REDUCE POLAR Command List
last updated 04/06/1993 by K. Nordsieck
To enter the POLAR REDUCE module, type "POLAR". Commands available
from POLAR are:
I) Halfwave Polarimetry
HCAL < calname >
Loads halfwave polarimetric calibration file "calname.hcal",
including halfwave filter positions, filter efficiency vs wavelength,
PA calibration, and telescope and spectrograph instrumental
polarization. Once this file is loaded, you never need to reload
it, even after exitting POLAR or REDUCE (as long as you don't
restart REDUCE). The hcal file name you are using is placed in
the DISK2 header of each new polarimetric scan on line 10. It
is also written on the right of each polarimetric plot. EG:
HCAL pbo2c3
HRECAL < calname > < qscan > < qscan > ...
Recalibrates q,u,err scans with a new halfwave polarimetric calibration
file. "calname.hcal" is the name of the new calibration file. For each
q,u,err set named in the list, the calibration listed in the
header is removed, the new one applied, and a new q,u,err set
is created on DISK2 (with the calibration field updated). At the
end the new calibration file is loaded for later reductions.
HRECAL will properly update old reductions whenever the calibration
is updated with a new instrumental polarization or position angle
zero-point. It does not work if the calibration update changes
the polarimetric efficiency model or makes use of a new "wing"
correction. EG:
HRECAL pbo2c3 1 4 7
A LOW-LEVEL COMMAND WHICH YOU PROBABLY WON'T NEED IS:
HPOL ( residual save ) < scan list >
Calculates polarization from ADDPOL spectra taken through
different halfwave filter positions. Scan list should contain one
(and only one) DISK2 spectrum of at least two filter pairs (all
four advised) in both arrays. EG, one complete filter pair
contains filter 0/ Array A, filter 0/Array B, filter 4/Array A,
and filter 4/Array B, so 16 scans are required for a complete list.
Scans may be in any order. These scans should NOT be normalized or
fluxed, but they SHOULD be scrunched. A "Q" spectrum, "U" spectrum,
and Error spectrum are put in DISK2. If the optional "residual" is
present, the residual from the fit for each filter pair is also
saved. If the optional "save" is present, the scans in the scan
list are not overwritten (to be avoided, as it clutters up disk2).
E.G:
HPOL 65 -80
reduces the 16 ADDPOLed, SCRUNCHed DISK2 scans, and stores the
resulting Q, U, Err triplet in disk2 slots 65 -67. The original
disk2 scans are lost (since the "save" option was not invoked).
USE THIS HIGH-LEVEL COMMAND:
HRED ( resi save ) < s1 list > ; < s2 list > ; < s3 list > ; < s4 list >
Performs a "script" which does ADDPOL, SCRUNCH, and HPOL starting
from disk1 raw scans. < s1 list > lists the scans for one filter
pair, etc. No intermediate scans are normally saved. HPOL options
apply. The NORM and FLUX flags should be OFF for ADDPOL, but there
should be an applicable wavelength calibration for SCRUNCH.
E.G:
HRED 5 -12 ; 13 -20 ; 21 -28 ; 29 -36
performs the reductions for the 32 disk1 scans produced by a
standard "4 DOPOL" run, and stores the resulting Q,U,Err spectrum
triplet in the next three DISK2 positions. A better procedure
would be
HRED 5 -9 ; 13 -16 ; 21 -24 ; 29 -32
HRED 10 -12 ; 17 -20 ; 24 -28 ; 33 -36
HCOMB < qscan1 > < qscan2 >
which reduces the first four and second four of each filter pair
separately, and combines the results see HCOMB below). This
minimizes spikes due to cosmic ray and detector ion events.
HROT < qscan >
Saves a new Q, U, and Error spectrum, with coordinate system rotated
by an input number of degrees ( Asks "Please enter degrees to rotate" ).
"QSCAN" is assumed to be the first of a Q,U, Error spectrum triplet.
EG, if the mean PA for the original data starting in "qscan" is 54
degrees, entering " -54 " will cause a new Q, U, Error triplet to be
saved, with the polarization at PA 54 rotated into the q spectrum.
E.G:
HROT 100
HCOMB < qscan1 > < qscan2 > ...
