MUSTANG-2 Overview#

MUSTANG-2 is a 223-feedhorn bolometer (continuum) camera with a bandpass from 75 to 105 GHz on the GBT.

MUSTANG-2 is inherently a mapping instrument and observes by scanning “on-the-fly” (OTF). Our most common scan pattern is that of a Lissajous Daisy that can observe objects from our resolution (9″) to several arcminutes in size (more details on mapping). For scans of ~a degree, we have switched to a raster scan. If you would like to consider another mapping strategy, please contact a member of the MUSTANG-2 instrument team to inquire about it. The instantaneous field of view (FOV) is just over 4 arcminutes (4.2′). For full bandpass details see this page.

MUSTANG-2 was commissioned on the GBT in spring 2016 (see development timeline), and has been offered for observations on a shared risk basis, in collaboration with the instrument team, since the 2018A GBO proposal call. Several features distinguish it from its predecessor, MUSTANG:

  • A new, microstrip-coupled detector design yields higher sensitivity and less susceptibility to environmental microphonics.

  • Detectors are feedhorn coupled, with the sum of two linear polarizations measured by a single TES per feed.

  • The instantaneous field of view is 4 arcminutes (vs 42 arcseconds for MUSTANG)

  • The receiver design incorporates a tilted refrigerator and receiver rotator, resulting in much lower dependence of cooling performance on telescope elevation.

  • The detector readout is the first astronomical use of microwave resonators to multiplex TES bolometers.

MUSTANG-2 has been developed by a collaboration including the University of Pennsylvania, NIST, NRAO, the University of Michigan, and Cardiff University. All critical MUSTANG-2 systems have already been proven in operation on the GBT in early 2015 during an engineering run using a partially populated version of the receiver (“MUSTANG-1.5”, which had 64 populated feed horns).

Many papers have been published using both MUSTANG and MUSTANG-2.

The Status of Future GBT Open-Skies Observing#

In order to cope with an evolving funding landscape the GBT is in the process of moving to a model which relies upon a larger fraction of private and collaborative (“pay-to-play”) partnerships. It is expected that a significant fraction of GBT time, depending on the future level of NSF funding, will remain open under something like the current proposable, open-skies arrangement; however the mix of observing capabilities that is available under this arrangement is TBD. If you are interested in forming or contributing to such a partnership to ensure continued access to MUSTANG-2 on the GBT, please contact the director of the Green Bank Observatory, Jim Jackson.