I've been wondering lately-- when you run an Amplitude & Phase Self-Cal run, often times this can make certain parts of your data look anomalously high or low. Usually it's pretty mild, but a couple of times, it has been rather dramatic. A bit distressing, as I don't really understand why CALIB chose to make my amplitudes worse...
But anyway, does anyone out there have opinions on whether you should flag your data again after an A&P self cal? If you do flag, do you then copy the flag table over to the un-A&P-self-calibrated data set, and the re-self-calibrate using this new flag table? And iterate so on till no more "bad" data pops up on the A&P self cal?
Sunday, June 8, 2008
Flagging After A&P Self Calibration?
Friday, June 6, 2008
DBCONing Data Sets From Different Epochs
If you are an archive monger like me, you might find yourself reducing one J2000. data set and one B1950. data set, and then wanting to concatenate them together. If you try to do this, DBCON will yell at you. So...
You will have to run EPOSWTCH on the 1950 data set to bring it into epoch 2000. However, if you try to run DBCON now, DBCON will still yell at you and say:
tsingt> DBCON1: DEC AXIS HAS UNEQUAL ATTRIBUTES
tsingt> DBCON1: Purports to die of UNNATURAL causes
As explained by Eric Greisen here , this is because the image you EPOSWTCHed now has a Declination axis with a rotation imposed upon it. For example:
AIPS 1: Image=NGC1569 (UV) Filename=N1569_3B .SC_P1 . 1
AIPS 1: Telescope=VLA Receiver=VLA
AIPS 1: Observer=AA116 User #= 53
AIPS 1: Observ. date=21-AUG-1990 Map date=06-JUN-2008
AIPS 1: # visibilities 135940 Sort order TB
AIPS 1: Rand axes: UU-L-SIN VV-L-SIN WW-L-SIN BASELINE TIME1
AIPS 1: WEIGHT SCALE
AIPS 1: ----------------------------------------------------------------
AIPS 1: Type Pixels Coord value at Pixel Coord incr Rotat
AIPS 1: COMPLEX 1 1.0000000E+00 1.00 1.0000000E+00 0.00
AIPS 1: STOKES 4 -1.0000000E+00 1.00 -1.0000000E+00 0.00
AIPS 1: FREQ 1 8.4149000E+09 1.00 5.0000000E+07 0.00
AIPS 1: IF 2 1.0000000E+00 1.00 1.0000000E+00 0.00
AIPS 1: RA 1 04 30 49.498 1.00 3600.000 0.00
AIPS 1: DEC 1 64 50 59.587 1.00 3600.000 -0.60
AIPS 1: ----------------------------------------------------------------
AIPS 1: Coordinate equinox 2000.00
AIPS 1: Rest freq 0.000 Vel type: OPTICAL wrt YOU
AIPS 1: Alt ref. value 0.00000E+00 wrt pixel 1.00
AIPS 1: Maximum version number of extension files of type FQ is 1
AIPS 1: Maximum version number of extension files of type HI is 1
AIPS 1: Maximum version number of extension files of type AN is 1
AIPS 1: Maximum version number of extension files of type WX is 1
AIPS 1: Maximum version number of extension files of type FG is 1
You can get rid of this rotation using UVSRT:
AIPS 1: UVSRT: Task which sorts UV data
AIPS 1: Adverbs Values Comments
AIPS 1: ----------------------------------------------------------------
AIPS 1: INNAME 'N1569_3B' Input UV file name (name)
AIPS 1: INCLASS 'SC_P1' Input UV file name (class)
AIPS 1: INSEQ 1 Input UV file name (seq. #)
AIPS 1: INDISK 1 Disk unit # of input UV data
AIPS 1: OUTNAME ' ' Sorted UV file name (name)
AIPS 1: OUTCLASS 'ROTAT' Sorted UV file name (class)
AIPS 1: OUTSEQ 0 Sorted UV file name (seq. #)
AIPS 1: OUTDISK 0 Disk unit # of sorted UV data
AIPS 1: 0 => highest with space
AIPS 1: If outfile spec. equals the
AIPS 1: infile spec., output will
AIPS 1: overwrite the input
AIPS 1: BADDISK *all 0 Disk drive #'s to avoid
AIPS 1: SORT ' ' Two char. sort order, eg.'XY'
AIPS 1: blank => 'XY'
AIPS 1: ROTATE 0.6 Angle thru which to rotate.
