Chandra Pitch Angle Restrictions:
Please note that new restrictions on the satellite pitch angle are in place. BEFORE SUBMITTING A REQUEST for either a TOO or DDT observation, please check the pitch angle for your desired target and observing date(s) to be sure your target can be observed. This can be done using the ObsVis tool either on the web or available for download.

• Target of Opportunity (TOO)
• Director's Discretionary Time(DDT)

1. Peer-reviewed TOOs are TOO proposals that were submitted and accepted as a result of the Chandra Call for Proposals (CfP). Since their scientific objectives have already been approved, we require only confirmation of a few details, a brief restatement of the scientific objectives (this because the probability is high that TOOs will get someone out of bed who does not happen to have your proposal on his/her bed table), along with a justification of the particular TOO "trigger".

   If the target details have not been specified, the user must supply the appropriate values (RA, Dec, instrument settings, etc.). The TOO observer is encouraged to use the Remarks box to report any changes in observing instructions, any special observing instructions, instrument parameters, or other alerts that will aid in obtaining a successful observation.

   To submit an RfO (Request for Observation) of this type, please use the Peer-reviewed TOO version of RPS.

2. Unanticipated TOOs are charged to Director's Discretionary Time. These will not have not been previously accepted through the Chandra Call for Proposals. For the unanticipated TOOs, a compelling scientific case must be made for inserting them into the mission timeline. In addition, all pointing and instrument parameters must be specified.

   Please note that this category also applies if you wish to observe someone else's accepted target as a TOO.

   To submit an RfO (Request for Observation) of this type, please use the DDT version of RPS. Please see the instructions for Director's Discretionary Time in the section below.

The decision whether to observe a TOO is made by the Observatory Director or his designated alternate. TOOs fundamentally interrupt the observing timeline (planned at least 72 hours in advance), so considerable work must be done to alter Chandra's schedule.

Modeled on the HST approach, up to 5% of the total Chandra observing time is reserved for CXC Director's Discretionary Time (DDT) observations. This allocation of time includes unanticipated, non-peer reviewed TOOs.

Proposals for DDT should be confined to unique scientific opportunities for which the scientific return might be compromised by waiting to propose during the next Chandra Call for Proposals . Proposals which could reasonably go through the peer review process generally will not be favorably received. The request will be assessed by the CXC director in consultation with the NASA Project Scientist.

Proposals should be submitted using the DDT version of RPS.

A modest proprietary period (of up to 3 months) may be granted by the CXC Director on request. Funding may also be provided for such observations if deemed necessary to facilitate maximal scientific return, following a simple, ad-hoc review which will include NASA representatives.

The Chandra X-Ray Center (CXC) is operated for NASA by the Smithsonian Astrophysical Observatory. 60 Garden Street, Cambridge, MA 02138 USA.    Email: cxcweb@head.cfa.harvard.edu Smithsonian Institution, Copyright © 1998-2004. All rights reserved.

Last modified: 11/16/07