Karen O'Neil

Set-up

• K-band
• 800 MHz Bandwidth
  
• 8192 channels
  
• 2 Quad
  
• 1 samplers/bank
  
• 3-level
  
• Linear Polarization
• Observing with data in beam 1 (Banks A & B)

Summary

• Taken in topocentric mode. Data is fine, although aips++ display velocities wrong.
• Pointing corrections were less than 1'.
• 40-60 MHz baseline ripples present in data.
• The bandpass shapes and rms levels for the IFs/samplers for each bank were virtually identical.
• No calibration was taken, but peak levels seem consistant with published values.
• The rms values was consitantly 40-50% higher than the theoretical value ,but they did fall as 1/sqrt(t).
• Further investigation into why the rms values were too high is warranted before this mode is opened to general use.

Observations

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

  Scan	Source	Comments
  1096-1097	Ori A	120s, position switched, TOPO
  1098-1099	Ori A	120s, position switched, TOPO
  1100-1101	Ori A	120s, position switched, TOPO
  1102-1103	Ori A	120s, position switched, TOPO
  1104-1105	Ori A	120s, position switched, TOPO
  1106-1107	Ori A	120s, position switched, TOPO
  1108-1109	Ori A	120s, position switched, TOPO
  1110-1111	Ori A	120s, position switched, TOPO

Analysis

I. Ori A

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

Fig 1.Blow-up on baseline for Ori A in Bank A for scan 1096.

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 1096.
• Blow-up on baseline for Ori A in Bank B for all scans.

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 1096.
• H₂O spectra from Bank A, Scan 1096.
• H₂O spectra from Bank B, average of all scans.
• Entire spectra from Bank B, Scan 1096.
• H₂O spectra from Bank B, Scan 1096.

  III. RMS

  The rms noise were 506 mK after removing a 6th order baseline from the channels of interest. The measured vs. theoretical RMS values are given below.

  Bank/Pol	Individual Scan	Average of Scans	Theor. rms (ind/all scans)
  A / L	5 - 6 mK	2 mK	4/1.4 mK
  B / L	5 - 6 mK	2 mK	4/1.4 mK

  The measured value are all approx 50% higher than the theoretical values, but the measured values do fall as 1/sqrt(t).