This paper describes the implementation of polycomp, a open-sourced, publicly available program for compressing one-dimensional data series in tabular format. The program is particularly suited for compressing smooth, noiseless streams of data like pointing information, as one of the algorithms it implements applies a combination of least squares polynomial fitting and discrete Chebyshev transforms that is able to achieve a compression ratio Cr up to ≈40 in the examples discussed in this work. This performance comes at the expense of a loss of information, whose upper bound is configured by the user. I show two areas in which the usage of polycomp is interesting. In the first example, I compress the ephemeris table of an astronomical object (Ganymede), obtaining Cr≈20, with a compression error on the x,y,z coordinates smaller than 1 m. In the second example, I compress the publicly available timelines recorded by the Low Frequency Instrument (LFI), an array of microwave radiometers onboard the ESA Planck spacecraft. The compression reduces the needed storage from ∼6.5TB to 0.75TB (Cr≈9), thus making them small enough to be kept in a portable hard drive.
|Titolo:||Polycomp : efficient and configurable compression of astronomical timelines|
TOMASI, MAURIZIO (Primo)
|Parole Chiave:||Coding theory; Information systems: Data compression; Methods: Numerical|
|Settore Scientifico Disciplinare:||Settore FIS/05 - Astronomia e Astrofisica|
|Data di pubblicazione:||2016|
|Digital Object Identifier (DOI):||10.1016/j.ascom.2016.04.004|
|Appare nelle tipologie:||01 - