Number 25, March 2003


1) Second Announcement, Fourth Annual FUSE Science and Data Workshop
2) CalFUSE Problem with Error Bars in Time-Tag Mode, v2.1.6

1) Second Announcement, Fourth Annual FUSE Science and Data Workshop

                         Second Announcement 

      Call for Papers: Fourth Annual FUSE Science and Data Workshop
                            May 12-13, 2003
                      Held at STScI, Baltimore MD

        In the last FUSE Electronic Newsletter we announced the upcoming two
day FUSE Science and Data Workshop which will be held in Baltimore at STScI
on May 12 and 13, 2003. Herewith we announce the deadline for receipt of 
abstracts for this meeting, which is Friday April 11, 2003. Both oral
(25 minutes plus time for questions) and poster presentation formats are
available.  If desired, shorter oral presentations (10 minutes with time for
questions) will also be supported.   Hence, please submit title, first
author, brief abstract (300 words or less), preference for oral or poster 
presentation, and in the former case a preferred length to 
fuse_support@pha.jhu.edu prior to the deadline.

In response to the Newsletter announcement, we have already received some 
submissions.  These do not have to be resubmitted unless you did not specify 
poster or oral presentation or if the materials submitted were otherwise 

To allow us a better basis for planning, we'd also like to ask that you 
submit a non-binding registration if you plan to attend, whether giving 
a paper or not to fuse_support@pha.jhu.edu.

We have set up a web page where we will post further information as it
becomes available:

Any questions should be addressed to the e-mail address above.  

We hope to see you in Baltimore in May!

2) CalFUSE Problem with Error Bars in Time-Tag Mode, v2.1.6

	One of the changes included in CalFUSE v2.1.6, released about a year
ago, was a modification of the way that error bars for individual pixels are 
calculated in the final, motion-corrected detector image 
are then propagated into the extracted spectra.  It was recently pointed out 
that our new algorithm does not yield SQRT(N) error bars for bright sources 
(fluxes > 1E-12 erg/cm2/s/A).  The trouble arises when we normalize the error 
for each detector pixel by 1/N^2.  For most targets, the number of counts per 
detector pixel is zero or one, so this normalization has no effect.  For bright 
targets, N can be as large as 3 or 4, so the error bars are greatly reduced. 

After considerable debate, we have decided to return to the 1/N normalization 
originally used by the CalFUSE pipeline.

To see if your data are affected, compare the CNTSERR array with SQRT(COUNTS). 
For most targets, you will find that the two arrays are comparable.  If not, a 
simple solution is to replace the flux-calibrated ERROR column with 
FLUX/SQRT(COUNTS).  Because the COUNTS array is background subtracted, 
SQRT(COUNTS) is slightly less than SQRT(N).  For bright targets, however, the 
difference will be negligible.

A new version of the pipeline module in question, v1.23 of cf_ttag_geodopp.c, 
is available on the CalFUSE FTP site at

ftp://fuse.pha.jhu.edu/fuseftp/calfuse/BUG_FIXES . 

A version of CalFUSE employing this new module, dubbed v2.3.0, will be 
installed behind the firewall later this month.

For more information, please see the CalFUSE White Paper "Error Propagation in 
CalFUSE" 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; sonneborn@stars.gsfc.nasa.gov

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