Combines the Q, U, ERR spectrum triplets starting in Qscan1, Qscan2,
etc, using a pixel-by-pixel error-weighted mean, and produces a new
Q, U, and ERR spectrum. Scans are registered in wavelength to qscan1,
and the qscan1 header is used as a header model. EG:
HCOMB 2 5 8 11
Might produce a new Q, U, ERR set combining four independent sets
from four HRED results in a single night or for four different nights.
See HADD below for situations where HADD should be used instead.
HADD < qscan1 > < qscan2 > ...
Do vector addition of halfwave pol scans. Asks:
Please enter weight for each scan (default=1)
For each pol scan, the program takes one number from the weight
line to weight the entire scan; if none is found, it uses a weight of 1.
The scans are registered in wavelength to qscan1, and the qscan1 header
is used as a header model. EG, to obtain the vector mean of two pol
scans:
HADD 2 5
Please enter weight for each scan (default=1)
0.5 0.5
This might produce an unweighted vector mean of the polarization of a
star at two epochs. A vector difference is produced by using weights of
1.0 and -1.0. It is advised to use a weighted vector mean instead
of an HCOMBINE to combine scans where the polarization is very
different (the mean polarization differs by more than the error
in a single pixel). Otherwise the pixel-by-pixel weighting in
HCOMBINE could introduce error into the result.
HPRINT < qscan1 qscan2 ... >
Prints out Q, U, Err, Pol, and PA between limits entered in
WSCALE and PSCALE. If data is binned, or if there are fewer than
60 unbinned pixels between the limits, the data for each pixel or
bin are printed out. Otherwise, only the mean for the whole
scan is printed out.
HSCOP(OVER),HPLOT(OVER) < qscan > < q,u,p,t, or qu > (e,b)
Plots halfwave polarimetry results, with optional halfwave
error-dependent binning. "qSCAN" is the first scan of a Q, U, and ERR
spectrum triplet. One of the plot types q, u, p (polarization),
t (position angle), or "qu" (U vs Q) must be present. Optional "b"
indicates halfwave data is to be binned; "e" then also causes
the error bars to be plotted. If binning is requested, the program
requests "Bin (% Err), Save (Y/N), and Protected Wavelengths".
Data will be binned until the binned error is less than "BIN" %.
If "Save" is requested, the binned Q, U, and ERR spectra will also
be saved; these can be used subsequently in plots without re-
entering the binning parameters each time. The binning value
will be put in the DISK2 header and printed on the right
on polarization plots. Any wavelengths or
wavelength ranges (stated as "lam1 -lam2") requested to be
"protected" will be exempted from binning. If PEN is "DOWN",
the points will be connected. For QU plots, a circle/cross
symbol will be plotted at the origin of Q and U, if it is on the
plot. Users units for scaling are percent for q, u, p, and qu;
and degrees for t. For "QU" plots the "Q" axis is scaled by the
command XSCALE and the "U" axis by YSCALE, and the plotting
symbol is controlled by the SYMBOL command described below.
Auto-scaling functions in all modes.
E.G:
HSCOP 118 p e b
(BIN = 0.1, SAVE = Y, Protect = 3640 -3660)
Assuming 118, 119, and 120 are unbinned Q, U, and ERR spectra, this
makes a terminal plot of polarization with error bars, binned to 0.1
percent, with the Balmer Jump protected from binning, and saves binned
versions of this data in the next three DISK2 slots. Subsequent HSCOP's
with these new scans will not require the "b" option and parameters.
SYMBOL < symbol > ( wavelength symbol wavelength symbol . . . )
Requests alernate symbols for QU plots:
symbol = 0 (or blank): default filled circle.
symbol = -1 to -50: symbols 1 -50 from the plot package symbol font.
Not all of these symbols are useful (see Marilyn for the full list).
I find the following ones best:
1, 41, 18, 2, 15 give an open diamond, square, circle, triangle,
and upside-down triangle.
12, 16, 17, 21, 20 give "hatched" versions of the above.
45, 46, and 47 give large cross, x, and asterisk.
symbol = any single character (except 0). Plots that character -
anything you can enter from your keyboard (upper or lower case).
The optional "wavelength" parameter allows wavelength-dependent
symbols. The wavelengths must be in ascending order, and the
symbol entered is used between the wavelengths as entered on
the command line.
NOTES: No matter what symbol is used, the bluest point will be
plotted double-size. The symbol command line is not retained
between REDUCE sessions - it reverts to default when you exit.
