New Directions and Requirements for the GBT Pipeline

Agenda:

• Brief summary of current pipeline (Joe) [10 min]
  • Top priority requirements (All Met)
    • Accurately calibrate position switched observations with the KFPA
    • Automatically create images with appropriate parameters
    • Calibrate Position Switched images
    • Include monitored atmospheric opacity and model GBT gain parameters.
    • Allow the observer to tune the calibration values based on additional measurements.
    • Facilitate combining a number of GBT observing sessions into a single map.
  • Secondary priority items (Also met)
    • Automatically find sets of map scans and reference observations
    • Parallel process calibration.
    • Reduce other GBT Rx data (tested with L band, Ku band and K band)
• Pipeline requirements & wish-list:

• • 4mm (Dave) [10 min]

The 4mm system uses a calibration wheel to collect cold+amb+sky data for calibration. Unlike all other GBT Rx's, there are no noise diodes for calibration. The majority of the data taken with the 4mm receiver will be spectral line observations with the spectrometer. The calibration document (pdf) provides the formulae for calibrating the data. For proper calibration, the system needs the measurements made during the calibration sequence, values from several temperature sensors, real-time estimates of the current weather conditions (tau_o and T_{atm}), and system parameters such as telescope efficiencies.

• • • Support the following observing modes
      • position switch
      • sub-beam nod
      • Frequency switching
      • On the fly mapping

• • • Read in weather parameters from weather database
      • Tau_o
      • T_atm
      • Outside temperature

• • • Read in calibration data from Rx fits files
      • Tcold(t)
      • Twarm(t)

• • • Apply pointing corrections from the quadrant detector (for mapping pointing reconstruction).

• • • Calibration via formula in the calibration document [TBD]. An initial version is available: http://www.gb.nrao.edu/4mm/ProjectBook/Chapter4/W2Rx_cal.pdf

• • • Support the following temperature and flux density scales
      • T_A -- Observed antenna temperature
      • T'_A -- Antenna temperature corrected for opacity
      • T*_A -- Antenna temperature from the chopper wheel calibration
      • T_mb -- Main-beam temperature appropriate for extended sources
      • S_nu -- Flux density scale appropriate for point sources

• • KFPA (Glen) Wish List
    • Tools for Re-sampling of spectra to observer specified channel widths and ranges. (Top priority)
    • Vector T cals (Top priority)
    • Imaging of individual beams, keeping weighting functions
      • Allows complete parallel processing of data, the summing sets of images.
    • Add a tool to automatically find line free regions in the spectra for baseline fitting.
      • (Use Target scan)
    • Allow position switch calibration of scans using selected regions of map scans
      • Ie calibrate using all scans with radius from sources greater than a fixed angular distance.
    • Better flagging tools
    • Allow access to all idlToSdfits command line arguments
    • Provide examples for how to add additional capabilities to the pipeline
  • Spectrometer (Anish) [10 min]
  • SW dev perspective (Amy, Bob and/or Joe) [10 min]
• Discuss and prioritize work for 2011 Q3 & Q4. (everyone)

Questions and Priorities

Anish

Anish would like to know about the current thinking on data stream, which he assumes Amy will talk about. The spectrometer requirement is related with the data stream.

Dave F.

Dave would like to know the status on accessing the weather data via the "pipeline" and what are the plans for saving meta data for proper archiving of GBT data.

Glen

-- JoeMasters - 2011-04-19