Vicki Kalogera (Wednesday only)
Nobuyuki Kawai (phone)
Smita Mathur (phone)
Chris Reynolds (chair)
Harvey Tananbaum and Paul Green welcomed the committee on behalf of the CXC. In particular, a new member (Jon Miller) was introduced. The CXC and CUC also thank the retiring member of the committee (Julia Lee) for her service.
Ed Mattison presented the CXC Managers Status Report in which the current status of the CXC and the observatory were summarized. The $2.5M cuts to the FY07 budget were discussed, as were several possible approaches for accommodating these cuts. As before, the CUC continues to be grateful that the CXC is aggressively protecting GO funding in this challenging financial environment.
The spacecraft appears to be operating extremely well, with no spacecraft anomalies during the reporting period. Thermal constraints imposed by the EPHIN, the fuel lines and the focal plane continue to be of concern, but the CXC is doing an admirable job in maintaining observing efficiency.
Belinda Wilkes summarized the current status of the Cycle-9 Proposal Review. A total of 661 proposals were received resulting in an overall over-subscription by time of 5.5. Consistent with previous years, LPs were the most oversubscribed component of the program. It was noted that proposal pressure on the LPs was slightly reduced from previous years in favour of VLPs. The implementation of the new "graded difficulty" levels for constraints observations was also described. The CUC continues to be impressed with the smooth and professional manner in which the peer review and proposal selection process are conducted.
Harvey Tananbaum presented a summary of the use of Director's Discretionary Time (DDT) for the period Oct-06 to Apr-07. The CUC continues to support the Director's approach to DDT and, in particular, supports the use of short DDT observations to localize high science value targets discovered by other observatories.
Harvey Tananbaum discussed the review of White Papers for the Extreme Large Project (ELP) program. A total of 10 White Papers were submitted and formally reviewed by a small panel convened by the Director. The projects discussed in the White Papers were also compared with VLPs and LPs from previous cycles in order to assess the ELP program against the science that it would displace. As a result of this review, the Director has determined that the ELP program is not warranted at this time - a compelling case was not made that any high-profile science question required 5Ms as opposed to the 3Ms that can be obtained via the VLP program. However, the need to encourage the proposing and fair review of longer VLPs was flagged.
The CUC supports both the ELP White Paper review process and the final conclusions of the Director. Recommendations are made below that we hope will encourage the acceptance of longer (and higher-impact) VLPs.
Paul Plucinsky provided an update of ACIS operations which continues to operate extremely well. There were only two small anomalies that were dealt with swiftly. The contaminant on the ACIS filter continues to build up, with marginal evidence for excess build-up above and beyond that predicted from the current time-constant model. The most challenging ACIS-related issue continue to be the thermal constraints on the allowable pitch angle. In addition to the EPHIN and fuel line constraints, solar heating of the SIM is also adding significant constraints to the allowable pitch angle. Mission operations has begun implementing the optional chip shutdown when necessary. In the period Oct-06 to Apr-07, optional chips needed to be turned off in only two observations. It is expected that the number of affected observations will increase. The CUC continue to support all efforts being made by the CXC to alleviate the thermal constraints on the observatory, including the implementation of the optional ACIS chips.
Tom Aldcroft presented a brief discussion about the revision of the default aimpoints. This revision is driven by the slow thermal drift of the optical axis and the desire to keep the default aimpoints away from ACIS node boundaries. The CUC agrees with the rationale for changing the default aim points.
Larry David gave a calibration update. The HRMA and the gratings are deemed to be well calibrated and hence most efforts are directed towards detector calibration. Current activities are focused on improving the calibrations for graded mode and CC-mode data, the early mission T=-110C data, and the formulation of time-dependent corrections for CTI and the ACIS-filter contaminant. The CUC continues to appreciate the excellent work of the calibration group.
Herman Marshall described cross-calibration issues. In direct response to a request from the CUC, the issue of internal cross-calibration between the Chandra instruments was summarized and, indeed, appears to be well in hand. On going progress on cross-calibrating Chandra with XMM and Suzaku were also discussed. The CUC appreciates the informative discussion on internal cross-calibration and is pleased to see the effort with which cross-calibration with XMM and Suzaku is being pursued.
Jonathan McDowell presented the status of work by SDS and Data Systems. In response to the comments from the last CUC meeting, a detailed project management plan for the Chandra Source Catalogue was revealed. The CUC concurs with CXC that this plan appears significantly more concrete and realistic than the timelines and schedules that had been presented in previous meetings. As discussed further in "Recommendation" below, the CUC continues to consider the Chandra Source Catalogue to be of high priority and strongly encourages the CXC to devote the resources required to keep the new revised schedule.
