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1\documentclass[11pt]{article}
2\usepackage{a4}
3\usepackage[dvips]{graphicx}
4
5% Adjust the page size
6\addtolength{\oddsidemargin}{-0.4in}
7\addtolength{\evensidemargin}{+0.4in}
8\addtolength{\textwidth}{+0.8in}
9
10\setlength{\parindent}{0mm}
11\setlength{\parskip}{1ex}
12
13
14\title{ATNF Spectral Analysis Package\\Cookbook }
15\author{Chris Phillips}
16
17
18\newcommand{\cmd}[1]{{\tt #1}}
19
20\begin{document}
21
22\maketitle
23
24\section{Introduction}
25
26ASAP is a single dish spectral line processing package currently being
27developed by the ATNF. It is intended to process data from all ATNF
28antennas, and can probably be used for other antnnas if they can
29produce ``Single Dish FITS'' format. It is based on the AIPS++
30package.
31
32%\section{Documentation Standards}
33
34%In most of the examples in this document, it has been assumed that the
35
36\section{Installation and Running}
37
38Currently there are installations running on Linux machines at
39
40\begin{itemize}
41\item Epping - use hosts {\tt draco} or {\tt hydra}
42\item Narrabri - use host {\tt kaputar}
43\item Parkes - use host {\tt bourbon}
44\item Mopra - use host {\tt minos}
45\end{itemize}
46
47To start asap log onto one of these Linux hosts and enter
48
49\begin{verbatim}
50 > cd /my/data/directory
51 > asap
52\end{verbatim}
53
54This starts the ASAP. To quit, you need to type \verb+^+-d
55(control-d).
56
57\section{Interface}
58
59ASAP is written in C++ and python. The user interface uses the
60``ipython'' interactive shell, which is a simple interactive interface
61to python. The user does not need to understand python to use this,
62but certain aspects python affect what the user can do. The current
63interface is object oriented. In the future, we will build a
64functional (non object oriented) shell on top of this to ease
65interactive use.
66
67\subsection {Integer Indices are 0-relative}
68
69Please note, all integer indices in ASAP and iPython are {\bf 0-relative}.
70
71\subsection{Objects}
72
73The ASAP interface is based around a number of ``objects'' which the
74user deals with. Objects range from the data which have been read from
75disk, to tools used for fitting functions to the data. The following
76main objects are used :
77
78\begin{itemize}
79 \item[\cmd{scantable}] The data container (actual spectra and header
80 information)
81 \item[\cmd{fitter}] A tool used to fit functions to the spectral data
82 \item[\cmd{plotter}] A tool used to plot the spectral line data
83 \item[\cmd{reader}] A tool which can be used to read data from disks
84 into a scantable object.
85\end{itemize}
86
87There can be many objects of the same type. Each object is referred to
88by a variable name made by the user. The name of this variable is not
89important and can be set to whatever the user prefers (ie ``s'' and
90``ParkesHOH-20052002'' are equivalent). However, having a simple and
91consistent naming convention will help you a lot.
92
93\subsection{Member Functions (functions)}
94
95Following the object oriented approach, objects have associated
96``member functions'' which can either be used to modify the data in
97some way or change global properties of the object. In this document
98member functions will be referred to simply as functions. From the
99command line, the user can execute these functions using the syntax:
100\begin{verbatim}
101 ASAP> out = object.function(arguments)
102\end{verbatim}
103
104Where \cmd{out} is the name of the returned variable (could be a new
105scantable object, or a vector of data, or a status return),
106\cmd{object} is the object variable name (set by the user),
107\cmd{function} is the name of the member function and \cmd{arguments}
108is a list of arguments to the function. The arguments can be provided
109either though position or \cmd{name=}. A mix of the two can be used.
110E.g.
111
112\begin{verbatim}
113 ASAP> av = scans(msk,weight='tsys')
114 ASAP> av = scans(mask=msk,weight='tsys')
115 ASAP> av = scans(msk,True)
116 ASAP> scans.polybaseline(mask=msk, order=0, insitu=True)
117 ASAP> scans.polybaseline(msk,0,True)
118 ASAP> scans.polybaseline(mask, insitu=True)
119\end{verbatim}
120
121\subsection{Global Functions}
122
123It does not make sense to implement some functions as member
124functions, typically functions which operate on more than one
125scantable (e.g. time averaging of many scans). These functions will
126always be referred to as global functions.
127
128\subsection{Interactive environment}
129
130ipython has a number of useful interactive features and a few things to be aware
131of for the new user.
132
133\subsubsection{String completion}
134
135Tab completion is enabled for all function names. If you type the
136first few letters of a function name, then type {\tt <TAB>} the
137function name will be auto completed if it is un-ambiguous, or a list
138of possibilities will be given. Auto-completion works for the user
139object names as well as function names. It does not work for
140filenames, nor for function arguments.
141
142Example
143\begin{verbatim}
144 ASAP> scans = scantable('MyData.rpf')
145 ASAP> scans.se<TAB>
146scans.set_cursor scans.set_freqframe scans.set_unit scans.setpol
147scans.set_doppler scans.set_instrument scans.setbeam
148scans.set_fluxunit scans.set_restfreqs scans.setif
149 ASAP> scans.set_in<TAB>
150 ASAP> scans.set_instrument
151\end{verbatim}
152
153\subsubsection{Leading Spaces}
154
155Python uses leading space to mark blocks of code. This means that it
156you start a command line with a space, the command generally will
157fail with an syntax error.
158
159\subsubsection{Unix Interaction}
160
161Basic unix shell commands (\cmd{pwd}, \cmd{ls}, \cmd{cd} etc) can be
162issued from within ASAP. This allows the user to do things like look
163at files in the current directory. The shell command ``\cmd{cd}''
164works within ASAP, allowing the user to change between data
165directories. Unix programs cannot be run this way, but the shell
166escape ``$!$'' can be used to run arbitrary programs. E.g.
167
168\begin{verbatim}
169 ASAP> pwd
170 ASAP> ls
171 ASAP> ! mozilla&
172\end{verbatim}
173
174\subsection{Help}
175
176ASAP has built in help for all functions. To get a list of functions type:
177
178\begin{verbatim}
179 ASAP> commands
180\end{verbatim}
181
182To get help on specific functions, the built in help needs to be given
183the object and function name. E.g.
