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GFM - The GBT Fits Monitor

The components of GFM are at different stages of completion; see Continuum Plugins and Spectral Line Plugins for more details. Go to the Usage page if you just want to get started!

1. Introduction

The GBT FITS Monitor (GFM) was initially developed in response to the needs of the PTCS project for analyzing continuum data, but has now evolved into the quick look data display for the Green Bank Telescope (GBT). This application provides sub-scan-based display and analysis of GBT data, either in real-time as the data is being collected, or in an offline mode where it can be used to simply step through the sub-scans from an observation. The user is prompted for a decision to work in either online or offline modes when GFM is started. There is an option under the "File" menu (that one may access after starting GFM) to connect/disconnect to/from data streaming in from the telescope.

2. Technical Features

• Different types of scans are handled by separate analysis modules, or plugins. See Continuum Plugins or Spectral Line Plugins for more information
• The application currently only has production plugins for Continuum data analysis. The plugin for Spectral Line data analysis is in the beta stage.
• Automatically detects the type of scan/observing (e.g. Focus, Pointing, Spectral Line) and calls the relevant analysis modules
• Knows how to handle groups of sub-scans properly, for example, the four sub-scans within a Peak scan
• Supports dual-beam/dual-polarization
• Supports dynamic focus corrections
• Graphics export to Portable Network Graphicss (PNG) and Postscript (PS and EPS) formats is supported. You can also print your plots to any network printer.
• Playback feature allows you to quickly review the plots within a range of sub-scans

3. Known Issues

• Can you make it any faster? Users outside of GB (or at GB who use Windows and Exceed) may notice appreciable delays in response when using GFM. This is always dependent upon how much other network traffic is present, because right now, every time you run GFM you are running the application itself over the network. This isn't the end solution, however - upcoming plans include making the GFM application distributable to users' desktops, so that it can be used effectively for offline looks at the data. When you are using a local copy of the program that just relies on the network for getting data (from files or the live telescope), performance is improved.

4. Performance

It takes between 2-10 seconds for the application to initialize and launch, depending upon the traffic on the machine you're using. Users on Windows machines launching the application using XWindows can expect slower response times than users who run the application natively from a RedHat Enterprise machine. The time it takes to load sub-scans from a new project depends upon the size of the observations and the number of sub-scans. Most continuum datasets we have used take 5-10 seconds to load (<1000 sub-scans). The largest data sets (8 IFs, 1 sec dumps from the spectrometer) we have experimented with have taken up to two minutes to load completely. Processing a single Continuum Peak/Focus scan should typically take ~2 seconds.

For some specific timing numbers, visit the GFM benchmarks page.

5. References

• GFM uses the Data Extraction and Analysis Program or DEAP for all its plotting.
• Search for all GFM documentation on the wiki.

6. Screen Shots

Core Team