The new generation of multi-object spectrographs

Last month I visited Barcelona for a short science meeting to discuss plans to use a new multi-object spectrograph currently being constructed. The instrument is called WEAVE, which stands for WHT Enhanced Area Velocity Explorer, and its going to be constructed on the William Herschel Telescope (WHT) in La Palma.

The William Herschel Telescope in
La Palma (Credit: ING)

The name of the instrument comes from the fact that one of its main goals will be to measure the velocities of stars over large areas, covering millions of stars over huge swathes of the sky. In doing so it will complement a lot of the work that Gaia is doing to measure the distances to stars and their proper motions.

The meeting was very productive and there's lots of interesting science that we're planning to do with this instrument. However, this isn't the only multi-object spectrograph (so-called because they can obtain spectra of multiple objects at the same time, thus making them very efficient instruments!) being constructed at the moment.

In addition to WEAVE there is also 4MOST for the VISTA telescope, MOONS for the VLT, and PFS for the Subaru telescope. There are also plans to build a multi-object spectrograph for the upcoming European Extremely Large Telescope (the E-ELT) called MOSAIC. This won't be constructed for almost a decade, but once operational it'll allow scientists to obtain spectra of hundreds of stars in other galaxies, allowing us to study how stars and star clusters evolve in other environments.

Each of these new instruments will be able to take spectra of hundreds of stars at the same time, allowing scientists to efficiently study the properties of lots of stars. This sort of approach is critical for building up large samples with which to do exciting science. I'm really excited to be part of one of the teams that hopes to do this, there's going to be lots of wonderful science to do!

Surveys, surveys, surveys

I have been in Naples, Italy, this week for a conference about the many wonderful astronomical surveys that have been produced recently. The last decade has been a rich time for survey science, thanks in part to the pioneering surveys at the turn of the century (such as SDSS and 2MASS), but also to the work of new dedicated survey telescopes such as VST and VISTA. These large surveys have provided astronomers with huge samples of stars and galaxies with which to investigate many important aspects of how stars and galaxies form and evolve.

The European Southern Observatory's (ESO) facilities at Cerro Paranal,
including the VLT, VST and VISTA telescopes (Credit: Wikipedia)

It is with one of these telescopes, the VLT Survey Telescope (VST), that I have been using data from over the last few years for the VPHAS+ survey, the VLT Photometric H-Alpha Survey. This is the follow-up survey to IPHAS, the INT Photometric H-Alpha Survey, which I discussed in a previous post.

The VPHAS+ survey was actually the subject of the talk I gave at the conference today. I presented both an outline of the survey and some of the most exciting science results that have come out of the survey in recent years. It was quite an honour to present so much exciting science from across our survey collaboration, and I'm grateful to everyone in the survey who contributed to the work and helped me prepare the presentation. If you want to learn more you can watch my presentation on youTube here (my talk starts at 56:00).

This conference has been a great opportunity to learn both about surveys going on at the moment and some of the surveys planned for the future. As well as the traditional photometric surveys, there are now surveys designed to study how astronomical objects change over time by making repeat observations of the same areas of the sky. Some surveys are already doing excellent work in this area, such as the VVV survey (Vista Variables in the Via Lactae), but there are also some very exciting projects planned for the future, such as the Large Synoptic Survey Telescope (LSST).

Finally, there have been looks to the future of astronomical surveys and particularly the future spectroscopic surveys that will, instead of just measuring the brightness of sources in a few bands, actually take detailed spectra that can be used to determine the physical properties of the sources. The European Southern Observatory, ESO, has plans to convert one of its survey telescopes, VISTA, from being an imaging telescope to being a spectroscopic telescope. This is something that I really look forward to seeing and hopefully using. These are really exciting times for survey astronomy!