We invite scientists to participate in Cycle 11 of the Chandra X-ray Observatory’s (CXO) science program. The Chandra program is sponsored by NASA’s Science Mission Directorate (SMD) and managed by the NASA Marshall Space Flight Center (MSFC). The Chandra X-ray Center (CXC), which is funded by NASA via a contract to the Smithsonian Astrophysical Observatory (SAO) in Cambridge, MA, has the responsibility for managing the Chandra science program, carrying out the Chandra Education and Public Outreach (EPO) program, conducting the peer review that recommends the allocation of observing time and funds to the user community, selecting the proposals, and operating the Chandra spacecraft. The Chandra X-ray Observatory is described in Chapter 2.

The funding of all awards associated with this Call for Proposals (CfP) flows from NASA through SAO and the CXC to the Awardees. The CXC is the organizational unit within SAO that carries out SAO’s contractual obligation to operate the Chandra X-ray Observatory and solicit proposals and when used in this document will encompass the NASA/SAO/CXC interrelationship.

1.2     Proposal Review Process: Deadlines and Schedule

Science proposal submission and review will be conducted in two stages to minimize the burden of proposal preparation. For details, please refer to Chapter 5:

·       Stage 1: Involves the scientific and technical merits of the proposed investigation. Evaluation criteria include overall scientific merit, relevance to the Chandra program and the competence of the proposers (Section 7.1).

·       Stage 2: The PIs of those proposals selected in Stage 1 will be invited to submit a cost proposal for the Stage 2 review (Chapter 8) and will also be given an opportunity to submit an Education/Public Outreach (EPO) proposal (Chapter 9).

Table 1.1     Schedule and Deadlines for the CfP Cycle

event	date
CfP Release	15 December 2008
Science Proposal Deadline (Stage 1)	6 p.m. EDT, 17 March 2009
Peer Review	22-26 June 2009
Selected Proposals Announced	Mid July 2009
Budget Deadline (Stage 2)	6 p.m. EDT, 17 September 2009
Cost Review	October 2009
Stage 2 Final Selection	November 2009
EPO Electronic Deadline	5 p.m. EDT, 23 October2009
EPO Hardcopy Deadline	4 p.m. EDT, 28 October 2009
EPO Review	December 2009
Cycle 11 Starts	About December 2009

Late Proposals will not be considered. We recommend submission well before the deadline.

1.3     Summary of the CfP

This CfP solicits basic research proposals for participation in the program for the conduct of space science observations and subsequent analysis of the resultant scientific data from the Chandra X-ray Observatory (CXO). The CfP also solicits proposals for research that makes use of publicly available archived Chandra data and for theoretical and modeling studies related to the Chandra mission. A separate supplementary CfP will be issued following the Stage 1 review to solicit EPO proposals from eligible PIs whose Chandra proposals have been selected in Stage 1. The primary goal of the Chandra mission is the investigation of the nature and physics of astronomical objects as revealed through their X-ray emission.

This CfP offers the opportunity for the submission of seven different types of proposals (Chapter 4) and two types of EPO proposals.

Types of Science Research Proposals:

1. General Observing Projects (GO) involving new Chandra observations, generally (but not limited to) requiring less than 300 ksec of observing time (regardless of the number of objects observed);
2. Large Observing Projects (LP) involving new Chandra observations that require 300 ksec or more (regardless of the number of objects observed) and designated as LPs by the PI;
3. Very Large Observing Projects (VLP) involving new Chandra observations that require 1 Msec or more (regardless of the number of objects observed) and designated as VLPs by the PI;
4. Target of Opportunity (TOO) Projects that are triggered by the occurrence of an unanticipated astrophysical phenomenon (e.g., a supernova);
5. Joint Observing Projects that require multi-wavelength sets of data taken by Chandra and one or more of the facilities described in Section 4.5;
6. Archival Research Projects that use data from the Chandra archives or the Chandra Source Catalog; and
7. Theory/Modeling Projects that seek to better understand and interpret the data that have been taken with Chandra, or that seek to determine what new observations might be taken to test a hypothesis.

The observations selected as a result of this CfP will be implemented during a one-year period beginning about December 2009. Based on guidelines set by the Chandra Observing Policy (Chapter 3), 3.5% (700 ksec) of the on-target observing time available during this cycle is allocated to calibration observations, and 700 ksec is allocated to Director’s Discretionary Time (DDT). Following this allocation, 85% of the remaining time is available for General Observations (GO), and 15% is allocated to Guaranteed Time Observations (GTO). The time available for General Observers (including Large and Very Large Projects) under this CfP is estimated at about 17 Msec. It is anticipated that further opportunities for participation in the Chandra Research Program will be announced annually, including the analysis of the increasing body of archival data.

1.4     Cancellation of the CfP

The CXC reserves the right to make no awards under this CfP and to cancel this CfP. The CXC, the Smithsonian Institution, and NASA assume no liability should the CfP be cancelled or for anyone’s failure to receive notification of a cancellation.

1.5         What’s New in Cycle 11

• Effective Area Files

  We plan to release updates within about a month of this CfP which will impact the effective areas of all instruments. At that time, we will provide an updated CALDB and Proposers' Observatory Guide (POG).