184
185\begin{verbatim}
186 ASAP> help scantable.get_scan
187 ASAP> help scantable.stats
188 ASAP> help plotter.plot
189 ASAP> help fitter.plot
190
191 ASAP> scans = scantable('mydata.asap')
192 ASAP> help scans.get_scan # Same as above
193\end{verbatim}
194
195Global functions just need their name
196
197\begin{verbatim}
198 ASAP> help average_time
199\end{verbatim}
200
201Note that if you just type \cmd{help} the internal ipython help is
202invoked, which is probably {\em not} what you want. Type \verb+^+-d
203(control-d) to escape from this.
204
205\subsection{.asaprc}
206
207ASAP use an \cmd{.asaprc} file to control the user's preference of
208default values for various functions arguments. This includes the
209defaults for arguments such as \cmd{insitu}, scantable \cmd{freqframe}
210and the plotters \cmd{set\_mode} values. The help on individual
211functions says which arguments can be set default values from the
212\cmd{.asaprc} file. To get a sample contents for the \cmd{.asaprc}
213file use then command \cmd{list\_rcparameters}.
214
215Common values include:
216\begin{verbatim}
217 # apply operations on the input scantable or return new one
218 insitu : False
219
220 # default ouput format when saving scantable
221 scantable.save : 'ASAP'
222
223
224 # default frequency frame to set when function
225 # scantable.set_freqframe is called
226 scantable.freqframe : 'LSRK'
227
228 # auto averaging on read
229 scantable.autoaverage : True
230\end{verbatim}
231
232\section{Scantables}
233
234\subsection {Description}
235
236\subsubsection {Basic Structure}
237
238ASAP data handling works on objects called scantables. A scantable
239holds your data, and also provides functions to operate
240upon it.
241
242The building block of a scantable is an integration, which is a single
243row of a scantable. Each row contains spectra for each beam, IF and
244polarisation. For example Parkes multibeam data would contain many
245beams, one IF and 2-4 polarisations, while the new Mopra 8-GHz
246filterbank will eventually produce one beam, many IFs, and 2-4
247polarisations.
248
249A collection of sequential integrations (rows) for one source is termed
250a scan (and each scan has a unique numeric identifier, the ScanID). A
251scantable is then a collection of one or more scans. If you have
252scan-averaged your data in time, then each scan would hold just one
253(averaged) integration.
254
255Many of the functions which work on scantables can either return a
256new scantable with modified data or change the scantable insitu. Which
257method is used depends on the users preference. The default can be
258changed via the {\tt .asaprc} resource file.
259
260\subsubsection {Contents}
261
262A scantable has header information and data (a scantable is actually an AIPS++
263Table and it is stored in Memory when you are manipulating it with ASAP.
264You can store it to disk and then browse it with the AIPS++
265Table browser if you know how to do that !).
266
267The data are stored in columns (the length of a column is the number of
268rows/integrations of course).
269
270Two important columns are those that describe the frequency setup. We mention
271them explicitly here because you need to be able to understand the presentation
272of the frequency information and possibly how to manipulate it.
273
274These columns are called FreqID and RestFreqID. They contain indices, for
275each IF, pointing into tables with all of the frequency information for that
276integration. More on these below when we discuss the \cmd{summary} function
277in the next subsection.
278
279There are of course many other columns which contain the actual spectra,
280the flags, the Tsys, the source names and so on, but those are a little
281more transparently handled.
282
283\subsection{Management}
284
285During processing it is possible to create a large number of scan
286tables. These all consume memory, so it is best to periodically remove
287unneeded scan tables. Use \cmd{list\_scans} to print a list of all
288scantables and \cmd{del} to remove unneeded ones.
289
290Example:
291
292\begin{verbatim}
293 ASAP> list_scans
294 The user created scantables are:
295 ['s', 'scans', 'av', 's2', 'ss']
296
297 ASAP> del s2
298 ASAP> del ss
299\end{verbatim}
300
301There is also a function \cmd{summary} to list a summary of the scantable.
302You will find this very useful.
303
304Example:
305
306\begin{verbatim}
307 ASAP> scans = scantable('MyData.rpf')
308 ASAP> scans.summary() # Brief listing
309 ASAP> scans.summary(verbose=True) # Include frequency information
310
311 # Equivalent to brief summary function call
312 ASAP> print scan
313\end{verbatim}
314
315Most of what the \cmd{summary} function prints out is obvious. However,
316it also prints out the FreqIDs and RestFreqIDs to which we alluded above.
317These are the last column of the listing.
318
319The summary function gives you a scan-based summary. So it lists all of
320the FreqIDs and RestFreqIDs that it encountered for each scan. If you'd
321like to see what each FreqID actually means, then set the verbose
322argument to True and the frequency table will be listed at the end.
323FreqID of 3 say, refers to the fourth row of the frequency table (ASAP
324is 0-relative). The list of rest frequencies, to which the RestFreqIDs
325refer, is always listed.
326
327%You can copy one scantable to another with the \cmd{copy} function.
328
329%Example:
330
331%\begin{verbatim}
332% ASAP> scans = scantable('MyData.rpf')
333% ASAP> scan2 = scans.copy()
334%\end{verbatim}
335
336\subsection{State}
337
338Each scantable contains "state"; these are properties applying to all
339of the data in the scantable.
340
341Examples are the selection of beam, IF and polarisation, spectral unit
342(e.g. km/s) frequency reference frame (e.g. BARY) and velocity Doppler
343type (e.g. RADIO).
344
345\subsubsection{Units, Doppler and Frequency Reference Frame}
346
347The information describing the frequency setup for each integration
348is stored fundamentally in frequency in the reference frame
349of observation (E.g. TOPO).
350
351When required, this is converted to the desired reference frame
352(e.g. LSRK), Doppler (e.g. OPTICAL) and unit (e.g. km/s) on-the-fly.
353This is important, for example, when you are displaying the data or
354fitting to it.
355
356For units, the user has the choice of frequency, velocity or channel.
357The \cmd{set\_unit} function is used to set the current unit for a
358scantable. All functions will (where relevant) work with the selected
359unit until this changes. This is mainly important for fitting (the fits
360can be computed in any of these units), plotting and mask creation.
361
362The velocity definition can be changed with the \cmd{set\_doppler}
363function, and the frequency reference frame can be changed with the
364\cmd{set\_freqframe} function.
