K-Band Focal Plane Array (KFPA) and Pipeline Observer's Guide

Note that much of the content of this documentation is out of date. Please refer to the GBT Pipeline documentation instead!!!

The KFPA observers must perform a sequence of steps, before during and after the GBT observations. Here these steps are summarized.

| Rotational Temperature Map produced from KFPA commissioning observations of W51.
Data are in GBT project TKFPA_29 |

Latest News

2011 Mar 22: New GBTIDL scripts are available to analyze time and frequency series KFPA data.

  • Files are in /home/astro-util/gbtidl/contrib

2011 Feb 25: Calibration Gain Values to apply to "Shared Risk Data"

Analysis of the intensities of from the observations during shared risk observations of NH3 (1,1) and (2,2) suggest that the noise diode values provided were too low during shared observing, from September 2010 through January 2011. The gain corrections may be applied to observations within the KFPA pipeline. A new GBT memo describes the measurements leading to these gain values. Please see GBT Memo 273: KFPA Calibration using observations of the Moon These gain values should only be applied to observations made during the "Shared Risk" interval.

Observing with the KFPA

Preparation - Choose Image Size, number of blocks and number of scans per block

Observing with the KFPA is very similar to observing with any GBT receiver. Currently it is recommended that when mapping, configure the observations such that each beam observes each location in the map. (When the mapping scripts are optimized it will be possible to observe each location with only one beam, speeding the mapping process). The fastest recommended spectral sampling rate is 1 Hz. During this time the GBT motion should be smaller than 1/4 of a beam or 8". This corresponds to 0.125 degrees/minute telescope motion. A one degree raster map requires 8 minutes of observation for one motion. Since point/focus observations should occur every hour, and there is a 10 % scan preparation time, 7 scans, each one degree long, can be scheduled. This would produce an rectangular image 1 x 0.058 degrees. A complete 1 x 1 map would require approximately 20 hours. The integration time per GBT telescope beam on the sky is 14 seconds.

If all else fails, read the documentation:

  • Example script to produce a NH3 Temperature map from (1,1) and (2,2) observations.

  • Revision includes example Astrid script and scan annotations. Made calibration consistent with the Pipeline documents.

  • The revision includes a summary of AIPS commands to produce images of Orion NH3 1-1 and 2-2 observations and measure system properties.

Observations - Run sequence of Astrid scripts to Setup GBT, Point, Focus, Map

The Observations are carried out using Astrid. The observing setup takes place in several steps. In order to assure optimum performance, the observer must periodically check the pointing and focus (approximately once an hour).

The KFPA is not yet fully incorporated into the GBT "configtool", so the observer must first setup the receiver and then other hardware using Astrid scripts developed during commissioning. This process is expected to be simplified when the "configtool" revisions are in place.
  • Setup the Receiver Manager/Default values (only once per session).
  • Configure DCR for Point and Focus
    • configPoint37: Configure the DCR to use Analog Filter samplers for pointing with beams 3 and 7
    • Venus-peak: Script to peak on Venus before Gain calibration
    • NGC1194-peak: Auto peak and focus example script
  • Configure Spectrometer for Mapping
    • configMap50MHzNH3Example for 7 beams, one spectral band 50 MHz, NH3 (1,1) and (2,2)
      • config71to42 Quickly switch from 7+1 beam mode and four beams, 2 spectral bands mode.
      • config42to71 Switch back from 4x2 beam mode to 7+1 beam mode
    • configMap200 Example for 4 beams, one spectral band with 200 MHz bandwidth
    • configMap200-2 Example for 2 beams, two spectral bands each with 200 MHz bandwidth
  • Calibration Observations
    • Venus-nod: Nod on target Venus between pairs of beams. Venus is bright, approximately 30K Ta
    • OnOffMoon: On Off Moon observations to calibration gain.
  • Due to the large data rates, Frequency Switched mapping is not recommended, but frequency switch configurations are available
    • configMap12Fs Frequency Switched with 7+1 beams, one spectral band with 12.5 MHz bandwidth
    • configMap50Fs Frequency Switched with 7+1 beams, one spectral band with 50 MHz bandwidth
    • configMap200Fs Frequency Switched with 4 beams, one spectral band with 200 MHz bandwidth
  • Position Switched Mapping (eg. Script mapW51)
    • Observe the target peak emission location (optional but valuable for checking the spectrometer setup)
    • Observe the map reference location
    • Observe the region of interest
    • Observe the target peak emission location (To check for any loss in intensity due to pointing/focus)
    • Observe the map reference location
  • Two Beam Nod observations NGC1194-spec Example for high redshift maser searches.
  • Configure DCR for Point and Focus
  • Point and Focus
  • ...