EXAMPLES:
symbol 1 [ plots the character "1" ]
symbol -1 [ plots an open diamond ]
symbol a [ plots a lower-case "a" ]
symbol 3 4000 4 5000 5 6000 6 7000 7
[ plots the thousands digit of the wavelength ]
symbol [ reverts to default filled point ]
XYLOG <0,1> <0,1>
Requests linear (0) or log (1) scales for X and Y axes, respectively.
(Except for QU plots, which are linear only). Default is linear/
linear. For log plotting, all values between the minimum and
maximum values must be positive, or an error message is generated.
REMARK, ENDPL, PSCALE, WSCALE, YSCALE, CAPTION, PEN UP, PEN DOWN
Work as in the mainline REDUCE.
II) Lyot Polarimetry
DIFFSUM < scan1 > < scan2 >
Puts ( s1 - s2 ) / ( s1 + s2 ) in next available DISK2 slot. Scans
are registered first if scrunched.
LCAL < calname >
Loads Lyot polarimetric calibration file "calname.lcal",
including Lyot filter constants, modulation efficiency and wavelength
shift, PA calibration, and telescope instrumental polarization.
This file needs to be reloaded every time you start REDUCE and every
time you go to a different filter/aperture configuration. However,
lcal and hcal calibrations are stored separately, so a calibration
may be loaded for each mode simultaneously. The lcal file name you
are using is placed in the DISK2 header of each new polarimetric scan
on line 10. It is also written on the right of each polarimetric
plot. Lcal files are conventionally named (prefix)(filter)_(aper).
v2_4.lcal is the WUPPE VCF calibration for filter 4, aperture 2. EG:
LCAL v2_4
LRECAL < calname > < vscan > < vscan > ...
Recalibrates v,q,u,err scans with a new Lyot polarimetric calibration
file. "calname.lcal" is the name of the new calibration file. For each
v,q,u,err set named in the list, the calibration listed in the
header is removed, the new one applied, and a new v,q,u,err set
is created on DISK2 (with the calibration field updated). At the
end the new calibration file is loaded for later reductions.
LRECAL will properly update old reductions whenever the calibration
is updated with a new instrumental polarization or position angle
zero-point. It does not work if the calibration update changes
the polarimetric efficiency model or makes use of a new "wing"
correction. EG:
LRECAL w2_st 1 4 7
LPOL ( resi ) < diffsum sum >
Calculates Lyot v,q,u,err scan quartet for normed, scrunched Lyot
diffsum. An unnormed, scrunched spectrum sum is also required to
compute CHISQ for the result. Uses the currently loaded lcal
file; if the filter number in the header of the diffsum scan
disagrees with the lcal file, the operation is aborted. The data
is stored in binned format, with the bin edges determined by the
calibration. The results go in the next four DISK2 slots, and
a summary printout is given. In Lyot data, the error in Q and in
U and V differ by a factor of 1.41: this factor is stored in the
header as "ERFAC" on line 11. If the optional "resi" is given, a
residual of the diffsum from the computed "fringe" pattern for this
data is stored in the next DISK2 slot; it is not stored by wavelength,
but equally spaced in retardation, with 16 pixels per Q fringe for
this filter.
The following "H" commands described above also work with Lyot data,
with the "qscan" number replaced by the "vscan" number - that is,
always name the first scan number in the polarization set:
HROT
Same function. A new v,q,u,err set is stored, but the V scan is
of course unaffected by the rotation. "ERFAC" is updated accordingly.
HCOMB < vscan1 > < vscan2 > ...
Combines Lyot data reduced with the same lcal only.
HADD < vscan1 > < vscan2 > ...
Adds Lyot data reduced with the same lcal only.
HPRINT < vscan1 vscan2 ... >
Prints out binned V, Q, U, Err, Pol, and PA between WSCALE and PSCALE
limits.
HSCOP(OVER) HPLOT(OVER) < vscan > < v,q,u,p,t, or qu > (e)
Works like in the halfwave case, except 1) the additional "v"
option is available, and 2) the data is already binned.
SYMBOL, XYLOG, ENDPL, PSCALE, WSCALE, YSCALE, CAPTION, PEN UP/DOWN
Work as above.
III) POLARIZATION ANALYSIS COMMANDS
PMAKE < qscan or vscan >
Import filter polarimetry or spectropolarimetry from other
observatories into REDUCE.
Reads in an ascii mongo-like file containing wavelength,bin,q,u,err,
("halfwave" mode) or wavelength,bin,v,q,u,err ("lyot" mode).