AIPS 1: positive rotates CCW
AIPS 1: DEFER 0 Defer output file creation?
Note that the ROTATE parameter is the negative of the rotation noted in the header. Now you should be able to DBCON the EPOSWTCHed data with the other J2000 data set!
(You may have to UVSRT the DBCONed data so that it is in TB order again.)
Monday, June 2, 2008
Calibrating One Calibrator with Two UVranges
The VLA calibrator manual recommends that if you are using 3c286 as your flux calibrator at 20 cm in A configuration, you should use the uvrange 0-18 AND 90-180 (for the latter, decrease flux by 6%). This makes me wonder how on earth one would do this. First of all, I do not know how to calibrate on two separate uvranges and then merge that information. Second of all, I do not know how to reduce a flux by 6%. Anyone? Anyone?
Friday, March 7, 2008
Help Miriad Selfcal Tip
IGNORE THE FOLLOWING POST. If Miriad is rescaling to large values during the self-calibration process, this is a sign that something is wrong with your self-calibration and you need to increase the self-calibration interval or need more clean components.This is a bit off the beaten path, but I'd thought I'd post it anyway. If you're self-calibrating in Miriad, it helps to set the noscale option.
The noscale option prevents Miriad from rescaling the gains during amplitude+phase self-calibrating so that the rms gain is 1.0. If you have a lot of outliers, not setting this option can play havoc with the derived amplitudes. A sign that this may be a problem for your data would be unrealistically large amplitudes (much greater than 1.0) after amplitude+phase self-calibration.
Monday, February 4, 2008
Bandpass calibration trauma
I've been working on bandpass calibrating some WSRT data. Usually this is a pretty simple process, but for some reason I can't get it to work out here. When I calibrate the data I'm getting large closure errors that seem to be baseline and polarization dependent. Before bandpass calibration, I went through the data and flagged anything that looked like it had an amplitude that was off. After flagging I thought the data looked pretty good in SPFLG. Changing the reference antenna or the calibration source doesn't fix the problem. What had partially fixed the problem for the LL feed at least was going from the default SOLTYPE to SOLTYPE='L1R', which uses a more robust method of fitting the bandpass that is less sensitive to variations in the input data.
Any ideas? I've put my inputs to BPASS and some sample output below.
Update (2/4/08): It looks like using bpassprm(5) = -1 instead of bpassprm(5) = 0 works. bpassprm(5) = -1 is only supposed to be used in cases of decent phase stability. It averages over time and then averages the ichansel channels rather than averaging the ichansel channels on a record-by-record base as does bpassprm(5)=0. Therefore, bpassprm(5)=-1 gives me a bit more signal enabling better bandpass calibration. The phase stability of my observations is pretty good, so I think I'm safe using this parameter.]AIPS 1: BPASS Task to generate a "Bandpass" (BP) table.
AIPS 1: Adverbs Values Comments
AIPS 1: ----------------------------------------------------------------
AIPS 1: USERID 0 User number
AIPS 1: INNAME 'POLANG' Input UV file name (name)
AIPS 1: INCLASS '13CM' Input UV file name (class)
AIPS 1: INSEQ 3 Input UV file name (seq. #)
AIPS 1: INDISK 2 Input UV file disk unit #
AIPS 1:
AIPS 1: Data Selection
AIPS 1: CALSOUR '3C286' Bandpass calibrator sources.
AIPS 1: *rest ' '
AIPS 1: QUAL -1 Calibrator qualifier -1=>all
AIPS 1: CALCODE ' ' Calibrator code ' '=>all
AIPS 1: UVRANG 0 0 UV range to select
AIPS 1: TIMERANG *all 0 Time range to select
AIPS 1: SELBAND -1 Bandwidth to select (kHz)
AIPS 1: SELFREQ -1 Frequency to select (MHz)
AIPS 1: FREQID 1 Freq. ID to select.