365
366Example usage:
367
368\begin{verbatim}
369 ASAP> scans = scantable('2004-11-23_1841-P484.rpf') # Read in the data
370 ASAP> scans.set_freqframe('LSRK') # Use the LSR velocity frame
371 ASAP> scans.set_unit('km/s') # Use velocity for plots etc from now on
372 ASAP> scans.set_doppler('OPTICAL') # Use the optical velocity convention
373 ASAP> scans.set_unit('MHz') # Use frequency in MHz from now on
374\end{verbatim}
375
376
377\subsubsection{Rest Frequency}
378
379ASAP reads the line rest frequency from the RPFITS file when reading
380the data. The values stored in the RPFITS file are not always correct
381and so there is a function \cmd{set\_restfreq} to set the rest frequencies.
382
383For each integration, there is a rest-frequency per IF (the rest
384frequencies are just stored as a list with an index into them).
385There are a few ways to set the rest frequencies with this function.
386
387If you specify just one rest frequency, then it is selected for the
388specified source and IF and added to the list of rest frequencies.
389
390\begin{verbatim}
391 # Select for specified source/IF
392 ASAP> scans.set_restfreqs(freqs=1.667359e9, source='NGC253', theif=0)
393
394 # Select for all sources and IFs
395 ASAP> scans.set_restfreqs(freqs=1.667359e9)
396\end{verbatim}
397
398
399If you specify a list of frequencies, then it must be of length the
400number of IFs. Regardless of the source, the rest frequency will be set
401for each IF to the corresponding value in the provided list. The
402internally stored list of rest frequencies will be replaced by this
403list.
404
405
406\begin{verbatim}
407 # Select for specified source/IF
408 ASAP> scans.set_restfreqs(freqs=1.667359e9, source='NGC253', theif=0)
409
410 # Select for all sources and IFs
411 ASAP> scans.set_restfreqs(freqs=1.667359e9)
412\end{verbatim}
413
414
415In both of the above modes, you can also specify the rest frequencies via
416names in a known list rather than by their values.
417
418Examples:
419
420\begin{verbatim}
421 ASAP> scans.lines() # Print list of known lines
422 ASAP> scans.set_restfreqs(lines=['OH1665','OH1667'])
423\end{verbatim}
424
425
426
427\subsection{Data Selection}
428
429Data selection is currently fairly limited. This will be improved in
430the future.
431
432
433\subsubsection{Cursor}
434
435Generally the user will want to run functions on all rows in a
436scantable. This allows very fast reduction of data. There are situations
437when functions should only operate on specific elements of the spectra. This
438is handled by the scantable cursor, which allows the user to select a
439single beam, IF and polarisation combination.
440
441Example :
442
443\begin{verbatim}
444 ASAP> scans.set_cursor(0,2,1) # beam, IF, pol
445 ASAP> scans.smooth(allaxes=F) # in situ by default or .aipsrc
446\end{verbatim}
447
448\subsubsection{Row number}
449
450Most functions work on all rows of a scan table. Exceptions are the
451fitter and plotter. If you wish to only operate on a selected set of
452scantable rows, use the \cmd{get\_scan} function to copy the rows into
453a new scantable.
454
455\subsubsection{Allaxes}
456
457Many functions have an \cmd{allaxes} option which controls whether the
458function will operate on all elements within a scantable row, or just
459those selected with the current cursor. The default is taken from the
460users {\tt .asaprc} file.
461
462\subsubsection{Masks}
463
464Many tasks (fitting, baseline subtraction, statistics etc) should only
465be run on range of channels. Depending on the current ``unit'' setting
466this range is set directly as channels, velocity or frequency
467ranges. Internally these are converted into a simple boolean mask for
468each channel of the abscissa. This means that if the unit setting is
469later changed, previously created mask are still valid. (This is not
470true for functions which change the shape or shift the frequency axis).
471You create masks with the function \cmd{create\_mask} and this specified
472the channels to be included in the selection.
473
474When setting the mask in velocity, the conversion from velocity
475to channels is based on the current cursor setting, selected row and
476selected frequency reference frame.
477
478Example :
479\begin{verbatim}
480
481 # Select channel range for baselining
482 ASAP> scans.set_unit('channels')
483 ASAP> msk = scans.create_mask([100,400],[600,800])
484
485 # Select velocity range for fitting
486 ASAP> scans.set_unit('km/s')
487 ASAP> msk = scans.create_mask([-30,-10])
488\end{verbatim}
489
490Sometimes it is more convenient to specify the channels to be
491excluded, rather included. You can do this with the ``invert''
492argument.
493
494Example :
495\begin{verbatim}
496 ASAP> scans.set_unit('channels')
497 ASAP> msk = scans.create_mask([0,100],[900-1023], invert=True)
498\end{verbatim}
499
500By default \cmd{create\_mask} uses the frequency setup of the first row
501to convert velocities into a channel mask. If the rows in the data
502cover different velocity ranges, the scantable row to use should be
503specified:
504
505\begin{verbatim}
506 ASAP> scans.set_unit('km/s')
507 ASAP> msk = q.create_mask([-30,-10], row=5)
508\end{verbatim}
509
510Because the mask is stored in a simple python variable, the users is
511able to combine masks using simple arithmetic. To create a mask
512excluding the edge channels, a strong maser feature and a birdie in
513the middle of the band:
514
515\begin{verbatim}
516 ASAP> scans.set_unit('channels')
517 ASAP> msk1 = q.create_mask([0,100],[511,511],[900,1023],invert=True)
518 ASAP> scans.set_unit('km/s')
519 ASAP> msk2 = q.create_mask([-20,-10],invert=True)
520
521 ASAP> mask = msk1 and msk2
522\end{verbatim}
523
524
525\section{Data Input}
526
527Data can be loaded in one of two ways; using the reader object or via
528the scantable constructor. The scantable method is simpler but the
529reader allow the user more control on what is read.
530
531\subsection{Scantable constructor}
532
533This loads all of the data from filename into the scantable object scans
534and averages all the data within a scan (i.e. the resulting scantable
535will have one row per scan). The recognised input file formats are
536RPFITS, SDFITS (singledish fits), ASAP's scantable format and aips++
537MeasurementSet2 format.
538
539
540Example usage:
541
542\begin{verbatim}
543 ASAP> scan = scantable('2004-11-23_1841-P484.rpf')
544
545 # Don't scan average the data
546 ASAP> scan = scantable('2004-11-23_1841-P484.rpf', average=False)
547\end{verbatim}
548
549
550\subsection{Reader object}
551
552For more control when reading data into ASAP, the reader object should
553be used. This has the option of only reading in a range of integrations
554and does not perform any scan averaging of the data, allowing analysis
555of the individual integrations. Note that due to limitation of the
556RPFITS library, only one reader object can be open at one time reading
557RPFITS files. To read multiple RPFITS files, the old reader must be
558destroyed before the new file is opened. However, multiple readers can
559be created and attached to SDFITS files.
