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ASCA Guest Observer Facility

ASCA: Rules for Targets of Opportunity (TOO)


This page describes the current policy and application procedure for a Target of Opportunity (TOO) with the ASCA Observatory. This is a new policy effective from June 1997 which is designed to increase the participation and opportunities for TOOs with ASCA. Prior to this change TOOs had been taken exclusively from the Japanese time allocation, by replacing a Japanese target with the TOO and assigning a Japanese principal investigator (PI). TOOs made from June 1997 onwards will utilize the general observatory time, with the PI designated to be the person who first requested the TOO, following the procedure described below. This will allow more flexibility in the scheduling of TOO targets, and broaden the participation in the data analysis.

About 7% of the ASCA observation time is allocated to observatory time which includes not only TOOs, but also for calibration and completing under exposed observations. Of this time typically 250-350 Ksec/yr is available for TOOs. This means the current capability is about 10 TOO observations/year (20-40 ksec). The TOO observations are compensated by Priority-C targets at the end of an AO cycle.

As has been the case for other observatories, the TOO program is designed to provide quick response to observe unexpected events, that could not be anticipated as part of the regular proposal process. For an ASCA TOO request to be approved requires a strong scientific justification and a clear demonstration that it involves a historically rare event that cannot wait to be included in the next AO cycle review.

The TOO observation will be made during the first available opportunity by replacing the most appropriate PRIORITY-B OR PRIORITY-C target. Only for the most extremely urgent case will we consider replacing a PRIORITY-A target. The operational constraints of ASCA (where up-linked commands can be made during contacts from Japan) mean that this will be at least 3 days after the request is made. The replaced target will be rescheduled in the current observing window if possible, otherwise in the next window typically six months later.

The guidelines to follow when applying for an ASCA TOO are as follows:

  • An e-mail request must be sent to either Fumiaki Nagase and/or Nick White specifying the target name, its coordinates and a justification as to why this target should be observed. Please include as much information as possible that will help to justify why the ASCA observation program should be interrupted.

  • The final decision to proceed will be made jointly by F. Nagase and H. Inoue at ISAS, and N.E. White and R. Petre at GSFC, who in turn will consult with experts in the Japanese and US communities.

  • If the TOO is approved, the PI of the observation will be the person who made the request. In the case of multiple requests for the same target, the designated PI will be the first to send by e-mail a clear description of the goals behind the observation that fully justifies the time request.

  • The ASCA scheduling is made by research staff and students from ISAS and the Japanese University community. To make TOOs places a large burden of extra responsibility on these people, at the expense of their research time. To provide some reward for their efforts and to ensure rapid analysis of the data, one or two CoIs from the ASCA team members will be assigned. Where ever possible these CoIs will be chosen to be experts in the field of science from the TOO. Other CoIs may be assigned with the agreement of the designated PI and the ASCA program/project scientists (F. Nagase and N.E. White).

  • The data from all TOO observations will be sent to the PI. It will be released for public access from the archive 1 year after the observation is made, irrespective of the nationality of the PI.

This file was last modified on Tuesday, 11-Jun-2002 14:08:46 EDT
Curator: Michael Arida (SP Sys); arida@milkyway.gsfc.nasa.gov
HEASARC Guest Observer Facility
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This file was last modified on Tuesday, 11-Jun-2002 14:08:46 EDT

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