History of Demo_science/ASTE_RCW38-CI (No. 5)

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ASTE Wiki

Demo [CI] map of a star forming region RCW38 ††

Last update

• 2021-03-08 copyed from the ASTE Web site on Google.

Table of contents

• Demo [CI] map of a star forming region RCW38 †
  • Data archive
  • Data information
  • CASA data reduction
    • Data reduction
  • Sample image

Data archive†

• CASA data (image FITS, CASA MS2) (~1.5 GB)

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

  Scan direction	File	Number of row	Note
  X	R38otfX.RCW_38.20161126043008.4.ms	81
  	R38otfX.RCW_38.20161126065817.4.ms	81
  	R38otfX.RCW_38.20161126091618.4.ms	81
  Y	R38otfY.RCW_38.20161126052449.4.ms	49	<= Stop Observation at 49 row
  	R38otfy.RCW_38.20161126060513.4.ms	16	<= Start observation from 46 row
  	R38otfY.RCW_38.20161126075453.4.ms	61
  	R38otfY.RCW_38.20161126101442.4.ms	61

  • 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

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

3. Imaging

   $ default(sdimaging)
   $ 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')

   • We made two imaging data (Xscan and Yscan)
4. Removing scanning effect (Basket-weave)

   $ default(sdfixscan)
   $ 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

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

Sample image†

• Integrated intensity map
  
  • Smoothing: gaussian, radius = 3 pixel (18 arcsec)
  • The black filled circles at the lower right corner show the beam size (FWHM) of the Band8 (at 492 GHz)