Chandra X-Ray Observatory

CXC response to CUC Recommendations following 2007 Sep CUC Meeting

> 1) LARGE AND VERY LARGE PROJECTS : The CUC is mindful of the need to
>     allow for ambitious projects that may produce very high-impact
>     results while not adversely affecting the community's ability to
>     perform the more modest (but still significant) investigations that
>     are often proposed as LPs.  The CUC supports the care exercised by
>     the Director in considering modifications to the LP and VLP
>     programs.
>     RECOMMENDATIONS : The CUC recommends that the 3Ms "barrier" between
>     the LP and VLP programs be removed.  In other words, the LP and VLP
>     proposals should be allowed to openly compete for a 6Ms pool of
>     observing time, with the peer review deciding upon the division of
>     time between the two categories depending upon the scientific value
>     of the proposals.  We believe that this will promote (or at least
>     make possible) ambitious projects requiring ~3Ms of observing time
>     while, at the same time, ensuring that only the most worthy of such
>     projects with extremely high scientific return are selected.

This open pool has been implemented, as described in the Call for
Proposals for Cycle 10, Section 4.2, 4.3 and also noted in "What's
New", Section 1.5. 

> 2) SPECTROSCOPIC OBSERVATIONS : A portion of the user community
>     continues to feel that the high-resolution spectroscopic
>     capabilities of Chandra are under-utilized, and that the basis for
>     this under-utilization is a perceived difficulty in winning a
>     spectroscopic proposal (which usually requires significant
>     observing times).  The CUC notes that the percentage of successful
>     grating proposals is similar to that of non-grating proposals,
>     which does not support the hypothesis that grating proposals are
>     more difficult to win than non-grating proposals with the exception
>     of Cycle 9 when HETG success rate decreased substantially.
>     However, we caution that the community is extremely sensitive and
>     responsive to both real and perceived trends and/or biases in the
>     review processes, and so many potential grating proposals may not
>     even be submitted as a result.
>     At a previous CUC meeting, we recommended that the awareness of the
>     community to the promise of high-resolution X-ray spectroscopy be
>     increased via a scientific workshop.  The CUC congratulates the CXC
>     and the Scientific Organizing Committee on running a successful
>     workshop in July 2007 on X-ray Grating Spectroscopy.
>     This meeting was a valuable forum in which to present the most
>     exciting results that have been obtained from X-ray grating
>     spectroscopy, as well as discuss future potential.  Unsurprisingly,
>     however, the conference attracted scientists who were already
>     well-acquainted with high-resolution X-ray spectroscopy.  We
>     encourage the CXC to continue to explore ways of increasing the
>     awareness and use of grating spectroscopy, most especially to the
>     parts of the community that have not traditionally been engaged in
>     this field.  This could involve more outreach at more
>     general-interest conferences, improved documentation for existing
>     software, or other methods.

We have taken this recommendation under consideration, and 
outline 4 key points A-D below, but we will continue to evaluate further
methods, and entertain suggestions.

A) GRATINGS ATLAS.  Pipe-line reduced science products from archived
gratings observations can also enhance the scientific productivity
from these data, and lower the bar for scientists unfamiliar
with their reduction/analysis.  For the HETG at least,
X-Atlas covers all object types and all Cycles now
        About the X-Atlas Catalog
X-Atlas is a database of the X-ray spectra of over 250 observations
made with the High Energy Transmission Grating (HETG) on the Chandra
X-ray Observatory. The atlas is intended to present an array of
high-resolution spectral morphologies and line identifications for the
rapid characterization and comparison of X-ray spectra. In addition,
each high-resolution dataset has been convolved with the response of
the ACIS detectors to match the low resolution of the ACIS image data,
potentially allowing for further understanding and classification of
sources observed by ACIS without the benefit of the gratings.  An
extension of X-Atlas to encompass the (less-numerous) LETG
observations is in the planning stage.

B) PUBLICATION RATE.  Wider scientific interest is enhanced when
gratings observations reliably result in refereed publications. 
We are analyzing the publications resulting from Chandra gratings 
observations, and will contact PIs to ask their plans in cases where no
publications have resulted within 2 years of their observations.

Workshop on X-ray Grating Spectroscopy was well-received by those
attending.  An excellent conference summary talk was delivered by
Randall Smith, linked at
Still, those attending already had a strong interest in
high-resolution X-ray spectroscopy.  We are planning on a simple 
email survey of the attendees to ask them for their suggestions for
enhancing the number of good gratings proposals and/or increasing
their success rate, including ideas for expanding the pool of
interested scientists. 

