Preliminary results of OOF holography at the GBT

Bellow is the preliminary analysis of data from the GBT. More info on OOF holography is at OOF holography home and there are some other results available at the results page

NEWS: Added FITS and ASCII formats of calculated phase maps. The ASCII file has a very simple format: the whole 128x128 pixel map is written to the file by outputting the value of each pixel on its own row.

Older News: We have now refined our procedures for gridding the data, which has resolved the outstanding issues with the magnitude of defocus movement and the taper of the fitted illumination pattern.

EXPLANATION OF PLOTS: The first plot labeled aperture shows the calculated surface errors. The phase of the aperture function is shown on the left and amplitude on the right. The phase is in radians -- therefore conversion to wavelengths of dish movement will look something like radians/2pi/(1+cos(theta)). The scale from black to white is one pi of phase. The second plot, labeled residuals, is divided into four rows: the top row is the data, the second is the model, the third is data-model, and the fourth is weighted data-model. The final plot is essentially the same as the residuals, only with log scales going to -50db. Notice the (data-mode) fields in these don't make much sense because they go negative as well as positive

• Scans 2002+: Aperture, Residuals, Residuals (log plot) , FITS file of the calculated phase map, ASCII file of the calculated phase map,
• Scans 3001+: Aperture, Residuals, Residuals (log plot) , FITS file of the calculated phase map, ASCII file of the calculated phase map,
• Scans 4001+: Aperture, Residuals, Residuals (log plot) , FITS file of the calculated phase map, ASCII file of the calculated phase map,

Some preliminary re-analysis

We have been developing an approach which is more suitable for use with sparsely and/or irregularly sampled data, which basically interpolates the model rather then data

• Scans 3001+: Aperture
• Scans 4001+: Aperture