AIPS 1: BIF 0 Lowest IF number 0=>all
AIPS 1: EIF 0 Highest IF number 0=>all
AIPS 1: SUBARRAY 0 Subarray, 0=>all
AIPS 1: ANTENNAS *all 0 Antennas to select
AIPS 1:
AIPS 1: CLEAN map (optional)
AIPS 1: IN2NAME ' ' Cleaned map name (name)
AIPS 1: IN2CLASS ' ' Cleaned map name (class)
AIPS 1: IN2SEQ 0 Cleaned map name (seq. #)
AIPS 1: IN2DISK 0 Cleaned map disk unit #
AIPS 1: INVERS -1 CC file version #.
AIPS 1: NCOMP *all 0 # comps to use for model.
AIPS 1: 1 value per field
AIPS 1: FLUX 0 Lowest CC component used.
AIPS 1: NMAPS 0 No. Clean map files
AIPS 1: CMETHOD ' ' Modeling method:
AIPS 1: 'DFT','GRID',' '
AIPS 1: SMODEL *all 0 Source model, 1=flux,2=x,3=y
AIPS 1: See HELP SMODEL for details.
AIPS 1:
AIPS 1: Control options
AIPS 1: DOCALIB 1 > 0 calibrate data & weights
AIPS 1: > 99 do NOT calibrate weights
AIPS 1: GAINUSE 2 CL table to apply (SN table
AIPS 1: to apply to single-source)
AIPS 1: DOPOL -1 If >0 correct polarization.
AIPS 1: BLVER -1 BL table to apply.
AIPS 1: FLAGVER 1 Flag table version
AIPS 1: DOBAND -1 If >0 apply bandpass cal.
AIPS 1: Method used depends on value
AIPS 1: of DOBAND (see HELP file).
AIPS 1: BPVER 0 Bandpass table version
AIPS 1: SOLINT 0 Solution interval (mins)
AIPS 1: -1 => do whole time range
AIPS 1: SOLTYPE 'L1R' Soln type,' ','L1','GCON',
AIPS 1: REFANT 5 Reference antenna
AIPS 1: OUTVERS 0 Output BP table version
AIPS 1: 0 => a new table to be
AIPS 1: generated.
AIPS 1: SMOOTH *all 0 Smoothing function.
AIPS 1: BE VERY CAREFUL HERE.
AIPS 1: ANTWT *all 0 Ant. wts (0 => 1.)
AIPS 1: WEIGHTIT 0 Modify data weights function
AIPS 1: MINAMPER 10 Amplitude closure error
AIPS 1: regarded as excessive in %
AIPS 1: MINPHSER 10 Phase closure error regarded
AIPS 1: as excessive in degrees
AIPS 1: BPASSPRM 0 2 Control information:
AIPS 1: 0 0 1: if > 0 use only the
AIPS 1: 0 10 autocorrelation data.
AIPS 1: 10 1 2: print level - see help
AIPS 1: 1 3 3: If > 0 do not divide data
AIPS 1: 0 by source model
AIPS 1: 4: If > 0 store phases only
AIPS 1: in the BP table.
AIPS 1: 5: Divide by 'channel 0'
AIPS 1: **** SEE HELP - NEW ****
AIPS 1: 6: amp closure error limit -
AIPS 1: print channels averaging
AIPS 1: over this if (2) > 0
AIPS 1: 7: phase closure error limit
AIPS 1: print channels averaging
AIPS 1: over this if (2) > 0
AIPS 1: 8: > 0 => scalar average
AIPS 1: 9: > 0 => interpolate over
AIPS 1: flagged channels if poss.
AIPS 1: 10:1 => normalize amplitudes
AIPS 1: using all channels
AIPS 1: 2 => normalize amplitudes
AIPS 1: using ICHANSEL channels
AIPS 1: 3 => normalize amplitudes
AIPS 1: and zero average phase
AIPS 1: using ICHANSEL channels
AIPS 1: 4 => normalize amplitudes
AIPS 1: and zero average phase
AIPS 1: using all channels
AIPS 1: 0 => no deliberate norm.
