The PoPSIcLe Project

The Polyclystic Pilot Survey of Intracluster Light(e)

Check out the PoPSIcLe Poster presented by John Feldmeier at the 197th meeting of the American Astronomical Society in San Diego from Januray 7-11, 2001.

Abstract from the latest observing proposal:

We propose to search for and quantify the properties of the intracluster light (ICL) in galaxy clusters as a function of cluster environment. The ICL is likely formed through tidal stripping of cluster galaxies, so that its properties should be linked both to the dynamical evolution of the cluster and to the distribution of dark matter in cluster galaxies. The structure of the ICL, therefore, should vary between clusters with different physical properties. We will target six rich Abell clusters which span a range of Bautz-Morgan type, from cD-dominated type I clusters to type III clusters where the galaxy population is more uniform. Inasmuch as the presence or absence of a central cD is a signature of the degree of dynamical evolution of a cluster, this sample allows us to probe how the properties of the ICL depend on the cluster's dynamical state. We are requesting 5 dark nights on the 2.1m to reach mu_V=26.5$ mag/sq arcsec in each cluster.


John Feldmeier Chris Mihos
Paul Harding Heather Morrison
Research Aide
Steve Rodney

Galaxy Clusters Observed
Click the thumbnail image for the full-sized image, click the name for info on the cluster.
Steps in the Flat-Fielding Process
(for a complete summary of the image processing done by Steve Rodney over the summer of 2000, please click here)

Images taken on the Kitt Peak National Observatory 2.1 meter telescope in Arizona.

Bias Subtraction and trimming:Using IRAF tools, we removed the electronic pedestal level from all the images and trimmed off the overscan region. more

Zero combination and subtraction: We combined the zero frames for each of the four nights and used IRAF again to smooth out the underlying bias structure which was not removed by the bias subtraction.more

Flat fielding: We combined the flat-field exposures and flattened the data. This initial flatfielding was enough for our first run of image analysis, but a more sophisticated flat-fielding procedure was required to bring the images to the necessary photometric quality. more

With the aid of CWRU post-doc Denise Hurley-Keller, we utilized an IRAF script to produce better sky flats for our flat-fielding. Each iteration of this script produces a sky flat to be used for flat-fielding the cluster images. Successive iterations improve on the quality of this flat. more

Preliminary Image analysis: The images were visually inspected and catalogued. We weeded out any out-of-focus or otherwise unusable images. more

Cluster Image combination: We have combined the images of each cluster into composite images. We began by sky-subtracting the flat-fielded images. We then recorded reference stars in each cluster and marked the coordinates of those stars in each image. This allowed us to shift the images so that they shared a common coordinate system. The images were stacked and added together. more

IcL home

This page created and maintained by Steve Rodney, CWRU.

Last updated on ... January 18, 2001