Karen O'Neil

Set-up

• K-band
• 800Hz Bandwidth
  
• 2048 channels
  
• 4 Quad
  
• 2 samplers/bank
  
• 3-level
  
• Linear Polarization
• Observing with data in beam 1

Summary

• Pointing corrections were less than 1'.
• All of the data has poor baselines, with 40-60 MHz ripples. This could cause serious problems for observers.
• The bandpass shapes and rms levels for the IFs/samplers for each bank were virtually identical.
• It was impossible to determine how well the measured flux compared to published values, as the baseline changes and the fact that the data was taken in the rain made accurate determininations impossible.
• The rms values were close to the theoretical value.
• This mode is recommended for general use provided the observer is willing to accept the baseline problems.

Observations

• Data taken on 23 May, 2003
  
• Data file is T_KBAND_23MAY03
  

  Scan	Source	Comments
  1039-1042	3C161	Peak Observation with DCR
  1043-1044	Ori A	120s, position switched
  1045-1046	Ori A	120s, position switched
  1047-1048	Ori A	120s, position switched
  1049-1050	Ori A	120s, position switched

Analysis

I. Ori A

Four 120s beam-switched observations were made of the 22GHz line in Orion A. In all cases, the baseline showed considerable structure, as exemplified below:

Fig 1.Blow-up on baseline for Ori A in Bank A for scan 1043.

Fig 2. Blow-up on baseline for Ori A in Bank A for average of all scans.

Other images available:

• Blow-up on baseline for Ori A in Bank B for scan 1043.
• Blow-up on baseline for Ori A in Bank C for scan 1043.
• Blow-up on baseline for Ori A in Bank B for all scans.
• Blow-up on baseline for Ori A in Bank C for all scans.
• Blow-up on baseline for Ori A in Bank D for all scans.

The measured flux of Ori A ranged from 9600 - 14500 K km/s, showing baseline paroblems and changes due to temperature dominated.

The peak velocity and velocity widths compare extremely well with that found in the literature, as can be seen below:

Fig 3. Average of all scans for Bank A.

Fig 4. Spectra of Orion A from Genzel & Downes (1977 A&A 61, 117)

Other plots:

• Entire spectra from Bank A, Scan 1043.
• H₂O spectra from Bank A, Scan 1043.
• H₂O spectra from Bank B, average of all scans.
• Entire spectra from Bank B, Scan 1043.
• H₂O spectra from Bank B, Scan 1043.
• H₂O spectra from Bank C, average of all scans.
• Entire spectra from Bank C, Scan 1043.
• H₂O spectra from Bank C, Scan 1043.
• Entire spectra from Bank D, Scan 1043.
• H₂O spectra from Bank D, Scan 1043.

  III. RMS

  The rms noise for polarizations L and R ranged from 9-24 mK after removing a 6th order baseline from the 200 channels of interest. The L channel was less noisy than the right, by a few percent, due to the smaller ripples in that channel and the lower temperature. The measured vs. theoretical RMS values, assuming 70K in L and 95K in R, are given below.

  Bank/Pol	Individual Scan	Average of Scans	Theor. rms (all scans)	Predicted from ind. measurements
  A / R	9 - 13 mK	6 mK	6 mK	5mK
  A / L	17 - 25 mK	12 mK	9 mK	10 mK
  B / R	10 - 15 mK	7 mK	7 mK	7 mK
  B / L	18 - 24 mK	15 mK	9 mK	11 mK
  C / R	12 - 18 mK	8 mK	7 mK	7 mK
  C / L	19 - 24 mK	9 mK	9 mK	11 mK
  D / R	11 - 19 mK	11 mK	7 mK	9 mK
  D / L	19 - 27 mK	11 mK	9 mK	11 mK

  The measured value are resonably close to that predicted.