Monday, August 17, 2009

Multiple contours on one plot

From reader Carl:

Hey I'm bumping this because I have a question regarding contour plots. I'd like to overlay 3 separate contour plots onto each other. The AIPS documentation indicates that it can display plots from multiple images, but is a little ambiguous as to whether it can display the contour plots of both images, or just the contour of one and the greyscale of another. Reading the AIPS help file and playing with the task seem to hint that the latter is the case. I'm just wondering if anyone knows for sure whether this can be done in AIPS, and if so, how. Thanks!

Thanks for the question Carl. See below for my response.

I don't know for sure because I've never tried it, but I'm pretty sure that you can only have one set of contours in KNTR. AIPS plotting is not the most flexible.

Some solutions that might not be great:

1) Use a programming language (Python, IDL, perl, C, fortran, etc) and a fits library to read in your files and then plot them exactly like you want.

2) Make three different contour plots of exactly the same area and overlay them in Illustrator.

Anybody else have some solutions?

I'm wishing that for my latest paper, I'd done custom plots instead of AIPS plots. My hope is that the plotting situation will improve with CASA since it's all plugged into Python and the plotting libraries there.


Adrienne said...

You might be able to use grchan to overlay contours, but I have never tried it. You can, however, overlay bandpass tables on the tv using the grchan keyword, so it might be possible!

I also don't know if it works for plot files.

Jake M said...

Along these lines (sort of - I'm not sure where to post my question). I'm using task PCNTR to plot a contour map with intensity, polarization intensity and polarization angle files. Now I'm trying to get a grey-scale map in the background. It's working, but it makes the plot unreasonably small. Does anybody know why this happens?