Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.atnf.csiro.au/research/masermeeting/web_papers/405_JGreen.pdf Дата изменения: Fri Apr 27 02:03:49 2007 Дата индексирования: Sun Dec 23 10:27:23 2007 Кодировка: Поисковые слова: m 106

IAU Symposium 242 Astrophysical Masers and their Environments Alice Springs, 13th March 2007 James Green

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The Methanol Multibeam Project
MMB

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The Methanol Multibeam Project: The Team
R. J. Cohen, J. L. Caswell, K. Brooks, M. G. Burton, A. Chrysostomou, P. J. Diamond, S. Ellingsen, G. A. Fuller, M. D. Gray, J. A. Green, M. G. Hoare, M. R. W. Masheder, N. McClureGriffiths, M. Pestalozzi, C. Phillips, L. Quinn, M. Thompson, M. Voronkov, A. Walsh, D. WardThompson, D. WongMcSweeney, J. A. Yates.

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Participants

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MMB 7-Beam Receiver
Jointly built by Jodrell Bank and ATNF. Hexagonal layout pattern of 7 equal receivers. Capable of dual polarisation over a large bandwidth. Calibration with noise injection sampled at 500Hz.

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Survey Characteristics I
4 MHz Bandwidth (180 km/s at 6668 MHz). Assume 150km/s fully useful bandwidth, so multiple centre velocities toward Galactic centre 10km/s overlap. Doppler tracking provided by the first two local oscillators. Correlator configured to provide 2048 frequency channels across each 4 MHz band, at each line frequency and each polarization. Velocity resolution 0.09 km/s at 6668 MHz. Spectra dumped every 5 seconds. System noise temperatures ~20 K.
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Survey Characteristics II
HPBW 3.2 arcmin at 6668 MHz and 3.4 arcmin at 6035 MHz. Beams spaced by 6.46 arcmin on sky. Multibeam footprint is 15arcmin across. SPOT and MX observations to monitor variation in calibration. Blocks of 2O in l, ±2O in b. Continuous scanning at 0.1O min-1. Optimal Orientation. Beam Sensitivity consistent to ±3.5%.

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Results: An Example Field

OBSERVATIONS LIVEDATA GRIDZILLA
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KVIS/RESULTS


Survey Progress
Surveyed 106 degrees galactic longitude. Observed 528 masers, of which 218 new. 53/100 days Parkes observing time. Most new are weak (Speak < 4 Jy). Narrow linewidths (FWHP < 0.2 km/s). Far-side outer Galaxy detections.

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Observational Distribution
2.5 2.0 1.5 1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0 -2.5 180 160 140 120 100 80 60 40 20
00 -20 -40 -60 -80 -100 -120 -140 -160 -180

L vs b
150 100

50

0

-50

-100

-150 180 160 140 120 100 80 60 40 20

0 0 0

-20

-40

-60

-80

-100

-120

-140

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-160

-180

L vs Velocity (LSR)


Survey Statistics
180 160 140

120

100 New Masers Known Masers 80

60

Flux Distribution
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Galactocentric Distance (Kp

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20

0

Galactocentric Distance

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ATCA & MERLIN
Positioning follow-up: Parkes positions accurate to ± 30 arcsec. Capabilities to do it in both hemispheres with ATCA and MERLIN:
ATCA ± 0.1 arcsec MERLIN ± 0.01 arcsec

ATCA observed and positioned all new detections. MERLIN observed 30 new in 20-30 region, positioned 25.

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Pulsar Survey Piggyback
Deep integrations through pointed observations conducted as part of the pulsar search program. No Doppler tracking. Just Methanol 6668 MHz frequency. Correlator configured for 8 MHz over 4096 channels for 7 beams, 2 polarisations. Same spectral resolution, but over wider velocity range. Focused on Galactic Centre, but covering -60 < l < +45 (maximum +/- 0.5 in b).

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The Work Plan : 2007-2011
Parkes Multibeam survey till 2008. ATCA positions, snapshots and 8.4 GHz continuum. MERLIN positions and snapshots. IR and CORNISH (VLA cont.) identifications. Distances and Galactic Distribution. Jodrell Bank Multibeam survey 2008-2010. MMB catalogue of Milky Way. MMB survey of LMC/SMC. Simultaneous survey of excited OH 6035 MHz. Methanol deep fields at Pulsar pointings. 13