ObsMode2021 Cycle 9 Go/No-Go Report for VLBI Capabilities

Abstract

We present a status summary of the primary Very Long Baseline Interferometry (VLBI) development efforts which are under consideration at ALMA as new offerings in Cycle 9. These activities are being carried out under the ALMA North America Development Project known as the ALMA Phasing Project Phase 2 (APP2). The two VLBI priorities previously identified for Cycle 9 by the ObsMode process are: (1) a submillimeter (Band 7) VLBI observing capability and (2) a prototype spectral line VLBI mode (in Band 3 only). This document provides an overview of the development, testing, and readiness of these capabilities. Updates on other APP2 development efforts of relevance for future cycles, including the phased-array mode offered for the first time in Cycle 8, are also provided. Warning: This report contains material that is considered proprietary to the Event Horizon Telescope Collaboration (EHTC). These results may not be publicly posted, cited, or shared in any form. They are presented here with permission from EHTC Management solely for the purpose of allowing an evaluation of ALMA's performance as a VLBI station for 345 GHz (Band 7) VLBI. This report also contains ALMA EOC (test) data which are subject to ALMA's standard policies on the use of such data. We are working to ensure that the EHTC follows the ALMA guidelines (Carpenter et al., 2019) in the appropriate publication and release of data to allow follow-up work for science.