Checkout: A:1N4-0A-12-9, B:1N4-1B-12-9

Checkout of spectrometer mode A:1N4-0A-12-9, B:1N4-1B-12-9
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Karen O'Neil

Set-up

L-band
12.5MHz Bandwidth
4096 channels
2 Quad
8 samplers (total)
2 IF/pol/bank
9-level
Linear Polarization
Observing using position-switching technique

Summary

Pointing corrections was less than 1'.
One observing pair, 30/31, show a 4MHz wiggle in the baseline. No individual scan appeared responsible for this behavior
The first on+off pair observed (which was also the first observation of the night) have an rms twice as large as both the thepretical prediction and than any the other of the 'good' pairs.
The bandpass shapes and rms levels for the eight spectra were virtually identical.
The determined velocities and fluxes for UGC 9179 agreed, within errors, with those found by Rick Fisher in his Galaxy HI survey

Observations

Data taken on 26/27 March, 2003

Data file is T_LBAND_26MAR03

Scan	Source	ON time	Comments
20-23	3C295	N/A	Pointing observations
24,25	UGC 9179	300s	RA offset=-87'
26,27	UGC 9179	300s	RA offset=-87'
28,29	UGC 9179	300s	RA offset=-87'
30,31	UGC 9179	300s	RA offset=-87' (Baseline wiggle)
32,33	UGC 9179	300s	RA offset=-87'

Analysis

I. Galaxy - UGC 9179

Five 600s positioned-switched observations were made of U9179. Most of the on+off pairs showed extremely flat baselines, as shown below:

Fig 1.UGC 9179 in Bank A, IF1 for scans 24/25.

Fig 2.UGC 9179 in Bank A, IF2 for scans 24/25. One scan pair (30/31), however, showed a 4-5MHz baseline ripple:

Fig 3. Baseline ripple in Bank A, IF1 for scans 30/31.

Fig 4. Baseline ripple in Bank A, IF2 for scans 30/31.

Fig 5. Baseline ripple in Bank B, IF1 for scans 30/31.

Fig 6. Baseline ripple in Bank B, IF2 for scans 30/31.

For the four 'good' data pairs the measured flux, peak, and velocity widths of UGC 9179 falls within the errors of the flux published by Rick Fisher for all IFS and all polarizations (Flux_obs = 101 - 114 Jy km/s; Flux_Rick=116 Jy km/s; v_obs = 307 km/s; v_Rick=304 km/s). The average of all 4 scans is below:

Fig 7. Average of all scans for Bank A, IF=1.

Fig 8. Average of all scans for Bank B, IF=1.

II. RMS

The rms noise for polarizations X and Y ranged from 0.02 - 0.04K, with no discernable difference between the eight samplers. The RMS of the four averaged scans, with all IFS averaged, was 13 and 14 mK for polarizations X and Y, respectively. Assuming a Tsys of 19.8K for the two polarizations (taken from the average values) gives a theoretical value of 21 mK for one 600s scan and 11mK for the average of the four scans. The match is quite good.