September 3, 2007
Announcement of Opportunity (AO-3) of Suzaku
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 Detector (HXD), although one CCD camera (XIS) is no longer operational. After the initial operation for instrument calibration and performance verification, which confirm the wide-bandpass, high-sensitivity, moderate spectral resolution capabilities of Suzaku, we entered the international AO phase of the mission in 2006 April, performing observations based on proposals received from the astronomical community world-wide. We plan to start AO-3 observations in 2008 April, and hereby invite submission of observing proposals as follows.
US based scientists should consult the parallel announcement at
while scientists in ESA member countries should consult the version at
Present version is applicable to scientists based in all other
2. Suzaku 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 and 2 can be found at
We plan to update the Technical Description document, as well as planning tools, with latest information in October; existing versions should suffice for early planning of proposals, except that proposers should now assume the use of 3 XIS units, not 4.
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. After the end of the SWG phase of the mission (through 2006 March), normal observations during AO-1, and 2 are entirely through an open proposal process. Similarly, observing time during international AO-3 (1 year period starting 2008 April) is open. This, however, excludes the following categories.
- Observatory Time (3%) for satellite maintainance and related purposes
- Calibration time (5%) for routine calibration of instruments
- Director's Discretionary Time (4%) for any genuinely unpredictable events including gamma-ray bursts, and other important observations granted at the discretion of the mission director.
The remaining 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 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 Japan researchers is 5056 ks, plus 1505 ks of joint time, assuming 38 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 (963 ks).
4. Observing Constraints
Over 700 objects will have been observed with Suzaku during the SWG
and AO-1 peirods. A full listing can be found on the web.
Observations of accepted priority A and B targets are guaranteed, 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 accepted C or TOO targets must re-propose if they wish to ensure that their observations are carried out (these targets are in principle open to competition). It must be noted that if the C target is observed in AO-2 with more than 70% of proposed time, basically it will not be observed in AO-3. If a C target observation is not completed (<70 %) in AO-2, it will be ignored, and new observation will be performed in AO-3 according to the new proposal in AO-3, unless the new author is the same as in AO-2.
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. Longer observations will naturally require stronger scientific justifications. Ordinary proposals can request less than 300 ksec.
In AO-3, we introduce a new category of Long program (L) between 300 ksec and 1Msec to encourage long exposure proposals, mapping of diffuse objects and other types to enhance the strength of Suzaku mission. The observed data of L-program will be open to public immediately for quick analysis by the community. A little different arrangements are planned for L-proposals, such as pages of the science justification, restrictions of time critical observations, and number of referees.
It is possible to specify the time of observations (time critical (TC) observations) to observe specific phases or for simultaneous observations. The monitoring observations can be proposed with certain interval. You also able to chose the roll angle of the optical system. The Suzaku operation team will do their best to perform the observations as requested. In all these cases, you have to put on the TC flag in the application form. If you are considering TC or TOO (mentioned below) observations in L-program, please contact us at,
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-3 of such an event, as well as its duration. Generic TOOs without a specific target (such as "a nearby supernova") will not be accepted. The number of targets listed in a reserved TOO proposal should not exceed 5.
Gamma-ray bursts or any genuinely unpredictable events may be observed outside the proposal process, as part of the 4% Director's Time. Data from such observations will not have a proprietary period. Please make a contact to us for these cases.
5. Review process and schedule
Researchers based in Japan, and non-US, non-ESA countries should submit proposals to ISAS/JAXA. The deadline is 2007 November 30 at noon JST for proposals. All proposals from Japan and other countries will be reviewed in the same process in Japan. After the review in Japan together with the ESA proposals, a Japan-US merging committee will be convened in February, and the final observing program will be published soon thereafter.
Accepted proposal will be classified into four categories. Priority L and A targets will be preferentially observed during the AO-3 period (2008 Apr to 2009 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 accept 0.6T, 0.3T, and 0.5T as L+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
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 L and A targets) or 70% (for B targets) of the proposed time is obtained. As is mentioned above, data of L-program will be released immediately.