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ASCA Guest Observer Facility
MINUTES OF THE ASCA USER'S GROUP
13 May 1998
Building 2, Goddard Space Flight Center, Greenbelt, MD

Prepared by: Alex Brown, Chair

Members Present: Alex Brown, Jules Halpern, Mark Henricksen, Christine Jones, Chris Mauche, Paul Plucinsky, and Kim Weaver

Members Absent: David Burrows, Ed Guinan, Greg Madejski, and Craig Sarazin Others: Keith Arnaud, Ken Ebisawa, Eric Gotthelf, Koji Mukai, Rob Petre, Nick White, Tahir Yaqoob

Welcome - Alex Brown

Those attending were welcomed by the chair and minutes from the previous meeting were distributed. The addition of Edward Guinan (Villanova University) as a new AUG member was announced.

Mission Status - Nick White

ASCA satellite operations continue to be ``nominal''. The satellite orbit should not raise any difficulties until 2003 1. Serious concerns still exist about the instrumental calibration, and these are discussed later. There will be a significant decrease in Japanese ASCA staffing during the run-up to the launch of Astro-E in February 2000 and consequently longer observations will be sought for AO8 to simplify scheduling. The US presence in Japan will continue during AO8. The mechanisms for TOO observations have changed with better patricipation available for US observers. TOOs will become much more difficult by the 2000-1 intervals due to the reduction in mission staffing, but are likely to be still possible for the most important cases.

Proposal Reviews - Past, Present, Future - Rob Petre

Rob summarized the AO6 review process (see handouts). There was an increase in long observations with 10 targets having exposures longer than 100 ksec. The review panels specified C+ targets directly. Of 8 submitted EUVE+ASCA proposals, 5 were accepted with another approved for ASCA only. The merging process was smooth with only six proposal pairs merged. There were three ESA - US clashes that resulted in the ESA target being dropped. All US targets made it into the program with one B/C target becoming C+. Almost all the pool of collaborative proposals came from the US.

AO7 proposals are due on 1998 Sep 1, with the review to be held in early November. Longer observations will be encouraged. Proposal submission is intended to be entirely electronic.
Recommendation passed by the AUG: The AUG supports the use of purely electronic submission with as simple structure as possible.

AO8 will be a 2-year AO covering 2000-2001 and only minimal operations support. Typical observations will be a week long.

Attitude Solution and ASCA Catalogs - Eric Gotthelf

ASCA pointing is stable but absolute pointing is uncertain at the 1 arcminute level. A new solution is being generated that is better by a factor of two. The temperature effects on the star tracker face plate are removed. The corrections will be available on the ASCA webpage and folded into the ASCA catalogs.

The AUG expressed concerns about positional determination between different detectors and instruments. Problems with performing spatially-resolved spectroscopy were a particular concern.

News from HQ - Guenter Riegler

The AUG was told via teleconference that the outlook is improving with funding stable for MO&DA. Until recently very little money was available for augmentations for existing missions via the Senior Review but due to slips in the Explorer timelines $10-20M may be available. Mission launches are running at 6-10 per year for OSS. The future steady state may be 40-50 simultaneously operating OSS missions. Planning for the upcoming (August 1998) Senior Review was outlined. We were told to tie the ASCA proposal directly to the NASA Straegic Plan and to explicitly request items, such as GO support, that the AUG has strongly supported previously.

The AUG expressed their concerns regarding changes in the ADP review process (through which ASCA GO funding is now channeled), including the potential incompatibility of the simultaneous review of ADP and LTSA proposals in the same panels. It was established that the ASCA and ROSAT proposal review sheets would be provided to the ADP panels.

SIS Status - Koji Mukai (see handout)

The CTI effect continues to degrade the spectral resolution and increase the number of flickering pixels. The RDD problem also degrades resolution and detector efficiency. The ftools V4.1 routine correctrdd now allows correction for the effect of RDD for FAINT mode data. RDD maps have been made monthly since September 1995. correctrdd also seems to work for 2-CCD mode data and is better for SIS0 than SIS1.

GIS Status - Ken Ebisawa (see handout)

GIS timing accuracy is better than 200 $\mu$s. There is a long-tern gain decline due to degradation of the quartz windows. GIS background subtraction techniques are evolving but need better background temporal sampling.

GIS/SIS Recalibration - Tahir Yaqoob (see handout)

No self-consistent calibration exists for the GIS, SIS, and XRT. NH estimates from the GIS are unreliable below 1021 cm-2. Ongoing calibration efforts are aiming for a self-consistent calibration obtained by only adjusting physical parameters. This calibration would contain the time-history of the instrumental sensitivity. Direct calibration will be attempted by measuring the Crab spectrum.

Senior Review Preparation

A Senior Review proposal for ASCA support during FY99-02 is due on 1998 July 2 with the Review itself held in August. The AUG discussed extensively strategy and writing assignments to produce this proposal. The proposal preparation would be coordinated by Keith Arnaud. In FY01-02 ASCA would need to move to very reduced operations and much longer pointings.

Next Meeting

The next AUG meeting is expected to be in the spring of 1999.


Note: 1 Subsequent events have overtaken this statement with reentry expected early in 2000 - AB Jan 99

Michael Arida
1999-04-27