********************************************************************************
             |                                            |
             |              CCC  XX   XX    OOO           |
Chandra      |             CC     XX XX    OO OO          | CXC
Electronic   |            CC       XXX    OO   OO         | Number 13
Bulletin     |             CC     XX XX    OO OO          | March
             |              CCC  XX   XX    OOO           | 2002
             |                                            |
********************************************************************************

Welcome to the Chandra X-ray Center's Electronic News Bulletin Number 13.

CXC Web site: cxc.harvard.edu

If you would like to unsubscribe from this alias, simply reply to this message
to let us know.  

Please use this website to update your address or email: 
          http://cxc.harvard.edu/cdo/udb/userdat.html

Contents:

1. ACIS Gain Caveat 

2. Temporary Email Address for Proposal Submission Problems

3. Chandra/CIAO Workshop Registration 

4. ObsVis Users 

-------------------------------------------------------------------------------

Item 1. ACIS Gain Caveat
========================


 We have discovered that ACIS-S3 spectra may contain spurious features near
 the energies 1.6 and 2.6 keV. This problem is present only in the spectra
 extracted in the PI channels from observations performed after Jan 29, 2000
 (at the focal plane temperature -120 C) and processed with the gain tables
 released in August 2001. The PHA spectra are not affected. We believe that
 the features are the result of abrupt changes in the slope of the PHA-Energy
 relation at these energies. CXC is working on the new gain tables that will
 eliminate the problem. In the meantime the users are urged to exercise
 caution in interpreting weak emission and absorption features near 1.6 and
 2.6 keV.

See: http://cxc.harvard.edu/cal/Acis/Cal_projects/index.html


-------------------------------------------------------------------------------


Item 2.  Temporary Email Address for Proposal Submission Problems
=================================================================

The CXC has set up a temporary email alias (below) to help the CXC
Director's Office staff keep track of the large volume of email we
receive in the days just before and after the proposal deadline.  This
email address should be used for proposal submission problems only.  It
will be activated Thursday March 14 at 9AM, and be turned off Monday
March 18 at 5pm.  Questions can always be sent to the CXC via the
Helpdesk and cxchelp@head-cfa.harvard.edu, however the new address will
allow a more efficient response on proposal submission questions.

                prophelp@head-cfa.harvard.edu

 
-------------------------------------------------------------------------------


Item 3. Chandra/CIAO Workshop Registration
==========================================

There is now a web interface that may be used to register for the 4th 
Chandra/CIAO Workshop:

http://cxc.harvard.edu/ciao/workshop_regform.html

The workshop will be held 20-22 May 2002 at the CXC.  More information is 
available online at http://cxc.harvard.edu/ciao/wrkshp_mayann.html.

-------------------------------------------------------------------------------



Item 4. ObsVis Users
====================


Please note that the default date range in the downloadable (command line) 
version of ObsVis was inadvertently left at the Cycle 3 values. To determine 
roll and visibility during Cycle 4, you will need to update the date range
accordingly. The web version does default to dates appropriate for Cycle 4.


-------------------------------------------------------------------------------

This Electronic Bulletin is used for the dissemination of important
announcements and information about the Chandra X-Ray Observatory to members
of the community. If you wish to unsubscribe from the list, simply reply to
this email to let us know.