Karen O'Neil

Set-up

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

Summary

• Pointing corrections were less than 1'.
• No baseline ripple were present.
• 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 10% 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
  1070-1071	Ori A	60s, position switched, LSRK
  1072-1073	Ori A	60s, position switched, LSRK
  1074-1075	Ori A	60s, position switched, LSRK

Analysis

I. Ori A

Three 60s beam-switched observations were made of the 22GHz line in Orion A. In all cases, the baseline was extemely flat, as exemplified below:

Fig 1.Blow-up on baseline for Ori A in Bank A for scan 1070.

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 1070.
• Blow-up on baseline for Ori A in Bank C for scan 1070.
• Blow-up on baseline for Ori A in Bank D for scan 1070.
• 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 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 1070.
• H₂O spectra from Bank A, Scan 1070.
• H₂O spectra from Bank B, average of all scans.
• Entire spectra from Bank B, Scan 1070.
• H₂O spectra from Bank B, Scan 1070.
• H₂O spectra from Bank C, average of all scans.
• Entire spectra from Bank C, Scan 1070.
• H₂O spectra from Bank C, Scan 1070.
• Entire spectra from Bank D, Scan 1070.
• H₂O spectra from Bank D, Scan 1070.

  III. RMS

  The rms noise for polarizations L and R ranged were 36-40mK and 38-54 mK after removing a 1st order baseline from the 1000 channels of interest. In Banks A & B the L channel was less noisy than the right, by a few percent, due to the lower temperature. The measured vs. theoretical RMS values are given below.

  Bank/Pol	Individual Scan	Average of Scans	Theor. rms (ind/all scans)
  A / R	36 - 38 mK	22 mK	33/19 mK
  A / L	49 - 54 mK	30 mK	47/27 mK
  B / R	36 mK	21 mK	33/19 mK
  B / L	50 mK	30 mK	47/27 mK
  C / R	39 mK	23 mK	33/19 mK
  C / L	38 mK	23 mK	33/19 mK
  D / R	40 mK	23 mK	33/19 mK
  D / L	38 mK	23 mK	33/19 mK

  The measured value are all approx 10% higher than the theoretical values, but the measured values do fall as 1/sqrt(t).