560
561
562Example usage:
563
564\begin{verbatim}
565 ASAP> r = reader('2003-03-16_082048_t0002.rpf')
566 ASAP> r.summary
567 ASAP> scan = r.read()
568 ASAP> s = r.read(range(100)) # To read in the first 100 integrations
569 ASAP> del r
570\end{verbatim}
571
572\section{Basic Processing}
573
574In the following section, a simple data reduction to form a quotient
575spectrum of a single source is followed. It has been assume that the
576\cmd{.asaprc} file has {\em not} been used to change the \cmd{insitu}
577default value from \cmd{True}.
578
579%\subsection{Editing}
580
581%How and when?
582
583\subsection{Separate reference and source observations}
584
585Most data from ATNF observatories distinguishes on and off source data
586using the file name. This makes it easy to create two scantables with
587the source and reference data. As long as there was exactly one
588reference observation for each on source observation for following
589method will work.
590
591For Mopra and Parkes data:
592\begin{verbatim}
593 ASAP> r = scans.get_scan('*_R')
594 ASAP> s = scans.get_scan('*_S')
595\end{verbatim}
596
597For Tidbinbilla data
598\begin{verbatim}
599 ASAP> r = scans.get_scan('*_[ew]')
600 ASAP> s = scans.get_scan('*_[^ew]')
601\end{verbatim}
602
603\subsection{Make the quotient spectra}
604
605Use the quotient function
606
607\begin{verbatim}
608 ASAP> q = s.quotient(r)
609\end{verbatim}
610
611This uses the rows in scantable \cmd{r} as reference spectra for the
612rows in scantable \cmd{s}. Scantable \cmd{r} must have either 1 row
613(which is applied to all rows in \cmd{s}) or both scantables must have
614the same number of rows. By default the quotient spectra is calculated
615to preserve continuum emission. If you wish to remove the continuum
616contribution, use the \cmd{preserve} argument:
617
618\begin{verbatim}
619 ASAP> q = s.quotient(r, preserve=True)
620\end{verbatim}
621
622\subsection{Time average separate scans}
623
624If you have observed the source with multiple source/reference cycles you
625will want to scan-average the quotient spectra together.
626
627\begin{verbatim}
628 ASAP> av = average_time(q)
629\end{verbatim}
630
631If for some you want to average multiple sets of scantables together
632you can:
633
634\begin{verbatim}
635 ASAP> av = average_time(q1, q2, q3)
636\end{verbatim}
637
638The default is to use integration time weighting. The alternative is
639to use none, variance , Tsys weighting or Tsys \& integration time.
640
641\begin{verbatim}
642 ASAP> av = average_time(q, weight='tintsys')
643\end{verbatim}
644
645To use variance based weighting, you need to supply a mask saying which
646channel range you want it to calculate the variance from.
647
648\begin{verbatim}
649 ASAP> msk = scans.create_mask([200,400],[600,800])
650 ASAP> av = average_time(scans, mask=msk, weight='var')
651\end{verbatim}
652
653\subsection{Baseline fitting}
654
655To make a baseline fit, you must first create a mask of channels to
656use in the baseline fit.
657
658\begin{verbatim}
659 ASAP> msk = scans.create_mask([100,400],[600,900])
660 ASAP> scans.poly_baseline(msk, 1)
661\end{verbatim}
662
663This will fit a first order polynomial to the selected channels and subtract
664this polynomial from the full spectra.
665
666\subsubsection{Auto-baselining}
667
668The function \cmd{auto\_poly\_baseline} can be used to automatically
669baseline your data with out having to specify channel ranges for
670the line free data. It automatically figures out the line-free
671emission and fits a polynomial baseline to that data. The user can use
672masks to fix the range of channels or velocity range for the fit as
673well as mark the band edge as invalid.
674
675Simple example
676
677\begin{verbatim}
678 ASAP> scans.auto_poly_baseline(order=2,threshold=5)
679\end{verbatim}
680
681\cmd{order} is the polynomial order for the fit. \cmd{threshold} is
682the SNR threshold to use to deliminate line emission from
683signal. Generally the value of threshold is not too critical, however
684making this too large will compromise the fit (as it will include
685strong line features) and making it too small will mean it cannot find
686enough line free channels.
687
688
689Other examples:
690
691\begin{verbatim}
692 # Don't try and fit the edge of the bandpass which is noisier
693 ASAP> scans.auto_poly_baseline(edge=(500,450),order=3,threshold=3)
694
695 # Only fit a given region around the line
696 ASAP> scans.set_unit('km/s')
697 ASAP> msk = scans.create_mask((-60,-20))
698 ASAP> scans.auto_poly_baseline(mask=msk,order=3,threshold=3)
699
700\end{verbatim}
701
702\subsection{Average the polarisations}
703
704If you are just interested in the highest SNR for total intensity you
705will want to average the parallel polarisations together.
706
707\begin{verbatim}
708 ASAP> scans.average_pol()
709\end{verbatim}
710
711\subsection{Calibration}
712
713For most uses, calibration happens transparently as the input data
714contains the Tsys measurements taken during observations. The nominal
715``Tsys'' values may be in Kelvin or Jansky. The user may wish to
716supply a Tsys correction or apply gain-elevation and opacity
717corrections.
718
719\subsubsection{Brightness Units}
720
721RPFITS files to not contain any information as to whether the telescope
722calibration was in units of Kelvin or Janskys. On reading the data a
723default value is set depending on the telescope and frequency of
724observation. If this default is incorrect (you can see it in the
725listing from the \cmd{summary} function) the user can either override
726this value on reading the data or later. E.g:
727
728\begin{verbatim}
729 ASAP> scans = scantable(('2004-11-23_1841-P484.rpf', unit='Jy')
730 # Or in two steps
731 ASAP> scans = scantable(('2004-11-23_1841-P484.rpf')
732 ASAP> scans.set_fluxunit('Jy)
733\end{verbatim}
734
735\subsubsection{Tsys scaling}
736
737Sometime the nominal Tsys measurement at the telescope is wrong due to
738an incorrect noise diode calibration. This can easily be corrected for
739with the scale function. By default, \cmd{scale} only scans the
740spectra and not the corresponding Tsys.
