Examination of autocorrelation data in search of the attenuator setting problem in early R8.1 datasets

* Steve Scott's description of ALMA correlator normalization

The shift log report for January 13/14, 2012 indicates that the BR1202 track was run in R8_0_3_30_FINAL. In principle, it should not show the problem. Here is an extract from the log:
UT 07:09 steDailySetup -- ALMA-8_0_3_30-FINAL
UT 13:22 SCIVER CII BR1202-0725 B7 v1.0 (Version 1.0)
The shift log report for January 15/16, 2012 indicates that the next BR1202 track was run in R8_1_0_B. In principle, it should show the problem. Here is an extract from the log:
23:56 almaop steDailySetup -- ALMA-8_1_0-B-JAV-2012-01-11-03-00-00
06:55 SCIVER CII BR1202-0725 B7 v1.1 (Version 1.0)

At first look, both observations appear to have the problem. Here are plots of autocorrelation amplitude vs. elevation for Jan 14 and Jan 16. Orange=BR1202, black=3C279, red=Titan:
April 2011 (ALMA-8_0_0_14) January 14, 2012 (ALMA-8_0_3_30) January 16, 2012 (ALMA-8_1_0)

But we need to be careful. On January 14, the PWV increased by 80% from the beginning to the end of the track, while on January 16, the PWV was more constant. So the apparent discrepancy in amplitude on the sky vs. elevation may be explained by this temporal variation.
April 2011 (R8.0.0_14) January 14, 2012 (R8.0.3_30) January 16, 2012 (R8.1.0)

Conditions on January 14, 2012 Beginning of track end of track
PWV 1.0 mm 1.8 mm
Transmission at 335 GHz at elev=37 deg 75.1% 61.2%
1-T 24.9% 38.8%

38.8/24.9 = 1.56. But roughly half the noise comes from Trx, and is constant, so the expected variation at elev=37 from the beginning to end of the run is sqrt(1.56) = 1.25 ~ 1 dB.

-- ToddHunter - 2012-03-23

Data reduction results

WYSIWYG content - do not remove this comment, and never use this identical text in your topics

Kim reduced the BR1202-0725 (high redshif quasar) data from 14 January. This data had the Tsys measurements but some concerns were expressed about the data quality because of low elevation.

The track includes Titan (amplitude cal), 3c279 (bandpass and phase), and the source (BR1202). The source was observed from about 12:40-13:20 at elevations of 25-35 degrees. So not great but not shameful. 3c279 was higher (~40-50 degrees elevation) and Titan was at ~65 degrees.

The source is clearly detected in both line (redshifted CII) and continuum and resolved into two distinct components, representing a big jump over the SMA data being verified. The source is strong enough for a selfcal, which I added to Kim's scripts.

JIRA: jira.alma.cl/browse/CSV-871

RMS and Flux (flux measured integrating the clean box):



Continuum Image
----------------------------
RMS in
... dirty map [ 0.78966637] mJy
... clean map [ 0.640193] mJy
... selfcal map [ 0.26757087] mJy
Flux in
... dirty map [ 6.55385935] mJy
... clean map [ 15.63448283] mJy
... selfcal map [ 23.22749576] mJy
----------------------------
Line Image
----------------------------
RMS in
... dirty map [ 3.45111964] mJy
... clean map [ 3.34070111] mJy
... selfcal map [ 3.31065012] mJy
Flux in
... dirty map [ 733.32013401] mJy*channel
... clean map [ 840.4469747] mJy*channel
... selfcal map [ 1446.20931582] mJy*channel

-- AdamLeroy - 2012-03-21

Topic attachments
I Attachment Action Size Date Who CommentSorted ascending
BR1202.cont.clean.image.pngpng BR1202.cont.clean.image.png manage 81 K 2012-03-21 - 16:39 AdamLeroy  
BR1202.cont.dirty.image.pngpng BR1202.cont.dirty.image.png manage 88 K 2012-03-21 - 16:39 AdamLeroy  
BR1202.cont.selfcal.image.pngpng BR1202.cont.selfcal.image.png manage 66 K 2012-03-21 - 16:40 AdamLeroy  
BR1202.line.clean.image.pngpng BR1202.line.clean.image.png manage 10 K 2012-03-21 - 16:40 AdamLeroy  
BR1202.line.dirty.image.pngpng BR1202.line.dirty.image.png manage 12 K 2012-03-21 - 16:40 AdamLeroy  
BR1202.line.selfcal.image.pngpng BR1202.line.selfcal.image.png manage 9 K 2012-03-21 - 16:41 AdamLeroy  
BR1202_14Jan2012_Band7_DV06_XX_spw0_chan64.pngpng BR1202_14Jan2012_Band7_DV06_XX_spw0_chan64.png manage 16 K 2012-03-23 - 15:04 ToddHunter  
BR1202_16Jan2012_Band7_DV06_XX_spw0_chan64.pngpng BR1202_16Jan2012_Band7_DV06_XX_spw0_chan64.png manage 15 K 2012-03-23 - 15:04 ToddHunter  
BR1202_nort_peak.pngpng BR1202_nort_peak.png manage 11 K 2012-03-21 - 16:41 AdamLeroy  
BR1202_south_peak.pngpng BR1202_south_peak.png manage 11 K 2012-03-21 - 16:41 AdamLeroy  
TWHya_22Apr2011_Band7_DV04_XX_spw1_17.pngpng TWHya_22Apr2011_Band7_DV04_XX_spw1_17.png manage 14 K 2012-03-23 - 17:04 ToddHunter  
X3c1.ms.pwv.pngpng X3c1.ms.pwv.png manage 43 K 2012-03-23 - 16:47 ToddHunter  
uid___A002_X36ffba_X3ef.pwv.pngpng uid___A002_X36ffba_X3ef.pwv.png manage 40 K 2012-03-23 - 15:24 ToddHunter  
uid___A002_X373584_X24c.pwv.pngpng uid___A002_X373584_X24c.pwv.png manage 40 K 2012-03-23 - 15:24 ToddHunter  
This topic: ALMA > WebHome > AlmaSci > AlmaTiger > ALMAImagingTigerTeamMeetings > ALMATigerTeamMtg2012Mar08 > BR1202SciVerData
Topic revision: 2012-03-23, ToddHunter
This site is powered by FoswikiCopyright © by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding NRAO Public Wiki? Send feedback