
	   *** CRUSH User's Manual Extension for SOFIA/HAWC+ ***

			      Attila Kovacs
		      <attila[AT]submm.caltech.edu>

		       Last updated: 14 April 2015



Table of Contents
=================

1. Introduction
  1.1. A brief description of of what CRUSH does and how...
2. Installation
  2.1. Installation from tarball (POSIX/UNIX, incl. Mac OS X)
  2.2. Optional system-wide installation.
  2.3. Optional Java configuration
3. Quickstart guide
  3.1. A few common options to use with SOFIA/HAWC+
4. Technical details for expert users
  4.1. HAWC+ specific pixel divisions
  4.2. Glossary of HAWC+ specific options
  4.3. HAWC+ specific log quantities





#####################################################################
1. Introduction
#####################################################################


   This document contains information specific to using CRUSH-2 with 
   SOFIA/HAWC+. 

   You may use it as a standalone quickstart guide, with instructions for 
   installation and basic use, or in conjucntion with the main CRUSH-2 README. 
   Either way, it is recommended that users also familiarize themselves with 
   the contents of the main CRUSH-2 README, found inside the distribution 
   directory, and its Section 1 (Getting Started) especially. 



1.1 A brief description of what CRUSH does and how...
=====================================================

   CRUSH is a reduction pipeline, designed mainly to remove correlated signals 
   (correlated noise) in the detector time-streams to arrive at clean & 
   independent bolometer signals, which are then used to derive a model of
   the source (usually an image).

   As such it is not an interactive reduction software (e.g. as opposed to
   e.g. BoA). The term 'scripting' in CRUSH mainly means defining configuration
   options (in the command line or through configuration files) which are
   parsed in the order they are read.

   During the reduction CRUSH aims to arrive at a consistent set of
   solutions for various correlated signals, the corresponding gains and
   the pixel weights, as well as tries to identify and flag problematic data,
   and applies appropriate spectral filtering.

   This means a series of reduction steps, which are iterated a few times
   until the required self-consistent solutions are arrived at.

   To learn more about the details please refer to Kovacs, A., "CRUSH:
   fast and scalable data reduction for imaging arrays," Proc. SPIE 7020, 45,
   (2008). If that does not satisfy your curiousity, then you can find yet
   more explanation in Kovacs, A., PhD thesis, Caltech (2006).





#####################################################################
2. Installation
#####################################################################


   2.1. Installation from tarball (POSIX/UNIX, incl. Mac OS X)
   ================================================================

     Step 1.
     -------
     Install Java (if necessary), e.g. from www.java.com. If you already have
     Java, check that it is version 1.6.0 (a.k.a. Java 6) or later, by typing:

	> java -version

     Note, that The GNU java a.k.a. gij (default on some older RedHat and 
     Fedora systems) is painfully slow and unreliable, and will not always run 
     CRUSH correctly. If you need Java, you can download the latest JRE from
     www.java.com

     Step 2.
     -------
     Unpack the tarball in the desired location (e.g. under '~/astrotools/'):

        > cd ~/astrotools
        > tar xzf crush-2.xx-x.tar.gz
   

     Step 3.
     -------
     Verify that CRUSH works:

	> cd crush
	> ./crush

     You should see a brief information screen on how to use CRUSH.



   2.2. Optional system-wide installation
   ======================================
   To create system-wide access to the crush executables, you may optionally 
   wish to run 'install.sh' (as root or with 'sudo'). It will link the
   executables to '/usr/bin', and install man pages.

        > cd crush
        > sudo bash install.sh

   You can check the success of the above optinal step by typing:

        > man crush

   If all is in order, you should see a basic description on the crush 
   command-line syntax and options.



   2.3. Optional Java configuration
   ================================
   CRUSH ships with a default Java configuration. On the most common UNIX
   platforms (Linux, Mac OS X, BSD, and Solaris), it will automatically attempt
   to set an optimal configuration. On other platforms, it comes with fail-safe
   default values (default java, 32-bit mode and 1GB of RAM use).

   To override the defaults on Windows, edit 'wrapper.bat' directly.

   On all other platforms, you can override the defaults by placing your
   settings in arbitrary files under /etc/crush2/startup or ~/.crush2/startup.
   (Any settings in the user's home under ~/.crush2/startup will overrride the
   system-wide values in /etc/crush2/startup. If multiple config files exist in
   the same location, these will be parse in non-specific order).