AIPS 1: 11: > 0 solution weights are
AIPS 1: independent of channel
AIPS 1: = -1 weights scaled
AIPS 1: by amplitude**2
AIPS 1: < -1.5 weights scaled by
AIPS 1: 1 / amplitude**2
AIPS 1: ICHANSEL 5 50 Array of start and stop chan
AIPS 1: 1 1 numbers, plus a channel
AIPS 1: 5 50 increment and IF to be used
AIPS 1: 1 2 to select channels to sum to
AIPS 1: 5 50 find a 'channel 0'. If all
AIPS 1: 1 3 0, range set to inner 75% of
AIPS 1: 5 50 observing band.
AIPS 1: 1 4 5 50
AIPS 1: 1 5 5 50
AIPS 1: 1 6 5 50
AIPS 1: 1 7 5 50
AIPS 1: 1 8 *rest 0
AIPS 1: SPECINDX 0 Spectral index to correct
AIPS 1: 'Channel 0' uv-data
AIPS 1: IN3NAME ' ' Channel 0 uv name (name)
AIPS 1: must be '' to suppress option
AIPS 1: IN3CLASS ' ' Channel 0 uv name (class)
AIPS 1: must be '' to suppress option
AIPS 1: IN3SEQ 0 Channel 0 uv name (seq. #)
AIPS 1: IN3DISK 0 Channel 0 uv disk unit #
AIPS 1: BADDISK *all 0 Disks to avoid for scratch
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 1 Rpol
localh> BPASS1: 1- 2 25% 0d 1- 10 123% 0d 1- 13 44% 1d
localh> BPASS1: 1- 14 32% 1d 2- 4 34% 1d 2- 6 73% 178d
localh> BPASS1: 2- 7 25% 2d 2- 8 133% 0d 2- 9 238% 180d
localh> BPASS1: 2- 10 917% 178d 2- 11 662% 2d 2- 12 298% 178d
localh> BPASS1: 2- 13 80% 0d 2- 14 118% 1d 3- 8 53% 0d
localh> BPASS1: 3- 10 13% 1d 3- 13 20% 0d 3- 14 27% 0d
localh> BPASS1: 4- 6 74% 0d 4- 8 20% 2d 4- 9 63% 1d
localh> BPASS1: 4- 10 120% 178d 4- 11 31% 0d 4- 12 52% 0d
localh> BPASS1: 4- 13 35% 1d 4- 14 52% 1d 5- 8 63% 1d
localh> BPASS1: 5- 13 19% 0d 5- 14 28% 0d 6- 7 28% 1d
localh> BPASS1: 6- 9 111% 1d 6- 10 906% 0d 6- 11 84% 1d
localh> BPASS1: 6- 12 126% 1d 6- 14 24% 2d 7- 8 243% 2d
localh> BPASS1: 7- 9 26% 0d 7- 10 167% 0d 8- 11 140% 176d
localh> BPASS1: 8- 12 19% 178d 8- 13 32% 2d 8- 14 51% 2d
localh> BPASS1: 9- 10 801% 0d 9- 11 72% 0d 9- 12 107% 1d
localh> BPASS1: 9- 14 18% 2d 10- 11 586% 1d 10- 12 864% 0d
localh> BPASS1: 10- 13 205% 0d 10- 14 60% 176d 11- 12 64% 1d
localh> BPASS1: 12- 13 11% 0d 12- 14 28% 0d
localh> BPASS1: Closure error statistics: IF 7 correlator 1
localh> BPASS1: Channel Mean amp & amp**2 Mean phase & phase**2 Excess
localh> BPASS1: 1 52.84 104.74 16.72 53.59 53
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 2 Rpol
localh> BPASS1: 1- 13 13% 0d 2- 8 19% 2d 2- 13 13% 7d
localh> BPASS1: 2- 14 21% 5d 4- 8 11% 1d 4- 13 11% 2d
localh> BPASS1: 4- 14 16% 0d 5- 14 10% 1d 6- 12 12% 0d
localh> BPASS1: 7- 10 11% 1d 8- 12 1% 11d 9- 12 12% 1d
localh> BPASS1: 10- 12 12% 3d 10- 14 13% 1d
localh> BPASS1: 2 4.90 6.60 2.13 3.30 14
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 3 Rpol
localh> BPASS1: 6- 10 13% 0d 6- 14 11% 1d 9- 10 13% 1d
localh> BPASS1: 3 2.66 4.15 0.58 0.78 3
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 4 Rpol
localh> BPASS1: 6- 10 11% 0d 6- 14 11% 1d 9- 14 10% 2d
localh> BPASS1: 10- 13 12% 1d