We have contacted the 2007 Workshop participants to remind
them of the opportunity for proposing a special session at the
2008 HEAD AAS.  

> 3) CHANDRA SOURCE CATALOGUE : The CUC continues to believe in the high
>     scientific value of the Chandra Source Catalogue, and commends the
>     CXC on making progress on the construction of this catalogue.
>     RECOMMENDATIONS : The CUC reiterates its previous recommendation
>     that, barring unexpected mission-critical occurrences, the
>     CXC/SDS/DS should commit to remaining on the current schedule.  We
>     also recommend that the catalogue requirements and specifications
>     document as well as science study reports be made publicly
>     available as soon as possible and linked to the CXC website.
>     The CUC recommends that the CXC explore including research based
>     primarily on the source catalogue within the purview of the
>     Archival Program.  As there may be significant interest in the
>     broader multiwavelength community to use the new catalogue as part
>     of a larger study, the question of how closely related such a
>     proposal must be to Chandra should be explicitly considered by the
>     CXC.

We included notice in the Cycle 10 CfP (What's New and Section 4.7.1)
that the Source Catalog would be released during 2008 and encouraging
submission of archival proposals which make use of the catalog. 
A web page describing the catalog is in preparation.
>     extremely satisfied with the highly professional and competent
>     manner in which the mission planning team manages a complex set of
>     constraints.  The CUC supports the steps taken by the CXC to
>     sub-classify "constrained observations" into easy, average and
>     difficult constraints.  We also agree with the decision made during
>     the peer review process to combine the easy and average constrained
>     time in order to achieve balance between these two categories.
>     RECOMMENDATION : The CUC requests an update at a future meeting on
>     the practical implementation of the sub-classified constrained
>     observations, and whether the sub-classification of constrained
>     observations aided the mission planning team in a meaningful
>     manner.

At the next meeting, Mission Planning will comment at least on
difficulties encountered when building the Long Term Schedule (and
how/if the new constraint classifications may have helped).  This
revised classification of constraints was done for Cycle 9 targets,
and we are just now starting to observe them.  It is really as the
year unfolds that we get a sense of how difficult the constraints are
(largely by dealing with TOOs, DDTs, and other replanning efforts). 

> 5) CIAO : The CUC continues to be extremely satisfied with the highly
>     professional and competent work of SDS and DS.  We are, however,
>     concerned that a large fraction of the user community may feel
>     unable to use the advanced functionality of the new CIAO, Sherpa
>     and CHIPS.
>     RECOMMENDATION : The CUC recommends that the CXC make steps to
>     educate the wider user community on the advanced functionality of
>     CIAO and related packages.  We suggest that this be achieved via
>     CIAO workshops at relevant large meetings (such as the AAS
>     meetings), as well as web-based "advanced science threads" that
>     walk the user through how to script and then execute a particular
>     data analysis task.
>     In addition, the long-term prospects for supporting both Python and
>     S-lang in CIAO seem poor and potentially wasteful to both the CXC
>     and users as eventually one of the two will dominate most uses.  We
>     recommend that the CXC consider a mechanism by which, on the
>     timescale of a couple of years, a decision can be made to support
>     just one of these languagues.

We will continue to have a booth presence at the AAS meetings.
In addition, we expect to have a demo at the HEAD meeting. We expect
to resume the CIAO workshops as resources allow and once the Sherpa 
software is released as a stable version. We continue to
work on web-based science threads and plan to include more scripting 

We expect to review our software, including the specific issue  
of supported scripting languages, within the next couple of years.

> 6) CHANDRA FELLOWS PROGRAM : The CUC is extremely pleased by the
>     success of the Chandra Fellowship Program, with 108 applicants
>     last year for 9 positions.  Chandra Fellowships continue to be one
>     of the top Fellowship programs in the field.
>     RECOMMENDATION : The Chandra Fellows' Symposium is a valuable
>     resource to the community.  The CUC recommends that talks at the
>     Symposium should be recorded and archived.  In addition, the CXC
>     may wish to consider live-streaming of the symposium.  These steps
>     would allow the wider community to benefit from these high-quality
>     presentations.

We requested and received generally positive responses from the Chandra 
Fellows concerning the recording and archiving of their
presentations. As a result we are planning to record and archive the
talks starting in 2008 and are also considering a live web-cast.  
PPT/PDF versions of the talks are posted on the web after the
symposium and so are available to the community. 

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