Data processing continues to operate smoothly, with observers typically receiving their data 30-32 hrs after the completion of the observation. The CUC remains impressed by this feat.
Development work on CIAO, Sherpa and CHIPs was also discussed. The need for CIAO-4.0 (which represents a major scrub of the software intrastructure) was detailed. Plans for a phased release of CIAO-4.0 (entailing several beta-releases) were revealed. The CUC supports this phased release plan.
Mike Nowak discussed various development projects within SDS, including a new tool that provides the user with fine-control over the ACIS bad-pixel file. The need for such a tool was specifically highlighted by the last report of the CUC and we thank SDS for their responsiveness.
Finally, Kathy Lestition summarized the press, education, and public outreach activities of the CXC. The utilization of new technologies and trends (e.g., an award winning podcast, image releases timed to maximize the natural cycles of science BLOGs etc.), and the encouragement for Chandra Fellows to participate in EPO (via targeted funds) are particularly noteworthy and commendable. The increasing collaboration with Hubble and Spitzer (including the Great Observatory composite images) is also a very positive trend. The CUC appreciates the extremely high-quality press and EPO activities of the CXC. The CUC also appreciates the response of the CXC to the issue of EPO-proposal password distribution that was raised in our last report. We feel that the new on-line system should be a significant improvement.
The CUC continues to be extremely satisfied with the quality and professionalism of support that the CXC brings to the spacecraft operations, data systems, and the user community. The CUC is also extremely pleased by the responsiveness of the CXC to previous CUC recommendations and requests.
On the basis of the presentations and subsequent committee discussion, we have a number of specific comments, suggestions and recommendations for the CXC.
VERY LONG AND EXTREMELY LARGE PROJECTS : The CUC supports both the ELP White Paper review process and the decision of the Director not to proceed with the ELP program. We are concerned, however, that the psychology of both the proposers and the peer review is strongly biased against the longest (3Ms) VLPs that might produce some of the most important science return of the mission. It seems very unlikely that the peer review process would approve a single 3Ms VLP when the total time available for the whole VLP program is capped at 3Ms.
RECOMMENDATION : The CUC recommends that the total time available for LP+VLP proposals be maintained at 6Ms. However, within that 6Ms allocation, the CUC recommends removing the 3Ms cap on VLPs. In other words, we recommend that LPs and VLPs should openly compete for this time. This would permit the peer review process to accept a 3Ms VLP and still be able to allocate time to a second VLP.
CHANDRA SOURCE CATALOGUE : The CUC commends the CXC for developing a detail schedule for the Chandra Source Catalogue. We remain convinced that the Catalogue will be an important scientific legacy of Chandra. The CUC is concerned, however, that the Catalogue schedule remains very vulnerable to any unexpected events. It has been concerning to see the release date of the Catalogue slip by approximately one year per year, and the CUC worries about a loss of confidence in the CXC's Catalogue efforts by the community.
RECOMMENDATION : The CUC recommends that, barring unexpected mission-critical occurrences, the CXC/SDS/DS should commit to remaining on schedule, issuing a first release of the Catalogue in Apr/May 08 and a complete formal release in Aug 08. If necessary, additional resources should be directed to this effort to maintain this schedule. The CUC consider the release of the catalog to be of higher priority than the development work on CHIPs and Sherpa; if trades need to be made in order to keep to the catalog release schedule these are areas where slower progress would have a relatively modest impact in the community.
RECOMMENDATION : The CUC would like to understand the archival program in more detail in order to assess these concerns and make meaningful recommendations. Hence, we request a specific presentation of the archival program in the Fall 2007 meeting of the CUC, including CXC's opinion as to the goals of the Chandra archival program in the context of the new ADP rules.
THE LONGER TERM FUTURE OF CHANDRA : Despite being 8 years old, the CUC feel that Chandra still has a tremendous potential to make new, high-impact discoveries that will significantly add to its scientific legacy. The CUC supports an active discussion of Chandra's future program amongst the community of users. The XMM-Newton mission recently concluded a 3 day meeting on this topic, reviewing a number of proposed long-term projects that could be completed by that mission. Many of these proposals could benefit from an organized program of joint Chandra observations or followup, although we note it would be difficult to win a "joint" very large proposal via either TAC. Consideration of such issues are especially timely given that Chandra will be included in the NASA Senior Review next year.
RECOMMENDATION : The Eight Years of Chandra meeting in Fall 2007 will be an excellent forum to initiate the discussion of Chandra's long term future science program. The CUC recommends that all invited speakers at this meeting be asked to explicitly address Chandra's future potential for discovery in their specific field of astrophysics. The CUC is aware of and strongly supports previous efforts to collaborate with XMM-Newton, and encourages continuation of these efforts in considering ways to collaborate on longer-term projects (while remaining within the proposal process).