741
742\begin{verbatim}
743 ASAP> scans.scale(1.05, tsys=True)
744\end{verbatim}
745
746\subsubsection{Unit Conversion}
747
748To convert measurements in Kelvin to Jy (and vice versa) the global
749function \cmd{convert\_flux} is needed. This converts and scales the data
750from K to Jy or vice-versa depending on what the current brightness unit is
751set to. The function knows the basic parameters for some frequencies
752and telescopes, but the user may need to supply the aperture
753efficiency, telescope diameter or the Jy/K factor.
754
755\begin{verbatim}
756 ASAP> scans.convert_flux # If efficency known
757 ASAP> scans.convert_flux(eta=0.48) # If telescope diameter known
758 ASAP> scans.convert_flux(eta=0.48,d=35) # Unknown telescope
759 ASAP> scans.convert_flux(jypk=15) # Alternative
760\end{verbatim}
761
762\subsubsection{Gain-Elevation and Opacity Corrections}
763
764As higher frequencies (particularly $>$20~GHz) it is important to make
765corrections for atmospheric opacity and gain-elevation effects.
766
767Gain-elevation curves for some telescopes and frequencies are known to
768ASAP (currently only for Tidbinbilla at 20~GHz). In these cases making
769gain-corrections is simple. If the gain curve for your data is not
770known, the user can supply either a gain polynomial or text file
771tabulating gain factors at a range of elevations (see \cmd{help
772scantable.gain\_el}).
773
774Examples:
775
776\begin{verbatim}
777 ASAP> scans.gain_el() # If gain table known
778 ASAP> scans.gain_el(poly=[3.58788e-1,2.87243e-2,-3.219093e-4])
779\end{verbatim}
780
781Opacity corrections can be made with the global function
782\cmd{opacity}. This should work on all telescopes as long as a
783measurement of the opacity factor was made during the observation.
784
785\begin{verbatim}
786 ASAP> scans.opacity(0.083)
787\end{verbatim}
788
789Note that at 3~mm Mopra uses a paddle wheel for Tsys calibration,
790which takes opacity effects into account (to first order). ASAP
791opacity corrections should not be used for Mopra 3-mm data.
792
793\subsection{Frequency Frame Alignment}
794
795When time averaging a series of scans together, it is possible that
796the velocity scales are not exactly aligned. This may be for many
797reasons such as not Doppler tracking the observations, errors in the
798Doppler tracking etc. This mostly affects very long integrations or
799integrations averaged together from different days. Before averaging
800such data together, they should be frequency aligned using
801\cmd{freq\_align}.
802
803E.g.:
804
805\begin{verbatim}
806 ASAP> scans.freq_align()
807 ASAP> av = average_time(scans)
808\end{verbatim}
809
810\cmd{freq\_align} has two modes of operations controlled by the
811\cmd{perif} argument. By default it will align each source and freqid
812separately. This is needed for scan tables containing multiple
813sources. However if scan-based Doppler tracking has been made at the observatory,
814each row will have a different freqid. In these cases run with
815\cmd{perif=True} and all rows of a source will be aligned to the same
816frame. In general \cmd{perif=True} will be needed for most
817observations as Doppler tracking of some form is made at Parkes, Tid
818and Mopra.
819
820\begin{verbatim}
821 ASAP> scans.freq_align(perif=True)
822\end{verbatim}
823
824To average together data taken on different days, which are in
825different scantables, each scantable must aligned to a common
826reference time then the scantables averaged. The simplest way of
827doing this is to allow ASAP to choose the reference time for the first
828scantable then using this time for the subsequent scantables.
829
830\begin{verbatim}
831 ASAP> scans1.freq_align() # Copy the refeference Epoch from the output
832 ASAP> scans2.freq_align(reftime='2004/11/23/18:43:35')
833 ASAP> scans3.freq_align(reftime='2004/11/23/18:43:35')
834 ASAP> av = average_time(scans1, scans2, scans3)
835\end{verbatim}
836
837\section{Scantable manipulation}
838
839While it is very useful to have many independent sources within one
840scantable, it is often inconvenient for data processing. The
841\cmd{get\_scan} function can be used to create a new scantable with a
842selection of scans from a scantable. The selection can either be on
843the source name, with simple wildcard matching or set of scan ids.
844
845For example:
846
847\begin{verbatim}
848 ASAP> ss = scans.get_scan(10) # Get the 11th scan (zero based)
849 ASAP> ss = scans.get_scan(range(10)) # Get the first 10 scans
850 ASAP> ss = scans.get_scan(range(10,20)) # Get the next 10 scans
851 ASAP> ss = scans.get_scan([2,4,6,8,10]) # Get a selection of scans
852
853 ASAP> ss = scans.get_scan('345p407') # Get a specific source
854 ASAP> ss = scans.get_scan('345*') # Get a few sources
855
856 ASAP> r = scans.get_scan('*_R') # Get all reference sources (Parkes/Mopra)
857 ASAP> s = scans.get_scan('*_S') # Get all program sources (Parkes/Mopra)
858 ASAP> r = scans.get_scan('*_[ew]') # Get all reference sources (Tid)
859 ASAP> s = scans.get_scan('*_[^ew]') # Get all program sources (Tid)
860
861\end{verbatim}
862
863To copy a scantable the following does not work:
864
865\begin{verbatim}
866 ASAP> ss = scans
867\end{verbatim}
868
869as this just creates a reference to the original scantable. Any
870changes made to \cmd{ss} are also seen in \cmd{scans}. To duplicate a
871scantable, use the copy function.
872
873\begin{verbatim}
874 ASAP> ss = scans.copy
875\end{verbatim}
876
877\section{Data Output}
878
879ASAP can save scantables in a variety of formats, suitable for reading
880into other packages. The formats are:
881
882\begin{itemize}
883\item[ASAP] This is the internal format used for ASAP. It is the only
884 format that allows the user to restore the data, fits etc. without
885 loosing any information. As mentioned before, the ASAP scantable is
886 an AIPS++ Table (a memory-based table). This function just converts
887 it to a disk-based Table. You can the access that Table with the
888 AIPS++ Table browser or any other AIPS++ tool.
889
890\item[SDFITS] The Single Dish FITS format. This format was designed to
891 for interchange between packages, but few packages actually can read
892 it.
893
894\item[FITS] This uses simple ``image'' fits to save the data, each row
895 being written to a separate fits file. This format is suitable for
896 importing the data into CLASS.
