Science Highlight




Announcement of 3mm VLBI in Cycle 7

It is expected that phased ALMA will participate in some GMVA observations during ALMA Cycle 7 (Oct 2019 - Sept 2020;  see the ALMA Cycle 7 Pre-announcement).   There are likely to be ~43 ALMA antennas available to the ALMA observation; but the phased sum used for VLBI may be constructed only from those that lie within a circle of radius 0.5 km.   GMVA session dates for 2020 are not yet fixed but Session I in 2020, which is traditionally in the period March - May, would provide an opportunity for  GMVA + ALMA observing. 

Any GMVA proposal requesting phased ALMA during Cycle 7 must be submitted via the NRAO PST at the February 1, 2019 deadline.

Proposers should:

  • specify "ALMA" in the¬†Other Stations¬†text field in the PST
  • select the default GMVA 3mm observing mode of 2 Gbps, dual polarization
  • specify the amount of time and GST range(s) needed for ALMA¬†separately, either in Session Constraints or Comments, or in the Technical Justification.

A separate proposal to ALMA must also be submitted at the deadline for ALMA Cycle 7 proposals on April 17, 2019.  For this, all proposers (PI and Co-I's) must be registered ALMA users (see:  http://www.almascience.org).

**Restrictions on GMVA+ALMA proposal in Cycle 7:

  • GMVA observations with ALMA will be limited to a fixed recording mode, which currently provides 2 Gbps on all baselines.¬† The KVN will not be available in this mode.¬† Only VLBA telescopes will be available at 7mm in this mode.
  • Due to the need to phase up on science target sources themselves, they will be restricted to those with a flux density >0.5 Jy contained within an unresolved core on ALMA baselines up to 1 km.
  • In order to make a clean linear-to-circular polarization transformation of ALMA recordings, any target source must be observed for a duration of at least 3 hours (breaks for calibrators permitted) to sample a range of parallactic angles.
  • Large Programs (>50 hours of observing time) are not permitted because phased ALMA is a non-standard mode.
  • No long-term programs may be proposed, and no proposals will be carried over into the next cycle.
  • There is a cap for VLBI of 5% of ALMA Cycle 7 observing time.¬† As time for GMVA observations will thus be scarce, proposals should include a quantitative justification as to why ALMA is essential for the goals of the project.

 Resubmission of ALMA Cycle 6 proposals:

The outcome of scheduled GMVA+ALMA Cycle 6 observations scheduled in April 2019 is unlikely to be known until after the ALMA Cycle 7 proposal deadline.  If the PI wishes to mitigate against the possibility that these observations are not completed successfully, the proposal must be resubmitted to ALMA by the Cycle 7 proposal deadline and undergo a new review. The proposal does not need to be resubmitted to the GMVA in this case.  Observations in Cycle 7 will only occur if the April 2019 observations are not completed successfully and the ALMA Cycle 7 proposal is ranked high enough for scheduling.

However, if the PI wishes to obtain a second epoch of GMVA+ALMA observations, even if the April 2019 observations are successful, a new proposal must be submitted to both the GMVA and ALMA by their respective proposal deadlines.

Any questions about the VLBI prospects for ALMA in Cycle 7 should be directed to the ALMA Helpdesk: http://help.almascience.org. Additional information on using ALMA with the GMVA can be found at the websites for the VLBA (https://science.nrao.edu/observing/call-for-proposals/2019b/vlba-proposal-guide) and the GMVA (http://www3.mpifr-bonn.mpg.de/div/vlbi/globalmm/).