source:
tags/casa3.1.0asap/tutorials/tutorial_1.rst@
2006
Last change on this file since 2006 was 1636, checked in by , 15 years ago | |
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Tutorial #1 - Basic ASAP
.. sectionauthor:: Kate Brooks
Main goal: Get a basic understanding of ASAP commands to import and plot data
Files
- 2008-03-12_09320-M999.rpf Data file (1.1 Mb)
Data Log
- ON-OFF Position switching mode with Mopra
- 2 Scans (1 OFF and 1 ON)
- 1 MOPS Zoom band
Instructions
Work through the list of commands given in the text file to calibrate data taken with the Mopra telescope. Commands should be typed line-by-line into ASAP. Seek help from the tutors if there are any commands you don't understand.
To start asap simply run the following at your prompt:
asap
Write a python script to automate the calibration procedure used in step 1. Your python script should permit interaction with the plotter and should be executed in a terminal (and not within ASAP) with the following command:
python -i myscript.py
The python script to be run outside asap needs to have the following line at the top of the file:
from asap import *
This will import all asap functionality into the "normal" python.
Commands
# Load data file into memory and view description s = scantable('2008-03-12_0932-M999.rpf') print s # Set the plotting mode plotter.set_mode(stacking='i', panelling='t') # Plot all raw data plotter.plot(s) # Set the doppler convention s.set_doppler('RADIO') # Set the rest frame s.set_freqframe('LSRK') # Set the observed rest frequency in Hz s.set_restfreqs([86243.37e6]) # Define the channel unit s.set_unit('km/s') # Form the quotient spectra q=s.auto_quotient() # Average all scans in time, aligning in velocity # Note: That for this dataset there is only 1 scan and so this step is redundant av = q.average_time(align=True) # Average the two polarisations together iav = av.average_pol() # Plot the spectrum plotter.plot(iav) # Remove the baseline (set to 0 order). Specify the signal-free channels msk = iav.create_mask([-200,-50],[50,180]) iav.poly_baseline(msk,0) plotter.plot(iav) # Smooth the data with boxcar, full width = 3 siav = iav.smooth(kernel = 'boxcar', width = 3, insitu = False) plotter.plot(siav) # Scale the data according to scaling fudge factor # Eg. With beam efficiency of 0.49 at 86 GHz iav.scale(2) # Make final plot for saving plotter.set_range(-20,30) plotter.plot(siav) plotter.set_legend(mode=-1) plotter.set_title(['Orion-SiO'], fontsize=18) plotter.text(10,95,"SiO (2-1 v=1) at 86243.440 MHz", fontsize=12) plotter.text(-19,95,"2008/03/12", fontsize=12) plotter.text(-19,90,"Zoom Mode", fontsize=12) # Save plot as postscript file plotter.save('Orion-SiO.ps')