897
898\item[ASCII] A simple text based format suitable for the user to
899processing using Perl or, Python, gnuplot etc.
900
901\item[MS2] Saves the data in an aips++ MeasurementSet V2 format.
902You can also access this with the Table browser and other AIPS++
903tools.
904
905\end{itemize}
906
907The default output format can be set in the users {\tt .asaprc} file.
908Typical usages are:
909
910\begin{verbatim}
911 ASAP> scans.save('myscans') # Save in default format
912 ASAP> scans.save('myscans', 'FITS') # Save as FITS for exporting into CLASS
913
914 ASAP> scans.save('myscans', stokes=True) # Convert raw polarisations into Stokes
915 ASAP> scans.save('myscans', overwrite=True) # Overwrite an existing file
916\end{verbatim}
917
918
919\section{Plotter}
920
921Scantable spectra can be plotter at any time. An asapplotter object is
922used for plotting, meaning multiple plot windows can be active at the
923same time. On start up a default asapplotter object is created called
924``plotter''. This would normally be used for standard plotting.
925
926The plotter, optionally, will run in a multipanel mode and contain
927multiple plots per panel. The user must tell the plotter how they want
928the data distributed. This is done using the set\_mode function. The
929default can be set in the users {\tt .asaprc} file. The units (and frame
930etc) of the abscissa will be whatever has previously been set by
931\cmd{set\_unit}, \cmd{set\_freqframe} etc.
932
933Typical plotter usage would be:
934
935\begin{verbatim}
936 ASAP> scans.set_unit('km/s')
937 ASAP> plotter.set_mode(stacking='p',panelling='t')
938 ASAP> plotter.plot(scans)
939\end{verbatim}
940
941This will plot multiple polarisation within each plot panel and each
942scan row in a separate panel.
943
944Other possibilities include:
945
946\begin{verbatim}
947 # Plot multiple IFs per panel
948 ASAP> plotter.set_mode(stacking='i',panelling='t')
949
950 # Plot multiple beams per panel
951 ASAP> plotter.set_mode(stacking='b',panelling='t')
952
953 # Plot one IF per panel, time stacked
954 ASAP> plotter.set_mode('t', 'i')
955
956 # Plot each scan in a seperate panel
957 ASAP> plotter.set_mode('t', 's')
958
959\end{verbatim}
960
961\subsection{Plot Selection}
962\label{sec:plotter_cursor}
963
964The plotter can plot up to 25 panels and stacked spectra per
965panel. If you have data larger than this (or for your own sanity) you
966need to select a subset of this data. This is particularly true for
967multibeam or multi IF data. The plotter \cmd{set\_cursor} function is
968used to select a subset of the data. The arguments \cmd{row},
969\cmd{beam} and \cmd{IF} all accept a vector of indices corresponding
970to row, beam or IF selection. Only the selected data will be plotted.
971To select on polarisation, see section~\ref{sec:polplot}.
972
973Examples:
974
975\begin{verbatim}
976 # Select second IF
977 ASAP> plotter.set_cursor(IF=[1])
978
979 # Select first 4 beams
980 ASAP> plotter.set_cursor(beam=[0,1,2,3])
981
982 # Select a few rows
983 ASAP> plotter.set_cursor(row=[2,4,6,10])
984
985 # Multiple selection
986 ASAP> plotter.set_cursor(IF=[1], beam=[0,2], row=range(10))
987\end{verbatim}
988
989Note that the plotter cursor selection is independent of the scantable
990cursor.
991
992\subsection{Plot Control}
993
994The plotter window has a row of buttons on the lower left. These can
995be used to control the plotter (mostly for zooming the individual
996plots). From left to right:
997
998\begin{itemize}
999
1000\item[Home] This will unzoom the plots to the original zoom factor
1001
1002\item[Plot history] (left and right arrow). The plotter keeps a
1003history of zoom settings. The left arrow sets the plot zoom to the
1004previous value. The right arrow returns back again. This allows you,
1005for example, to zoom in on one feature then return the plot to how it
1006was previously.
1007
1008\item[Pan] (The Cross) This sets the cursor to pan, or scroll mode
1009 allowing you to shift the plot within the window. Useful when
1010 zoomed in on a feature.
1011
1012\item[Zoom] (the letter with the magnifying glass) lets you draw a
1013 rectangle around a region of interest then zooms in on that
1014 region. Use the plot history to unzoom again.
1015
1016\item[Save] (floppy disk). Save the plot as a postscript or .png file
1017
1018\end{itemize}
1019
1020\subsection{Other control}
1021
1022The plotter has a number of functions to describe the layout of the
1023plot. These include \cmd{set\_legend}, \cmd{set\_layout} and \cmd{set\_title}.
1024
1025To set the exact velocity or channel range to be plotted use the
1026\cmd{set\_range} function. To reset to the default value, call
1027\cmd{set\_range} with no arguments. E.g.
1028
1029\begin{verbatim}
1030 ASAP> scans.set_unit('km/s')
1031 ASAP> plotter.plot(scans)
1032 ASAP> plotter.set_range(-150,-50)
1033 ASAP> plotter.set_range() # To reset
1034\end{verbatim}
1035
1036Both the range of the ``x'' and ``y'' axis can be set at once, if desired:
1037
1038\begin{verbatim}
1039 ASAP> plotter.set_range(-10,30,-1,6.6)
1040\end{verbatim}
1041
1042To save a hardcopy of the current plot, use the save function, e.g.
1043
1044\begin{verbatim}
1045 ASAP> plotter.save('myplot.ps')
1046\end{verbatim}
1047
1048\section{Fitting}
1049
1050Currently multicomponent Gaussian function is available. This is done
1051by creating a fitting object, setting up the fit and actually fitting
1052the data. Fitting can either be done on a single scantable row/cursor
1053selection or on an entire scantable using the \cmd{auto\_fit} function.
1054
1055\begin{verbatim}
1056 ASAP> f = fitter()
1057 ASAP> f.set_function(gauss=2) # Fit two Gaussians
1058 ASAP> f.set_scan(scans)
1059 ASAP> scans.set_cursor(0,0,1) # Fit the second polarisation
1060 ASAP> scans.set_unit('km/s') # Make fit in velocity units
1061 ASAP> f.fit(1) # Run the fit on the second row in the table
1062 ASAP> f.plot() # Show fit in a plot window
1063 ASAP> f.get_parameters() # Return the fit paramaters
1064\end{verbatim}
1065
1066This auto-guesses the initial values of the fit and works well for data
1067without extra confusing features. Note that the fit is performed in
1068whatever unit the abscissa is set to.
