Can I change the list of targets of my approved proposal without affecting my scientific goal?
The answer is no for multiple reasons. One is to avoid duplication of observations unless scientifically justified, and conflict/scooping between different scheduled programs. Furthermore, the allocation of time in Service Mode is made to balance pressure factor on each right ascension interval, derived from the distribution in the sky of the targets that the accepted programmes proposed at Phase 1. The Long Term Schedule that results from the time allocation process would thus be invalidated if changes of target were allowed at Phase 2, this is, after the time allocation has been made.
It is however possible to accept a limited number of target change requests in cases for which a sound scientific justification exists, such as the existence of new observations that demonstrate that a given object of the original sample had been misclassified and is no longer relevant to the purpose of the programme. Target change requests are reviewed by ESO to ensure the strength of the justification and also that there is no other approved programme that intends to execute observations of the new target in a similar configuration.
Target change requests must be submitted via a dedicated web form in the Phase 2 preparation tool p2 (or p2ls for La Silla instrument observations). Once logged in to p2 (p2ls) select the Run for which Change Request needs to be submitted. By clicking on the Run, the Change Request menu can be accessed on the top right. A very useful tutorial is provided here.