localh> BPASS1: 4 2.66 4.08 0.57 0.76 4
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 5 Rpol
localh> BPASS1: 6- 10 11% 0d 6- 14 10% 1d 10- 13 12% 1d
localh> BPASS1: 5 2.60 3.99 0.53 0.69 3
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 6 Rpol
localh> BPASS1: 6- 7 10% 0d 6- 10 11% 0d 6- 14 12% 1d
localh> BPASS1: 9- 14 11% 2d 10- 13 12% 1d
localh> BPASS1: 6 2.65 4.10 0.55 0.73 5
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 7 Rpol
localh> BPASS1: 6- 7 10% 1d 6- 14 12% 1d 10- 13 12% 1d
localh> BPASS1: 7 2.58 3.92 0.51 0.69 3
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 8 Rpol
localh> BPASS1: 10- 13 10% 1d
localh> BPASS1: 8 2.20 3.30 0.55 0.73 1
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 9 Rpol
localh> BPASS1: 6- 7 11% 1d 10- 13 11% 1d
localh> BPASS1: 9 2.24 3.37 0.51 0.68 2
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 35 Rpol
localh> BPASS1: 6- 14 11% 1d
localh> BPASS1: 35 2.27 3.37 0.56 0.75 1
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 36 Rpol
localh> BPASS1: 6- 14 11% 1d
localh> BPASS1: 36 2.23 3.38 0.55 0.74 1
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 37 Rpol
localh> BPASS1: 6- 14 12% 1d
localh> BPASS1: 37 2.28 3.46 0.52 0.71 1
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 38 Rpol
localh> BPASS1: 6- 7 11% 0d 6- 14 12% 1d
localh> BPASS1: 38 2.32 3.58 0.54 0.73 2
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 39 Rpol
localh> BPASS1: 6- 7 10% 1d 6- 14 11% 1d
localh> BPASS1: 39 2.31 3.52 0.54 0.73 2
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 40 Rpol
localh> BPASS1: 6- 7 11% 0d 6- 14 11% 1d
localh> BPASS1: 40 2.28 3.49 0.54 0.73 2
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 41 Rpol
localh> BPASS1: 6- 7 11% 1d 6- 14 11% 1d 9- 10 10% 0d
localh> BPASS1: 10- 13 12% 1d
localh> BPASS1: 41 2.47 3.78 0.52 0.70 4
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 42 Rpol
localh> BPASS1: 6- 10 11% 0d 6- 14 10% 1d 7- 14 13% 1d
localh> BPASS1: 10- 13 12% 1d
localh> BPASS1: 42 2.79 4.24 0.54 0.73 4
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 43 Rpol
localh> BPASS1: 6- 7 10% 1d 7- 10 15% 0d 7- 14 13% 1d
localh> BPASS1: 9- 10 11% 1d 10- 13 10% 1d
localh> BPASS1: 43 2.85 4.38 0.55 0.75 5
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 44 Rpol
localh> BPASS1: 6- 14 10% 1d 7- 14 13% 1d 9- 10 10% 1d
localh> BPASS1: 10- 13 10% 1d
localh> BPASS1: 44 2.57 3.94 0.56 0.76 4
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 45 Rpol
localh> BPASS1: 6- 7 11% 1d 6- 14 11% 1d 7- 14 12% 1d
localh> BPASS1: 9- 10 10% 0d 9- 14 10% 2d 10- 13 10% 1d
localh> BPASS1: 45 2.57 3.97 0.54 0.74 6
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 46 Rpol
localh> BPASS1: 6- 7 10% 1d 6- 14 11% 1d 7- 14 12% 1d
localh> LOGFILE FOR USER 333 GETTING LARGE: USE PRTMSG AND CLRMSG NOW!
