Name
       eclipse - (ESO C Library for an Image Processing Software Environment)

Description
       eclipse is a general FITS image processing library written in ANSI C.

History
       Initially  written  for  Adonis,  eclipse  has since grown to a general
       multi-purpose FITS handling utility. It has been reported to be used on
       many telescope workstations and observatories.

       Today,  eclipse is used in ESO to implement fast image processing algo-
       rithms for the VLT infrared instruments.

Overview
       eclipse offers an  open  environment  for  image  processing  algorithm
       developments.   At  the  highest level, only Unix commands are offered,
       giving users the possibility to call the algorithms embedded  into  the
       library. One level below is a library of several hundred functions tak-
       ing care of many aspects of astronomical image processing.  Users  will
       want  to  use only Unix commands to process their data, programmers and
       algorithm developers will want to peek into the libraries to  implement
       their own routines.

       All  of these procedures are running without user interaction, which is
       typical of a pipeline, number-crunching approach.

       Notice that a link to off-line data processing softwares is  essential.
       eclipse  does not provide any complex post-processing algorithm such as
       deconvolution, nor does it contain any image or data displayer.  Global
       data  analyzers such as MIDAS provide the full range of functionalities
       needed for evolved post-processing and analyses; eclipse is to be  used
       as a pre-processor, a signal processing engine.

       Since  version 4.2, all FITS read/write functions have been moved  away
       from eclipse to give birth to a small, efficient and  easy-to-use  FITS
       io library: qfits.  eclipse needs and is distributed with qfits

Adonis
       A set of scripts and Unix commands has been especially designed to take
       care of most basic data reductions for Adonis. This  has  been  set  up
       during August 1996 in la Silla, with h.PP from observers, telescope and
       Adonis team.

       The following set of operations has been automated:

           flat-field creation
           bad pixel detection
           sky extraction from data cube, averaging, and subtraction from
           object frames
           average of the result

       There is a preparation phase, during which the observer has to identify
       their  files according to their logbook, and sort them out, preferrably
       in separate directories. It is then possible to design quickly  a  Unix
       script to launch a unique reduction command on all directories, and get
       cleaned data in a very short time.

       Since version 2.0, a new set of commands is available for Adonis Fabry-
       Perot mode. This work has been validated in Summer 1997 in la Silla, by
       Christian Drouet d’Aubigny, with h.PP from Patrice Corporon  and  David
       le Mignant.

Sofi/Isaac
       SOFI and ISAAC are two ESO infrared instruments. SOFI is working on the
       NTT in la Silla, ISAAC is installed on the UT1 telescope  of  the  VLT.
       These  instruments are mostly used in jitter mode, which requires dedi-
       cated optimized algorithms for data processing. Some commands have been
       written  to handle pipeline data processing, they are integrated in the
       VLT data flow system as data reduction engine for  these  modes,  as  a
       complement  to  on-line MIDAS. Both imaging and spectroscopic modes are
       supported for ISAAC.

Naco
       NACO is an infrared instument that work with an adaptive optic  system.
       The  data  reduction  is  similar  as the one used for ISAAC. Reduction
       recipe have been developed with the ISAAC  experience  and  adapted  to
       this  new  instrument. Support for the NACO instrument has been present
       in eclipse since version 4.0

License
       eclipse is covered by the GNU public general license, which makes  pos-
       sible  to distribute it on the World Wide Web. It should be included in
       future MIDAS distributions as a contribution for pipeline processing.

       I would like to thank all people participating in the  High  Resolution
       Data  Reduction  Working  Group  for  their  kind  h.PP and patience in
       detailing the secrets of Infra-red data processing

       Special thanks to our friends in la Silla, Patrice Corporon  and  David
       le Mignant, for their invaluable h.PP.

       Most  eclipse  documentation  is available on-line on the ESO server at
       the following address:

       http://www.eso.org/eclipse

Internal Pixel Representation
       A note about the internal pixel representation:

       The convention in use throughout eclipse is to work with single  preci-
       sion  pixels internally, i.e. all pixel buffers are float *, which lim-
       its the precision to 32 bits in IEEE  floating  point  format  for  all
       pixel operations. This is usually enough for most data reduction proce-
       dures, and gains time in terms of memory use.

       You may want however to work with double precision pixels, to  increase
       computation  accuracy.  Know that the memory use in much more intensive
       in this case, the most probable case  being  that  all  cubes  will  be
       swapped  to  disk for any pixel operation involving several planes of a
       cube, the amount of time used for the same operation  being  more  than
       twice  the  one  needed with single-precision pixels: disk accesses are
       usually a factor 1000 slower than memory accesses.

       Since version 2.1, it is possible to work with pixels stored as  double
       precision  numbers.  The  FITS  interfaces  have been upgraded to allow
       input and output in FITS -64 IEEE double format, and the internal pixel
       representation may be double, on user request.

       This change from single to double precision is not dynamic but can only
       be requested at compilation time. The procedure to  follow  to  compile
       eclipse  with double precision pixels is described in the INSTALL file.

Availability
       eclipse is distributed on the WWW under the following URL:
       http://www.eso.org/eclipse