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How can I request Atacama Compact Array (ACA) observation time in Cycle 2? - Knowledgebase / General - ALMA Science

How can I request Atacama Compact Array (ACA) observation time in Cycle 2?

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You can request use of the Atacama Compact Array (ACA) when you prepare a proposal with the Observing Tool (OT) (please see section 5.3.5.1 "Imaging Considerations - Arrays and Configurations" in the ALMA OT User Manual).

The OT can advise if the ACA is needed, based on the PI-requested "largest angular scale" (LAS). This value is compared to the "Maximum Recoverable Scale" (MRS) for the 12-m Array (as listed in Table 2 of the ALMA Cycle 2 Capabilities). If LAS>MRS, then the ACA should be used. The PI can decline the additon of the ACA (which adds to the total time required for the project), but then must explain in the Technical Justification for the relevant Science Goal why this will not affect the science they propose to do.

Note that Total Power (TP) observations are only allowed for spectral line observations in Band 3-8. For Band 9 observations or continuum observations in any band, the TP is not allowed, and such projects requesting the ACA must additionally have a PI-requested LAS that is less than the Maximum Recoverable Scale for the ACA 7-m Array (as listed in Table 3 of the ALMA Cycle 2 Capabilities). 

For more details, see Section 7.6 of the Cycle 2 Technical Handbook. For a video explanation on the definition of Largest Angular Scale, please follow: Largest Angular Scale Video