Minutes of AXAF Users' Committee (AUC) Meeting, June 25-26 1997
Committee members present: Jill Bechtold, Webster Cash, JP Caillault,
Kathy Flanagan, Steve Kahn, Craig Sarazin, Fred Seward, Allyn Tennant,
Mike Watson, Ray White
NASA HQ personnel present: Alan Bunner, Paul Hertz
The status of AXAF was reported by Harvey Tananbaum, ASC Director
The status of the ASC was reported by Roger Brissenden, ASC Manager.
The panel had been asked to review the draft NRA plus the SIN
in advance of the meeting. Their comments and concerns were discussed
in turn. The AXAF NRA is the first to go through NASA's
new, standardized NRA procedure and so will require reformatting
and additional review to make it comply. This will not affect the
procedures for proposers. NASA HQ also feels that Oct 1 is an unlikely
date given the 11 weeks they require to review the material.
"It will be released when it is ready." says NASA HQ.
The AXAF Observing Policy document is ready for approval at HQ and
will be forwarded to the ASC shortly.
Funding of US co-Is on non-US-PI proposals has been misused in the past.
The phase 2 review must affirm that the US co-I is valid and
involved in the project. The standard wording will appear in the NRA
and this will be carefully monitored, if/when necessary a policy will
The AXAF NRA will also include opportunities for optional, linked
but independent proposals for Education and Outreach funds (from a different
pot of money).
A number of recommendations were made concerning specific revisions to
the NRA. The most important conceerned clarification of rules for
targets of opportunity.
SIN and Proposers Guide
The committee expressed concern over the schedule for the SIN and
Proposers Guide, particularly since MSFC also wants a month to review
them. The ASC noted that this material has now been separated from the NRA
and so can be delivered to HQ around Oct 1st. Detailed comments
on the SIN and NRA will be provided by the committee members directly
to ASC User Support personnel.
General comments included:
ensuring we are aiming at the correct audience
ensuring the material is coherent
making sure the Proposers Guide gives essential details on the
instruments, satellite, orbit etc and use the SIN as a more detailed
visibility of earth-blocked region - clear information on this is
needed (and is in preparation)
provide some simulated data (also in preparation and now on WWW)
include moving target/nudge mode description
state minimum overhead time per observation (10-15 mins settling/locking time)
note that time allocation will be based on real time not on-source time
add reference(s) for line diagnostics
suggested additions: sensitivities of instruments, ACIS PSF(E),
analytic estimate of PSF, update references (include SPIE and links)
add "no pileup problem for extended sources"
Proposal Submission Software
There was general agreement that this works well and is familiar to many.
Concern was raised over the complexity of the ACIS parameters. The
documentation needs to be improved and choices for the most common cases
included. This is planned for the NRA once these are known. KF notes
that they (MIT) have 4 common cases which she will provide. Excessive
complex modes should be avoided because this will compromises the
usefulness of the archive. A description of HESF needs to be added to
the RPS help file.
Proposal Planning Tools:
the JAVA interface to planning tools is a major concern. Only 25%
of the committee succeeded in running
the software. This includes those who regularly use JAVA. The ASC needs to
continue debugging to assess the magnitude of the problem.
It could be a disaster at deadline time. The balance between being
current and having users able to use the tools is a hard one to make.
Actions for the ASC:
research and find out how big a problem JAVA is likely to be
research and provide alternatives, eg. remote login to our system,
or downloading CLI versions
warn people up-front and prominently in the NRA of what is required
and strongly recommend that they try out this software early
include system managers in mailings
include print facility since java prevents printing
AUC members might ask 10 friends to try and report back to help with
assessment, but not until after NRA.
The individual tools were discussed. Detailed comments will be made via email.
There was a general positive response to the roll visualizer,
but still concern of JAVA which is needed for realtime update of display.
SIM motion possibilities should be included. Other
suggestions include linking to SPEX and a clean program to take an Einstein
image (eg.) and make it a backdrop.
There was general opinion that MARX is a tool of primary importance.
A 1-2 page walkthrough is needed (KF offered to do this) to help users.
The AUC should be included in beta tests before general release with NRA.
The Committee discussed ways of avoiding conflict of interest
during proposal handling and review. NASA HQ stated that it was very
important that AXAF procedures be ``clean'', and above reproach. The
technical evaluations should concern only the mechanics of instruments
and observation parameters. The contents of proposals should be
accessible to a minimum number of ASC staff, should be strictly treated
as confidential information, and should not be discussed outside of
the peer review.
The ASC will write exact rules for the review including a list of
elements to be considered in the technical review and will send to
NASA HQ and MSFC for review.
