Monitoring A2055 data
jun05
Sections:
How the data was processed
1 second total power vs position in strip to
show sources, rfi
jan01
How the 100 Mhz wapp
data was processed:
A2055 does 840 second drift scans sampling at 1 hz.
With the wapps, it takes a 100 Mhz bandwidth centered at 1385 Mhz and uses
3 level sampling. Each 840 second drift is a single scan. After each drift
scan a 1 second cal is fired and then the process repeats. The processing
of the drift scan data for monitoring is:
-
compute the rms/mean by channel for n secs (840) seconds worth of data.
There must be a cal record in the file for the file to be processed.
-
Do a robust linear fit to the rms/mean by channel throwing out outliers.
The remaining channels will be the mask used to compute the total power
for each spectra of the 840 seconds (and the cal).
-
compute the total power (mean) for each 1 second record using the
above mask.
-
Over the entire strip compute the median of the total power using the data
from 4.
-
Compute the cal scale factor : calK/(calOn-calOff).
-
Scale the total power data (from 4) to kelvins using the cal scale factor.
-
Save the following to disc (one save file per day). assume there are NstripsTot
total strips:
-
tpIAr[nstripsTot] (tpI struct), brmsAr[nstripsTot] (corget struct) ,bcalRAr[nstripsTot]
(corget struct), and maskAr.
TpI struct:
SCAN LONG 503514951
FNAME STRING '/proj/a2055/wapp.20050623.a2055.0007.fits'
NPNTS LONG 840
RMSFITA FLOAT Array[2, 7] (ao + a1*channum) fit torms polA
RMSFITB FLOAT Array[2, 7] (ao + a1*channum) fit to rms polB
MASKFRACT FLOAT Array[2, 7] (fraction of band each mask contained)
TPCORA FLOAT Array[840, 7] (tot power deg K each point (polA)
TPCORB FLOAT Array[840, 7] (tot power deg K each point (polB)
TPMEDIAN FLOAT Array[2, 7] (median tot pwr each strip cor Units (a,b)
CALK FLOAT Array[2, 7] (calval degK for [pols,pixels])
CALSCL FLOAT Array[2, 7] ( calK/(calOn-calOff) tp [pols,pixels]
NCALOFF FLOAT 2.00000 (number of cal offs used)
AZ FLOAT 359.638 ( azimuth feed)
ZA FLOAT 9.22350 ( za )
JD DOUBLE 2453405.3 (jd start of strip)
ALFAANGLE FLOAT 18.9999 (alfa rotation angle)
-
bcalRAr . This is a corget struct holding the calon/caoff spectra
for each cal
-
maskAr . This holds the masks used to compute the total power.
Note that the daily save files are done by ast date so they may include
data from 2 different observing runs.
The save files can be input and merged using inpsav.pro. This routine
creates one large array of tpI structs. It only takes strips that have
840 seconds worth of data.
1 second total power samples vs position in
strip (top)
The 1 second total power by strip are plotted for the
first 10 strips of each day ( days start at ast midnite). This data
comes from the wapps. Each strip is one page. There are up to 10 pages
per link.
The top plot is polA, the bottom plot is polB. The
7 pixels are color coded and offset for display. Black (at the bottom)
is pixel 0, red pixel1, green pixel 2, etc.. The units are Tsys.
On each plot the median power value for the strip
is printed. These units are measured/optimum power (linear scale).
All of the files are .pdf.
The plots show sources drifting through the beam
as well as rfi. When the total power was computed, any frequency channels
that had variations in time are not included. If a channel was excluded
from the total power computation, then the 5 adjacent channels on each
side of it were also excluded.
processing: usr/a2055/wapp/cmppwr_do.pro,montp_day.pro
jan01 1 second total power samples
vs position in strip
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