History of Demo_science/ASTE_RCW38-CI (No. 2)

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ASTE Wiki

Demo [CI] data†

Last update

• 2021-03-xx

Table of contents

• Demo [CI] data
  • Data archive
  • Data information
  • CASA data reduction
    • Data reduction

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Data archive†

Data information†

• Literature value for frequency of [CI] is 492.16065 GHz. <= The difference (6 kHz) corresponds to ~ 3 m/s.

CASA data reduction†

• Measurement Set
  • X scan

    R38otfX.RCW_38.20161126043008.4.ms	(number of row : 81)
    R38otfX.RCW_38.20161126065817.4.ms	(number of row : 81)
    R38otfX.RCW_38.20161126091618.4.ms	(number of row : 81)

  • Y scan

    R38otfY.RCW_38.20161126052449.4.ms	(number of row : 49)	<= Stop Observation at 49 row
    R38otfy.RCW_38.20161126060513.4.ms	(number of row : 16)	<= Start observation from 46 row
    R38otfY.RCW_38.20161126075453.4.ms	(number of row : 61)
    R38otfY.RCW_38.20161126101442.4.ms	(number of row : 61)

• Note
  • Amplitude calibration with the chopper wheel method is already finished (The unit of amplitude in all measurement sets are Ta*).
• Spectral window

  0, 1 (A1, A2) : [CI] (same signal (polarization) input into 0 and 1 (A1 and A2))

  2, 3 (A3, A4) : no data

• Software
  • CASA version 5.1.1

Data reduction†

1. Baseline subtraction

   $ default(sdbaseline)
   $ sdbaseline(
       infile='R38otfX.RCW_38.20161126043008.4.ms',
       datacolumn='float_data',
       spw='0:350~470;560~650,1:350~470;560~650',             # 350-470 ch and 560-650 ch correspond to -46.44~-9.93 km/s and 17.45~44.84 km/s, respectively.
       blfunc='poly', order=1,                                # fit function to subtract baselines
       outfile='R38otfX.RCW_38.20161126043008.4.A1A2.bl.ms',
       overwrite=True)

2. Scaling to convert Ta* to Tmb
   1. Making table for scaling

      $ default(gencal)
      $ gencal(
          vis='R38otfX.RCW_38.20161126043008.4.A1A2.bl.ms',
          caltable=‘R38otfX.RCW_38.20161126043008.4.A1A2.bl.mb.tbl',
          caltype='amp',
          parameter=[sqrt(0.45)])  # Main beam efficiency of 45 % is used. 
                                   # See the ASTE home page (https://alma.mtk.nao.ac.jp/aste/instruments/telescope.html).

   2. Applying the scaling table Task : applycal (Apply calibrations solution(s) to data) Parameters (examples) vis = '○○○.bl.ms' # Name of input visibility file field = '' # Select field using field id(s) or field name(s) spw = '' # Select spectral window/channels intent = '' # Select observing intent selectdata = True # Other data selection parameters timerange = '' # Select data based on time range uvrange = '' # Select data within uvrange (default units meters) antenna = '' # Select data based on antenna/baseline scan = '' # Scan number range observation = '' # Select by observation ID(s) msselect = '' # Optional complex data selection (ignore for now) docallib = False # Use callib or traditional cal apply parameters gaintable = [] # Gain calibration table(s) to apply on the fly gainfield = [] # Select a subset of calibrators from gaintable(s) interp = [] # Interp type in time[,freq], per gaintable. default==linear,linear spwmap = [] # Spectral windows combinations to form for gaintables(s) calwt = [False] # Calibrate data weights per gaintable. parang = False # Apply parallactic angle correction applymode = '' # Calibration mode: ""="calflag","calflagstrict","trial","flagonly","flagonlystrict", or "calonly" flagbackup = True # Automatically back up the state of flags before the run?

Command example applycal(vis=‘R38otfX.RCW_38.20161126043008.4.A1A2.bl.ms', gaintable=['R38otfX.RCW_38.20161126043008.4.A1A2.bl.mb.tbl'], calwt=[False])

3. Imaging

Task : sdimaging (Imaging for total power and spectral data) Parameters (examples) nfiles = ['○○○.bl.ms','×××.bl.ms',...] # a list of names of input SD Measurementsets (only MS is allowed for this task)

outfile = '○○○.int' # name of output image

overwrite = True # overwrite the output file if already exists [True, False]

field = '' # select data by field IDs and names, e.g. "3C2*" (""=all)

spw = '' # select data by IF IDs (spectral windows), e.g. "3,5,7" (""=all)

antenna = '' # select data by antenna names or IDs, e.g, "PM03" ("" = all antennas)

scan = '' # select data by scan numbers, e.g. "21~23" (""=all)

intent = '*ON_SOURCE*' # select data by observational intent, e.g. "*ON_SOURCE*" (""=all)

