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Telescope and Datataking status

Telescope and Datataking status. 2010 Visiting Committee Meeting Phil Perillat. Talk Outline. Telescope performance Pointing Gain/Sefd/Tsys:cband,lband, 800 Mhz New telescope observing limitations Datataking: Backends Commensal observing Future Backends 12 meter Summary

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Telescope and Datataking status

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  1. Telescope and Datataking status 2010 Visiting Committee Meeting Phil Perillat

  2. Talk Outline • Telescope performance • Pointing • Gain/Sefd/Tsys:cband,lband, 800 Mhz • New telescope observing limitations • Datataking: • Backends • Commensal observing • Future • Backends • 12 meter • Summary Online: http://www.naic.edu/~phil/talks/talks.html apr10 vc10

  3. Pointing • Pointing model made dec07/jan08 after painting shutdown.

  4. Pointing Errors: mar09-mar10 • Mar09-jan10 data before break • Errs vs za • Errs vs az (1 az term y08-09 removed in model) • Mar10: after beam repair: • Errs vs za (limits: 3.5 to 12 deg za) • Errs vs az (looks like 1az term..) • RmsError: • Before break: 4.9,6.3 (za,az). Tot: 8.0 asecs • After break: 9.0, 10.6 (za,az). Tot:13.9 asecs

  5. Gain,SEFD,Tsys:lband,cband • Data mar09 - mar10 • Lband @ 1400Mhz • Cband @ 5000 Mhz • Gain • Tsys • Sefd • Beam width

  6. 700-800 Mhz rcvr • Installed jul to dec09. penn state feed • Cooled to 70K, cavity filter in front of lna. • Gain,Tsys: Tsys high.. Cavity filter, over illuminates tertiary. • Sefd ,BeamWidth • Rfi: Chn 67 (879 Mhz) LP tv. • Helped buy parts for lp dtv so they would go off the air • BYU single pol rcvr 5% smaller bm width • Still working on dual pol mode. • Running out of time for clean band: • Emg services: 763-775,793-805 ready to go.

  7. Alfa • Alfa tsys measured during survey runs: • 4048 measurements mar09 thru mar10. • Each color is a different project: • White:A2010 (alfalfa), Red:A2048(ages), Green:A2433(auds), Blue:(A2453) • PolA on left, polB on right. • Beams 0-3 • Beams 4-6 • Beam 2a has unstable Tsys.

  8. observing limitations • The weights and distances on az arm. • Za for dome center of mass: 1.9deg below optic axis za • Ratio DomeWeight/ChWeight = 6. • For constant moment arm: dzaCh = 6*dzaDome. • How we observe: • Ch sits at 8.8 degrees, dome moves in za. • Azarm imbalance changes with dome za. • Elevation rails shimmed high so imbalance tilts receiver in dome, onto the paraxial surface. • 3 tiedowns keep the average platform height fixed with temperature (no tilting of platform done by td’s)

  9. The problem: • Max allowed imbalance:15000 kip-ft • Various configs for ch, dome motion: • BUT: max allowed imbalance depends on td tension • Td tension relieves tension in beams. • Td tension used to keep avg platform height in focus. • This is a function of temperature since main cables change length with temp. • Examples showing za range vs temp: • Dome tracks: Ch at stow: normal astronomy • Dome tracks: Ch tracks dome above 8.8 deg za • Dome tracks: Ch at 0 (aeronomy az swings).

  10. What we can do: • Removing weight from the dome • decreases the unbalanced moment arm • Removing weight from the platform • Allows more tension in the tiedowns • Installing the tertiary motor drives. • Lets you make the optical axis longer • This lets you increase the td tension (pull down on platform) to get back in focus. • 1 platform inch is 2-3 kips per corner • 1 deg F is .75 kips per corner.

  11. Datataking: Backends

  12. Datataking:new functionality • Mock single pixel observing • 7x172Mhz covers 1Ghz IF with 20Khz res. • 1 Ghz, 10Khz res. Possible with 2nd 7x172 set • Different settings allowed for 7 bands: • Center freq, channels, bw, config:sumPols, 2pol, stokes. • Mock file server upgrade: • 3.2 -> 5.5 Tb/server. TotalDisk:14*5.5=70 Tb online. • Mock aeronomy sampling system • 6 bands: 32Mhz widest, samples @160Mhz • Example:10 sec clp spectra (ch)

  13. Datataking:Commensal • Alfalfa extragalactic search, short integrations, large area • Ages – extragalactic search, median integration • Auds – extra galactic search: long integration • Zoa : zone of avoidance • Galfacts: galactic polarization survey • Rrl: recombination line survey • Togs- galactic survey • Palfa: pulsar search. • Survey names: • Routine survey commensal observing: • Example: • Igalfa/galfacts/zoa,rrl: may09-sep09 56 3hour sessions • Igalfa- galactic survey galspect, • Galfacts: mock,full stokes, 300 Mhz Bw. • 65Mb/sec *7 =455 Mb/sec, 4Tb/night • Zoa/rrl:mock2, 300 Mhz Bw, .1 sec integrations.

  14. Future:Backends • Vlbi: Digital BackEnd: dbe • 2: 1 for 305meter, 1 for 12 meter • Has mode to run 500 Mhz bw spectra • Aeronomy • Integrate mock device with datataking. • Planetary radar with mock: • Needs fgpa programming (or use regular baseband sampling with pdev).

  15. Future:Backends • Mock single pixel Baseband sampling: • Need to add functionality to cima • Work on pdev headers. • 7 or 14 boxes.. • Bandwith per box:

  16. Future:12 meter • 12 meter telescope • Integrate with vlbi station observing using dbe • Allow non vlbi usage of telescope with 305m • Needs pointing program • IF signal needs to be piped into standard backends. • Software to support it.

  17. Summary • Telescope performance: • Pointing: • rmsError: za: 9.0 az:10.6 tot:13.9 asecs • Need to fix 1 az term from tilted platform • Gain,Tsys,sefd,Tsys • Sefd:800:13.Jy, lbw: 2.5Jy, Cband : 3.3Jy • Get 800 antenna replaced • Tsys alfa 26-35 K (vs za). fix bm2a. • Limitations: • Za 3.5->12, daytime fixed position. • Future: • 12 meter integration. • Backends: • Integrate aeronomy, do planetary radar, mock baseband sampling.

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