   E.g., placing the following lines in ~/.crush2/startup/java.conf overrides
   all available settings: 

	JAVA="/usr/java/latest/bin/java"
	DATAMODEL="64"
	USEMB="4000"
	JVM="server"
	EXTRAOPTS=""

   Upon startup CRUSH will find and apply these settings, so it will use
   "/usr/java/latest/bin/java" to run CRUSH, in 64-bit mode, with 4GB of RAM, 
   using the HotSpot 'server' VM, with no extra Java options.

   (Note, these config files are parsed as bash scripts, so you may use other
   bash commands too, such as printing earlier settings via 'echo')

   Below is a guide to the variables that you can override to set your own
   Java runtime configuration:

	JAVA		Set to the location of the Java executable you want
			to use. E.g. "java" to use the default Java, or
			"/usr/java/latest/bin/java" to use the latest from
			Oracle or OpenJDK.

	DATAMODEL	Set to "32" or "64", to select 32 or 64-bit mode.
			To use 64-bit mode you will need both a 64-bit OS
			and a 64-bit JRE (Java Runtime Environment)
			installation.

	USEMB		Set to the maximum amount of RAM (in MB) available to
			CRUSH. E.g. "4000" for 4GB. Note, that when DATAMODEL
			is "32", you this value must be somewhere below 2000.
			Thus, "1900" is a good maximum value to use in 32-bit
			mode.  Due to the volume of full-rate HAWC+ data
			(> 500MB/min), you will need to configure Java with at 
			least 1.2GB of RAM to process the test simulation.

	JVM		Usually set to "server" for Oracle or OpenJDK. If using
			IBM's Java, set it to "" (empty string). On ARM
			platforms, you probably get better performance using
			"jamvm" or "avian". o see what VM options are
			available, run 'java -help'. The VM options are listed
			near the top of the resulting help screen.

	EXTRAOPTS	Any other non-standard options you may want to pass
			to the Java VM should go here. Typically set to "".
			(Note, the "-Xbatch" options is set for CRUSH, by
			default).

  


#####################################################################
3. Quickstart guide
#####################################################################

   For SOFIA/HAWC+ CRUSH will be launched exclusively from the DRP pipeline.
   See the DRP documentation for details.

   However, if you wish to run CRUSH manually, you may easily do so from the
   command-line with 'hawc+' as your instrument. E.g.:

     ./crush hawc+ [...]

   See the main README for more details.  

 

3.1 A few common options to use with SOFIA/HAWC+
================================================

   The DRP interface to CRUSH allows manually specifying reduction options,
   which are passed to CRUSH verbetum as a single line. Each option in the
   line begins with a dash '-', and should not contain white spaces, unless
   these are enclosed in quotes. E.g. below is a valid option line, with
   three options, one of which contains a white-space characters:

     -faint -name="My HAWC+ image.fits" -projection=TAN

   Below is a brief guide to a few useful options, grouped by functionality.

   
   Source type options
   -------------------
   The default reduction is generally OK for sources smaller than the field of 
   view (<FoV/2) with S/N in the 10--1000 range. Outside this range, the 
   following options can be used to obtain better results:


     -bright		Reduce very bright sources (S/N > 1000).

     -faint		Reduce faint sources (S/N < 30).

     -deep		Optimized for the extraction of deep-field point
			sources. It is similar to '-faint' (above) but it
			also spatially filters the map, removing all signals
			above a few beam scales. Use only for very faint
			point sources.
    
     -extended		Reduce extended sources (>FoV/2). The retention of
			scales larger than ~FoV/2 come at a price of
			increased map noise (on those scales). See Section
			2.4 of the main README on the 'Recovery of Extended
			Emission'. Can be used on its own (assuming the 
			default brightness setting) or together with '-faint'
			or '-bright'.

     -sourcesize=X	Can be used together with '-extended' (above), to
			tweak just how extended the source is expected to be.
			The argument is an approximate source diameter in
			arcseconds. E.g. '-sourcesize=300.0'. 
   

     -source.sign=Z	By default, CRUSH assumes that sources are seen in
			emission (+), and biases the reduction as such to 
			produce images without filter bowls or other negative 
			reduction artifatcs. However, your object may contain 
			absorption features, for which you may want ot bias in 
			the opposite direction (-), or not bias at all (0).
			Set the sign accordingly to +, -, or 0. E.g.
			'-source.sign=+'

     -moving		Indicate that the object is a moving source, such as
			a planet, a moon, an asteroid, or a comet. CRUSH will
			use only relative coordinates w.r.t the tracking center
			to construct a map. The map's nominal center will be 
			that of the first scan.
	

