ChangeLog for merge
===============================
Open SPRs:
- none

Version 0.14  - 2015-05-13 (RDS)   
-------------------------------
 + (src/merge_mod.f90): Remove useless debug line

Version 0.13.1  - 2012-05-17 (RDS)   
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 + (src/merge_mod.f90): Refuses to merge events from different observations unless
			a new parameter "mergedifferentobs" is set to "yes" by
			the user (SPR-6728)

Version 0.13  - 2007-01-11 (HB)   
-------------------------------

 + (src/merge_mod.f90): Added new warnings to address the situation where 
	                STIGTI or GTI extensions are present in only one 
	                of the input datasets, which in most cases will result
	                in incorrect exposure times. 
	                General warning added, highlighting limitations when 
	                using merged eventsets as input in downstream tasks   
 + (doc/merge_description.tex): new warnings; minor changes in description 
	                and comments section.
	                
Version 0.12  - 2006-06-021 (RDS)   
-----------------------------------
 + (src/merge_mod.f90): Now merges GTIs as well as STDGTIs. (SPR-2608)

Version 0.11 - 2003-12-02 (HB)
-----------------------------------
 + (src/merge_mod.f90): TSTOP keyword was not updated correctly; fixed.
closed SPR:
 + SSC-SPR-3158: "merge" does not update the TSTOP keyword
	
Version 0.10 - 2003-05-07 (HB)	
-----------------------------------
 + (config/merge.par): modified to enable param-2.0 functionality	
		
Version 0.9  - 2003-04-04 (HB)
-----------------------------------
 + (doc/merge_description.tex): LaTeX error corrected	
	
Version 0.8  - 2003-03-24 (HB)
-----------------------------------
 + (src/merge_mod.f90): merging of additional user-specified event table columns
 + (doc/merge_description.tex): updated	
		
Version 0.7  - 2002-08-21 (AMR/MJF)
-----------------------------------
 + (src/merge_mod.f90): implemented changes as in version 0.4.5 [SSC-SPR-2933,
   and further fix for SSC-SPR-2905]
 + (doc/merge_description.tex): updated
closed SPR:
 + SSC-SPR-2933: Should propagate WEIGHT

Version 0.6  - 2002-07-17 (AMR/MJF)
-----------------------------------
 + (DEPEND): added "sas" as required by new infrastructure (sas-1.302)
 + (src/merge_mod.f90): implemented changes as in versions 0.4.3 and 0.4.4 to
   fix problems with time related keywords
closed SPR:
 + SSC-SPR-2905: LIVETIME header in merged file is not being updated correctly

Version 0.5  - 2002-05-27 (MJF)
-------------------------------
 + (config/merge.par): updated for `param-2.0'
 + (DEPEND): needs `param-2.0', updated all other entries to latest

Version 0.4.2 2002-05-27 (AMR)
-------------
 + (src/merge_mod.f90) Further start/stop time attributes and durations corrected
 + (doc/merge_description.tex) Updated

Version 0.4.1 2001-11-08 (AMR)
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 + (src/merge_mod.f90) STDGTI files now merged (SSC-SPR-2617). 
   Various start & stop time attributes corrected
 + (doc/merge_description.tex) Updated

Version 0.4 2001-06-19 (AMR)
-------------
	+ (src/merge_mod.f90) New functionality, allowing adjustments of 
	  individual event file sky coordinates, for attitude errors etc, prior
   to merging. 
	+ (config/merge.par, merge.lyt) New parameters for sky coordinate 
	  adjustments. Also withuserradec changed to withradec. 
 + (doc/merge_description.tex) Above change described. 

Version 0.3.1 2000-11-23 (AMR)
-------------
 + (doc/merge_description.tex) Documentation updated (SSC-SPR-2115)

Version 0.3 2000-09-22 (AMR)
------------

Initial SAS version - non-accepted (version number same as documentation). 
Experimental and under development - treat all output with caution. 
Comments welcome, especially as regards improvements in output file. 

Examples:
---------	
>  Merging two event files (reprojecting X/Y coordinates to mean ref.point)

merge set1=ev1.fits set2=ev2.fits outset=evout.fits

>  Merging two event files (reprojecting X/Y coordinates to user ref.point)

merge set1=ev1.fits set2=ev2.fits outset=evout.fits withuserradec=Y ra=10.2 dec=-13.7

>  Merging two attitude files (atthkgen output files)

merge set1=att1.fits set2=att2.fits outset=attout.fits

>  Merging two orbit files (orbit output files)

merge set1=orb1.fits set2=orb2.fits outset=orbout.fits

-- Note, it is possible in many cases to treat the output files as ordinary 
(non-merged) files. e.g. creation of an exposure map is possible for merged 
data: First merge the relevant event files and associated attitude files, then 
form a sky image (via evselect) from the merged event file, then run eexpmap
as normal using this image and the merged event and attitude files. 
-- Just to reiterate, do take care with any merged output. This task is still 
under development.