These scripts are all available on the GB Kinux environment in directory

  • /home/astro-util/projects/TKFPA

-- GlenLangston - 2010-10-20
Topic attachments
I Attachment Action Size Date Who Comment
NGC1194-peakEXT NGC1194-peak manage 553 bytes 2011-02-08 - 10:13 GlenLangston Auto peak and focus example script
NGC1194-specEXT NGC1194-spec manage 192 bytes 2011-02-08 - 10:34 GlenLangston Nod test
OnOffMoonEXT OnOffMoon manage 1 K 2011-03-21 - 12:46 GlenLangston Spectroscopy On-Off Moon calibration pair
Venus-nodEXT Venus-nod manage 558 bytes 2011-03-21 - 12:45 GlenLangston Spectroscopy Nod on Venus for calibration
Venus-peakEXT Venus-peak manage 514 bytes 2011-03-21 - 12:45 GlenLangston Peak on Venus position
accumNH3-22.py.txttxt accumNH3-22.py.txt manage 4 K 2010-10-06 - 11:00 GlenLangston Python/ParselTongue Script to make NH3 2-2 image and clean up
aipsNumberEXT aipsNumber manage 1 K 2010-10-06 - 16:50 GlenLangston Linux Script to retrieve a Pipeline AIPS number or assign a new one
config42to71EXT config42to71 manage 1 K 2011-02-08 - 11:29 GlenLangston Switch between 4x2 and 7+1 mode for 12.5 or 50 MHz bandwidth
config71To42EXT config71To42 manage 1 K 2011-02-08 - 11:17 GlenLangston Switch between 7+1 and 4x2 modes for 12.5 or 50 MHz
config71to42EXT config71to42 manage 982 bytes 2011-02-08 - 11:27 GlenLangston Switch between 7+1 and 4x2 modes for 12.5 or 50 MHz
configMap12FsEXT configMap12Fs manage 6 K 2011-02-09 - 16:41 GlenLangston Frequency switched 12.5 MHz
configMap200EXT configMap200 manage 3 K 2011-02-08 - 10:33 GlenLangston 4 beams, one spectral band 200 MHz
configMap200-2EXT configMap200-2 manage 3 K 2011-02-08 - 10:21 GlenLangston Two band, 4 beams 200 MHz configuration
configMap200FsEXT configMap200Fs manage 3 K 2011-02-09 - 16:42 GlenLangston Frequency switched 200 MHz
configMap50FsEXT configMap50Fs manage 6 K 2011-02-09 - 16:41 GlenLangston Frequency switched 50 MHz
configMap50MHzNH3EXT configMap50MHzNH3 manage 5 K 2011-02-08 - 10:29 GlenLangston 7 Beams+1, 50 MHz bandwidth
configPoint37EXT configPoint37 manage 3 K 2011-02-09 - 14:10 GlenLangston Script for continuum observations with beams 3 and 7
demoW51EXT demoW51 manage 2 K 2011-02-11 - 13:06 GlenLangston end to end pipeline test
imNH3-11.py.txttxt imNH3-11.py.txt manage 9 K 2010-10-06 - 11:00 GlenLangston Python/ParselTongue Script to combine spectra and make NH3 1-1 image
kfpaObsGuide-10Aug23.pdfpdf kfpaObsGuide-10Aug23.pdf manage 436 K 2010-08-24 - 10:33 GlenLangston Revised KFPA Observers Guide
kfpaObsGuide-10Aug23.textex kfpaObsGuide-10Aug23.tex manage 29 K 2010-08-24 - 10:33 GlenLangston Latex version of observers guide
kfpaObsGuide-10Oct19.pdfpdf kfpaObsGuide-10Oct19.pdf manage 634 K 2010-10-20 - 11:36 GlenLangston Observers guide with Temperature map
kfpaObsGuide-10Sep20.pdfpdf kfpaObsGuide-10Sep20.pdf manage 436 K 2010-09-21 - 16:24 GlenLangston revision
kfpaObsGuide-11Feb4.pdfpdf kfpaObsGuide-11Feb4.pdf manage 641 K 2011-02-28 - 13:19 GlenLangston  
kfpaObsGuide-11Feb6.pdfpdf kfpaObsGuide-11Feb6.pdf manage 641 K 2011-02-08 - 10:40 GlenLangston Expand parsel tongue section
kfpaObservingSteps.txttxt kfpaObservingSteps.txt manage 2 K 2011-03-21 - 12:39 GlenLangston Recent updates to simple steps
kfpaRxSetValues.py.txttxt kfpaRxSetValues.py.txt manage 10 K 2011-02-08 - 10:09 GlenLangston KFPA Rx setup
mapW51EXT mapW51 manage 1 K 2011-02-08 - 10:13 GlenLangston Example mapping script
orionNH3-1-12-2.pdfpdf orionNH3-1-12-2.pdf manage 179 K 2010-08-24 - 10:34 GlenLangston Image in Observers guide
pipeW51-1122EXT pipeW51-1122 manage 1 K 2010-10-06 - 16:49 GlenLangston Linux Script to Reduce a previous W51 observation
w51NH3TempMap.pngpng w51NH3TempMap.png manage 22 K 2010-10-20 - 11:36 GlenLangston Temperature map
Topic revision: r19 - 2013-06-06, JoeMasters
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