A configuration $(p_q, n_k)$ is a collection of $p$ points and $n$ straight lines in the Euclidean plane so that every point has $q$ straight lines passing through it and every line has $k$ points lying on it. A configuration is astral if it has precisely $\lfloor {q+1\over2} \rfloor$ symmetry classes (transitivity classes) of lines and $\lfloor{k+1\over2} \rfloor$ symmetry classes of points. An even astral configuration is an astral configuration configuration where $q$ and $k$ are both even. This paper completes the classification of all even astral configurations.

A conjecture of Branko Grünbaum concerning what astral (n 4 ) configurations exist is shown to be true.

We describe the design, fabrication, and validation of a cryogenically-compatible quasioptical thermal source designed to be used for characterization of detector arrays. The source is constructed using a graphite-loaded epoxy mixture that is molded into a tiled pyramidal structure. The mold is fabricated using a hardened steel template produced via a wire EDM process. The absorptive mixture is bonded to a copper backplate enabling thermalization of the entire structure. The source reflectance is measured from 30-300 GHz and compared to models.

A simplicial arrangement of pseudolines is a collection of topological lines in the projective plane where each region that is formed is triangular. This paper refines and develops David Eppstein's notion of a kaleidoscope construction for symmetric pseudoline arrangements to construct and analyze several infinite families of simplicial pseudoline arrangements with high degrees of geometric symmetry. In particular, all simplicial pseudoline arrangements with the symmetries of a regular $k$-gon and three symmetry classes of pseudolines, consisting of the mirrors of the $k$-gon and two other symmetry classes, plus sometimes the line at infinity, are classified, and other interesting families (with more symmetry classes of pseudolines) are discussed.

A geometric k-configuration is a collection of points and straight lines in the plane so that k points lie on each line and k lines pass through this point. We introduce a new construction method for constructing k-configurations with non-trivial dihedral or chiral (i.e., purely rotational) symmetry, for any k ≥ 3; the configurations produced have 2 k−2 symmetry classes of points and lines. The construction method produces the only known infinite class of symmetric geometric 7-configurations, the second known infinite class of symmetric geometric 6-configurations, and the only known 6-configurations with chiral symmetry.