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Chandra Electronic Bulletin No. 8

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             |              CCC  XX   XX    OOO           |
Chandra      |             CC     XX XX    OO OO          | CXC
Electronic   |            CC       XXX    OO   OO         | Number 8
Bulletin     |             CC     XX XX    OO OO          | November
             |              CCC  XX   XX    OOO           | 2001
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Welcome to the Chandra X-ray Center's Electronic News Bulletin Number 8.

CXC Web site: cxc.harvard.edu

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to let us know.  


1. DDT data on the Neutron Star RX J 185636-375 now available

2. CIAO 2.2: New Threads

3. Chandra Press Releases

4. Location of ASPSOL and OBCSOL files

Item 1.  DDT data on the Neutron Star RX J 185636-375 now available   

The 4 Cycle 2 observations of the Neutron star RX J 185636-375 
are now available in the Chandra public archive. Information and links to the 
Cycle 2 data, the Cycle 1 observation and various combinations of the data can 
be found on our website, direct link:



Item 2. CIAO 2.2: New Threads

Hello Chandra Users

Now that the CIAO 2.2 software package has been released, the weekly email 
updates of new and updated analysis threads is resuming to the 
chandra_users email discussion group.   (Instructions for signing up at
http://asc.harvard.edu/chandra-users/discussion_group.html  ).  All the threads were 
reviewed and updated to take into account new tool functionality; all those 
updates will not be outlined here as there are many.  Remember that the CIAO 
threads page is located at http://cxc.harvard.edu/ciao/documents_threads.html.

If you have not yet done so, you can download CIAO 2.2 from 

As always, please send questions to the CXC HELPDESK 
(http://cxc.harvard.edu/helpdesk/) and comments on the threads to 

Liz Galle, for the CIAO Documentation Team

--Summary of Changes--

Ten new threads have been added; these threads were made possible by new tools 
or tool upgrades in CIAO 2.2:

Introduction to Toolagent

Toolagent is a component of the CIAO graphical user interface (GUI) 
applications that makes it possible to run command-line tools from 
within the GUI.   The thread outlines the basic tasks - editing
parameter files and running tools - and explains how to customize the
configuration of toolagent.


Use the New geom.par File


A new analysis data file (telD1999-07-23geomN0004.fits) was added to
CALDB version 2.9, released on 2001 October 22.  The updates to the
file are explained, as well as how they affect the data.  It then
shows how to recreate the level 2 event file, if necessary.


Create an Image of Diffuse Emission

This thread describes the method by which one can create a 
smoothed, exposure-corrected image of diffuse emission.  After
removing unwanted point sources from the image, it uses one
of the new CIAO 2.2 tools, dmfilth, to fill in the holes left behind. 


Use merge_all Script to Compute ACIS Exposure Maps and Fluxed Image
A wide variety of exposure maps may be created using the script
merge_all.  It can take as input an arbitrary number of level 2 event
files, the corresponding aspect solution files, and a list of the CCD 
numbers in which you are interested.  The script creates a merged
level 2 event file and, if you like, a merged exposure map and 
exposure-corrected image for these CCDs. 


Weighting ARFs and RMFs


If you want to extract the spectrum of a large region, or combine 
data from multiple regions (either from the same or different
observations), then you may need to use a weighted ARF and RMF for 
the spectral analysis.  This thread describes how you can use the
mkwarf (new to CIAO 2.2) and mkrmf tools to create the weighted responses. 


Create Grating RMFs


This thread describes when it is necessary to run the new tool mkgrmf
to create a grating RMF (gRMF) file, as opposed to when it is
sufficient to use the gRMFs distributed in the CALDB. 


Create a Color Spectrum


This thread uses the dmimg2jpg tool to create a color spectrum of
grating data.  It goes through examples in both sky coordinates and
grating angular coordinates.


Fitting Spectral Data With/Without Independent Background Responses


There have been some changes made in how Sherpa treats background
data; it may be fit alone, with no source data specified, and 
background datasets may have their own instrument models.  One of the 
examples that this thread goes through is fitting the source and
background with independent responses.


Fitting Spatial (2-D) Data: Using an Exposure Map


This thread shows how to use the EXPMAP command in Sherpa to define 
an exposure map model. The exposure map file is input to Sherpa 
through the GRIDMODEL command and then can be used in fitting image


CIAO and S-Lang


CIAO 2.2 provides a number of significant improvements in the
interface between the CIAO system and the S-Lang programming
language. Unfortunately, some of the improvements in CIAO 2.2 
have lead to incompatabilities with S-Lang code written for previous 
versions of CIAO. We provide here a list of these issues as well as
some basic examples on using S-Lang. 


