Galaxies in the Shapley Supercluster
A point pattern recording the sky positions of 4215 galaxies in the Shapley Supercluster.
data(shapley)
shapley is an object of class "ppp"
representing the point pattern of galaxy locations
(see ppp.object).
shapley.extra is a list containing additional data
described under Notes.
This dataset comes from a survey by Drinkwater et al (2004) of the Shapley Supercluster, one of the most massive concentrations of galaxies in the local universe. The data give the sky positions of 4215 galaxies observed using the FLAIR-II spectrograph on the UK Schmidt Telescope (UKST). They were kindly provided by Dr Michael Drinkwater through the Centre for Astrostatistics at Penn State University.
Sky positions are given using the coordinates Right Ascension (degrees from 0 to 360) and Declination (degrees from -90 to 90).
The point pattern has three mark variables:
Galaxy magnitude (a negative logarithmic measure of visible brightness).
Recession velocity (km/sec) inferred from redshift, with corrections applied.
Estimated standard error for V.
The region covered by the survey was approximately the UKST's standard quadrilateral survey fields 382 to 384 and 443 to 446. However, a few of the galaxy positions lie outside these fields.
The point pattern dataset shapley consists of all 4215 galaxy
locations. The observation window for this pattern is a
dilated copy of the convex hull of the galaxy positions,
constructed so that all galaxies lie within the window.
Note that the data contain duplicated points (two points at the
same location). To determine which points are duplicates,
use duplicated.ppp.
To remove the duplication, use unique.ppp.
The auxiliary dataset shapley.extra contains
the following components:
UKSTfieldsa list of seven windows
(objects of class "owin") giving the UKST standard survey
fields.
UKSTdomainthe union of these seven fields,
an object of class "owin".
plotita function (called without arguments) that will plot the data and the survey fields in the conventional astronomical presentation, in which Right Ascension is converted to hours and minutes (1 hour equals 15 degrees) and Right Ascension decreases as we move to the right of the plot.
M.J. Drinkwater, Department of Physics, University of Queensland
Drinkwater, M.J., Parker, Q.A., Proust, D., Slezak, E.
and Quintana, H. (2004)
The large scale distribution of galaxies in the Shapley
Supercluster.
Publications of the Astronomical Society of Australia
21, 89-96. DOI 10.1071/AS03057
data(shapley)
if(require(spatstat.geom)) {
shapley.extra$plotit(main="Shapley Supercluster")
}Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.