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Suzaku Guest Observer Facility

Call for Suzaku Proposals

                                                                               2006 September
Announcement of Opportunity for observations with the X-ray astronomy satellite Suzaku
International Announcement of Opportunity 2 (AO-2)


The Japanese-US X-ray Astronomy satellite Suzaku was launched by ISAS/JAXA on 2005 July 10, and has since successfully carried out astronomical observations using the 4 X-ray CCD cameras (XISs) and Hard X-ray Detctor (HXD), although the X-Ray Spectrometer (XRS) is no longer operational. Between 2005 September and 2006 March ("SWG phase" - see below), observations were carried out for instrument calibration and performance verification, which confirm the wide-bandpass, high-sensitivity, moderate spectral resolution capabilities of Suzaku. In 2006 April, we entered the 1-year international AO-1 phase of the mission, performing observations based on proposals received from the astronomical community world-wide. We plan to start AO-2 observations in 2007 April, and hereby invite submission of observing proposals as follows.

Scientists in ESA member countires should consult the version at ESA, while scientists in Japan as well as all non-US, non-ESA county should consult the version at ISAS/JAXA.

The Suzaku X-ray Observatory

The Suzaku satellite carries four X-Ray Telescopes (XRTs) that focus X-rays up to 12 keV with a high efficiency, each with an XIS unit at its focus. The XIS has a high sensitivity particularly for extended sources, as well as 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, though non-imaging, 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 (see below) time and AO-1 can be found at the Suzaku GOF home page as well as at the ISAS/JAXA Suzaku home page. We plan to update the Technical Description document, as well as planning tools, with latest information in early October; existing versions should suffice for early planning of proposals, but may not give accurate results when detailed simulations are performed.

Mission Phases and Time Allocation

The Suzaku mission has been developed as a Japanese-US collaboration, and is overseen by a Science Working Group (SWG) that consists of researchers involved in the development and operation. After the end of the SWG phase of the mission (through 2006 March), normal observations during AO-1 were entirely through open proposal process. Similarly, observing time during international AO-2 (1 year period starting 2007 April) is open. This, however, excludes the following categories.

  1. Observatory Time (4%) for satellite maintainance and related purposes
  2. Calibration time (3%) for routine calibration of instruments
  3. 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.
The remainig 88% of total time is available to proposers. This 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, within the "Japanese" allocation, 8% of the total observing time is reserved for proposals submitted to ESA as joint Japan-ESA observations. Thus the purely Japanese time is 42%. The total time 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.

Observing Constraints

Over 200 objects will have been observed with Suzaku during the SWG and AO-1 periods. A full listing can be found on the web. Observations of accepted priority A and B targets are guranteed, while those of priority C targets and Targets of Opportunity (TOOs) are not (see below for definitions of target priorities). Proposals for targets already observed are 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. Proposers with an accepted C or TOO target must re-propose if they wish to ensure that their observations are carried out (these targets are in principle open to competition). If a C target is observed during AO-1 with more than 70% of the proposed time, that observation is considered complete and the target will be subject to the re-observation rule described above. In case a C target has an incomplete observation during AO-1, and is accepted in AO-2 by a different proposer, the two teams will share the data.

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. Monitoring observations (repeated observations with a specified interval) or roll-angle constrained observations are also considered time critical, and must be so flagged on the proposal form.

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-2 of such an event, as well as its duration. Generic TOOs without a specific target (such as "a nearby supernova") will not be accepted. In the same spirit, the number of targets in TOO proposals should not exceed 5.

Gamma-ray bursts or any genuinely unpredictable events may be observed outside the proposal process, as part of the 5% Director's Time. Data from such observations will not have a proprietary period. To request such unproposed TOO observations, please e-mail:
Suzaku Manager e-mail

Review Process and schedule

Researchers based in the US and affiliated with a US institution should submit their proposals to NASA. The deadline is 2006 December 1 at 4:30 pm EST for proposals submitted to NASA. After the US national review, a Japan-US merging committee will be convened in February, and the final observing program will be published soon thereafter.

Accepted targets will be classified into three categories. Priority A targets will be preferentially observed during the AO-2 period (2007 Apr to 2008 Mar). Priority B targets will be scheduled in this period as much as possible, but may be carried over to the next cycle. Priority C targets will be used as fillers when there are gaps in the schedule. For the total available time T, we currently plan to accept 0.5T, 0.4T, and 0.5T as As, Bs, and Cs (for a total oversubscription by 40%). If the utilized amounts of observatory, calibration, and director's times add up to less than 12%, then the remainder will be used to observe additional C targets.

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

Data rights

Observers will have exclusive rights to the data for a 1 year period after receipt of processed data. This, however, does not apply to real time TOO observations or 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.

                                                               Kazuhisa Mitsuda
                                                               Tadayuki Takahashi
                                                             & Hideyo Kunieda

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

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