Robert W. Garwood

Advanced multi-beam spectrometer for the Green Bank Telescope

A new spectrometer for the Green Bank Telescope (GBT) is being built jointly by the NRAO and the CASPER, University of California, Berkeley. The spectrometer uses 8 bit ADCs and will be capable of processing up to 1.25 GHz bandwidth from 8 dual polarized beams. This mode will be used to process data from focal plane arrays. The spectrometer supports observing mode with 8 tunable digital sub-bands within the 1.25 GHz bandwidth. The spectrometer can also be configured to process a bandwidth of up to 10 GHz with 64 tunable sub-bands from a dual polarized beam. The vastly enhanced backend capabilities will support several new science projects with the GBT.

The General Single-Dish Data format: A retrospective

The General Single-Dish Data format (GSDD) was developed in the mid-1980s as a data model to support centimeter, millimeter and submillimeter instrumentation at NRAO, JCMT, the University of Arizona and IRAM. We provide an overview of the GSDD requirements and associated data model, discuss the implementation of the resultant file formats, describe its usage in the observatories and provide a retrospective on the format.

AIPS++ and the GBT: a layered approach to processing and analysis of single-dish data

The Green Bank Telescope (GBT) is a new 100-m diameter antenna with an unblocked aperture and an active surface. It is designed to observe at frequencies from 300 MHz to 100 GHz, and includes state of the art continuum and spectral backends. The GBT is also capable of pulsar work and recording as a VLB station, and array receivers are being developed as well. AIPS++ is the integral software package for analysis of GBT data both for scientific analysis as well as for control and engineering analysis of the component systems. In this paper we will give an overview of how the AIPS++ system is used with the GBT, with special consideration to the development of spectral analysis software. AIPS++ allows a layered approach to software development, and the spectral analysis capability gives a strong example of the usefulness of the layered approach. At the heart of AIPS++ is a suite of tools which are capable of astronomy-specific calculations as well as general purpose mathematical analysis, data visualization, GUI development, and scripting. A tool for analyzing single-dish data, DISH, is developed on this platform. DISH includes a number of modern features such as bulk processing of datasets and versatile GUI interaction. A simplified package using a familiar CLI, known as UNI-jr, is built on DISH and is available as an easy to learn path for processing scan-based data. Finally, the Interim Automated Reduction and Display System (IARDS) is built on UNI-jr and provides an automated reduction package and pseudo real-time display.