Data Reduction Summary


TIP Last Modified: JeffMangum - 10 May 2011

  • Spectra shown in the Formaldehyde Observation Summary below have been minimally processed with only baseline removal and 10-channel boxcar smoothing.
  • Spectra shown in the Results farther below have been minimally processed with only baseline removal and 20-channel boxcar smoothing.
  • Temperature scale is Ta.

Data Reduction Steps Used for 06B Measurements (Paper I):

  • Inspected all scans for bad baselines, correlator lag problems (rare), and band suckouts (even rarer). See comments in results table below.
  • In a few cases, where the results were surprising, I dug a bit deeper into the measurements and analyzed each individual 10 second sample for problems (none found).
  • Summed spectra for each source/IF in files exgalh2co-N.fits, where N = session number.
  • Summed all spectra for each H2CO frequency and resolution in file exgalh2co-sum.fits.
  • Spectra shown in the Formaldehyde Observation Summary below have been minimally processed with only baseline removal and 10-channel boxcar smoothing.
  • Spectra shown in the Results farther below have been minimally processed with only baseline removal and 20-channel boxcar smoothing.
  • Temperature scale is Ta.

Data Reduction Steps Used for Final All-Measurements Analysis (Paper II):

  • Inspected all scans for bad baselines, correlator lag problems (rare), and band suckouts (even rarer). See comments in results table below.
  • Summed all spectra for each H2CO and H111alpha frequency and resolution in file exgalh2co-sum-all.fits.
  • Analysis branched at this point to accommodate need for varying spectral resolution as a function of source:
    • Path A:
      • Averaged all "like" spectra. This effectively means that I average all 4.8 GHz spectra by first smoothing to a common spectral resolution.
      • Smooth all averaged spectra to 10 km/s spectral resolution using gaussian smoothing (macro smoothit.pro).
        • Input File(s) = exgalh2co-sum-all.fits
        • Output File = exgalh2co-combsmo10-all.fits
      • Perused each spectrum and experimented with various baseline fits before determining which was appropriate. Used knowledge of other molecular emission (H2CO, NH3, CO, HCN, etc.) to guide baseline region setting.
        • Input File = exgalh2co-combsmo10-all.fits
        • Output File = exgalh2co-base10-all.fits
    • Path B:
      • Average all "like" spectra. This effectively means that I average all 4.8 GHz spectra by first smoothing to a common spectral resolution.
      • Smooth all averaged spectra to 1 km/s spectral resolution using gaussian smoothing (macro smoothit.pro). This output spectral resolution will allow for later smoothing on a source-by-source basis.
        • Input File(s) = exgalh2co-sum-all.fits
        • Output File = exgalh2co-combsmo1-all.fits
    • Used knowledge gained from Path A above as guide to analysis of each source, and specifically which ones are detections and which are not. From this point on only analyzed detected sources. Use 10 km/s smoothing analysis for nondetection results.
    • The following is a repeat of the Path A procedure above, but only for detected galaxies and using a variable, source-catered spectral resolution for the "final" results.
    • Perused each spectrum and experimented with various baseline fits before determining which was appropriate. Used knowledge of other molecular emission (H2CO, NH3, CO, HCN, etc.) to guide baseline region setting.
      • Input File = exgalh2co-combsmo1-all.fits or exgalh2co-base10-all.fits
      • Output File = exgalh2co-base-detected.fits
  • Final Results FITS Files are:
    • exgalh2co-base10-all.fits
    • exgalh2co-base-detected.fits

-- JeffMangum - 2010-05-13
Topic revision: r3 - 2011-05-10, JeffMangum
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