 14 00:54:04 2004 Дата индексирования: Tue Oct 2 00:04:36 2012 Кодировка: Поисковые слова: п п п п п п п п п п п п |
ALFA - 'dishspot' (pre-cursor for 'leapfrog' mode - we've called it 'dishspot' because it observes a constant range of positions on theMore info on dishspot: 10 positions measured, 300 s each pointing.
dish, we will re-name this eventually....).
This mode:
1) Moves to the requested RA and Dec, and remembers the AZ and EL.
2) The telescope tracks a source at sidereal rate, for the user-requested
length of time.
3) The telescope moves back to the original AZ and EL, calculates the new
RA, and loops back to 2)
For proper operation, the current mode needs to predict the slew time to the next point. In
theory, this should be accurate to less than 10 seconds
Data taken at around midday on the 16th May (the sun generated
some problems)
10 positions measured, 300 s each pointing.
4096 channels, 100MHz Bandwidth, centred on 4120 MHz.
These data here are for the first polarisation on the first pixel.
(there are no real reasons why any other polarisations on any other pixels
would be much more or less stable.)
For Dishspot:
Start time (lst hrs):1.6805090
Finish time (lst hrs):2.6052562
Number of tracks: 10
Time per track (min):5
Total observing time (mins): 55.4848
Total integration time (mins): 50
Mean Slew time for between each step (sec)=32.9088
observing efficiency for dishspot:90%
NB: For Regular ononff, Wait 1 min at each new 'off'
Total observing time=55.4848+Ntracks
observing efficiency for onoff:76%
Estimates for leapfrog
(expected wait at each new 'on' is MAX 10 sec)
total observing time=55.4848+Ntracks*0.6
observing efficiency for leapfrog:81%
Efficiency will improve for longer integration times.
RA (hrs) | Dec(deg) |
1.38993 | 34.4629 |
1.47482 | 34.4674 |
1.55956 | 34.4707 |
1.64392 | 34.4740 |
1.72857 | 34.4767 |
1.81321 | 34.4789 |
1.89806 | 34.4803 |
1.98258 | 34.4808 |
2.06706 | 34.4805 |
2.15136 | 34.4802 |
click here for this image as ps. |
click here for this image as ps. |