|FUSE Observer's Advisory Committee|
|Meeting Minutes No. 4|
|3 November 2000|
Present: Bregman, Deharveng, Dinerstein (replacing Chu), Federman (chair),
Guinan, Harper, Koratkar, Raymond, Robert, Wannier
NASA: Sonneborn, Hasan
JHU: Andersson, Blair, Kruk, Moos, Oegerle, Sankrit, Weaver
Sonneborn opened the meeting by giving the current status of the Mission and plans for Cycle 3. Since May, the observing efficiency (defined as the ratio of on-target exposure time to clock time) is averaging about 30%. He showed the spectrum of BD+28-4211, in which multiple exposures mimicked the smoothing effects of FP-SPLITS/dithering and allowed the attainment of a signal to noise of 100 per resolution element (based on the root-mean-square deviations in the stellar continuum). He discussed the outcome of the June 2000 NASA Senior Review. The budget was increased by $500k for FY02 and a 2-year extension was approved with data analysis funds at the level of 35% of the prime mission.
Sonneborn also described the results of the Cycle 2 GI proposal review, that were recently announced by NASA HQ, and of discussions with review panel chairs regarding Cycle 3 issues. This discussion was in response to a lower than expected number of Cycle 2 proposals and oversubscription. The discussion suggests that the capabilities and early scientific results of FUSE were not widely known at the time leading up to the proposal deadline. The Committee discussed ways to increase the visibility of the Mission's scientific achievements and potential in advance of the Cycle 3 proposal deadline.
The Cycle 3 proposal deadline is expected to be about two months earlier (May) than for Cycle 2 (July). The Committee discussed the desireability of a special category for very large proposals. There was general agreement that all propoasls in the same subject area should be reviewed by the same panel regardless of proposal size. One suggestion was that a block of time be set aside for such large proposals (over 100 or 150 ksec) that would be discussed by panel chairs as a group.
The Committee commended the Project's policies regarding GI program budgets and grants. In particular, they felt that the decision by NASA to make budget allocations for each program at the time proposal selections are announced simplified the work required of the investigators and their institutions and expedited the grant process.
Oegerle gave a report on the status of FUSE and operations. As for the instrument and spacecraft, reboots due to SEUs (Single Event Upsets) occur infrequently (once every month or so). An autonomous high voltage ramp-up in the event of an SEU is being developed. Gain sag is evident in the LWRS, especially at Lyman-beta, but the rate is slower than expected. Since the sag affects calibrations, a high voltage increase in planned. The QE loss at other wavelengths is very low, essentially within the measurement uncertainties. The Inertial Reference Unit-A continues to operate nominally; the decrease in laser intensity is now believed to be on the exponential tail. One of the reaction wheels excited a resonance in the instrument when operated at high speeds. The wheels are now running at lower speeds to avoid the resonance.
Oegerle summarized the status of operations as well. The observing efficiency continues to improve. Mission planning operations has benefitted from the hiring of two new staff members. The Project has taken a cautious approach in archiving the data, and as a result, there were delays last summer getting some observations into the archive. The goal is to have data without problems archived within 48 hrs. and data with problems within 2 weeks. Data checks are now performed automatically, with human follow-up in cases with problems. He also noted that bright objects have their spectra shifted slightly, likely due to the detector electronics. Several recent improvements in operation were noted: 1) can keep all channels aligned in MDRS about 75% of the time, with only a slight loss of observing efficiency from the need for peakups; 2) are developing the capability of attaining signal-to-noise ratios in excess of 30 (S/N ~ 100 may be possible), but this currently requires manual scheduling -- more automated procedures are planned so that this capability will be available for Cycle 3; 3) can now guide on fainter stars and observe closer to orbital noon, thereby improving efficiency; and 4) can observe moving (Solar System) objects.
Blair described the current scheduling efficiency. Overall, there are fewer problems, and those that arise are addressed more speedily. The success rate for operations is now greater than 90%. About 70% of the Cycle 1 GI programs are complete; now the MDRS observations are in the queue. Typical lead times are 7-10 days for short-term scheduling, and constrained targets are tracked earlier now (about 1 month or so). A second GI support person has been hired. Further work is needed in the automation of alignments, FP-SPLITs, and multiple peakups, and improved long-range planning is progressing.
Moos provided a science update. Highlights included the detection of Jovian aurorae in H2 emission, hot gas in the low z Universe via O VI detections (and the consequences for a measure of the baryonic content), an update on the D/H measurements (5 detections and one limit of the dozen sight lines probing the local ISM), the status of H2 measurements in the Magellanic Clouds, and the Gunn-Peterson Effect seen in He II. The Committee also discussed ways of highlighting FUSE results at the upcoming AAS meeting in San Diego.
Kruk summarized the status of the calibration software. Improvements to deadtime corrections and wavelength zero point were noted. HIST data are now corrected for grating rotation, and the installation process for GIs was made easier. The ability to peruse data via GIFs will soon be available; the Committee concurred on the need for this product. A prototype for the astigmatism correction, event burst detection and correction, background subtraction, and optimal extraction are under development, and flat fields still need to be characterized. Available software includes calibration and utility programs. A Web-based plot of the distortion in wavelength calibration, typically 0.030 A, will soon be available.
Sankrit described the development of a FUSE cookbook, which is expected to be made available in February (by the next Data Workshop). The Cookbook will include discussions of faint/bright sources, point/extended emission line sources, and how to run the pipeline with modified parameters. Now that Cycle 1 GIs are seeing their data, this was viewed by the Committee are very timely.
Andersson led the discussion on the next Data Workshop. It is scheduled for 22-23 February and will focus on GI results -- i.e., how data reduced and analyzed by those not associated with the Science Team. More of the presentations will involve science results from both the PI Team and GIs, including a Poster Session.
Most of the afternoon was devoted to issues arising in the reduction and analysis of GI data. The need for a Cookbook was stressed throughout. Harper suggested that the improvements be placed on the Web as soon as possible. Harper and Federman raised concerns regarding the wavelength scales; these, too, should be addressed in the Cookbook. Other points brought up included the question of wavelength solutions for the MDRS and HIRS slits and the ability to do on-the-fly calibrations. It was pointed out that automatic on-the-fly calibrations will be addressed in the future; the Cookbook should suffice in most instances.
The meeting ended with an executive session. The issue of new members was discussed; the consensus was to bring in two members each year, starting with the 2001 Fall meeting. The Committee was pleased with the improvements to the Calibration and Scheduling Programs and endorsed the development of quick-look GIFs. A question concerning the ability of the exported pipeline to generate GIFs was raised, and a graphical interface to the pipeline was thought to be useful. The Cookbook is seen as a much needed tool and its development should proceed as quickly as possible. Better background corrections, before flat fielding, are needed. Finally, a goal for Mission Planning should be to send observers notification of upcoming target acquisitions (on a weekly basis) and/or when the actual observations take place. For example, an automated message could be generated and sent to the PI of each program scheduled in each new MPS.