Program: GN-2007B-DD-6

White dwarfs are the end-point of stellar evolution for the vast majority of stars. Once at this stage, the degenerate remnants cool in a well-understood way. The coolest white dwarfs can thus constrain the age of the Disk, or even older components of the Galaxy if they can be found. Around 15 white dwarfs are currently known with effective temperatures around 4000K and ages 8-9 Gyr. Of these around 12 have hydrogen-rich atmospheres. We have initiated a project to identify more very cool hydrogen-rich white dwarfs using the UKIDSS, SDSS and USNO databases. We request 10 hours of dark Christmas DD time with GMOS-N to obtain optical spectra of seven candidates. We expect contamination of the sample to be minimal, and so we expect to find several new cold and old degenerate stars. The results will also allow us to refine our search technique so we can find more such objects in future, larger, UKIDSS data releases.