Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.naic.edu/alfa/ealfa/meeting1/talks/spekkens.pdf Дата изменения: Mon May 8 22:43:33 2006 Дата индексирования: Sun Dec 23 01:45:27 2007 Кодировка: Поисковые слова: comet tail

On-The-Fly Mapping at AO: Sensitivity and Baseline Quality
K. Spekkens, C. M. Springob, R. Giovanelli, M. P. Haynes, K. L. Masters; Cornell

- Map 3 fields in 4 ways:

1. 2. 3. 4.

DRIFT MODE: 12s/beam "SLOW" OTF: 6s/beam "FAST" OTF, RA-Dec: 3s/beam "FAST" OTF, Dec-RA: 3s/beam

- Setup and preliminary analysis:
- L-narrow, 1385-1425 MHz coverage (4x12.5 MHz BPs, 12 kHz ch.) - 1s integrations across ~5 min strips; Nyquist sampled beam - Bandpass correction: divide each record by strip average


Sensitivity Across a Strip ­ Drift vs. "Slow" OTF
DRIFT
1s integrations
1415 ­ 1419 MHz 1421 ­ 1425 MHz

"SLOW" OTF

1405 ­ 1415 MHz 1s int. + Hanning smooth in freq.


Sensitivity Across a Strip ­ "Fast" OTF
Dec-RA
1s integrations
1415 ­ 1419 MHz 1421 ­ 1425 MHz

RA-Dec

1405 ­ 1415 MHz 1s int. + Hanning smooth in freq.


Baseline Quality ­ "Fast" OTF Dec-RA Map
Raw spectrum: 1s integration

3s average: rms/beam

3s average + Hanning smooth

Intensity (x Tsys)


Baseline Quality ­ Power Spectrum
High freq. Low freq.

Raw spectrum: 1s integration

3s average: rms/beam

3s average + Hanning smooth


Baseline Quality ­ Average Power
High freq. Low freq.

Raw spectrum: 1s integration

3s average: rms/beam

3s average + Hanning smooth


OTF Mapping: Sensitivity and Baseline Quality
For all methods (Drift, "slow" OTF , "fast" OTF):

· Theoretical sensitivity limit achieved; no trend in RMS across strip · "Flat" baselines: no harmonics in power spectrum Map sensitivity and baseline quality independent of mapping technique


Baseline Quality ­ "Fast" OTF RA-Dec Map
Raw spectrum: 1s integration

3s average: rms/beam

3s average + Hanning smooth

Intensity (x Tsys)


Baseline Quality ­ Power Spectrum
High freq. Low freq.

Raw spectrum: 1s integration

3s average: rms/beam

3s average + Hanning smooth


Baseline Quality ­ Average Power
High freq. Low freq.

Raw spectrum: 1s integration

3s average: rms/beam

3s average + Hanning smooth


Baseline Quality ­ "Slow" OTF Map
Raw spectrum: 1s integration

6s average: rms/beam

6s average + Hanning smooth

Intensity (x Tsys)


Baseline Quality ­ Power Spectrum
High freq. Low freq.

Raw spectrum: 1s integration

6s average: rms/beam

6s average + Hanning smooth


Baseline Quality ­ Average Power
High freq. Low freq.

Raw spectrum: 1s integration

6s average: rms/beam

6s average + Hanning smooth


Baseline Quality ­ Drift Map
Raw spectrum: 1s integration

12s average: rms/beam

12s average + Hanning smooth

Intensity (x Tsys)


Baseline Quality ­ Power Spectrum
High freq. Low freq.

Raw spectrum: 1s integration

12s average: rms/beam

12s average + Hanning smooth


Baseline Quality ­ Average Power
High freq. Low freq.

Raw spectrum: 1s integration

12s average: rms/beam

12s average + Hanning smooth


Baselines, 1s Integrations (Drift Map)

time