mode = 'velocity' # spectral gridding type ["channel", "frequency", "velocity"]

nchan = 167 # number of channels (planes) in output image (-1=all)

start = '-49.7km/s' # Velocity of first channel: e.g “0.0km/s" (""=first channel in first SpW of MS)

width = '0.6km/s' # Channel width e.g "-1.0km/s" (""=width of first channel in first SpW of MS)

veltype = 'radio' # velocity definition ["radio", "optical", "true" or "relativistic"]

outframe = '' # velocity frame of output image ["lsrk", "lsrd", "bary", "geo", "topo", "galacto", "lgroup", "cab"] (""=current frame or LSRK for multiple-MS inputs)

gridfunction = 'GJINC' # gridding function for imaging ["BOX", "SF", "PB", "GAUSS" or "GJINC"] (see description in help)

imsize = [60,80] # x and y image size in pixels, e.g., [64,64]. Single value: same for both spatial axes ([] = number of pixels to cover whole pointings in MSes)

cell = ['6arcsec','6arcsec'] # x and y cell size, (e.g., ["8arcsec","8arcsec"], default unit arcmin. ("" = 1/3 of FWHM of primary beam)

phasecenter = 'J2000 08:59:05.78 -047.31.00.020' # image center direction: position or field index, e.g., "J2000 17:30:15.0 -25.30.00.0". ("" = the center of pointing directions in MSes)

projection = 'SIN' # map projection type

ephemsrcname = '' # ephemeris source name, e.g. "MARS"

pointingcolumn = 'direction' # pointing data column to use ["direction", "target", “pointing_offset", "source_offset" or "encoder"]

restfreq = '' # rest frequency to assign to image, e.g., "114.5GHz"

stokes = '' # stokes parameters or polarization types to image, e.g. "I", "XX"

minweight = 0.1 # Minimum weight ratio to use

brightnessunit = # Overwrite the brightness unit in image ( = respect the unit in MS) ['K' or 'Jy/beam']

clipminmax = False # Clip minimum and maximum value from each pixel

Command example sdimaging(infiles=['R38otfX.RCW_38.20161126043008.4.A1A2.bl.ms','R38otfX.RCW_38.20161126065817.4.A1A2.bl.ms','R38otfX.RCW_38.20161126091618.4.A1A2.bl.ms'], outfile='R38otfX.RCW_38.20161126.4.A1A2.bl.int',intent='*ON_SOURCE*',gridfunction='GJINC',cell=['6arcsec','6arcsec'],mode='velocity',nchan=167,start='-49.7km/s',width='0.6km/s', overwrite=True,imsize=[60,80],phasecenter='J2000 08:59:05.78 -047.31.00.020') Note We made two imaging data (Xscan and Yscan)

4. Removing scanning effect (Basket-weave) Task : sdfixscan (Task for single-dish image processing) Parameters (examples) infiles = ['Xscan.int','Yscan.int'] # list of name of input SD images (FITS or CASA image)

mode = 'fft_mask' # image processing mode ["fft_mask", "model"]

direction = [0,90] # scan direction (p.a.) counterclockwise from the horizontal axis in unit of degree

maskwidth = [5.0,3.0] # mask width for Basket-Weaving (on percentage)

tmax = 0.0 # maximum threshold value for processing

tmin = 0.0 # minimum threshold value for processing

outfile = '○○○.int' # name of output file

overwrite = True # overwrite the output file if already exists [True, False]

Command example sdfixscan(infiles=['R38otfX.RCW_38.20161126.4.A1A2.bl.int','R38otfY.RCW_38.20161126.4.A1A2.bl.int'], direction=[0,90],maskwidth=[5.0,3.0],outfile='R38otfXY.RCW_38.20161126.4.A1A2.bl.int',overwrite=True)

5. Making Fits file Task : exportfits (Convert a CASA image to a FITS file) Parameters (examples) imagename = '○○○.int' # Name of input CASA image

fitsimage = '○○○.fits' # Name of output image FITS file

velocity = True # Use velocity (rather than frequency) as spectral axis

optical = False # Use the optical (rather than radio) velocity convention

bitpix = -32 # Bits per pixel

minpix = 0 # Minimum pixel value (if minpix > maxpix, value is automatically determined)

maxpix = -1 # Maximum pixel value (if minpix > maxpix, value is automatically determined)

overwrite = True # Overwrite pre-existing imagename

dropstokes = True # Drop the Stokes axis?

stokeslast = True # Put Stokes axis last in header?

history = True # Write history to the FITS image?

dropdeg = False # Drop all degenerate axes (e.g. Stokes and/or Frequency)?

Command example exportfits(imagename='R38otfXY.RCW_38.20161126.4.A1A2.bl.int', fitsimage='RCW_38.20161126.4.CI.casa.fits',velocity=True,dropstokes=True)

Sample images Integrated intensity map