Telescope and Datataking status

NAIC AUSAC Meeting – April 19-20, 2010

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

Online: http://www.naic.edu/~phil/talks/talks.html apr10 vc10


Pointing

Date Az Err

(arcsec)

Za Err

(arcsec)Total Err (arcsec)

2003 mod14 5.38 3.48 6.41

2004 mod15 4.20 2.41 4.84

2007mod17 4.39 2.99 5.31

Jul08-feb09 6.8 4.6 8.2

Mar09-jan10 6.3 4.9 8.0

Mar10-> 10.6 9.0 13.9

• Pointing model made dec07/jan08 after painting shutdown.


• 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

Pointing Errors: mar09-mar10


Gain,SEFD,Tsys:lband,cband

• Data mar09 - mar10• Lband @ 1400Mhz• Cband @ 5000 Mhz• Gain• Tsys• Sefd• Beam width

Lband

1400

Cband

5000

Gain K/Jy 11.3 8.2

Tsys K 28 K 27 K

SEFD 2.5 Jy 3.3 Jy

bmWidth 202” 56”


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.


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.


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)


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).


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.


Datataking: Backends

Device Type/bits # device Bw MHz Pols

Interim cor Cor:3/9lvl 4 50 4

Wapps Cor:3/9lvl 8 100 4

GalSpect Pfb/fft:8 2 8 2

Mock Pfb/fft:12 2*7*2=28 172 4

Daeron Smp:14 1 or 2 10,5 1

Pfs smp:2-4 1 20 1

RI Smp:1-12 2 10 2


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)


•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.

Datataking:Commensal

Primary Com1 Com2

alfalfa/wapp Togs/galspect Palfa/mock1*

Ages/mock1 Togs/galspect

Palfa/mock1 Zoa,rrl/mock2

Galfacts/mock1 Zoa/mock2

Igalfa/galspect Galfacts/mock1 Zoa/rrl/mock2

•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.


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).


Future:Backends

• Mock single pixel Baseband sampling:– Need to add functionality to cima

– Work on pdev headers.

– 7 or 14 boxes..

– Bandwith per box: Bits 1pol

Mhz

2pol

Mhz

4 70 35

8 35 17.5

16 17.5 8.75


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.


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.

Documents

Telescope and Datataking status