public:meetings:2009-02_processing_school:exercise_51

 Source directory /data/lofarschool/data/exercise 51 Joe Masters and Casey Law

This exercise demonstrates a PyDAL script that produces plots of the “total power”, or autocorrelation, for each antenna. This kind of plot is commonly used as a quick check of the quality of the data.

#### Prerequisite

A little knowledge of shell and python programming (or at least a curiosity to learn).

You will run a script that uses the PyDAL to read in a Measurement Set and plot some of the data. This script plots the total power or one or more antennas.

You will find the following in the exercise directory:

1. `L4086_sSB10.MS` – Uncalibrated CS1 Measurement Set taken with the LBA over roughly 80 hours.
2. `run_script.sh` – bash script to run the python script
3. `total_power_all.py` – python script that uses the PyDAL
4. `vvL4086_sSB10.MS_0tp.png` – an image of the plot output by “total_power_all.py”.

1) Run “run_script.sh” and answer the following questions:

a) The plot should show a rising and falling pattern for each antenna's total power. What causes this pattern? How often does it repeat (to minute precision)?

b) Do you expect the different antennas to have different patterns? Why?

c) Cas A and Cyg A are located near the Galactic plane. Use that to estimate “galactic day” and “galactic night”. If you want to observe the EoR, when will you observe?

d) Why does the shape of the total power curve look different between the xx and yy curves?

See the png file for an example of what “total_power_all.py” produces when run from the csh script.

Corrected - ER