NGC7771 Scan 171


Observing log information

  Object:           NGC7771
  On scan num:      171 173 175 177 179 181
  Off scan num:     172 174 176 178 180 182
  R.A.:             23.856900 hrs
  Dec.:             20.111727 deg
  On azimuth:       265.560854 deg
  On zenith dist.:  50.929469 deg
  Off azimuth:      265.529915 deg
  Off zenith dist.: 50.893567 deg
  MJD:              52421
  UTC:              0.688021
  Center freq.:     1400.536680 MHz
  Doppler:          0.00007862
  Num. correlators: 2
  Spectrom. atten.: 35 42 dB
  Bandwidth:        10.0 MHz
  Num. channels:    1024
  Eff. integration: 1800 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.

Figure 2. Measured spectrum

Measured parameters

  Peak intensity:      0.040 Jy
  Lower 20% velocity: 4004.0 km/s
  Upper 20% velocity: 4575.0 km/s
   Systemic velocity: 4289.5 km/s
   Line width (20%):   571.0 km/s
  Profile integral:   17.70 Jy * km/s
                 A:   20.26
                 B:   19.87
         Ratio B/A:   0.981
  Flux integral
     velocity range:  3918.8 - 4682.1 km/s


very poor baseline, flux integral very inaccurate