1069
1070If you want to confine the fitting to a smaller range (e.g. to avoid
1071band edge effects or RFI you must set a mask.
1072
1073\begin{verbatim}
1074 ASAP> f = fitter()
1075 ASAP> f.set_function(gauss=2)
1076 ASAP> scans.set_unit('km/s') # Set the mask in channel units
1077 ASAP> msk = s.create_mask([1800,2200])
1078 ASAP> scans.set_unit('km/s') # Make fit in velocity units
1079 ASAP> f.set_scan(s,msk)
1080 ASAP> f.fit()
1081 ASAP> f.plot()
1082 ASAP> f.get_parameters()
1083\end{verbatim}
1084
1085If you wish, the initial parameter guesses can be specified and
1086specific parameters can be fixed:
1087
1088\begin{verbatim}
1089 ASAP> f = fitter()
1090 ASAP> f.set_function(gauss=2)
1091 ASAP> f.set_scan(s,msk)
1092 ASAP> f.fit() # Fit using auto-estimates
1093 # Set Peak, centre and fwhm for the second gaussian.
1094 # Force the centre to be fixed
1095 ASAP> f.set_gauss_parameters(0.4,450,150,0,1,0,component=1)
1096 ASAP> f.fit() # Re-run the fit
1097\end{verbatim}
1098
1099The fitter \cmd{plot} function has a number of options to either view
1100the fit residuals or the individual components (by default it plots
1101the sum of the model components).
1102
1103Examples:
1104
1105\begin{verbatim}
1106 # Plot the residual
1107 ASAP> f.plot(residual=True)
1108
1109 # Plot the first 2 componentsa
1110 ASAP> f.plot(components=[0,1])
1111
1112 # Plot the first and third component plus the model sum
1113 ASAP> f.plot(components=[-1,0,2]) # -1 means the compoment sum
1114\end{verbatim}
1115
1116\subsection{Fit saving}
1117
1118One you are happy with your fit, it is possible to store it as part of
1119the scantable.
1120
1121\begin{verbatim}
1122 ASAP> f.storefit()
1123\end{verbatim}
1124
1125This will be saved to disk with the data, if the ``ASAP'' file format
1126is selected. Multiple fits to the same data can be stored in the
1127scantable.
1128
1129The scantable function \cmd{get\_fit} can be used to retrieve the
1130stored fits. Currently the fit parameters are just printed to the
1131screen.
1132
1133\begin{verbatim}
1134 ASAP> scans.get_fit(4) # Print fits for row 4
1135\end{verbatim}
1136
1137\section{Polarisation}
1138
1139Currently ASAP only supports polarmetric analysis on linearly
1140polarised feeds and the cross polarisation products measured. Other
1141cases will be added on an as needed basic.
1142
1143Conversions of linears to Stokes or Circular polarisations are done
1144``on-the-fly''. Leakage cannot be corrected for nor are these routines
1145able to calibrate position angle offsets.
1146
1147\subsection{Simple Calibration}
1148
1149{\em Currently the receiver position angle is not stored in the RPFITS
1150file. This severely hampers correct handling of polarimetry. In the future
1151we aim to define a general framework and populate the RPFITS files
1152with the data required for transparent polarimetric calibration.}
1153
1154It is possible that there is a phase offset between polarisation which
1155will effect the phase of the cross polarisation correlation, and so give
1156rise to spurious polarisation. \cmd{rotate\_xyphase} can be used to
1157correct for this error. At this point, the user must know how to
1158determine the size of the phase offset themselves.
1159
1160\begin{verbatim}
1161 ASAP> scans.rotate_xyphase(10.5) # Degrees
1162\end{verbatim}
1163
1164Note that if this function is run twice, the sum of the two values is
1165applied because it is done in-situ.
1166
1167A correction for the receiver parallactic angle may need to be made,
1168either because of how it is mounted or if parallactifiying had to track
1169at 90 degrees rather than 0. Use \cmd{rotate\_linpolphase} to correct
1170the position angle. Running this function twice results in the sum of
1171the corrections being applied because it is applied in-situ.
1172
1173\begin{verbatim}
1174 ASAP> scans.rotate_linpolphase(-20) # Degrees; correct for receiver mounting
1175
1176 # Receiver was tracking 90 degrees rather than 0
1177 ASAP> scans.rotate_linpolphase(90)
1178\end{verbatim}
1179
1180\subsection{Plotting}
1181\label{sec:polplot}
1182
1183To plot Stokes values, the plotter \cmd{set\_cursor} function should
1184be called first using the \cmd{pol} argument. The values which can be
1185plotted include a selection of [I,Q,U,V], [I, Plinear, Pangle, V],
1186[RR, LL] or [XX, YY, Real(XY), Imaginary(XY)]. (Plinear and Pangle are
1187the percentage and position angle of linear polarisation). Conversion
1188to circular polarisations are currently not available.
1189
1190Example:
1191
1192\begin{verbatim}
1193 ASAP> plotter.set_cursor(pol=[``I'',''Q'']
1194 ASAP> plotter.set_cursor(pol=[``RR'',''LL'']
1195 ASAP> plotter.set_cursor(pol=[``XX'',''YY'']
1196 ASAP> plotter.set_cursor(pol=[``I'',''Plinear'']
1197\end{verbatim}
1198
1199Row, beam and IF selection are also available in \cmd{set\_cursor} as
1200describe in section~\ref{sec:plotter_cursor}.
1201
1202\subsection{Saving}
1203
1204When saving data using the \cmd{save} function, the \cmd{stokes}
1205argument can be used to save the data as Stoke values when saving in
1206FITS format.
