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Suzaku Guest Observer Facility

Call for Suzaku Proposals

                                                                  2005 November
Announcement of Opportunity for observations with the X-ray astronomy satellite Suzaku

1. Overview

This announcement solicit proposal for observations using the Japanese-US X-ray astronomy satellite Suzaku, which was successfully launched into orbit on 2005 July 10.

During the course of commissioning, all helium cryogen was lost from the X-Ray Spectrometer (XRS), the highest resolution X-ray spectrometer to date. The XRS team believes they have identified the immediate cause of the cryogen loss, but the underlying cause is being investigated by committees both in Japan and in the US. The remaining instruments, 4 X-ray CCD cameras (X-ray Imaging Spectrometer, XIS) and the Hard X-ray Detector (HXD) have been commissioned successfully by mid August. Since then, we have performed calibration and verification observations, which confirms that Suzaku has high sensitivity over a wide energy range as planned. This has already published on newspapers, on ISAS/JAXA and NASA/GSFC web pages and on other venues. The current strengths of Suzaku can be summarized as (1) highest sensitivity to date for hard X-rays (10-300 keV); and (2) higher sensitivity and spectral resolution in the soft X-ray band (0.3-0.8 keV) using a new generation backside-illuminated CCD chip. We have already started normal observations in September; we plan to begin open observations starting in 2006 April, after roughly 7 months of performance verification observations.

Although Suzaku (then called Astro-E2) observing proposals were solicited, selected, and announced in 2004, the selection process emphasized the use of the XRS. The selected proposals may or may not represent the best use of the HXD and the XIS, and the observation parameters may or may not be optimized for these instruments. We are therefore starting anew with this solicitation; the results of the earlier solicitation will be disregarded.

This first announcement of opportunity is for a one year period starting 2006 April. The deadline and other details are described below. We invite application from researchers in a wide range of field.

This is one of three parallel announcements, and solicit proposals from researchers affiliated with a US institution.

Researchers in ESA member countries should consult the version at ESA.

Researchers based in Japan, and all non-US, non-ESA countries, should consult the version at ISAS/JAXA.

2. The Suzaku X-ray Observatory

The Suzaku satellite carries five X-Ray Telescopes (XRTs) that focus X-rays up to 12 keV with a high efficiency, and one unit of XRS and 4 units of XIS (X-ray CCD Cameras) at their foci. Although we have unfortunately lost the use of the XRS, one unit of XIS has a high sensitivity and good spectral resolution for soft X-rays below 0.8 keV, a capability that is superior to those of Chandra and XMM-Newton. At the same time, the HXD has unprecedented sensitivity in the wide energy range up to several hundred keV. The wide bandpass coverage with the XIS and the HXD is an important characteristic of the Suzaku mission, so we invite observing proposals that make strong use of their sensitivities. The details of the instruments (Technical Description document), and a list of targets that have been observed or will be observed within the SWG time (see below) will be published on the Suzaku GOF home page in the very near future.

3. Mission Phases and Time Allocation

The Suzaku mission has been developed as a Japanese-US collaboration, and the Science Working Group (SWG) that consist of researchers involved in the development and operation oversees the project overall.

The mission is divided into three phases.

(i) Phase 0, from the launch through end of 2005 August, when the mission operation focused on in-orbit check-out of the spacecraft including the attitude control system, and the initial operations of the scientific instruments.

(ii) Phase I, from 2005 September through 2006 March, is the performance verification phase. During Phase I, observation program is chosen exclusively by the SWG, to verify the performance of Suzaku instruments, and to observe typical targets.

(iii) Phase II refers to the period after 2006 April, in which observing time is 100% open to the community. We plan to solicit proposals once a year; this is the first such announcement (AO-1). The time is divided into Japan, US, Joint Japan/US; furthermore, a fraction of Japanese time is allocated to European (ESA) solicitation. The following summarizes the time allocation through AO-1.

Mission PhasePeriodSWGJapanUSJ/US
Phase 0 2005 Jul 10-2005 Aug 0 0 (0) 0 0
Phase I 2005 Sep-2006 Mar 100 0 (0) 0 0
AO-1 2006 Apr-2007 Mar 0 50 (8) 37.5 12.5

The total time available for proposals is calculated after subtracting Observatory Time (4%; for satellite maintenance and other similar purposes), 3% set aside for ongoing calibration observations, as well as Director's Discretionary Time (5%; for gamma-ray bursts or any genuinely unpredictable events, and other important observations granted at the discretion of the mission director).

During AO-1, the available (88% of total) time will be divided into (1) 50% for Japanese observations; (2) 37.5% for US observations; and (3) 12.5% for joint Japanese-US observations. The joint time will be used if proposals were received for the same target both in Japan and in the US, and if both PIs accept such merging (the proposal form will have a check box for the PI to indicate yes or no). This allocation is based on an ISAS-NASA agreement. Additionally, 8% of the observing time is allocated to proposals submitted to ESA as joint Japan-ESA observations, thus the purely Japanese time is 42%. This means that the total available to US researchers is 4396 ks, plus 1465 ks of joint time, assuming 37 ks of good time per day and 360 days of operation per year. Proposals from non-US, non-ESA countries will be accepted within the Japanese time up to the ESA portion.

4. Observing Constraints

The Suzaku Science Working Group (SWG) have decided the target list of observations during Phase I. Proposals to observe targets in this list is allowed, but must include a justification for an additional observation, such as a much longer exposure, different pointing within an extended object, or different observing window of a variable object.

The length of the observation should be justified based on the specific scientific objectives, preferably using simulations. However, we set the minimum observing time at 10 ksec, considering the efficiency of satellite operation. There is no upper limit to for the observing time, but longer observations will naturally require stronger scientific justifications.

It is possible to specify the time of observations (time critical observations) to observe specific phases or for simultaneous observations.

Target of opportunity (TOO) proposals are allowed for short-lived events on known objects whose timing is uncertain. The name and coordinates of the object(s) as well as the triggering conditions must be specified. We also require the estimated probability during AO-1 of such an event, as well as its duration. Generic TOOs without a specific target (such as "a nearby supernova") will not be accepted.

Gamma-ray bursts or any genuinely unpredictable events may be observed outside the proposal process, as part of the 5% Director's Time. Details mechanism for applying for such observations will be published later. Data from such observations will not have a proprietary period.

5. Review Process and schedule

The deadline is 2006 January 6 at 5 pm EST for proposals submitted to NASA. After the US national review, a Japan-US merging committee will be convened in March, and the final observing program will be published soon thereafter.

Accepted proposal will be classified into three categories. Priority A targets will be preferentially observed during the AO-1 period (2006 Apr to 2007 Mar). Priority B targets will be scheduled in this period as far as possible, but may be carried over to the following AOs. Priority C targets will be used as fillers when there are gaps in the schedule. For the total available time T, we will adopt 0.5T, 0.4T, and 0.5T as As, Bs, and Cs (for a total oversubscription by 40%). If the actual amounts of observatory, calibration, and director's times add up to less than 12% that is set aside, then the remainder will be used to observe additional C targets.

TOOs and time critical observations will be accepted only as priority A targets.

6. Data rights

Observers will have exclusive rights to the data for a 1 year period after receipt of data, after processing. This, however, does not apply to real time TOO observations and for Gamma-ray burst data. We will deem an observation complete if 90% (for A targets) or 70% (for B targets) of the proposed time is obtained; however, this is subject to revision with experience.

                                                               Kazuhisa Mitsuda
                                                             & Hideyo Kunieda

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This file was last modified on Wednesday, 25-Jan-2017 10:47:39 EST

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