localh> BPASS1: 46 2.52 3.87 0.56 0.77 3
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 47 Rpol
localh> BPASS1: 6- 14 11% 1d 7- 14 13% 1d 9- 10 10% 0d
localh> BPASS1: 47 2.67 4.04 0.58 0.76 3
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 48 Rpol
localh> BPASS1: 6- 14 11% 1d 10- 13 11% 1d
localh> BPASS1: 48 2.58 3.86 0.57 0.76 2
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 49 Rpol
localh> BPASS1: 6- 14 10% 1d 10- 13 12% 1d
localh> BPASS1: 49 2.59 3.87 0.55 0.72 2
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 50 Rpol
localh> BPASS1: 6- 14 11% 1d 9- 10 10% 0d 10- 13 12% 1d
localh> BPASS1: 50 2.59 3.88 0.56 0.73 3
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 51 Rpol
localh> BPASS1: 9- 10 10% 0d
localh> BPASS1: 51 2.27 3.41 0.52 0.70 1
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 52 Rpol
localh> BPASS1: 9- 10 10% 0d 9- 14 10% 2d
localh> BPASS1: 52 2.07 3.11 0.52 0.69 2
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 62 Rpol
localh> BPASS1: 8- 11 11% 0d 8- 14 12% 1d 9- 14 10% 0d
localh> BPASS1: 10- 13 14% 2d
localh> BPASS1: 62 2.98 4.31 0.88 1.11 4
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 63 Rpol
localh> BPASS1: 1- 12 11% 3d 2- 4 15% 4d 2- 12 10% 8d
localh> BPASS1: 3- 7 13% 1d 4- 7 7% 12d 4- 8 19% 10d
localh> BPASS1: 4- 11 14% 5d 5- 11 10% 3d 5- 12 11% 1d
localh> BPASS1: 7- 11 11% 7d 7- 12 16% 4d 8- 12 16% 3d
localh> BPASS1: 8- 13 14% 4d 8- 14 18% 2d 10- 13 13% 5d
localh> BPASS1: 10- 14 13% 6d 11- 13 12% 3d 11- 14 12% 1d
localh> BPASS1: 63 6.02 7.44 3.66 4.36 18
localh> BPASS1: Closure errors at 3/ 2 47 50. IF/Chn no. 7 64 Rpol
localh> BPASS1: 1- 7 23% 2d 1- 8 35% 12d 1- 11 2% 12d
localh> BPASS1: 1- 12 17% 8d 1- 13 2% 11d 1- 14 2% 15d
localh> BPASS1: 2- 3 14% 5d 2- 4 63% 8d 2- 6 16% 12d
localh> BPASS1: 2- 7 203% 27d 2- 8 156% 14d 2- 10 15% 7d
localh> BPASS1: 2- 11 4% 55d 2- 12 107% 48d 2- 13 34% 45d
localh> BPASS1: 2- 14 3% 56d 3- 7 28% 4d 3- 8 41% 12d
localh> BPASS1: 3- 11 6% 12d 3- 12 9% 13d 3- 14 4% 13d
localh> BPASS1: 4- 7 73% 35d 4- 8 68% 28d 4- 10 5% 10d
localh> BPASS1: 4- 11 53% 23d 4- 12 5% 46d 4- 13 64% 2d
localh> BPASS1: 4- 14 66% 20d 5- 6 10% 2d 5- 7 11% 17d
localh> BPASS1: 5- 8 2% 21d 5- 11 27% 4d 5- 12 30% 1d
localh> BPASS1: 5- 13 16% 9d 5- 14 30% 8d 6- 7 6% 19d
localh> BPASS1: 6- 8 27% 26d 6- 11 19% 9d 6- 12 34% 7d
localh> BPASS1: 6- 14 27% 6d 7- 8 178% 15d 7- 9 15% 16d
localh> BPASS1: 7- 10 12% 11d 7- 11 125% 45d 7- 12 257% 31d
localh> BPASS1: 7- 13 50% 47d 7- 14 88% 43d 8- 9 11% 22d
localh> BPASS1: 8- 10 22% 21d 8- 11 55% 55d 8- 12 164% 42d
localh> BPASS1: 8- 13 17% 56d 8- 14 9% 53d 9- 11 5% 12d
localh> BPASS1: 9- 12 27% 3d 9- 13 4% 13d 9- 14 3% 15d
localh> BPASS1: 10- 11 10% 14d 10- 12 20% 9d 10- 13 12% 9d
localh> BPASS1: 10- 14 20% 13d 11- 12 128% 20d 11- 13 72% 6d
localh> BPASS1: 11- 14 90% 1d 12- 13 96% 23d 12- 14 106% 16d
localh> BPASS1: 13- 14 47% 6d
localh> BPASS1: 64 27.85 45.82 15.40 21.64 67
localh> BPASS1: Antenna 1 IF 7 corr 1 had 12 excess closure errors
localh> BPASS1: Antenna 2 IF 7 corr 1 had 26 excess closure errors
