|FUSE Observer's Advisory Committee|
|Meeting Minutes No. 9|
|10 October 2003|
Present: Dinerstein, Dupree, Federman, Harper (chair),
Holberg, Leighly, Prochaska (via conference call), Sembach
(a.m. via conference call), Starrfield, St. Louis
JHU: Blair, Dixon, Kaiser, Kruk, Moos, Sonnentrucker
Sonneborn opened the meeting and informed the committee that the gyro failure in July has passed almost unnoticed, and that the response to the Cycle 5 NRA had been very positive. He noted that Evan Skillman would join the committee at the next meeting.
Mission Status Report
Blair presented a report on the mission status. He reviewed statistics for the extended mission (Apr-Sept 2003), and stressed that survey and observatory programs have kept the total science efficiency near 37%.
The sensitivity has remained very good with all the channels showing a slow decline through the mission life. There has been no detection of degradation resulting from low RAM angle (low declination) observations.
Blair then reviewed the performance of the zero-gyro (ZG) software, which was loaded on 16 April 2003. A problem where cosmic rays caused guide star acquisition problems has been fixed, while an FES reset problem remains undiagnosed. In July 2003 the IRU-B yaw gyro failed with minimal disruption to FUSE, which remained on its time-line - a tribute to the ZG effort. ZG has some impact on the mission, such as the need for more re-acquisitions, some failed acquisitions and lost observing time. Datasets are also taking longer to process. Blair noted that the torque predictions for Satellite control were not always accurate; earlier this week control was compromised such that the telescope pointed in the solar exclusion zone causing the safety doors to close.
The extended mission operations were delayed until the ZG upload and now staffing has been reduced to 16 hours (Mon-Fri). Staffing changes were reviewed. SAA shutdown recoveries have been automated, and the SAA model has been refined leading to an extra clean orbit per day. Blair indicated that a full mission risk assessment, including loss of reaction wheel, old hardware and unsupported software would take considerable resources to remedy.
Blair then reviewed the bright star observing techniques. The SiC-only mode has been used but it is not a standardized technique, while the defocusing technique will be tested in mid-November. A new technique which lowers the detector voltage is being studied. However, Moos cautioned that there could be severe calibration problems. More tests are required for this technique as well.
Cycle 4 and Previous Cycles
Blair reviewed the status of science programs carried over from previous cycles. Many of those carried over suffer from scheduling issues, and some are bright or moving targets. The committee requested that the completion criteria for science programs be reviewed and posted clearly on the GI web page. Because of long delays between Guest Investigators (GIs) being informed that observations were scheduled and the data arriving (or not) at MAST, it was also suggested to Blair that GI's be informed when individual observations are deemed completed.
Sonneborn presented a brief overview of the response to the Cycle 5 NRA. The number of proposals submitted was similar to Cycle 4 but there were fewer new GIs. Several proposals were submitted in response to the new Legacy component. The time over subscription has risen to about 3.3:1.
FUSE 2004 Senior Review
Kaiser led a session on the preparation of the FUSE 2004 Senior Review. The NRA proposal schedule and suggested time-lines for the preparation of the proposal were presented. The committee discussed the best way to present recent FUSE scientific highlights.
Kruk made a presentation of the potential of FUSE to respond to the detection of gamma ray bursts (GRB), especially after SWIFT is launched. If observations are feasible one could obtain an FUV spectrum of a GRB or its afterglow, and it also may provide a background source for IGM studies. Prior to the ZG software this would not have been possible. The committee felt that investigation of predicted FUV flux levels versus time was needed, and if indeed FUSE could play a role then the requirements and implication for FUSE's rapid response to a SWIFT detection be studied further. This session continued in the afternoon.
MAST/FUSE Presentation of Retrieval and Security Problems
The afternoon session began with a presentation by representatives from MAST (Abney, Hauser and White). Abney gave an overview of the MAST ingest and distribution of FUSE (and HST) data. She stressed that the recent extremely long data retrieval times are common to all MAST users. For several months this summer the MAST software and hardware infrastructure was unable to handle the data requests, leading to very long retrieval times. MAST had anticipated the large data volumes generated by ACS, but new Data Archive and Distribution System (DADS) software was severely delayed. Also, later on, it was realized that the hardware was not robust and required upgrading. Specific hardware changes were described. The problem of bandwidth was also discussed; the combination of Mars Outreach pictures, Great Observatories Origins Deep Survey, and DADS used all the available Internet bandwidth causing the data delivery almost to grind to a halt. The median retrieval time in early-July was 2 days, quickly escalated to a week by mid-July, and remained high through mid-September. At this time the new hardware was installed and retrieval times have improved.
