DDO216 Scan 542


Observing log information

  Object:           DDO216
  On scan num:      542
  Off scan num:     543
  R.A.:             23.475367 hrs
  Dec.:             14.742263 deg
  On azimuth:       147.578566 deg
  On zenith dist.:  26.842542 deg
  Off azimuth:      147.470082 deg
  Off zenith dist.: 26.866097 deg
  MJD:              52241
  UTC:              0.969225
  Center freq.:     1421.122563 MHz
  Doppler:          -0.00008944
  Num. correlators: 2
  Spectrom. atten.: 32 38 dB
  Bandwidth:         5.0 MHz
  Num. channels:    1024
  Eff. integration: 300 seconds

Raw spectrum

This spectrum is the integration of all data for the scan with spectra from both polarizations added together. The spectral intensities are Ssys * (on - off) / off, where Ssys is the system temperature in Jy. The system noise flux density equivalent is calibrated for each scan with a calibration noise source firing during each scan. The cal value, in Jy, is calibrated by comparison with a number of continuum sources as described in the summary web page

Figure 1. Unedited spectrum

Measured spectrum

This is the section of spectrum measured to obtain the parameters listed below. The three horizontal dotted lines are the baseline, the peak level selected, and 20% of the peak level. The two vertical dotted lines mark the selected 20% line width edges. The solid horizontal line marks the velocity range chosen for the the line profile flux density integral. This spectrum has a second-order least squares fit baseline removed using most of the baseline shown in Figure 1. Narrow band interference was removed from 3 channels by interpolation between the nearest valid channels

Figure 2. Measured spectrum

Measured parameters

  Peak intensity:      0.808 Jy
  Lower 20% velocity: -205.7 km/s
  Upper 20% velocity: -167.7 km/s
   Systemic velocity: -186.7 km/s
   Line width (20%):    38.0 km/s
  Profile integral:   20.55 Jy * km/s
                 A:   16.54
                 B:   20.11
         Ratio B/A:   1.216
  Flux integral
     velocity range:  -228.5 - -145.1 km/s


something at -360 km/s