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public:meetings:glowbi2008:tutorial_tuesday [2008-11-14 13:10] – created James M Andersonpublic:meetings:glowbi2008:tutorial_tuesday [2017-03-08 15:27] (current) – external edit 127.0.0.1
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 Enno will have us working on a VLBI dataset.  LOFAR is fundamentally a VLBI instrument, so it will be useful to explore how VLBI is different from connected-element interferometry. Enno will have us working on a VLBI dataset.  LOFAR is fundamentally a VLBI instrument, so it will be useful to explore how VLBI is different from connected-element interferometry.
 +
 +
 +====== Testing ======
 +
 +
 +====== J Eisloeffel's notes ======
 +
 +
 +<file>
 +load the data, get FITS files from
 +
 +http://www.astro.rub.de/middelberg/tmp/v211a_calib.fits
 +http://www.astro.rub.de/middelberg/tmp/v211b_calib.fits
 +
 +chdir to directory where FITS files are, then start Aips
 +
 +
 +load the data
 +=============
 +
 +tget fitld (or use "task 'fitld'")
 +default
 +datain 'PWD:v211a_calib.fits
 +outname 'v211a'
 +go
 +
 +Do the same with the other file
 +===============================
 +
 +tget fitld
 +default
 +datain 'PWD:v211b_calib.fits
 +outname 'v211b'
 +go
 +
 +
 +make sure the new files have catalog numbers 1 and 2!
 +
 +
 +Take a look at the scans
 +========================
 +
 +tget listr
 +default
 +getn 1
 +optype 'SCAN
 +go
 +
 +
 +
 +plot spectra
 +============
 +
 +tget possm       * or   task 'possm'
 +default
 +getn 1
 +dotv 1
 +flagver -1
 +nplots 4
 +aparm (9) 1
 +solint 1
 +aparm 0, 1, 0, 0, -180, 180, 0, 0, 1, 0
 +go
 +
 +* stop possm by clicking into the window and then pressing d like "done"
 +
 +
 +* where do the slopes and offsets across the band come from?
 +* how would one fix it?
 +
 +plot the spectra with first calibration
 +=======================================
 +
 +tget possm 
 +default
 +getn 1
 +dotv 1
 +docalib 1
 +gainuse 2
 +flagver -1
 +nplots 4
 +aparm (9) 1
 +solint 1
 +aparm 0, 1, 0, 0, -180, 180, 0, 0, 1, 0
 +go
 +
 +
 +the edges of the passband have low amplitudes, flag them:
 +=========================================================
 +
 +tget possm
 +default
 +getn 1
 +dotv 1
 +docalib 1
 +gainuse 2
 +flagver 1
 +nplots 4
 +aparm (9) 1
 +solint 1
 +aparm 0, 1, 0, 0, -180, 180, 0, 0, 1, 0
 +go
 +
 +
 +Now we can average the data across the band and have a look at the
 +phases as a function of time
 +========================================================
 +
 +tget vplot  * or task 'vplot'
 +tvinit
 +default
 +getn 1
 +nplots 6
 +docalib 1
 +gainuse 2
 +dotv 1
 +flagver 1
 +bchan 1
 +echan 64
 +avgif 1
 +bparm 0 2
 +go
 +
 +
 +Hmmm, that was a bit messy, zoom into a short section
 +=====================================================
 +
 +tget vplot
 +tvinit
 +default
 +getn 1
 +nplots 6
 +docalib 1
 +gainuse 2
 +dotv 1
 +flagver 1
 +bchan 1
 +echan 64
 +avgif 1
 +bparm 0 2
 +timerang 1 0 0 0 1 2 0 0
 +go
 +
 +
 +
 +*** some tests done on the spot
 +
 +timerang 1,0,0,0,1,2,0,0
 +bparm 0
 +go
 +timerang 0
 +go
 +
 +
 +
 +
 +Look at the uv plane coverage
 +=============================
 +
 +tget uvplt   * or  task 'uvplt'
 +tvinit
 +default
 +getn 1
 +bparm 6 7
 +bif 1
 +eif 1
 +bchan 30
 +echan 30
 +dotv 1
 +go
 +
 +
 +Compare that to the uv plane coverage of the v211b file (after above
 +commands, just "getn 2" and "go" again).
 +
 +
 +
 +tget imagr    * or   task 'imagr'
 +default
 +getn 1
 +sources '0022-423'
 +docalib 1
 +gainuse 6
 +bchan 1
 +echan 64
 +bif 1
 +eif 4
 +nchav 64
 +flagver 1
 +outname 'DEMO'
 +cellsi 0.002 0.002
 +imsize 1024
 +niter 100
 +dotv 1
 +go
 +
 +dowait 1
 +go
 +
 +* set a box around the dirty image using tvbox, click a, resize box, exit d
 +* clean with a small clean window
 +* continue cleaning (wait for 30sec)
 +* stop cleaning   
 +
 +tvzoom
 +* d for done
 +
 +tvfiddle  * a to change colour, b/c to zoom in/out, d for done
 +
 +* make a contour map
 +task 'kntr'
 +pcat
 +getn 4
 +
 +* help
 +
 +docont 1
 +dogrey 1
 +dovect 0
 +blc 450,450
 +trc 560,560
 +clev = 8.5503E-03
 +levs = -2,2,4,8,16,32,64
 +dowedge = 1
 +cbplot = 1   * cbplot = 2 to set beam plot to lower right
 +dotv = 1
 +
 +tvinit
 +go
 +
 +dogrey = 1
 +go
 +
 +* draw to plot file
 +tget kntr
 +dotv = -1
 +go
 +
 +* make a postscript file
 +
 +task 'lwpla'
 +inp
 +outfile = 'PWD:demo.ps'
 +go
 +
 +
 +
 +* make a fits-file
 +
 +task 'fittp'
 +inp
 +dataout = 'PWD:demo_enno.fits        * final ' to capitalise
 +go
 +
 +
 +
 +getn 1
 +task 'listr'
 +optyp = 'scan'
 +go
 +
 +</file>
  
  • Last modified: 2008-11-14 13:10
  • by James M Anderson