The week of the HST deadline

Hubble Space Telescope, Image credit: NASA

You might have been wondering why the blog has been so quiet this week. Well, the deadline for another round of proposals using the Hubble Space Telescope (HST) is this Friday, March 1st. Many CANDELS team members are caught up in frantically writing and finishing observation proposals. An observational proposal requires a lot of work. Not only does one have to present a scientifically interesting idea, the so-called science justification, for the use of an expensive facility like the HST, the proposal writers also need to put together a technical justification. The latter includes a more detailed observation strategy that outlines number and length of the proposed observations and which available instruments will be used. Since often many astronomers build a team (just like CANDELS although usually a lot smaller) to propose for their idea, everybody is involved in putting the proposal together and constantly communicates with each other right up until the deadline to make their proposal as strong as possible. For HST several types of proposals can be submitted. The first type is the so-called archival and theoretical proposal, which is mainly a proposal for funding to support one's research. As the name indicates, astronomers base their research idea upon already existing observations in the HST archive or theoretical work that they need support for. The second type is proposing to carry out new observations with HST.

Like all telescopes, observing time with HST (and funding) is highly competitive and many more astronomers will submit proposals than there is time available (or money to spend). However, we won't know which proposals were accepted before the end of May. Once an observing proposal is accepted it has to successfully pass Phase II. This includes working with an assigned program coordinator at the Space Telescope Science Institute in Baltimore, that runs HST, to put together a plan for the observations which then can be scheduled on HST. This observational plan has to be submitted by the end of June, so only about a month after one has been notified that the proposal was accepted. However, a proposal is only fully accepted once all the technical details for the observation plan have been successfully worked out, it has been assured that the same (or very similar) observations are not carried out more than once (e.g. different proposers want to observe the same piece of sky in the same filter bands and depths or an observation exists already in the archive) and it has been checked that all observational requirements are technically possible and feasible for HST. When all these hoops have been jumped through, HST can take the data and astronomers can analyze and interpret it and then publish their results.