NRAO Home  >  Green Bank  |  Wiki Topic:    GB > Data > PlanOfRecordC42004 > StandardObservingModes > HowToReduceContinuumOTFData
   Changes | Index | Contents | Search | Statistics | Jump to Topic

Data Reduction Case #8

Continuum OTF data

Continuum OTF data is just a special case of spectral line OTF data, in which there is a single spectral channel. The data reduction is similar.

Reducing Continuum OTF data proceeds as follows:

  1. Calibrate
  2. Grid the data, interpolate if necessary
  3. Normalize by sampling density if necessary
  4. Convolve, or deconvolve, if necessary
  5. Generate contour or grayscale images

Continuum maps are taken in total power mode. They may include a calibration signal, or not. If there is a calibration signal, the antenna temperature at each integration can be calculated as T_{ant} = \frac{1}{2} \times \frac{calon + caloff}{calon - caloff} \times T_{cal} - \frac{T_{cal}}{2}

More sophisticated calibration algorithms are possible, to account for gain variations across different strips in the map for example. Some calibration algorithms may take advantage of a basketweaving scanning pattern to remove gain variations and striping in the final image. See RonsDetailedCalibrationDocument? for details.

-- JimBraatz - 28 Jul 2004

Topic HowToReduceContinuumOTFData . { Edit | Attach | Ref-By | Printable | Diffs | r1.2 | > | r1.1 | More }
Revision r1.2 - 29 Jul 2004 - 19:01 GMT - JimBraatz
Parents: PlanOfRecordC42004 > StandardObservingModes 		Content copyright © 1999-2007 by the contributing authors.
All material on this collaboration platform is the property of the contributing authors.