  The updates will affect PIMMS, Effective Area Viewer and proposal threads which use this software, as well as all CIAO software which accesses instrument effective areas in the CALDB. Information on the status of this update and about the updated effective area files will be posted prominently on the Proposer Webpages and on the Cycle 11 Effective Area download webpages as well as described in the POG.  In most cases proposal and observation planning will not be impacted, so that proposers may start by using the tools released with this Cycle 11 CfP. However we recommend that proposers revisit count rate and other estimates or simulations after we have issued the updates and before they submit their proposals.

  The updates involve two issues. The first adjusts the time dependence of the contamination buildup on the ACIS Optical Blocking Filters (OBF) and the second better takes into account a small level of contaminant on the Chandra Telescope (HRMA) that appears to have been present prior to launch.

  1. Contaminant Build up on the ACIS Optical Blocking Filter (OBF):  The primary impact of the change in ACIS filter modeling is to allow for more accurate extrapolation of throughput to future times, bringing it in-line with current measurements using the ACIS External Calibration Souce (ECS).  However, this change will not remove a current uncertainty in the filter throughput below ~500 eV. At the Carbon K-edge, (284 eV) the uncertainty would lead to systematically high, derived column densities at a level ~1e20 cm^-2. For proposers, the lack of an accounting for the additional optical depth results in over-estimated count rates at low energies. We will provide information and guidance to proposers as to the possible effects the remaining uncertainty in the <500 eV absorption will have on predicted feasibility determinations for Chandra proposals with the January release.
  2. HRMA Effective Area:  The primary impact of the change in the telescope effective area is a lower effective area at low energies which will result in lower continuum-derived temperatures for high-temperature thermal sources such as clusters of galaxies, steeper derived power law slopes (~0.1) and a few percent higher derived fluxes. In terms of estimates for proposals, those made with the current release (i.e. before the January update) will over-estimate the low energy (<2 keV) count rate.
• Updates to Joint Time Program
  • Spitzer: With the transition to Spitzer's warm mission, the Chandra review will once again allocate Spitzer time to highly ranked projects whose science requires data from both satellites. The available time is 100 hours. Please see Section 4.5.3 for details.
  • RXTE:   There will be no joint program with RXTE.
  • Suzaku:  Starting this cycle, the Chandra review will allocate up to 500 ksecs of Suzaku time to highly ranked projects whose science requires data from both satellites.  Please see Section 4.5.6 for details.
  • HST: Due to the uncertainty concerning which instruments will be available, proposers are asked to include discussion of alternative(s) in the event that their preferred  instrument is not available.
• RPS updates:
  • Constraint/Slew time tool:  Since the number of time-constrained targets is limited at Peer Review by class (Easy, Average and Difficult), RPS now provides a tool which, given the entered target parameters, generates an estimate of the constraint class of each target and the “slew tax” (pointing overhead) which will be charged at the peer review. Final constraint classifications will be determined by the CXC after the proposal deadline, taking into account all declared constraints, including those that must be specified in the remarks.

  • Monitoring Observations: the specifications for monitoring observations have been simplified to request the observing time, time interval and the maximum and minimum possible time interval for each target.

• Pitch, Roll, and Visibility Tool  (PRoVis): This target visibility interface has undergone a major upgrade and is no longer packaged with the observation field-of-view visualizer (ObsVis).  The new PRoVis adds indicators for the current restricted pitch angle ranges and allows for interactive plot manipulation, parameter updates and cursor readout.  PRoVis is provided to assist in planning your proposed observation, in particular to ensure that any requested time constraints are feasible. However, as always, the detailed Mission Planning will be done by the CXC.

• Maximum Exposure Web Page:  For time-constrained targets which must be uninterrupted, a new web page available (http://cxc.harvard.edu/proposer/maxexpo.html) on the CXC website provides tables allowing estimation of the maximum uninterrupted exposure time for a target observed at a given pitch angle and season.

• Chandra Source Catalog: The Catalog is in production and has been publicly accessible since 8 Oct 2008. Archive proposals (Section 4.7.1) making use of the catalog are welcomed.

1.6     Proposal Submission

Science proposals must be submitted electronically via the Remote Proposal System (RPS) software (cxc.harvard.edu/cgi-bin/RPS/Chandra/RPS.pl), available on the CXC website; see Section 5.3 for more details. Cost proposals will also be submitted electronically using forms available from the CXC website; see Chapter 8 for more details.  EPO proposal submission is discussed separately in Chapter 9.

1.7     How to Get Help

Questions concerning the Chandra mission and requests for assistance in Stage 1 proposal submission may be addressed to the Chandra Director’s Office (CDO) via the HelpDesk at: http://cxc.harvard.edu/helpdesk/  or by email to cxchelp@cfa.harvard.edu.

The full contact information for the CDO is:

Chandra Director’s Office
Chandra X-ray Center
Smithsonian Astrophysical Observatory     Telephone: (617) 495-7268

Garden Street, Mail Stop 6     FAX: (617) 495-7356

Cambridge, MA 02138-1516     Email: cxchelp@cfa.harvard.edu

For questions concerning the Stage 2 Cost Proposals or EPO proposals, please refer to the information in Chapters 8 and 9.

1.8     Relevant Documents and Web Addresses

Documents recommended to proposers for additional information are listed in Table 1.2. Web addresses, which may be useful in preparing scientific, cost, and EPO proposals in response to this CfP, may be found in Table 1.3.

Table 1.2.     Useful Documents

Table 1.3.     Web Addresses