Number 16 July 2001


1) Correction to CalFUSE v(HELIO) calculations  
2) Release of CalFUSE v2.0 in sight

1) Correction to CalFUSE v(HELIO) calculations

        Following a careful analysis, the FUSE team at JHU has established 
that the correction for the Earth's orbital motion has been applied with the 
wrong sign in the CalFUSE pipeline.  This problem affects all CalFUSE versions 
prior to, and including, v1.8.7.  Specifically, the problem originates in an
inconsistency between the sign of the file header keyword containing the 
velocity correction from Geocentric to Heliocentric frames, and the implemented 
algorithm.  The correction from spacecraft to Geocentric frame is done 
correctly.  Note that, although not used by the CalFUSE pipeline, the header 
keywords for the LSR corrections (V_LSRDYN and V_LSRSTD) are populated using 
the same sign convention.  This inconsistency will be removed in the upcoming 
(v2.0) release of the CalFUSE pipeline.  In the meantime, data processed by 
CalFUSE, v1.8.7 and earlier can be easily corrected for the error in the 
application of V_HELIO (from file header): 

       lambda[new] = lambda[old] * ( 1. - 2.*V_HELIO / c ) 
       A full discussion of the problem, investigation and remedies can be 
found at:

2) Release of CalFUSE v2.0 in sight

        On a related note, the new, significantly updated, version of the 
CalFUSE data reduction pipeline, v2.0, is now expected to be released for beta 
testing in the next few weeks.  A general release is expected by September 
2001.  This version of the calibration pipeline features the following 
improvements over v1.8.7:

        - Corrected heliocentric wavelength scale 
        - Detection and removal of event bursts 
        - Walk correction (for low-pulse-height events)
        - Improved scattered-light model 
        - Astigmatism correction 
        - Optimal (weighted) spectral extraction 
        - Improved wavelength calibration 
        - Improved flux calibration 

Those FUSE users who wish to participate in the beta testing of v2.0 are 
encouraged to contact us at

The Observer's Electronic Newsletter is published by the FUSE project and is 
aimed at the FUSE user community.

Editor: B-G Andersson, FUSE Guest Investigator Officer.

The FUSE Project is managed by Johns Hopkins University's Center for 
Astrophysical Sciences in Baltimore, MD, for NASA's Goddard Space Flight 
Center.  The FUSE Principal Investigator is Dr. Warren Moos, the FUSE Project 
Manager at JHU is Mr. J.B. Joyce, and the NASA Project Scientist for FUSE 
is Dr. George Sonneborn.

Further information about the FUSE Guest Investigator Program can  be
obtained from:  Dr. George Sonneborn;

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