Group meeting 02 August

Yesterday was the first group meeting and features a news round-up, discussion of some interesting papers and an update on the next group outing!

News Roundup:

1. We got an update on the status of the PAU survey, a project to measure Baryonic Acoustic Oscillations (BAOs, see this paper) and a discussion on how to observe 40 bands simultaneously followed:

How to theoretically design the 40 filters to detect at best the signal from BAOs? How to turn a theoretical filter into a real one? The current technology is such that multiple layers are applied to a piece of glass, but the more layers, the more photons are lost.

A telescope detects light. This light is broken into various wavebands of interest using filters. Every time the light is filtered, all that isn’t allowed through by the filter is lost, so to use multiple filters the light must be split. Each time the light is split, there are two beams, each of which can be sent to a filter, but that divides the amount of light into two. If you use 4 filters, or 4 bands, you needs to split the light twice, meaning that each receiver only gets a 4th of the light, and that gets reduced further by the filter. If you divide it n times you can use 2n filters, each of which get filtered. In the end there are not many photons left for each detector.

So for 40 bands, you need 6 layers of splitting. Most telescope use two, at most three filters simultaneously, which makes the 40 band idea a technological challenge. We are keen to read about how they will address it.

2. An agreement between the International Astronomical Union (IAU) and the NRF was signed last week, officially committing both parties to set up, fund and run the IAU's Office for Astronomy Development (OAD), which will place the global coordination of Astronomy development at the SAAO in Cape Town. This is exciting for us because of the NASSP programme and AIMS, both of which are designed to welcome students from the whole of the African continent, thereby opening collaboration possibilities and help to develop astronomy in all of those countries. The setting up of the OAD is the first step in the implementation of a 10-year plan of the IAU to develop astronomy globally, in which Sub-Saharan Africa receives is mentioned as a region of special focus.

3. The next group retreat will take place at Avalon Springs resort in Montagu. Click this button to add this event to your own Google Calendar:

Image credit: the PAU survey

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