Magellan Target of Opportunity Program - July 2008

Guidelines for the GRB Target-of-Opportunity Program for Carnegie/CfA Observers


The Time Assignment Committees for the Carnegie Observatories and the Harvard-Smithsonian for Astrophysics (CfA) have allocated interrupt time on the Magellan Telescopes in the 2008B semester to support Edo Berger's study of the properties of Gamma Ray Bursts (GRB). Given the importance of the program and the need to collect as complete a sample of objects as possible with minimum interruption to observers, this note describes the guidelines for these observations to clarify the roles of Carnegie and CfA observers and to encourage their continued collaboration with Edo in this work. We have an opportunity with the excellent instruments on the Magellan telescopes to support Edo's research and to have a major impact on the study of GRB's.

The science goals of the CfA/Carnegie gamma-ray burst follow-up program focus on the rapid identification and spectroscopy of GRB afterglows, with particular attention given to short-duration and high redshift GRBs. Because of the unpredictable nature of GRBs and their timing, as well as changing conditions at the telescope, unusual situations beyond the scope of these basic guidelines may arise. As a result, an open exchange of information between the observer and Edo is encouraged and expected.


Carnegie and CfA observers are strongly encouraged to participate in the GRB follow-up program outlined in this document.
GRB observations should be executed as soon as possible following a request, subject to conditions at the telescope. This is designed to increase the scientific returns of the observation and, given the usual rapid decline in the brightnesses of the GRB afterglows, to save time for the observer. The decision to immediately terminate any long exposure is left to the observer. It is Edo's responsibility to supply information on the urgency of the request and any relevant scientific details. Setup and observing time will be counted in the total of allocated observing hours.
The observer should send a brief account of the total time used (on source and overhead) from the time the observations were initiated to the time the normal program was resumed to Ian Thompson and to Scott Kenyon for each interrupt observation, and to include this information in the usual nightly telescope reports.
Carnegie and CfA observers are encouraged to observe GRB targets for Edo before responding to requests from individuals outside of the Carnegie/CfA GRB program. It is recognized that many observers have ongoing collaborations with non-Carnegie and non-CfA observers who have an interest in GRB's. The success of Edo's program relies on the cooperation of his colleagues, and observers should take this into consideration before responding to other requests for GRB data.
An override observation shall not exceed 1.5 hours, unless agreed to by the observer. A typical request is expected to be about 1 hour (on-source) for spectroscopy, and about 0.5-1 hour for imaging (e.g., search for a short GRB).
Multiple overrides during an individual observing run are possible, for timely followup observations can sometimes significantly increase the value of a set of data on a GRB.
A change of instrument for the purpose of a GRB observation is indicated in the most extreme circumstances (e.g., a very bright high redshift GRB). It is Edo's responsibility to explain the scientific reasons for such a change. The extra time required to switch back and forth will be charged to the GRB program. Such a change can only occur if the second instruments is ready for observations and the scheduled observer is skilled in its use.


Wendy Freedman & Charles Alcock

Directors, Carnegie Observatories & Harvard-Smithsonian Center for Astrophysics

July 2008