   Output map options
   ------------------
   These options change how the output FITS image will be constructed. All 
   these options have reasonable default values, and so you should only
   use them to override those if needed.


     -grid=X		Set the pixelization of the map to X arcseconds.
			(The default pixelization is chosen to be be around
			1/5th of a beam for each HAWC+ band).

     -projection=XXX	Change the WCS spherical projection. The following
                        projections are supported:

                                SFL  --  Sanson-Flamsteed
                                SIN  --  Slant Orthographic
                                TAN  --  Gnomonic
                                ZEA  --  Zenithal Equal Area
                                MER  --  Mercator
                                CAR  --  Plate-Carree
                                AIT  --  Hammer-Aitoff
                                GLS  --  Global Sinusoidal
                                STG  --  Stereographic
                                ARC  --  Zenithal Equidistant

			The default is SFL (Sanson-Flamsteed). E.g. 
			'-projection=TAN'.

     -ecliptic		Produce maps in ecliptic coordinates, instead of the
			default equatorial (same as '-system=ecliptic').

     -galactic		Produce maps in galactic coordinates, instead of the
			default equatorial (same as '-system=galactic').

     -supergalactic	Produce maps in super-galactic coordinates, instead of 
			the default equatorial (same as 
			'-system=supergalactic').

     -horizontal	Produce maps in horizontal coordinates, instead of
			the default equatorial (same as '-system=horizontal').

     -focalplane	Produce maps in focal-plane coordinates, instead of the
			default equatorial (same as '-system=focalplane').

     -final:smooth=X	Smooth the final map by a Gaussian with X arcsec FWHM.
			Alternatively, X can be one of 'minimal', 'halfbeam'
			'2/3beam' or 'beam'. E.g. '-smooth=8.0' or 
			'-smooth=2/3beam'. To turn smoothing off completely
			use '-final:forget=smooth'.




#####################################################################
4. Technical details for expert users
#####################################################################

From this point on, the documentation is of more technical nature, intended
for expert users only.


4.1. HAWC+ specific pixel divisions
===================================

For a general overview of channel divisions, please consult Section 3.
(Correlated Signals) in the main README document.


   polarrays	Pixels of the the R and T polarization arrays, respectively.
		
   subarrays    Pixels of each of the 4 HAWC+ subarrays (40x32). Each subarray
		may contain correlated signals to themselves, e.g. do to
		correlated thermal fluctuations on their wafers.

   mux		A grouping of pixels based on their SQUID multiplexing scheme
		Each 4x8 pixel quadrant of the array is read out through the
		same SQUID amplifier. Therefore, it is not suprizing that 
		correlated signals are present on these quadrants. The
		decorrelating on 'mux' groups is default in GISMO reductions

   pins		The GISMO multiplexing scheme is implemented in the time-domain
		Thus, the first channels of each SQUID are read out at the same
		time, followed by the second channel in each group etc. Thus,
		if there is any pickup of high-frequency signals in the
		multiplexing scheme, one could expect some correlated signals
		to be present on these virtual readout pin groups. There
		is little evidence for these, but the reduction of very faint
		compact sources may benefit from the additional decorrelation
		on these groups.
		You can group neighboring 'pins' together for decorrelation
		via the 'correlated.pins.group' option, or the equivalent
		'pins.group' shorthand.

   rows		Geometric rows of the array (it has 16 rows and 8 columns).
		You can also group n rows together for the decorrelation via
		the 'correlated.rows.group=n' option, or the equivalent
		'rows.group=n' shorthand.

   cols		Geometric columns of the array (it has 16 rows and 8 columns).
		You can also group n columns together for the decorrelation via
		the 'correlated.cols.group=n' option, or the equivalent
		'cols.group=n' shorthand.



4.2. Glossary of HAWC+ specific options
=======================================

   band=X		Set the observing band to A, B, C, D, or E. Normally,
			the band setting is automatic through the SPECTEL1
			fits keyword. However, setting the band manually may
			be useful for polling band specific settings. E.g.

