12 meter first light
updated sefd,Tsys after fixing extended source correction)
first light with the 12meter telescope on 19jun12.
The plots show the system response
to the crab nebula (.ps) (.pdf):
- This is not the final configuration of the electronics:
- Dana used a temporary cable from the 1st amps down to the
12meter control box. It then hops on the fiber. Eventually we
will have the fiber go all the way to the 1st amps.
- The pointing program is not "written". We used the ra,dec
tracking of in current coordinates provided by the patriot
program. I precessed the sources to the date of the
- The original pointing model was used.
- I used x-el, el offsets to peak up on the source
- 500 MHz bandwidth at 8600 MHz was routed through the if/lo to
square law detectors with .2 sec time constant and then
digitized at 10 Hz rate.
- We tracked the crab nebula (5x7 arcminutes) starting at about
3 hours after transit.
- black is polA, red is polB
- the blue line shows where we moved off source
- The signal was normalized to the off source value (Tsys).
- 612Jy was the flux used for the crab.
- The SEFD was 4943 Jy.
- The raw SEFD was 5345 Jy, but the crab is an extended
- The crab is 7x5 arcminutes. The beam is about 12.5
- I corrected for the source extension by assuming it had a 6
arc minute extent.
- Tsys= 128 K
- I used a physical illuminated area of 12 meter diameter and
an effective aperture of .63.