1207
1208Example:
1209
1210\begin{verbatim}
1211 ASAP> scans.save('myscan.sdfits', 'SDFITS', stokes=True)
1212\end{verbatim}
1213
1214\section{Function Summary}
1215
1216\begin{verbatim}
1217 scantable - a container for integrations/scans
1218 (can open asap/rpfits/sdfits and ms files)
1219 copy - returns a copy of a scan
1220 get_scan - gets a specific scan out of a scantable
1221 summary - print info about the scantable contents
1222 set_cursor - set a specific Beam/IF/Pol 'cursor' for
1223 further use
1224 get_cursor - print out the current cursor position
1225 stats - get specified statistic of the spectra in
1226 the scantable
1227 stddev - get the standard deviation of the spectra
1228 in the scantable
1229 get_tsys - get the TSys
1230 get_time - get the timestamps of the integrations
1231 get_unit - get the currnt unit
1232 set_unit - set the abcissa unit to be used from this
1233 point on
1234 get_abcissa - get the abcissa values and name for a given
1235 row (time)
1236 set_freqframe - set the frame info for the Spectral Axis
1237 (e.g. 'LSRK')
1238 set_doppler - set the doppler to be used from this point on
1239 set_instrument - set the instrument name
1240 get_fluxunit - get the brightness flux unit
1241 set_fluxunit - set the brightness flux unit
1242 create_mask - return an mask in the current unit
1243 for the given region. The specified regions
1244 are NOT masked
1245 get_restfreqs - get the current list of rest frequencies
1246 set_restfreqs - set a list of rest frequencies
1247 lines - print list of known spectral lines
1248 flag_spectrum - flag a whole Beam/IF/Pol
1249 save - save the scantable to disk as either 'ASAP'
1250 or 'SDFITS'
1251 nbeam,nif,nchan,npol - the number of beams/IFs/Pols/Chans
1252 history - print the history of the scantable
1253 get_fit - get a fit which has been stored witnh the data
1254 average_time - return the (weighted) time average of a scan
1255 or a list of scans
1256 average_pol - average the polarisations together.
1257 The dimension won't be reduced and
1258 all polarisations will contain the
1259 averaged spectrum.
1260 quotient - return the on/off quotient
1261 scale - return a scan scaled by a given factor
1262 add - return a scan with given value added
1263 bin - return a scan with binned channels
1264 resample - return a scan with resampled channels
1265 smooth - return the spectrally smoothed scan
1266 poly_baseline - fit a polynomial baseline to all Beams/IFs/Pols
1267 auto_poly_baseline - automatically fit a polynomial baseline
1268 gain_el - apply gain-elevation correction
1269 opacity - apply opacity correction
1270 convert_flux - convert to and from Jy and Kelvin brightness
1271 units
1272 freq_align - align spectra in frequency frame
1273 rotate_xyphase - rotate XY phase of cross correlation
1274 rotate_linpolphase - rotate the phase of the complex
1275 polarization O=Q+iU correlation
1276 [Math] Mainly functions which operate on more than one scantable
1277
1278 average_time - return the (weighted) time average
1279 of a list of scans
1280 quotient - return the on/off quotient
1281 simple_math - simple mathematical operations on two scantables,
1282 'add', 'sub', 'mul', 'div'
1283 [Fitting]
1284 fitter
1285 auto_fit - return a scan where the function is
1286 applied to all Beams/IFs/Pols.
1287 commit - return a new scan where the fits have been
1288 commited.
1289 fit - execute the actual fitting process
1290 store_fit - store the fit paramaters in the data (scantable)
1291 get_chi2 - get the Chi^2
1292 set_scan - set the scantable to be fit
1293 set_function - set the fitting function
1294 set_parameters - set the parameters for the function(s), and
1295 set if they should be held fixed during fitting
1296 set_gauss_parameters - same as above but specialised for individual
1297 gaussian components
1298 get_parameters - get the fitted parameters
1299 plot - plot the resulting fit and/or components and
1300 residual
1301 [Plotter]
1302 asapplotter - a plotter for asap, default plotter is
1303 called 'plotter'
1304 plot - plot a (list of) scantable
1305 save - save the plot to a file ('png' ,'ps' or 'eps')
1306 set_mode - set the state of the plotter, i.e.
1307 what is to be plotted 'colour stacked'
1308 and what 'panelled'
1309 set_cursor - only plot a selected part of the data
1310 set_range - set a 'zoom' window
1311 set_legend - specify user labels for the legend indeces
1312 set_title - specify user labels for the panel indeces
1313 set_ordinate - specify a user label for the ordinate
1314 set_abcissa - specify a user label for the abcissa
1315 set_layout - specify the multi-panel layout (rows,cols)
1316
1317 [Reading files]
1318 reader - access rpfits/sdfits files
1319 read - read in integrations
1320 summary - list info about all integrations
1321
1322 [General]
1323 commands - this command
1324 print - print details about a variable
1325 list_scans - list all scantables created bt the user
1326 del - delete the given variable from memory
1327 range - create a list of values, e.g.
1328 range(3) = [0,1,2], range(2,5) = [2,3,4]
1329 help - print help for one of the listed functions
1330 execfile - execute an asap script, e.g. execfile('myscript')
1331 list_rcparameters - print out a list of possible values to be
1332 put into .asaprc file
1333 mask_and,mask_or,
1334 mask_not - boolean operations on masks created with
1335 scantable.create_mask
1336
1337 Note:
1338 How to use this with help:
1339 # function 'summary'
1340 [xxx] is just a category
1341 Every 'sub-level' in this list should be replaces by a '.' Period when
1342 using help
1343 Example:
1344 ASAP> help scantable # to get info on ths scantable
1345 ASAP> help scantable.summary # to get help on the scantable's
1346 ASAP> help average_time
1347
1348\end{verbatim}
1349
1350\section{Scantable Mathematics}
1351
1352It is possible to to simple mathematics directly on scantables from
1353the command line using the \cmd{+, -, *, /} operators as well as their
1354cousins \cmd{+=, -= *=, /=}. This works between two scantables or a
1355scantable and a float. (Note that it does not work for integers).
1356
1357\begin{verbatim}
1358 ASAP> sum = scan1+scan2
1359 ASAP> scan2 = scan1+2.0
1360 ASAP> scan *= 1.05
1361\end{verbatim}
1362
1363%\section{Scripting}
1364
1365%Malte to add something
1366
1367\section{Appendix}
1368
1369\subsection{Installation}
1370
1371ASAP depends on a number of third-party libraries which you must
1372have installed before attempting to build ASAP. These are:
1373
1374\begin{itemize}
1375\item AIPS++
1376\item Boost
1377\item Matplotlib
1378\item ipython/python
1379\end{itemize}
1380
1381Debian Linux is currently supported and we intend also
1382to support other popular Linux flavours, Solaris and Mac.
1383
1384Of the dependencies, AIPS++ is the most complex to install.
1385
1386\subsection{ASCII output format}
1387
1388\subsection{.asaprc settings}
1389
1390\end{document}
1391
1392
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