How to Propose with MUSTANG-2#

General properties (such as FOV, resolution, bandpass information) can be found on the MUSTANG-2 overview page.

If you have general questions about feasibility or initial questions feel free to reach to the members listed under the Contact section on MUSTANG-2 instrument team webpage. However, we ask that you please do this in a reasonable amount of time before a proposal deadline as the team will be busy with many proposals right before the deadline.

Proposal Requirements#

Team Approval#

All MUSTANG-2 proposals are shared-risk and must be approved by the MUSTANG-2 instrument team. Furthermore, the entire MUSTANG-2 instrument team must be included as co-investigators on the proposal.

In order to get your proposal approved by the MUSTANG-2 team, contact one or all of the members listed under the Contact section on MUSTANG-2 instrument team webpage with a draft of your proposal at least a week in advance of the proposal deadline. The MUSTANG-2 team will principally focus on the technical feasibility of a proposal and make suggestions accordingly. The technical justification on a proposal should reference publicly available mapping speeds (e.g. from the MUSTANG-2 mapping webpage and/or MUSTANG-2 mapping speeds memo). The GBT sensitivity calculator does not currently incorporate MUSTANG-2 mapping speeds.

Overhead observing constraints#

The overhead for MUSTANG-2 is dominated by initial setup and calibration. We generally recommend a minimum session length of 2 hours. Allowing for weather and calibration and observing overheads, observers should conservatively allow an observing efficiency of 50% (or 100% overheads relative to on-target time). Thus in the end to account for setup and calibration time to get thier final time request the user should multiply thier on-target time by a factor of 2.

Source visibility considerations#

Daytime observing at 90 GHz is currently not advised. The changing solar illumination gives rise to thermal distortions in the telescope structure which make calibrating 90 GHz data extremely difficult. Useful 3mm observations are currently only possible between 3h after sunset and a half hour past sunrise. Further cooler temperatures are required for observing at 90 GHz thus the high-frequency observing season for MUSTANG-2 is typically ~October - late April/early May. Thus your target must be visibile to the GBT 3h after sunset and a half hour past sunrise in ~October - late April/early May.

Other things of note#

Data and Observing#

Though the entire MUSTANG-2 instrument team will be invovled in the proposal process, conversely, the MUSTANG-2 team will reduce the data and provide appropriate data products (principally a calibrated map, transfer function, and beam characterization) to the proposal team (see the list of possible data products. End-to-end data reduction is currently fairly involved. We will work to provide documentation on data processing and hope to eventually allow proposers to process their own data.

MUSTANG-2 instrument team also asks that the PI and team get trained to observe with MUSTANG-2 and observe for their project whenever possible.

Calculating sensitivities#

MUSTANG-2 is NOT included in the GBT sensitivity calculator thus sensitivities are typically calculated using simulations or previous observations.

For galaxy clusters, one can run simulations or use the tables in this memo to compute the expected compton Y or peak and corresponding required sensitivity. Then reference the table on the mapping webpage and use the following relation to compute required integration time.

As a general rule one can use the relationship between integration time (t) and sensitivity (\(\sigma\)) where t \(\propto\) 1/\(\sigma ^2\) and the values in the table above to calculate the required integration time or desired sensitivity. For example, if one would like to calculate the required integration time corresponding to a desired sensitivity:

  • From the radiometer equation \(t \propto\) 1/\(\sigma ^2\)

  • set up in a proportional relationship \(t_2\)/\(t_1\) \(\propto\) (\(\sigma_1\)/\(\sigma_2\)) \(^2\) where \(t_2\) is the required integration time that you are solving for, \(t_1\) is 1 hour, \(\sigma_1\) is the sensitivity corresponding to the map size from the table on the mapping webpage, and \(\sigma_2\) is the desired sensitivity that you have calculated

  • \(t_2\) \(\propto\) (\(\sigma_1\)/\(\sigma_2\)) \(^2\) \(\times\) \(t_1\) and thus \(t_2\) is your integration time