Data Processing School :: Exercise 52
Source directory | /data/lofarschool/data/exercise 52 |
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Contact person | Joe Masters, Casey Law |
Context
This script demonstrates another way to use PyDAL. In this case, it reads the data into Python and plots the uv coverage of a Measurement Set.
Prerequisite
A little knowledge of shell and python programming (or at least a curiosity to learn).
Description
This exercise shows how to interact with uv data with the PyDAL. The plot will show a point for each integration in the observation in units of wavelengths.
Files & Directories
Here is a list of the files for this exercise:
L2007_01810_SB18-20_OB20.MS
– Measurement set for an LBA observationrun_script.sh
– bash script to run “uv_coverage.py”uv-coverage_plot.png
– Example output of exerciseuv_coverage.py
– Python script to plot uv coverage
Step-by-step instructions
1) Run “run_script.sh” and answer the following questions:
a) The plot appears as many lines. Each line is actually a set of points; one point for each integration and each baseline. Use the length of the line to estimate the length of the observation in hours.
b) What is the length of the longest baseline in wavelengths? What is the size of the synthesized beam for this observation?
c) Use your knowledge of the physical size of CS1 to estimate the wavelength of this observation.
2) Look at “uv_coverage.py” and find where it selects the data to plot. Now modify the script to plot the u and w coordinates for this observation.
Example outputs
See “uv-coverage_plot.png”.
Outstanding problems
None known.