Item 3. Chandra Press Releases

Dear Chandra Users,

I would like to take this opportunity to remind you of the procedures
involving publicity.  (Please note that if you allow your colleagues or
students to use your data for scientific research, you are responsible
for making them aware of these guidelines.)    In addition to the press
guidelines below, I encourage anyone with a visually interesting image
to bring it to my attention as a candidate 'image release'.

Please take particular note of the information regarding scientific
meetings, as we are rapidly approaching the January AAS meeting in
Washington, DC.   Feel free to call or email me at any time.  Thank you.

 Megan Watzke
 Chandra X-ray Center Press Officer

 When Should a Chandra News Release be Issued?
 1. Presentation at a major scientific meeting.
 If you know of a potentially interesting result that is to be presented
at a meeting, please contact Megan Watzke as soon as possible.  The
Chandra X-ray Center (CXC) does not need to wait for an invitation from
meeting organizers to write a press release.  If we know of a particular
exciting result, we can then ask the AAS to consider us for a press

Additionally, press officers for a scientific meeting (usually the AAS's
Steve Maran or Lynn Cominsky) send out emails to scientists about the
potential newsworthiness of a submitted abstract.  If you are contacted
by Steve Maran or Lynn Cominsky for the January AAS meeting, for
example, please follow the procedures outlined below.

2. Acceptance of a paper to a scientific journal.
If you plan to submit a paper to Science or Nature, please contact Megan
Watzke immediately.  These journals have strict policies about
publicizing their publications and the more advanced the warning the CXC has
to work with these journals the better.  Please contact Megan with any
other potentially newsworthy papers once a paper is submitted or
immediately after notice of acceptance.

3. Breaking story or time-sensitive discovery.
This is probably the trickiest situation for a press release.
Occasionally, there might be a Chandra result that should be rushed
through the system.  However, this situation is rife with the potential
for the need to retract--something that NASA and CXC would like to
avoid if at all possible. However, if there is a result with any
urgency, contact the CXC Press Office immediately.

Procedures for Chandra News Releases:

If you determine that your Chandra data might warrant a press release,
get in touch with CXC Press Office at 617-496-7998, or send email to
mwatzke@cfa.harvard.edu.  At this point, the CXC Press Office will
consult with NASA HQ and MSFC to decide the best organization to put out
the release.  NASA has first right of refusal for any newsworthy
information, which means that NASA HQ needs to review any potential
press release.  If NASA does not choose to issue the release, CXC/MSFC
may choose to issue the news via its Press Office. Whether the release
is issued as a CXC/MSFC or NASA/CXC/MSFC release, Megan Watzke will be
responsible for consulting with the scientists, preparing the release,
and getting final drafts approved by appropriate parties. The CXC/MSFC
will also make sure the release goes out to media outlets and that
release and images are posted on the chandra.harvard.edu and
chandra.nasa.gov websites.

If the CXC Press Office passes on doing a release, then the Principal
Investigator (PI) has the option to ask his/her organization's News
Office (also called Public Information Offices in many institutions) to
write a release.  As additional support, the NASA Structure and
Evolution of the Universe theme employs a science writer, Christopher
Wanjek (wanjek@gsfc.nasa.gov), who can either write the release or work
with a News Office to prepare a draft.

A copy of the release and any accompanying images must be sent to the
CXC Press Office as soon as possible, so that the CXC Press Office, NASA
HQ and MSFC can be aware of all Chandra-related news being
disseminated.   Please keep in mind that in this situation, the PI would
be responsible for all images, websites, etc. regarding the release.
The CXC may mirror the release on its public site as well.

In any case, Megan Watzke will inform the News Office of the Principal
Investigator whenever a press release involving that Principal
Investigator is being written, and will assure that the News Office of
the Principal Investigator is included when circulating drafts for

More information on Chandra press release guidelines can be found on the
Chandra website at


Megan Watzke


Item 4.  Location of ASPSOL and OBCSOL files    

There has been some confusion recently about the use and location of
the ASPSOL and OBCSOL files (filenames pcadf*asol.fits and
pcadf*osol.fits, respectively) in Chandra data distributions.
"ASPSOL" and "OBCSOL" are the values of the CONTENT keyword in their
headers, the official way to distinguish data products.

The ASPSOL files are the result of ground-based aspect analysis 
using all PCAD data. The OBCSOL files are based on aspect determined 
by the On-Board Computer (OBC).  Ground processing gives a better 
product, clearly, because more information is available.

ASPSOL has been  moved from the Secondary to the Primary
Data Products category because it is essential for 
making exposure maps. This change took place in June 2001 for ChaSeR,
Nov 2001 for the provisional archive interface and in Sept 2000 in propietary 
datasets. The Primary Products are now all you 
need to run any of our Threads, as was the original CXC intent
(ASPSOL was the only hold-out in that respect).  The OBCSOL files were
left in the Secondary category, where they belong.

Arnold Rots

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Last modified: 12/03/10

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