Uses header (with name, wavecal, and scan type) from listed qscan or
vscan as a model for the header of the new scans.
Asks: 'PLEASE ENTER INPUT FILENAME'. The file must be in the current
working directory.
The input file must have the following columns:
Wave Dwave %q %u %err if using qscan or
Wave Dwave %v %q %u %err if using vscan
If Dwave=0 (it cannot be blank), the data is assumed to be continuous
and in order of increasing wavelength (e.g., spectropolarimetric
data). It is interpolated into pixels defined by the wavecal in the
header, and the error is adjusted to the new pixel width.
IF Dwave>0, bins are created centered on the effective wavelength
"Wave", with total width "Dwave" (e.g., filter data).
These bins should be non-overlapping.
All wavelengths are in Angstroms.
Sample filter files for UBVRI, and for JHKL data are:
! Visible filter polarimetry for HD62542
!
! Wav Dwav %q %u %err comment (anything out
3790 680 0.673 0.919 0.020 U here is OK)
4410 980 0.708 1.087 0.022 B
5610 890 0.878 1.087 0.022 V
6680 1000 0.839 1.096 0.017 R
7920 1000 0.816 0.998 0.023 I
! Infrared filter polarimetry for HD197770
!
! Wav Dwav %q %u %err comment
12500 3800 -0.248 -1.763 0.07 J
16000 4400 -0.138 -0.980 0.04 H
22000 4800 0.007 -0.550 0.03 K (2 Obs)
36000 7000 -0.201 -0.298 0.30 L
The UBVRI filter data is compatible with the wavecal in the header
of any scrunched PBO-2 halfwave spectropolarimetry scan,
covering 3000-9000 Angstroms.
The model header for the JHKL data would have to be edited to values
in the IR, for instance C(1) = 30000, C(2) = 50 Angstroms,
which covers 0.5-5.5 microns.
The following commands work for both unbinned halfwave data and binned
halfwave, Lyot, or filter data;
ISREMOVE < ps1 -ps2 ... >
Removes Serkowski-law interstellar polarization from
polarization scans in list ("ps" = qscan for halfwave
polarimetry) and stores results as new scans of same type in
DISK2. For each resulting "intrinsic polarization", prints mean
intrinsic pol and Chisq of fit to constant intrinsic PA.
At beginning, asks
'PLEASE ENTER PA(deg) Pmax(%) Wmax(ang) DPA(deg) K(bl=WLR)'
DPA is an optional PA rotation with wavelength. If it is specified,
PA(lam) = PA + DPA*((1 micron)/lam - (1 micron)/Wmax)
so that the specified "PA" is the value at Wmax and DPA is the slope
in deg/(inverse microns).
If K is blank, use WLR formula relating K to Wmax.
The same interstellar polarization is removed from all the polarization
scans in the list.
EXAMPLE. Scan 3 -5 contains Q,U,E for Phi Cas, a pol standard:
isrem 3
Please Enter:
PA(deg) Pmax(%) Wmax(ang) DPA(deg) K(def=WLR)
93 3.4 4700
Residual Polarization for Scan 3
Wav1 Wav2 % Q % U % Err % Pol PA
3099.0 7797.0 -0.066 0.100 0.009 0.119 61.68
Chisq par to IS Pol = 2.4
Chisq resi to Intr Pol = 2.4
Best fit PA of Intr Pol = 51.3
Q TO DISK2 POSITION 21
U TO DISK2 POSITION 22
ERROR TO DISK2 POSITION 23
ISFIT < ps1 ps2 ... >
Perform fit of Serkowski Interstellar polarization simultaneously to
scans in polarization scan list.
Asks 'PLEASE ENTER:
'ISM PA(deg) Pmax(%) Wmax(ang) DPA(deg) K(bl=WLR)'
'Vary? DPA/0 DPM/0 DWM/0 DDPA/0 DK/0=WLR'
The fit is performed by searching for the minimum CHISQ residual
as a function of the ISREM parameters. In the first line enter
your first guess for PA, Pmax, and Wmax, and (optionally) DPA and K.
If K is not given, it will be varied per the WLR relation,
which ties it to Wmax: this is advised for all PBO data.
On the second line, give a step size to vary these parameters.
It is best to give a step size which is AT LEAST TWICE the
ultimate error in the parameter: otherwise, the search may end
too soon and give unrealistically small error estimates.
