source: branches/asap-3.x/tutorials/tutorial_1.rst@ 2075

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Tutorial #1 - Basic ASAP

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.. 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

  1. 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

  2. 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')
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