eSMA workshop
February 1-2 2007
Leiden, The Netherlands
eSMA specifications
A few facts...
SMA: 8 6-m antennasJCMT: 15-m dish
CSO: 10-m dish
Longest baseline = 770m
Tuning range = 325-355 GHz; when the new receivers will be avaible, the tuning range will be 325-375 GHz, with dual polarization capabilities restricted to the 330-350 GHz range.
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eSMA expected sensitivities and resolutions, and comparison with competing facilities
(based on a report of the eSMA science case review panel by Di Francesco, Hogerheijde and Richer)The punchline: the dual-polarization eSMA (330-350 GHz) is expected to reach the same noise level as the current single-polarization 8-antenna configuration of the SMA in 1/4th of the time.
| Expected norm for the eSMA | |||||
 |
|||||
| SMA_sp(1) 270-355 GHz |
eSMA_sp(1) 325-355 or 325-375 GHz |
SMA_dp(2) 270-355 or 320-420 GHZ |
eSMA_dp(2) 330-350 GHz |
CARMA 230 GHz |
PdBI 230 GHz |
|---|---|---|---|---|---|
| Continuum rms in 5 h (mJy/beam) | |||||
| 0.99 | 0.64 | 0.70 | 0.49 | 0.23 | 0.12 |
| Line rms in 1 km/s channel in 5 h (K) | |||||
| 3.1 | 2.2 | 2.2 | 1.5 | 4.8 | 0.6 |
| Longest baseline (m) | |||||
| 510 | 790 | 510 | 770 | 2000 | 790 |
| Spatial resolution (") | |||||
| 0.43 | 0.28 | 0.43 | 0.28 | 0.16 | 0.42 |
(2) dp = dual polarization ; Note that for eSMA_dp, 2 SMA antennas are dropped from the array because the SMA correlator does not have the capacity to process signals form 10 antennas and 2 polarizations.
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eSMA sensitivity calculator
Courtesy of Mark Gurwell there now is an online eSMA sensitivity calculator:
 | Important note: | you have to use the custom configuration in order for the JCMT and/or CSO to be taken into account. |
Description:
eSMA users can now specify, using the custom configuration, the inclusion of the JCMT and/or the CSO into the array. NOTE THAT THIS CAPABILITY IS STRICTLY FOR PLANNING AND DEVELOPMENT PURPOSES; SMA proposals cannot request eSMA capability at this time. For the calculator, some simplifying assumptions have been made: that the JCMT and CSO have the same surface accuracy as the SMA antennas, and they also have the same receiver performance. They are treated essentially as SMA antennas except for their fixed locations, and their dish area (JCMT = 15 m diameter, CSO = 10.4 m diameter, SMA = 6 m diameter). The increased collecting area of the array is reflected in improved noise performance, and the beam calculations also properly handle the increased weight of eSMA baselines in determining the naturally weighted beam. Note that the observing efficiency (66%) is kept the same; however, the actual eSMA efficiency will likely be lower, due to the slower slew rates and longer settling times of the JCMT and CSO. Expect changes to the eSMA assumptions in the future.↑ Back to top