Note that the program requires TWO LINES of input before it will
proceed.
The minimized fit parameter is the sum of chisq of the residual Q and U
after removal of the ISM. The fit is done in three passes, a major
search, a check search around the result of the first pass, and an
error estimate search. Iteration details are printed out at terminal
level 4 and printer level 5.
EXAMPLE: ISM fit to Phi Cas polarimetry. An hprint is done first
to get a good first guess:
hprint 3
Wav1 Wav2 % Q % U % Err % Pol PA
3099.0 7797.0 -3.344 -0.245 0.009 3.353 92.09
isfit 3
PLEASE ENTER:
ISM PA(deg) Pmax(%) Wmax(ang) DPA(deg) K(bl=WLR)
Vary? DPA/0 DPM/0 DWM/0 DDPA/0 DK/0=WLR
92 3.4 5000 0
1 0.1 200 1
[ Progress of fit iteration: takes about 1 sec/iteration. 15-25
iterations for Pmax,Wmax fit (try this first). 25 -50 iterations
for PA, Pmax, Wmax, DPA. A full PA, Pmax, Wmax, DPA, K fit would only
be used on combined WUPPE-PBO data. Note that when both PA and Pmax
are selected for variation, the actual iteration variables are
Qmax and Umax to make the search better behaved ]
Iter 1 Chisq 4.684 Vars -3.39 -0.24 5000.00 0.
Iter 2 Chisq 5.556 Vars -3.29 -0.24 5000.00 0.
Iter 3 Chisq 5.318 Vars -3.39 -0.14 5000.00 0.
Iter 4 Chisq 4.915 Vars -3.39 -0.24 5200.00 0.
Iter 5 Chisq 4.397 Vars -3.39 -0.24 5000.00 1.00
Iter 6 Chisq 4.922 Vars -3.49 -0.19 5100.00 0.50
Iter 7 Chisq 4.706 Vars -3.44 -0.31 5150.00 0.75
Iter 8 Chisq 5.409 Vars -3.32 -0.32 5075.00 0.38
[ Continue first pass . . . ]
Iter 48 Chisq 3.975 Vars -3.44 -0.32 4703.70 2.70
Iterations: 48
Chisq,Dchisq = 3.9728 0.0023
[ Second pass . . . ]
Iter 35 Chisq 3.976 Vars -3.45 -0.30 4714.76 2.78
Iterations: 35
Chisq,Dchisq = 3.9728 0.0026
[ Several more iterations around the optimal fit are used to estimate
the errors, then the answer is printed out: ]
Value Error
PA = 92.58 0.10
Pmax = 3.463 0.013
Wmax = 4695. 41.
DPA = 2.733 0.198
K = 0.773 0.
[ This may now be removed via ISREM above ]
STFIT < ps1 ps2 ... ( ; ps3 ps4 ... ; ... ) >
Attempt to determine Serkowski interstellar polarization contribution
to intrinsic polarization scans. Observations grouped by ";"
delimiter are assumed to have the same intrinsic polarization
position angle (but not necessarily the same *degree* of intrinsic
polarization). All scans are assumed to have the same interstellar
polarization.
Asks 'PLEASE ENTER:
'ISM PA(deg) Pmax(%) Wmax(ang) DPA(deg) K(bl=WLR)'
'Vary? DPA/0 DPM/0 DWM/0 DDPA/0 DK/0=WLR'
Note that the program requires TWO LINES of input before it will
proceed.
Minimized fit parameter is sum of chisq of a fit of the residuals
of each ';' group to a constant intrinsic position angle, after
removal of ISM. Iteration details are printed out at terminal
level 4 and printer level 5.
EXAMPLE: WUPPE psim scans for HD50896. Scans 120 and 135 have
intrinsic continuum polarization at PA 106 and 136, respectively,
with unpolarized emission lines. To this has been added inter-
stellar polarization of 0.473% at PA 161.46, and both were
"observed" in halfwave mode for 2000 sec. The fit attempts
to find the interstellar PA and Pmax with an assumed Wmax of
5000 Ang and no PA rotation.
In general, you should beware of overmodelling the interstellar
polarization: you will get an answer, but it may not be unique.
