3. Observation Policies

The current schedule for the time allocation of the Suzaku mission is given in Table 3.1. For the purpose of proposal selection, we assume 37 ksec of good on-source time per day, and 360 days of operations per year. From the total of 13320 ksec, we subtract 4% of the available time as observatory time used for satellite maintenance and similar purposes, and 3% for ongoing calibration observations. Finally, 5% is earmarked as Director's Discretionary Time (DDT) for unproposed TOOs (including observations of gamma-ray bursts) and other important observations, granted at the mission director's discretion. Therefore 13320 $\times$ 0.88 = 11722 ksec is nominally available to the community via the proposal selection process.

The project will oversubscribe this total by 40% including category C targets whose observations are not guaranteed (see §3.4 below). If the actual observing efficiency is higher than 37 ksec per day, or if less the actual sum observatory, calibration, and director's times is less than 12%, additional C targets will be observed.

Therefore, the net observing time in the current AO available for purely Japanese proposals is 4923 ksec, while US-only proposals will occupy 4396 ksec, with an additional 1465 ksec of joint Japanese-US time. European (ESA) proposals will receive 938 ksec of observing time. Proposals from non-US, non-ESA countries will be accepted within the Japanese time up to the ESA portion.

Table 3.1: The schedule for Suzaku and percentage of time for each group of observers. The ESA time is in parentheses as it is part of the Japanese allotment.

Phase	Months Post-Launch	SWG	Japan (ESA)	US	Japan/US
I (SWG)	1-8	100	0 (0)	0	0
II(AO-1)	9-20	0	50 (8)	37.5	12.5

The nationality of the PI's institution determines which agency should receive the proposal. That is, resident researchers at US institutions must submit their proposals to NASA and those at institutions in ESA member countries must submit theirs to ESA. While the ISAS/JAXA proposal process is primarily aimed at researchers resident in Japan, proposals from researchers in other (non-US, non-ESA) countries will also be considered. In addition, Co-Is from any country may be part of any proposal.

In this AO, 12.5% of the total observing time is set aside for Japan-US joint investigations. When the respective national reviews have selected the same target, the two proposals will be merged if both teams indicated their willingness to collaborate on the RPS form, and the observation will be counted against the Japan-US time. If such mergers do not take up 12.5% of total time, the remainder will be divided between separate Japanese and US investigations.

3.1 Data Rights

The data rights policy for Suzaku is similar to previous missions. The normal exclusive period for both SWG and GO data is one year, except that all Phase Ia SWG science data will be made available at the end of this AO.

During the GO phase, data from calibration and TOOs requested outside the proposal process (see below) will not be considered proprietary. It is also expected that some selected targets from the SWG list will be released immediately to the community, although which targets will be released is not available as of this writing. Please check the Suzaku websites (see Appendix C) for updates.

Data taken during spacecraft maneuvers (often called ``slew data'') will be proceeded and made public immediately. Maneuver data is defined as data taken when the source out of the Suzaku FOV, defined as being more than $1^{\circ}$ away. Observation time, however, will not begin until the source is stable in the FOV.

3.2 Target of Opportunity (TOO) proposals

TOO proposals are allowed for Suzaku through the normal proposal process, although they must be ranked as category A targets (see below) to be accepted, and proposals with TOOs should not be mixed with non-TOO targets. These should only include unpredictable phenomena in a specific target (e.g. SS Cyg in outburst; ``Triggered Observations'' in XMM-Newton parlance), not a generic target (e.g. the next Galactic supernova). The triggering criteria must be explicit and quantifiable, and stated in detail in the proposal text; a brief summary should appear in the Remarks section of the target form. In addition, TOO proposals must provide an estimated probability of a successful trigger during the AO-1 period. It will be the PI's responsibility to notify the Suzaku project when the criteria are met.

The Suzaku project plans to set up a mechanism through which TOO observations can be requested outside the formal proposal review process. Such observations will be performed within the DDT and there will be no proprietary period for such data (see above). This mechanism will allow previously unknown objects to be observed, once a specific object is discovered.

3.3 Pointing constraints

The Solar panels on the Suzaku satellite are fixed. This places a restriction on the pointing direction with respect to the satellite-Sun line: the Sun angle constraint is normally 65 - 110 degrees. This means that at any given time of the year, only a swath of the sky 45 degrees wide is accessible for astronomical observations, and thus most celestial sources are available for observations for about 50 days every 6 months. If a specific observing date or a coordinated observation with other missions is required, the proposer must first determine if the observation is possible. This can be done using the ``Viewing'' tool on the Suzaku proposal website (see Appendix C). Note that a constrained observation must be ranked as Category A (see below) to be accepted.

It is anticipated that long ($>$1 day) observations will be the norm for Suzaku, based on the Suzaku SWG target list. In addition, a large number of short observations is an inefficient use of the satellite because of the unusable time during slews and attitude settling. The pointing is expected to be accurate to 0.3 arcmin and can be reconstructed to better than 0.2 arcmin, except during the initial settling period of up to 10 minutes. Moreover, there is a limit on the number of slews that can be uploaded to Suzaku. For these reasons, a minimum exposure time of 10 ksec has been set for all proposed observations. However, raster observations over a small ($< 0.5^\circ$) area of the sky may be allowed where the individual pointings are at least 3 ksec. For such observations, the total exposure time (which must still be at least 10 ksec) and the number of separate pointings should be entered into the RPS form. Particularly complicated operations may not be feasible; please contact either the ISAS/JAXA Suzaku team or the NASA Suzaku GOF for assistance on difficult or unusual observation plans.

