ACCELERATING IN-MEMORY CROSS MATCH OF ASTRONOMICAL CATALOGS

MPhil Thesis Defence


Title: "ACCELERATING IN-MEMORY CROSS MATCH OF ASTRONOMICAL CATALOGS"

By

Mr. Senhong WANG


Abstract

New astronomy projects generate observation images continuously and these 
images are converted into tabular catalogs online. Furthermore, each such new 
table, called a sample table, is compared against a reference table on the same 
patch of sky to annotate the stars that match those in the reference and to 
identify transient objects that have no matches. This cross match must be done 
within a few seconds to enable timely issuance of alerts as well as shipping of 
the data products off the pipeline.

To perform the online cross match of tables on celestial objects, or star 
tables in short, we propose three parallel algorithms, zoneMatch, gridMatch and 
quadtreeMatch. For zoneMatch and gridMatch, they adapt existing indexes for the 
spherical coordinate system of celestial objects. Specifically, zoneMatch 
divides the observation area by the declination coordinate of the celestial 
sphere whereas gridMatch utilizes a two-dimensional grid on the declination and 
the right ascension. For quadTreeMatch, the space is regularly subdivided into 
4 children until each bucket contains no more than B points, where B is the 
bucket capacity. With either index on the reference table, we match the stars 
in the sample table through parallel index probes on the reference. We 
implemented these algorithms on a multicore CPU as well as a desktop GPU, and 
evaluated their performance on both synthetic data and real-world astronomical 
data. Our results show that gridMatch is faster than zoneMatch at the cost of 
memory space and quadTreeMatch is the slowest one.  All parallelization 
achieves speedups of orders of magnitude.


Date:			Tuesday, 27 May 2014

Time:			3:30pm – 5:30pm

Venue:			Room 3501
 			Lifts 25/26

Committee Members:	Dr. Qiong Luo (Supervisor)
 			Dr. Kai Chen (Chairperson)
 			Dr. Raymond Wong


**** ALL are Welcome ****