A Wmax fit would require at least combined WUPPE and PBO data,
since only then would the curvature of the interstellar curve be
separable from intrinsic polarization. DPA should not be used
if the intrinsic polarization has no features, since this will be
put into interstellar PA rotation. A full 5-parameter fit is
probably never justified.
stfit 120 ; 135
PLEASE ENTER:
ISM PA(deg) Pmax(%) Wmax(ang) DPA(deg) K(bl=WLR)
Vary? DPA/0 DPM/0 DWM/0 DDPA/0 DK/0=WLR
140 .4 5000
1 .1
Iter 1 Chisq 1.789 Vars 0.07 -0.39
Iter 2 Chisq 1.723 Vars 0.17 -0.39
Iter 3 Chisq 1.844 Vars 0.07 -0.29
Iter 4 Chisq 1.775 Vars 0.17 -0.49
Iter 5 Chisq 1.780 Vars 0.27 -0.49
[ ... ]
Iter 16 Chisq 1.686 Vars 0.42 -0.20
Iterations: 16
Chisq,Dchisq = 1.6858 0.0004
Iter 1 Chisq 1.688 Vars 0.38 -0.18
Iter 2 Chisq 1.689 Vars 0.48 -0.18
Iter 3 Chisq 1.701 Vars 0.38 -0.08
Value Error
PA = 167.11 11.33
Pmax = 0.421 0.166
Wmax = 5000. 0.
K = 0.830 0.
The following commands currently work only for unbinned halfwave data:
PSEP < qscan >
"Separates" a polarization scan into two pol scans with known
position angles whose sum is the original scan. Asks:
PLEASE ENTER TWO POSITION ANGLES TO SEPARATE:
The two angles must be different. The result pol scans have
all their linear polarization rotated into Q. E.G:
PSEP 137
PLEASE ENTER TWO POSITION ANGLES TO SEPARATE:
12.5 175.0
(Results to 210-212 and 213-215)
The following sequence will return the values in scan 137-139
exactly:
HROT 210
Please enter degrees to rotate
12.5
(Results to 216-218)
HROT 213
Please enter degrees to rotate
175.0
(Results to 219-221)
HADD 216 219
Please enter weight for each scan (default=1)
(Carriage return - gives default)
This is useful in cases where the polarization is the sum
of two processes whose position angles are known from some
external evidence (e.g., binary orbits or a position angle
derived from PFEW). Only the two PAs are required to
seqarate these two processes uniquely.
PFLUX < qscan fscan >
Compute "polarized flux" scans from polarization*flux.
Qscan is the scan number of the first of a q,u,err
scan set, and fscan is the number of a corresponding
flux calibrated scan (either Fnu or Flam is OK).
Output is a "polarized" flux set: q*flux, u*flux, err*flux.
Polarized flux scans may be manipulated with regular
REDUCE spectrum analysis tools (scope/plot, line analysis,
etc), or with any polar commands that can handle q,u,err
scans. For instance, hscope may be used with any of the
usual options, although bin errors and plot scales should
be specified in the appropriate flux units.
For example, an overplot of an EW Lac spectrum and polarized
flux spectrum was created as follows. The polarization
scans are in 12, 13, and 14, and the flux scan is in 15:
polar
pflux 12 15
Q *REL. FL TO DISK2 POSITION 16
U *REL. FL TO DISK2 POSITION 17
ER*REL. FL TO DISK2 POSITION 18
C NEXT, A PRELIMINARY EXPLORATION FOR SCALING:
wscale 3000. 8000.
WAVELENGTH LIMITS = 3000.00, 8000.00
hscope 16 p
retu
scope 15
C FINALLY, THE OVERPLOT:
polar
caption
TYPE CAPTION
:EW Lac 090289 :
yscale 0 1e-23
Y LIMITS = 0.000e+00, 1.000e-23
hplot 16 p
EW Lac 090289
PLOT FILE NAME = ewlacpf1.plt
retu
yscale 0 5e-22
Y LIMITS = 0.000e+00, 5.000e-22
plotover 15
EW Lac 090289
Polarized flux is most useful in looking for features in
intrinsic polarization; it will be very confusing on
mixed ISM and intrinsic polarization. With intrinsic
polarization, the polarized flux is just the spectrum of
the illuminating source as seen by the polarizing scatterer.
Any emission feature which is in the spectrum but not in the
polarized flux must be external to the scatterer.
