[ ESO ] La Silla

Policy for Target of Opportunity Observations


Policy for Target of Opportunity Observations

Doc LSO-POL-MAN-000-001
Prepared Olivier Hainaut, 2002-May-20
Reviewed J. Melnick, J.Breysacher 2002-Jul-01
Released J. Melnick, 2002-Jul-04
Date/issue/author/revision 2003-apr-09/2.2.3/clarified compensation, ohainaut 2003-jan-18/2.2.2/clarified dead line, ohainaut
2002-nov-08/2.2.1/link updated, ohainaut
2002-sep-24/2.2.0/minor changes for Web Form, ohainaut
2002-jul-15/2.1.0/minor changes, visas
2002-may-20/2.0.0/update for SciOp
1999-jan-1/1.0 first official version
1998-jul/0.1/include restrictions
1997/0.0/ internal La Silla policy, Ch.Lidman


1. Preliminary Remarks and Definitions

Target of Opportunity Observations (ToO) are needed to follow-up transient phenomena of great  scientific interest.  There are basically two types of events that trigger ToO:

Because the support scientist on La Silla are already fully occupied with normal observing programmes, ToO impose an additional, often heavy, work load on them. ToO can also consume a significant fraction of a scheduled observing programme.  Therefore, it is necessary to restrict ToO's in order to limit their effect on staff and scheduled programmes, while preserving their scientific return. This document describes the restrictions to be applied at La Silla to achieve this goal.

Also, to ensure the success of the ToO observations, it is critical that La Silla receives all the information needed in the shortest possible time. This document describes the information needed and the procedure to make it available to La Silla.

2. Delegation of Authority

2.1- DDT ToOs

DDT ToO's can only be authorized by the following persons: The normal procedure is that the proponent sends a request to Director's Discretionary Time Committee (DDTC) following the procedure described in the DDT Proposal Page. The DDTC transmits its decision to La Silla. During holiday periods, week-ends, or after working hours in Garching, the proposals are transmitted automatically to La Silla. For these cases, upon receipt of a proposal, the La Silla Shift Leader must contact the La Silla Director to request approval of the observations. When the Director cannot be reached, his authority is automatically delegated to the Head of SciOp, then to the Head of Astro, then to the Shift Leader.

2.2- OPC ToOs 

Only the PI of a OPC ToO program can trigger an observation for that program. For large consortia, the PI can send in advance a list of authorized triggerer. An observation triggered by a Co-I not included in that list will be rejected. Once a trigger is received from an authorized person, the SciOp Shift Leader will check that the requested observations fit within the available time quota for that program.

3.ToO Rules

3.0 Dead line

ToO trigger must reach La Silla before 16:00 local time.

3.1 ToOs on National Telescopes

ToO observations on national telescopes during national time must be requested through the chairpersons of the corresponding committees, to be executed either by the scheduled observers, or by La Silla staff.  In the latter case, the La Silla Shift Leader must be kept fully informed, and s/he will follow the rules described below.

3.2 Trigger of ToO observations

An OpC ToO trigger must be submitted using the ToO Web Form available on the SciOp Web Page, and it must include the name of the Observation Block(s)  (OBs) to be executed. In case these OBs cannot be updated for coordinates of the objects, the coordinates must be included in the form.
A DDT ToO trigger must by submitted following the procedure listed on the DDT page. Once the program is accepted, you will receive further instructions. In case of extreme emergency, a request can be sent to lasilla@eso.org. Ideally, this should include the name of the OB to be executed. However, considering the urgency of the observations, this can be relaxed to a detailed description of the OBs.

3.3 Time spent on ToO

The OPC recommends programmes for telescope time (TT) allocation for OPC ToO observations. The Director (or DDTC) allocate shutter time (ST) for emergency DDT ToO observations. 

3.4 Restrictions

The above restrictions can only be over-ridden by the Director General or the Observatory Director, and this approval will be granted only in very exceptional cases.

To summarize, the table below lists the maximum number of hours that can be allocated to ToOs.

4.Compensation time

Observers of Visitor Mode programs interrupted by a ToO for more than 1 hour TT (per run or 3-night period) may request compensatory observations in "Queue Scheduling" Service Mode by the La Silla Science Operation Department., for a total telescope time less than or equal to the time they lost minus 1h (e.g. a program that has lost 2.5h can request 1.5h compensation). Whenever possible, SciOp will schedule and execute these observations during special nights reserved for this purpose.  The affected visitor will have to submit a reduced "Phase II" package using the ToO Web Form, including
SciOp will attempt to schedule the lost OT on a best effort basis, subject to the usual astronomical constraints (weather, coordinates, moon, etc.).  Since in general it may not be feasible to compensate all the lost time, priority will be given to the observers who lost the largest fractions of their scheduled time. The pending compensations will be declared obsolete and removed from the queue at the end of the visibility period of the OBs.

5- Requirements to ToO PI's

5.1- OPC ToO

In order to be scheduled, an OPC-approved ToO PI must provide the following information:
This Phase II package has to be submitted before the Phase II deadline defined by SciOp, and has to be approved by the corresponding support astronomer.

5.2- DDT ToOs

For DDT ToO proposals, an effort should be made to provide as much as possible of this information, and the PI must be available for questions before and during the observations. The following information must be included in the ToO Web Form

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