Tuesday, September 04, 2007

Sitting on a TAC

I spent my Labor Day weekend doing a lot of reading, because I will soon be sitting on a TAC. No, no, no, I will not be sitting on a thumbtack, a but a TAC. I guess I should explain.

Astronomers are not just freely given nights at a telescope or time on orbiting satellites. There is a well-defined process to getting this time. It starts by the astronomer developing a project to do on the telescope. Then she/he writes the project down in a few-page summary we call a proposal.

The proposals from all astronomers interested in using a telescope in a given time period (usually 6 months or a year are dealt with at a time) are collected and given to a committee, the Time Allocation Committee, or TAC. This committee is made of astronomers who are familiar with either the science and/or the telescope in the proposal. The committee reads all of the proposals, talks about how important the science is, whether the science can be done on a given telescope, and whether a project represents the best use of a given telescope.

For example, one proposal may have the best science, but is not technologically feasible. Another proposal may be good science but requires 95% of the telescope for the next year. Another proposal may be okay science but could be done with a smaller telescope. And another proposal may be poorly written. So time goes to the remaining dozen proposals that do reasonable science in a reasonable amount of time.

I've been asked to be a member on a TAC that meets later this month. I have a few dozen proposals I need to read through, and a handful that I need to read in detail so I can lead the discussion about those particular proposals. The assignments (which proposals I have to read and which ones I have to lead discussion on) were made by other people, so I have a wide mix of things to read, some of which I know a lot about, some of which I don't know much about. And I will get to spend two full days talking about all of these proposals with the rest of the committee, which doesn't sound like a lot of fun. But it is an vital bit of community service, so I'm willing to do my share.

This is the first time I've been on a TAC, so it is a bit nerve-wracking. I want to make sure to do all the preparations I need to and make sure I give each proposal the consideration it deserves. At least it will keep me out of trouble for the next few weeks!


  1. I remember that your proposal to use the Hubble was approved. Does having your personal proposals approved improve your chances of being invited to sit a TAC more likely? Once you have sat on a TAC, does that improve your chances of having your personal proposals being more highly regarded as containing "good science" the next time they are considered for approval? I am thinking about the prestige factors involved among astronomers and how those might help determine good science or not as good science.

  2. It is likely that having successful proposals increases your chance of being on a TAC, since the people who organize such things will likely recall your name. But sitting on a TAC should not increase your chances of having proposals approved, any more than being a good juror would increase your chances of being acquitted of a crime in a jury trial. But I could imagine the opposite happening. If you are on a TAC and do a lousy job, such as not preparing, making stupid comments, or other such misbehavior, that could well be held against you.
    In astronomy, people tend to be very good at separating good science from other issues much of the time. If you have a proven track record of good science, that might enhance your chances of being successful, but merely serving on a TAC probably won't (and shouldn't).