PFEW < qscan fscan>
Performs an "equivalent width" analysis on spectral features in
the intensity and polarized flux spectrum. Qscan is the scan
number of the first member of a q,u,err halfwave triplet, and
fscan is the number of the corresponding flux calibrated scan
(either Fnu or Flam is OK). The program asks:
PLEASE ENTER CONT, LINE, CONT WAVL, EW0:
C1 C2 L1 L2 C3 C4 EW0 (CR TO QUIT)
C1, C2 and C3, C4 are wavelength limits for continuum samples to
the left and right of the line, and L1, L2 are the line limits.
EW0 is an optional equivalent width of an underlying line
which will be considered to be part of the continuum (positive
for emission, negative for absorbtion). The program then
integrates over the three intervals in the flux, q*flux, and
u*flux curves and removes the continuum from the line to give
pure line properties. This may then be repeated for other lines
on the same data until terminated by a null input line. For
example, the output below is for the H-alpha line in the EW-Lac
run described above:
pfew 12 15
PLEASE ENTER CONT, LINE, CONT WAVL, EW0:
C1 C2 L1 L2 C3 C4 EW0 (CR TO QUIT)
6100 6500 6520 6600 6620 6820
I Q U Err Pol PA
Flam Left 1.778e-11 -1.800e-13 2.008e-13 5.200e-15 2.697e-13 65.94
Flam Cntr 2.094e-11 -1.457e-13 1.607e-13 1.462e-14 2.169e-13 66.10
Flam Right 1.487e-11 -1.409e-13 1.602e-13 9.058e-15 2.133e-13 65.67
Flam Cont 1.597e-11 -1.557e-13 1.756e-13 5.963e-15 2.347e-13 65.79
Flux Line 3.878e-10 7.830e-13 -1.157e-12 1.231e-12 1.397e-12 152.04
EW Line 24.3 0.049 -0.072 0.077 0.087
% Cont -0.975 1.099 0.037 1.469 65.79
% Line 0.202 -0.298 0.318 0.360 152.04
% Cnt-Lne -1.177 1.397 0.320 1.827 65.05
The output is defined as follows. The spectral fluxes (in erg/s*cm2*Ang)
are Fc1lam and Fc2lam (the mean flux for the left and right continuum
intervals), Ftlam (the *total* mean flux (continuum+line) in the line
interval), and Fclam (the mean continuum flux under the line).
Qc1, Qc2, Qt, and Qc are the mean (flux-weighted) degree of polarization
in the Q sense for the same intervals, with a similar definition for
U. Finally, Fl, Ql, and Ul are the total flux in the line and the
degree of polarization in the line with continuum removed. Dlam is
the width of thelne interval. "Equivalent widths" based on the line
values are all normalized to the mean continuum flux. These quantities
are calculated as in the following table:
line formula Title I Q U
1=mean(pflux) "Flam Left" Fc1lam Fc1lam*Qc1 Fc1lam*Uc1
2=mean(pflux) "Flam Cntr" Ftlam Ftlam *Qt Ftlam *Ut
3=mean(pflux) "Flam Right" Fc2lam Fc2lam*Qc2 Fc2lam*Uc2
4=interp(1,3) "Flam Cont" Fclam Fclam *Qc Fclam *Uc
5=(2-4)*dlam "Flux Line" Fl Fl * Ql Fl * Ul
6=5/Fclam "EW Line" Fl/Fclam (Fl/Fclam)*Ql (Fl/Fclam)*Ul
7=4/Fclam "% Cont" Qc Uc
8=5/Fl "% Line" Ql Ul
9=7-8 "% Cnt-Lne" Qc-Ql Uc-Ul
"Flam Cont" is determined by linear interpolation between the two
continuum points. For the common case of interstellar polarization
overlying a star with intrinsically polarized continuum and unpolarized
emission lines, % Cont will be ISM + Intrinsic, % line will be ISM, and
% Cnt-Lne will be Intrinsic. With interstellar polarization
removed, % Cont and % Line are just the intrinsic polarization of
the continuum and line, and % Cnt-Lne is not useful.
PFIL < qscan > < flux-scan >
Compute synthetic filter polarimetry from halfwave spectro-
polarimetry.
Asks: " Filter(s) (.fil assumed) "
Computes filter polarization data from specified scan.
Reads in filter bandpass curve from file FILE.fil in USERDATA
directory, computes value of integrands at each diode, and
performs integral using linear interpolation and trapezoid
rule.
File.fil is in mongo format: one wavelength and one
bandpass point (relative to 1.) per ascii line.
