Automatically adding fake sources to real data, part 2

In a previous entry, I described how to go use the new ORAC-DR recipe REDUCE_SCAN_FAKEMAP to automatically add fake sources to the raw time series in order to get a handle on the transfer function of the map-maker. That's all very well, but how about starting with something simpler, such as a Gaussian? Now you can add a Gaussian of given amplitude and FWHM without first creating an image to feed in to the pipeline. As before, the Gaussian properties are defined using recipe parameters:

[REDUCE_SCAN_FAKEMAP]
FAKEMAP_FWHM = 15
FAKEMAP_SCALE = 0.5
FAKEMAP_OFFSET = dx,dy

The FWHM is in arcsec and is the only mandatory parameter (the SCALE and OFFSET are optional). In this case, the FAKEMAP_SCALE parameter is the amplitude of the Gaussian in Jy/beam. The Gaussian can be positioned anywhere in the map by giving an offset (RA, Dec in arcsec).

The pipeline can help you out further by using a couple of useful defaults. If the world "beam" is given as the FWHM, then the pipeline will use the default beam size appropriate for the current wavelength (14" at 850 um, 8" at 450 um). If the amplitude is not specified then (somewhat arbitrary) defaults of 1 and 4 Jy/beam are assumed (at 850 and 450 um respectively).

Note that the FWHM must be greater than half the pixel scale (the pipeline will set it to that value if the given value is less), but in principle there is no upper limit. In practice the upper limit is defined by the array footprint (about 2.5 arcmin for S2SRO data): anything much larger than that will be removed by makemap as part of fitting the common mode.

As usual, update your Starlink installation (with rsync) to try it out.

Recipe Parameters and the Science Archive

When processing jobs are submitted to the science archive ORAC-DR is configured to load a specialist recipe parameter file associated with the project. This can be used by PIs or surveys to tune processing to their liking. The idea is that PIs or survey teams send us their recipe parameter files and we then make sure that the processing jobs use them.

This week I've updated the recipe parameter system to allow tuning based on the object name as well as the recipe name. In some projects the objects are completely different so a single parameter file was not useful. Hopefully this change will encourage more people to send us parameter files.

To use the object based scheme simply append the object name to the recipe name in the file along with a colon. No spaces in the object name.

  [REDUCE_SCAN:M82]
  PAR1 = A
  PAR2 = B

If there is also a recipe-based entry those parameters will be merged in

  [REDUCE_SCAN]
  PAR1 = Aprime
  PAR3 = C

So in this example if the object name is "M82" PAR1, PAR2 and PAR3 will be set and PAR1 will have a value "A". If the object is no "M82" only PAR1 and PAR3 will be set and PAR1 will have value "Aprime".

This change is currently on the stardev rsync server, or if you have git installed you can update your own ORAC-DR distribution.