There are also orbital constraints upon the orientation of the projection of the XIS CCDs on the sky. Since the Suzaku XIS arrays are square, with calibration sources in different corners, selecting a specific roll angle is rarely significant. However, if a specific roll angle is scientifically advantageous, the proposer must first determine if it is allowed. This can be done using the MAKI tool described in §4.7. Then the required roll range can be entered on the RPS proposal form. For objects close to the ecliptic poles it is possible to arrange for any XIS orientation by scheduling observations at a specific time, but for those located close to the ecliptic, the XIS will project on the sky in a nearly fixed orientation. Note that any roll constraint will make a proposal time critical. Due to their increased overhead, only a fraction of the total available time can be used for constrained observations, and proposers should justify their requirements carefully.

During a pointed observation, there will be interruptions due to the location of Suzaku in a low Earth orbit. Normally, a target will be occulted by the Earth for $\sim$30 minutes every satellite orbit. In addition, Suzaku will pass through the South Atlantic Anomaly (SAA) during parts of 5 or 6 orbits every day. Due to the harsh radiation environment of the SAA, scientific observation is not possible during SAA passages. There are other variations in the particle background, depending primarily on the cut-off rigidity^3.1. The optimal criteria to reduce times of high background while maximizes the science return is still being determined from SWG observations; please check the Suzaku websites (see Appendix C) for the most up-to-date suggestions.

3.4 Sequence of events after submission

After the Suzaku proposal deadline, there will be three independent proposal reviews for the US, Japan, and ESA proposals. Each review will create a target list from the proposed observations, ranking the accepted targets as category A, B, or C. Only category A and B targets are guaranteed to be observed. As stated above, TOOs and constrained observations are only accepted if they are in category A. Category C targets will be observed as time permits, and will not be carried over into the next AO if not observed in this AO.

Category A observations will be deemed to be complete when they have received at least 90% of the requested time with the XIS or HXD detector, as specified by the user. Category B observations are considered complete after they have been observed with the XIS or HXD for 70% of the requested time. However, these percentages are subject to change as experience warrants. Category C observations are performed on a best-effort basis.

Even though observations are scheduled to acquire roughly the approved exposure time, and ASCA experiences suggest this will usually be achieved with Suzaku, occasional losses of usable observation time are inevitable. Additional observations will be scheduled automatically for non-time-critical targets whose observations are considered incomplete by the project scientist at ISAS. In the case of time-critical observations which are incomplete or unusable, it will be the PI's responsibility to determine the best course of action.

An international merging committee will collate the three target lists and produce a single, unified list. Overlaps between US and Japanese targets will be resolved, either by merging the investigations (if both parties are willing) or by choosing one. In the latter process, the priority given by the national reviews, as well as the lengths of the accepted observations, will be considered. The final target list will be $\sim 40$% oversubscribed. Category A targets will have 50% of the available time, category B 40%, and category C 50%.

US PIs, or US Co-Is on foreign PI projects, may propose for funding once notified that their target has been accepted. This process is described in ROSES 2005 document; further details of this process will be made available on the NASA Suzaku GOF website listed in Appendix C.

Each PI will be assigned a contact scientist, either at ISAS or the NASA Suzaku GOF, who will work with the PI to assure the maximum science return. This will include double-checking coordinates and confirming the XIS configuration. It is important to note that once an observation has been scheduled, any delay in responding to questions from the contact scientist may result in targets being removed from the schedule. Special scheduling request and TOOs will be accommodated on a best effort basis. For simultaneous observations, the mission scheduler at ISAS, in consultation with the contact scientist, will contact the PI in advance for detailed scheduling information, and will often work directly with schedulers of other missions. For this AO, we do not have a mechanism to approve coordinated observations with Suzaku and another observatory through a single proposal. It is the PI's responsibility to secure observing time with other observatories, when simultaneous observations are desirable; the Suzaku component of such a proposal may be approved contingent on the success of other proposals.

Once the observation has been completed, the data will be promptly run through the processing pipeline and put into both the US and Japanese archives, initially in encrypted form. The PI will be sent the decryption key along with instructions on how to download and decrypt the data. The only exception to the one year exclusive period for GO data, in regards to the HXD Wide-band All-sky Monitor (WAM) data (see Chapter 7). The WAM is primarily used for anticoincidence shielding in the HXD, but it can also be used as an all-sky monitor, detecting solar flares, gamma-ray bursts, and other bright X-ray sources (e.g. Cyg X-1). All data from the WAM will be monitored by the HXD team, which will alert the GRB community to any detected bursts. In addition, the HXD team will make analysis results from WAM, such as light curves and fluences, available to the public as soon as possible. These may be used to put limits on GRBs or other events triggered by other satellites or observatories. However, the PI will receive the complete WAM data from their observation and will share data rights with the Suzaku team for the normal 1 year proprietary period. This unusual arrangement is due to the time-critical and non-source-specific nature of the WAM data.

With the exception of the code that converts raw binary telemetry into FITS format files, all Suzaku software will be written as FTOOLS and distributed through the Suzaku team at ISAS/JAXA and the NASA/GSFC HEASARC. This includes the tools used in the processing. All calibration files will be distributed through the HEASARC caldb (Calibration Database) system. This will enable users to apply any calibration updates themselves. The Suzaku team at ISAS and the NASA Suzaku GOF will provide additional FTOOLS that may be necessary or desirable in analyzing Suzaku data. Use of other software packages will only be supported at a lower priority level.