A list of filters available is in filters.doc in USERDATA directory
PHAR
Finds the second harmonic variability component in a series of Q,U,Err
scans of a binary star with known ephemeris. For each phase observation,
the program asks,
PLEASE ENTER QSCAN PHASE (CR TO QUIT)
Respond with the DISK2 scan number of the Q scan, and the binary phase
(0 < phase < 1) of the observation. Repeat for each observation and end
the series with a carriage return. (This is most easily done as a script
which just has "phar" in the first line, followed by a two-column table
of scan numbers and phases, and finishing with a blank line.) The program
calculates a weighted least squares fit for each pixel of Q and U to,
Y(lam) = A(lam) + B(lam)*cos(2*twopi*phase) + C(lam)*sin(2*twopi*phase).
Each pixel is weighted by the individual pixel error of the observation.
The Q,U,Err result for the constant A, the cosine harmonic B, and the
sine harmonic C are then put in the next 9 disk2 positions. The CHISQ
for each pixel is calculated from the residual to the fit and put in a
CHISQ scan in a tenth disk2 position. The mean CHISQ across the spectrum
is also printed out. The expected CHISQ for a good fit is
CHISQ(expected) = 2 * (N - 3).
where N is the number of observations, there are three adjustable
parameters for each fit, and there are two independent fits (Q and U).
If the fit is good (CHISQ = expected +/- 1), then the McLean and Brown
binary reflection model may be used. For instance, the
wavelength dependence of the harmonic amplitude is related to the
wavelength dependence of the scattering modified by competing absorption,
unpolarized emission, etc. If all the amplitude is in the cosine, then
the scattering path is at the same angle as the line between the two
stars (maximum polarization at quadrature); otherwise there is a non-zero
angle between the two (eg, scattering from mass transfer plume).
MAKE2 < scan >
Creates a new DISK2 scan based on user-input data. Header and
wavelength coefficients are obtained from the header of the named
DISK2 scan. Asks:
PLEASE ENTER FILENAME OR POLY COFS:
Enter either the filename of a mongo-style text table residing in
the current working directory, or up to 6 polynomial coefficients.
The file should have two columns, wavelength (in Angstroms) and value.
The table is interpolated for the value of each pixel; pixels out of
range are given the value of the nearest wavelength. Polynomial coef-
icients are used to construct a polynomial in wavelength, where
the wavelength is in Angstroms.
POLAR COMMAND SUMMARY
I) Halfwave Polarimetry
HCAL < calname >
HRECAL < calname > < qscan > < qscan > ...
HPOL ( residual save ) < scan list >
HRED ( resi save ) < s1 list > ; < s2 list > ; < s3 list > ; < s4 list >
HROT < qscan >
HCOMB < qscan1 > < qscan2 > ...
HADD < qscan1 > < qscan2 > ...
HPRINT < qscan1 qscan2 ... >
HSCOP(OVER),HPLOT(OVER) < qscan > < q,u,p,t, or qu > (e,b)
SYMBOL < symbol > ( wavelength symbol wavelength symbol . . . )
XYLOG <0,1> <0,1>
REMARK, ENDPL, PSCALE, WSCALE, YSCALE, CAPTION, PEN UP, PEN DOWN
II) Lyot Polarimetry
DIFFSUM < scan1 > < scan2 >
LCAL < calname >
LRECAL < calname > < vscan > < vscan > ...
LPOL ( resi ) < diffsum sum >
The following "H" commands described above also work with Lyot data:
HROT
HCOMB < vscan1 > < vscan2 > ...
HADD < vscan1 > < vscan2 > ...
HPRINT < vscan1 vscan2 ... >
HSCOP(OVER) HPLOT(OVER) < vscan > < v,q,u,p,t, or qu > (e)
SYMBOL, XYLOG, ENDPL, PSCALE, WSCALE, YSCALE, CAPTION, PEN UP/DOWN
III) POLARIZATION ANALYSIS COMMANDS
PMAKE < qscan or vscan >
ISREMOVE < ps1 -ps2 ... >
ISFIT < ps1 ps2 ... >
STFIT < ps1 ps2 ... ( ; ps3 ps4 ... ; ... ) >
The following commands currently work only for unbinned halfwave data;
PSEP < qscan >
PFLUX < qscan fscan >
PFEW < qscan fscan >
PFIL < qscan fscan >
PHAR
MAKE2 < scan >