			  > crush hawc+ -band=A -poll=beam

			The above line will report the Gaussian FWHM beam size
			(in arcsec) used when reducing band A (53um) data.

   calibrated		Set this option when the reduction includes the final
			calibration (opacities and other calibration
			corrections) to produce Level 3 data. Otherwise, CRUSH
			will produce Level 2 output.

   cols                 @Alias: 'correlated.cols'
                        @Expert
                        Decorrelate geometric detector columns. All
     			correlated modality suboptions apply.
                        @See: 'correlated.<?>', 'rows'

   filter=<wavelength>	@Expert
			Sets the filter band to one of:

			  53um, 62um, 89um, 155um, or 216um

			Normally, the filter is set automatically to the 
			correct value based on the 'SPECTEL1' SOFIA header key.
			For this reason, it is not recommended, nor trivial
			for the user to override this automatic behaviour.
			Rather, the setting of this option is useful for
			setting conditional settings, which depend on the
			HAWC+ waveband.

   mux			@Alias: 'correlated.mux'
			@Expert
			Decorrelate on SQUID muxes. All correlated modality
			suboptions apply.
			@See: 'correlated.<?>'

   offset.R1=dx,dy
   offset.R2=dx,dy
   offset.T1=dx,dy
   offset.T2=dx,dy	@Expert
			Specify the subarray offset (as dx,dy arcseconds in
			the focal plane) from their nominal positions, for
			both the first and second subarrays of the R and T
			polarization arrays. For example, specifying zero
			offsets for all (default) describes the focal plane
			where R and T are perfectly aligned relative to
			one another, and the two subarrays of each form a 
			single seamless polarization array.


   pcenter=<row>,<col>	@Expert
			Specify the pointing center as a row,col combination 
			on the array. There are 16 rows and 8 columns on the 
			GISMO array, and the numbering starts from 1. Thus, 
			the geometric center of the array corresponds to 
			8.5,4.5. This option is not used (ignored) if pixel
			positions are defined by the 'rcp' option (which is 
			default). In those cases, the pointing center can be 
			adjusted via the 'rcp.center' option.
			@See: 'rcp', 'rcp.center', 'pixelsize', 'rotation'


   pins			@Alias: 'correlated.pins'
			@Expert
			Decorrelate along the 'pins' direction of the 
			SQUID mulitplexed channels. All correlated modality
			sub-options apply.
			@See: 'correlated.<?>'

   pins.group=<n>	@Alias: 'correlated.pins.group'
			@Expert
			Because there are only four SQUID multiplexers in 
			GISMO, there is little redundancy among the pixels, 
			which are read out at exactly the same instant. This 
			option allows to group together <n> consecutive 
			samples, to combine pixels read in some time-interval.
			@See: 'pins'

   pixelsize=<a>[,<b>]	@Expert
			Specify the size of the pixels for calculating pixel 
			positions based on a regular grid. A better way of 
			setting the pixel positions is through the 'rcp' 
			option. 
			The argument can be either a lateral size (in arcsec) 
			for square pixels, or two comma separated sizes for 
			rectangular pixels.
			@See: 'rcp', 'rotation', 'pcenter'

   polarrays		@Alias: 'correlated.polarrays'
			@Expert
			Decorrelate each polarization array separately. All 
			correlated modality sub-options apply.
			@See: 'correlated.<?>'


   rotation=<deg>	@Expert
			Specify the array rotation (in degrees), when pixel 
			positions are calculated from a regular grid. A better 
			way is to specify pixel positions via the 'rcp' option 
			their rotation via 'rcp.rotate'.
			@See: 'rcp', 'rcp.rotate', 'pixelsize'

   rotation.T=<deg>	@Expert
			Specify the rotation of the T polarization subarray
			relative to the R subarray.

   rows                 @Alias: 'correlated.rows'
                        @Expert
                        Decorrelate on geometric detector rows. All correlated
			modality sub-options apply.
                        @See: 'correlated.<?>', 'cols'


   subarray=<list>	@Expert
			Restrict the reduction only to the subarrays listed.
			The argument is a comma-separated list of subarray 
			codes: R1, R2, T1, T2 or R (= R1,R2) or T (= T1,T2). 
			E.g.:

			  > crush hawc+ -subarray=R1,T1 [...]

   subarrays		@Alias: 'correlated.subarrays'
			@Expert
			Decorrelate on physical subarrays (two 40x32 subarrays
			per polarization). All correlated modality options
			apply.
			@See: 'correlated.<?>'


4.3. HAWC+ specific log quantities
==================================

  Coming soon...





------------------------------------------------------------------------------
Copyright (C)2015 -- Attila Kovacs <attila[AT]submm.caltech.edu>