As a review model, the Committee considered 500 proposals
split into 8-10 panels, each with about 8 members. There would be one
ASC administrative aide (Ph.D) per panel. There would be duplicate
subject panels so proposers could serve as reviewers. In any panel,
no PIs on that group of proposals could be panel members and Co-I
participation should be minimal. ASC staff participation as peer
reviewers should be minimal. There should be 4-5 panel topics -
probably: AGN and deep surveys, normal galaxies and clusters, normal
stars, accretion sources, and diffuse galactic. The times assigned
each panel might be the median request time, times the number of
Panel chairs and senior people could be picked before proposal
submission. Panel chairs could help choose panel members and could
decide who reviews what proposal.
Technical reviews will be done by instruments and not by subject.
Written results of technical reviews will be available to the panels
and will be sent to the proposers. The peer committee can suggest
changes of instrument or instrument operating parameters to overcome
There was discussion of using outside reviewers for proposals
but most felt that this was not practical for the large number of
proposals expected. The committee felt that it was okay to publish
the list of reviewers after the review (but not the proposal
Budget requests will be considered in a second review. There
is currently $10M available for cycle 1. 200-300 projects would thus
average 33-50K/grant. Foreign proposals are ineligible. Multiple
projects to one P.I. average less than single projects. Phase 2
proposals should contain budget, statement of work, and current and
pending NASA support. The panel for the second review should consist
or one or two members of each first review panel. The first part of
the second review should be done electronically. Somehow, a
level-of-effort should be assigned to each successful proposal;
probably by the phase 1 panel. Care must be taken that the
budget-panel members do not have input regarding money given to
his/her own institution. The ASC will develop rules for the phase II
review and submit to NASA.
The AUC unanimously supported a proposal to have AXAF Postdoctoral Fellowships.
It is valuable for promotion of X-ray astronomy in general and for AXAF in
particular. It is worth dedicating part of the GO budget for support.
The suggested arrangement would be similar to Hubble fellows but with
3 per year and a 3 year tenure. This leads to an estimated $500K per
year steady state budget, about 5% of the anticipated budget for
Key results and some unanticipated results of the MSFC/XRCF calibration
The mirror PSF is not a strong function of energy.
There is a slight misalignment of paraboloids and hyperboloids which
leads to an asymmetric on-axis PSF for shell 6.
The effective area is still 10-20% below prediction, perhaps due to
uncertainty in calibration of BND detectors, this is being studied.
Two misaligned HETG gratings result in small images displaced from
the main PSF
There is a small amount of scattering in the dispersion direction,
0.5% total, so this is a small effect.
The HETG effective area is still being analyzed.
In-flight calibration plans were outlined, suggested targets identified,
and AUC comments solicited. The ASC will email a proposed list
including observing times.
General support was expressed for including some pretty picture-type
observations for publicity purposes. These would be public immediately,
as will all calibration observations.
Emission Line Project
An Emission Line Project was presented and discussed. This is a
proposal to extend the AXAF calibration in order to provide grating spectra
of sufficient quality to calibrate the standard plasma models which are
in use by the X-ray community. This would require adding 150ks of time
to the estimated 350 ks grating calibration. There was extensive
discussion. The argument for centered on "If calibration is done,
do it well." The points against were: The project should be peer
reviewed; it is a large block of time; some data can be obtained in
the laboratory. The committee voted in favor of including this in the
calibration plan (5 to 3, with 2 abstaining) but would like to see
the full in-flight calibration plan in parallel with its review by MSFC.
The HETG team noted that the ACIS finite (40ms) shift time results
in "bleeding" for high count rate sources.
ACIS pileup is still a major concern. The ACIS team is studying it
based on XRCF data. They estimate that 1-10% pileup can probably be
calibrated out. Pileup affects not only the spectrum but also the PSF
since the core will be affected more than the wings.
It is not clear yet how well the HESF/HRC-S will work and, unless
there is a breakthrough in understanding, it should be downplayed
for cycle 1. In-flight calibration will be necessary to supplement
the XRCF calibration in order to understand its performance fully.
It was suggested that the Proposers Guide label this as "only for
AXAF and Snapshot observations
It is not at all clear that AXAF will have gaps in its schedule similar to
those for HST. It was recommended that we hold off on this and to assess the
actual on-orbit observing efficiency. Possible improvements in
efficiency (such as this) can be best evaluated with experience in orbit.
The minimum practical observing time given the overheads of slewing and
locking on to a target (~15 mins) should be advertised.
Last year's recommendations to the Director
Concern was raised over the minimum computer power requirements to run
data analysis software. The ASC needs to check this clearly and be
conservative so that GOs can justify requests for workstations and
prepare properly to handle the data.
New Members of AUC
Ray White has replaced Joe Patterson.
The chair rotation schedule was discussed. The present Chair stated
that an outsider would command more respect from the ASC Director and
from the MSFC Project office and was heartily in favor of such a
change. The AUC was asked for recommendations for a new chair.
If a new Chair can be selected, she/he should attend the next meeting.