localh> BPASS1: Antenna 3 IF 7 corr 1 had 11 excess closure errors
localh> BPASS1: Antenna 4 IF 7 corr 1 had 24 excess closure errors
localh> BPASS1: Antenna 5 IF 7 corr 1 had 13 excess closure errors
localh> BPASS1: Antenna 6 IF 7 corr 1 had 51 excess closure errors
localh> BPASS1: Antenna 7 IF 7 corr 1 had 40 excess closure errors
localh> BPASS1: Antenna 8 IF 7 corr 1 had 31 excess closure errors
localh> BPASS1: Antenna 9 IF 7 corr 1 had 29 excess closure errors
localh> BPASS1: Antenna 10 IF 7 corr 1 had 54 excess closure errors
localh> BPASS1: Antenna 11 IF 7 corr 1 had 26 excess closure errors
localh> BPASS1: Antenna 12 IF 7 corr 1 had 31 excess closure errors
localh> BPASS1: Antenna 13 IF 7 corr 1 had 40 excess closure errors
localh> BPASS1: Antenna 14 IF 7 corr 1 had 62 excess closure errors
Friday, January 4, 2008
Double Sources-- and not the AGN kind
I'm having this problem with some archival data from 1990. I have two nights of data on a galaxy, spaced a few nights apart from one another. I calibrate the nights separately, and image them separately. It rapidly becomes obvious that the images from the two nights are shifted relative to one another, but not in any simple way. The galaxy center, at the image center, is at the same position in both, but as you go out radially, the first night's sources are further out, radially. It's as if the image is stretched one night, relative to the other.
AIPS thinks that both images have the same pixel scale, so that means a source will have different R.A. and Dec (by about an arcminute, pretty bad!) between the two nights' images. If I DBCON the two nights, I get lots of double sources.
The observational setup claims to be exactly the same between the two nights-- same pointing center, same correlator set-up.
Anyone have any idea what might be causing this? I think I've had a similar problem with GMRT data before, and gave up temporarily and went on to a different project. I'm guessing it's a calibration issue?
Monday, December 3, 2007
Setting up New Data Disks
My latest organizational scheme for AIPS is to give each project a new AIPS data disk. I just spent some time adding a new data disk to my AIPS installation on my laptop. Here's what I did to get it. (BTW, I've got a MacBook, but that shouldn't matter for this.)
In $AIPS_ROOT, cd to DA00. Save a copy of the DADEVS.LIST file as DADEVS.LIST.old. Then edit the DADEVS.LIST. I just copied the first uncommented line (set up by AIPS) and incremented the data disk number by 1, i.e., LOCALHOST_2. Now save a copy of the NETSP file in the same directory to NETSP.old. Again, edit the file by copying the first uncommented line and incrementing the data disk number by 1. Finally, cd to $AIPS_ROOT/DATA, mkdir LOCALHOST_2 (or whatever your new data disk is named), cd to LOCALHOST_2, and create a file named SPACE (touch SPACE). Now when you start up AIPS you should have additional data disks available.
Most of this tip was taken from the AIPS Manager FAQ (see "How do I configure new AIPS data areas?").
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