FUSE specific problems were then described. The tool for pushing data to MAST had developed intermittent failures, but this is now fixed. FUSE also shared a data ingestion disk with ACS and the disk tended to fill up. FUSE now has its own disk. Most datasets reach MAST from the FUSE pipeline within three weeks.
Two improvements are scheduled for the secure delivery of data to users. Secure FTP will become available with DADS 10.2 (in late November 2003), and DADS 10.3 will support staging of proprietary data (date unknown). The presentation concluded with a summary of areas where MAST will improve its response to users.
Following the presentation there was a discussion with the committee. Dupree noted the very long retrieval times in July/August/September 2003 and suggested that an estimated retrieval time be posted as part of the WEB data request form to inform users of current delays. These delays particularly handicapped FUSE users who were working towards the Cycle 5 deadline in mid-September.
In response to a question as to how things would change based on this summer's experience, the MAST representatives indicated they would communicate with individual projects with respect to deadlines etc. Myron Smith is the MAST liaison with FUSE. It was acknowledged by the MAST representatives that they need to establish more frequent communication with their user community.
Harper stressed the importance of computer security for MAST users, especially those at universities and colleges with little astronomy computer support, and requested that an explicit warning also be posted on the WEB data request form informing users that FTP delivery of data is not secure. The committee enquired how MAST was preparing to deal with further HST instruments, and other missions such as Kepler that MAST is committed to support. The MAST representatives felt that they had installed high capacity, robust, highly redundant hardware that has dynamic flexibility and could cope with those additional data requirements. The committee noted that only one SunFire had been purchased, and that hardware can suffer from single point failures.
[Note added: FUSE Project now has monthly meetings with MAST personnel.]
Susan Neff presented an overview of the GALEX mission. The primary science goals are to study star formation over 80% of the age of the universe, and perform the first sensitive UV all-sky survey covering 90% of the sky - avoiding bright sources. GALEX has both imaging [1.25 degree field of view with 4 arcsec FWHM resolution] and spectroscopic modes [two UV channels 1350-1700 (R~200-350), and 1700-3000 (R~80-150) Angstroms]. Neff then described the GALEX Guest Investigator program which contains both archival and new observations. The NRA will be released in January 2004 and GI proposals are due 9 April 2004. The committee showed much interest in the mission, and discussed the possible synergy between FUSE and GALEX. It was not known what source brightness ranges could be usefully observed by both missions, and Holberg offered to communicate with Neff to establish brightness limits for both imaging and spectroscopic modes.
Dixon presented a review of the CalFUSE pipeline status. V2.4.1 was installed on 22 May 2003. The v3.0 pipeline software, calibration files, and post-processing tools are mostly complete. An important development will be the IDL v6.0 "Virtual machine" which will allow users without an IDL license to run tools such as CF_EDIT. A revised time-line for v3.0 was presented; v3.0 will be released in January 2004. The committee stressed the importance of ensuring v3.0 is available at the AAS Atlanta 2004 winter meeting. Sonnentrucker made a brief presentation comparing spectra reduced with CalFUSE v2.4 and v3.0. The spectra are very similar with the main different being an occasional local improvement in spectral resolution.
Upcoming FUSE Presentations
Sonneborn reviewed the details for the FUSE clinic at the Atlanta AAS meeting. FUSE will have computers at the booth which will be used to demonstrate the latest CalFUSE software. He then reviewed the preparations of the 2004 FUSE science meeting in Victoria BC. The scientific organizing committee has been selected and there has been a good response for the notice of intent for the meeting.
The meeting was concluded with an executive session. Prior to the meeting the Chair had requested of Sonneborn that he respond to the committee with his intended action (where appropriate) to the specific "Recommendations of the Committee" within a couple of weeks of the Minutes being finalized. This request was made to maintain the vitality of the committee, and ensure that actions were made in a timely fashion. Sonneborn agreed.
Harper thanked Wannier and Federman for their service and many contributions to the committee. Harper asked the committee to consider nominations for a new Chair to be elected the end of the next meeting (Spring 2004).
The committee asked Sonneborn to contact the NASA Peer Review Services to inquire about the submission of FUSE Cycle 6 proposals in SYS-EYFUS, especially for overseas proposers. The committee appreciated the MAST presentation but felt that if things did not improve in a timely fashion, then a presentation of the MAST IT officer (Wolff) would be desirable.
Recommendations of the Committee