M. Mello

MUSTANG: 90 GHz science with the Green Bank Telescope

MUSTANG is a 90 GHz bolometer camera built for use as a facility instrument on the 100 m Robert C. Byrd Green Bank radio telescope (GBT). MUSTANG has an 8 by 8 focal plane array of transition edge sensor bolometers read out using time-domain multiplexed SQUID electronics. As a continuum instrument on a large single dish MUSTANG has a combination of high resolution (8) and good sensitivity to extended emission which make it very competitive for a wide range of galactic and extragalactic science. Commissioning finished in January 2008 and some of the first science data have been collected.

MUSTANG2: a large focal plan array for the 100 meter Green Bank Telescope

MUSTANG 2 is a 223 element focal plane that operates between 75 and 105 GHz on the 100 meter Green Bank Telescope. It shares many of the science goals of its predecessor, MUSTANG, but will have fifteen times the sensitivity and five times the field-of-view. Angular scales from 900 to 60 will be recovered with high fidelity providing a unique overlap between high resolution instruments such as ALMA and lower resolution single dish telescopes such as ACT or SPT. Individual TES bolometers are placed behind feedhorns spaced by 1.9λ f and are read out using a microwave SQUID multiplexing system.

Towards the development of a high-sensitivity cryogenic phased array feed

A cryogenic phased array feed operating at L-band is in development for the Green Bank Telescope (GBT). The feed consists of electrically small feed elements optimized for active impedance matching to cooled front end low noise amplifiers (LNAs), down-converters, a real-time streaming data acquisition system, and beamforming algorithms applied in post-processing. A prototype cryogenic array feed was recently tested on the GBT. This results will be an important step towards the development of a new receiver instrument, the focal L-band array for the GBT (FLAG).

A 19 element cryogenic phased array feed for the Green Bank Telescope

A low-noise cryogenic phased array feed (PAF) is in development for the Green Bank Telescope (GBT). The feed consists of electrically small elements tuned to operate near 1.4 GHz and optimized for active impedance matching to cooled front end low noise amplifiers (LNAs). A prototype cryogenic PAF with analog fiber link, down-converters and streaming data acquisition system was recently tested on the GBT. Preliminary results are presented. These efforts form an important step towards the development of a new receiver system, the focal L-band array for the GBT (FLAG).

The versatile GBT astronomical spectrometer (VEGAS): Current status and future plans

The VEGAS multi-beam spectrometer (VEGAS) was built for the Green Bank Telescope (GBT) through a partnership between the National Radio Astronomy Observatory (NRAO) and the University of California at Berkeley. VEGAS is based on a Field Programmable Gate Array (FPGA) frontend and a heterogeneous computing backend comprised of Graphical Processing Units (GPUs) and CPUs. This system provides processing power to analyze up to 8 dual-polarization or 16 single-polarization inputs at bandwidths of up to 1.25 GHz per input. VEGAS was released for “shared-risk” observing in March 2014 and it became the default GBT spectral line backend in August 2014. Some of the early VEGAS observations include the Radio Ammonia Mid-Plane Survey, mapping of HCN/HCO+ in nearby galaxies, and a variety of radio-recombination line and pulsar projects. We will present some of the latest VEGAS science highlights.

An Enterprise Software Architecture for the Green Bank Telescope (GBT)

The enterprise architecture presents a view of how software utilities and applications are related to one another under unifying rules and principles of development. By constructing an enterprise architecture, an organization will be able to manage the components of its systems within a solid conceptual framework. This largely prevents duplication of effort, focuses the organization on its core technical competencies, and ultimately makes software more maintainable. In the beginning of 2003, several prominent challenges faced software development at the GBT. The telescope was not easily configurable, and observing often presented a challenge, particularly to new users. High priority projects required new experimental developments on short time scales. Migration paths were required for applications which had proven difficult to maintain. In order to solve these challenges, an enterprise architecture was created, consisting of five layers: 1) the telescope control system, and the raw data produced during an observation, 2) Low-level Application Programming Interfaces (APIs) in C++, for managing interactions with the telescope control system and its data, 3) High-Level APIs in Python, which can be used by astronomers or software developers to create custom applications, 4) Application Components in Python, which can be either standalone applications or plug-in modules to applications, and 5) Application Management Systems in Python, which package application components for use by a particular user group (astronomers, engineers or operators) in terms of resource configurations. This presentation describes how these layers combine to make the GBT easier to use, while concurrently making the software easier to develop and maintain.