LBA Calibrator Survey

Chris Phillips

eVLBI Project Scientist

23 July 2009

ATCA

Hobart

Sydney

Ceduna

ASKAP

The LBA

Perth

Melbourne

Tidbinbilla

Mopra

Parkes

The LBA

• 6 telescopes within Australia• Parkes, 64m• ATCA, 5x22m phased array• Mopra, 22m• Hobart, 26m• Ceduna, 30m• Tidbinbilla, 34m&70m

• Also • Hart, Kokee, TIGO, O’Higgins, Shanghai, Kashima

• 1-20 GHz • Data rates up to 1 Gbps

• LBADR recording system (Mark5b mode)• eVLBI up to 1 Gbps

• Pa, At, Mp, Ho (64-128 Mbps)

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LBA Operations

• Coordinated VLBI for 3 weeks/year• 3-4 dedicated sessions/year

• Fixed schedule• Actual schedule depends on experiment request

and TAC grading

• Correlated using DiFX• Correlation contracted to Curtin University

(Steve Tingay, Cormac Reynolds, Hayley Bignall)

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LBA - Future

• Wide band DAS• 1-2 GHz• ATCA CABB commissioned• DFB3 Pulsar Backend for Parkes/ATCA

• AuScope• 3x12m for geodesy• WA, NT and Tasmania• S/X only• No operational funds for astronomy

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ASKAP

• Number of dishes 36 • Dish diameter 12m• Max baseline 6km• Resolution 30 • Sensitivity 65 m2/K

• Observing frequency 700 – 1800 MHz• Field of View 30 deg2

• Processed Bandwidth 300 MHz

• Multiple VLBI beams• Up to 30, requested at least 2

• Combined with cluster-cluster VLBI at other stations

• Parkes multibeam, ATCA array, Hobart 12mCSIRO. eVLBI-Aus

LBA Astrometry

• Adam Deller’s PhD Thesis• Parallaxes to 7 pulsars

• J0437-4715: Most accurate pulsar distance to date

• 1E 1547.0–5408 magnetar propermotion• 6.7 GHz methanol maser parallax

• H20 maser proper motion in LMC

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LBA Astrometry – The Problem

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AT20G

• All Southern sky 20 GHz survey• South of Dec 0

• 8 GHz bandwidth• Analog correlator

• 3 antenna• Sensitivity limit ~50 mJy

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Survey Design

• Wideband (8 GHz) analogue correlator

• Fast scan rate: 15°/min at meridian

• Follow-ups at 4.8, 8.6 & 20 GHz to confirm detection and for spectral info

Survey Parameters

SurveyFrequency

(GHz)Source

#Area

(sq. Deg.)Slim(mJy)

Taylor et al. 2001 15 66 60 20

9C (Waldram et al. 2003 - 2007)

15 (22, 43) 465 520 25

WMAP (Wright et al. 2008) 23, 33, 41, 61, 94

390 Full Sky (40000)

1000

AT20G 20 (4.8,8.6) 5800 ½ Sky (20000) 50

LBA Calibrator Survey

• Using AT20G as a basis for sample to increase density of Southern calibrators

• σ > -0.55• S(8.4 GHz) > 190 mJy• Dec < -40

• Correlated at Bonn• Native Mark5A, Mark5B, translated Mark5b

shipped electronically• Processed with CALC/Solve by Leonid Petrov

• 8 GHz only – limited by LBA DAS• 4x 24hr observed

• 3x 24hr correlated/analyzed

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LBA Calibrator Survey - Results

• 422 new sources observed• 326 processed• 317 detections

• 97.2% detection rate

• 4 more epochs proposed

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Results

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BeforeNowFinal

Results

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Probability of Close Calibrator

Zone [-90, -40] [+40, +90]

Jan 2008 Now 2010 Now

2deg radius 21.2% 57.8% 78.0% 73.4%

3deg radius 41.2% 84.4% 96.2% 95.0%

4deg radius 60.5% 96.0% 99.5% 99.6%

# objects 163 517 1000 721

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Results – Formal Errors

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Compactness

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Contact UsPhone: 1300 363 400 or +61 3 9545 2176

Email: enquiries@csiro.au Web: www.csiro.au

Thank you

ATNFChris PhillipseVLBI Project Scientist

Phone: +61 2 93724608Email: Chris.Phillips@csiro.auWeb: www.atnf.csiro.au/vlbi