The ESSENCE Project
The ESSENCE Project is a 6 year supernova search undertaken using the Blanco 4m telescope at Cerro Tololo Inter-American Observatory. It started in 2002 and finished in 2007. The goal was to discover 200 type Ia supernova in the redshift range 0.2 < z < 0.8 . We have successful detected over 220 Ia's in addition to numerous supernovae of other types.
My work with ESSENCE started off creating a program that would determine a photometric redshift for a transient candidate. This was necessary in order to have an estimated redshift for various classification and follow reasons and until a spectroscopic redshift could be obtained.
The bulk of my work has been with the host galaxies of the supernova. Tucker et al 09a, in prep, will describe the photometric properties of the host galaxies using R and I band photometry and differences between the nearby set of SN used for cosmology. It will also illustrate how these differences can create a bias and affect our cosmological results.
A subsequent paper will use the B, R, I, and z photometry with full photometric properties including a few new techniques and properties for high redshift host galaxies.
We also have undertaken a major campaign to obtain spectra of all the host galaxies. Since so little is know about them, we are aiming to obtain and spectra and thus metallicity and star formation rate measurements of the host galaxies.
As part of my work, I have been working on the photometric reduction and calibration. This will eventually lead to obtaining 1% photometry through out all the images, a project started previously by a postdoc in the group.
Lastly I have been involved with the 6 year final results paper from ESSENCE. The biggest systematic effect, as discussed in Wood-Vasey et al. 07, is that of host galaxy extinction and treatment. We have been working on methods and ways to account for the effect of the host galaxy and to better correct the cosmological results.