The GBT as a MM Telescope

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The GBT as a MM Telescope
ALMA Science Workshop May 2004 Brian Mason
(NRAO-GB)
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PTCS Team Richard Prestage Kim
Constantikes Dana Balser et al.
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Current Performance

• Blind ptg 5''
• (2.5mm focus)
• Offset ptg (90 min) lt 3''
• (1.5mm focus)
• Tracking (30min) 1''
• Q-band Efficiency 40-45

(All pointing numbers are 1 sigma 2D RMSs)
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(Lockman et al.)
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The Penn Array
UPenn NASA/GSFC NRAO NIST Cardiff

• Initial Bandpass 86 94 GHz
• 8x8 array of TES bolometers
• A fully sampled (0.5fL) focal plane
• 8 beam, 4 beam spacing
• SQUID Mulxiplexed
• Cooled by Pulse Tube Cooler
  closed-cycle He7 Fridge

Technologies suitable for a much larger
bolometer array
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5 x 5
OVRO 50h ?1 mJy/Bm
Penn Array 8 min ? 0.1 mJy/Bm
80x80GBT 5 sec ? 0.1 mJy/Bm (snapshot)
Testi Sargent (1998)
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Z0
Z5
Z10
5 Hours 3x3 to 10 uJy RMS
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SZE
Z0.686
100 kpc at zgt1 ? 20
RX J22282037
Z0.421
LaRoque et al. (2003)

• Penn Array? 5 hours
• 80x80GBT? 3 minutes

Pointecoateau etal. 2002
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(SHARC-II 350 um figure courtesy of Dominic
Benford)
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Ka W Band Receivers
Ka 26 40 Ghz W 68 - 92 Ghz
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GBT ACS 4 Ghz Wideband Analog
Spectrometer -25 Ghz auto/cross
correlation Very stringent requirements on
stability flatness
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Wideband Spectroscopy
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• GBT currently operational through 52 Ghz
• Near Future prototype operation up to 94 Ghz
• Fall/Winter 2005/2006 Regular 3mm operation
• Stay tuned...

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(extra material)
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(Thilker et al. 2004)
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Dealing with Systematics
Use atmosphere to flat-field pixel gains
(Dowell Hildebrand)
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BU/FCRAO GRS (Simon et al 2001)
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The Penn Array
UPenn NASA/GSFC NRAO NIST Cardiff

• Initial Bandpass 86 94 GHz
• 8x8 array of TES bolometers
• A fully sampled (0.5fL) focal plane
• 8 beam, 4 beam spacing
• SQUID Mulxiplexed
• Cooled by Pulse Tube Cooler
  closed-cycle He7 Fridge

Technologies suitable for a much larger
bolometer array
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Blank
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GBT Instrumentation

• LIST PAST/FUTURE
• SHOW PICTURE OF FREQ COVERAGE

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GBT Instrumentation

• LIST PAST/FUTURE
• SHOW PICTURE OF FREQ COVERAGE

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Mapping with Single Dishes
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SED T58 K, beta1.35 (Yun Carilli 2002)
Z0
10 minutes 5x5 to 10 uJy RMS
Z5
Z10
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• Point source photometry D4
• Point source discovery Nfeed D2
• Extended source mapping Nfeed
• simultaneous high resolution zero spacing

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Spectral Lines

• Recombination lines
• HCN HCO DCO
• SiO masers
• Redshifted CO optically obscured galaxies
  redshift desert (1.5 lt z lt 2)

Chapan et al. (2003 Nature) figure from Andrew
Blain
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NASA/GSFC
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Closed-Cycle 7He Fridge
40 K
Charcoal

3K
3K
4He
1K
To focal plane
3He
250mK
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The GBT
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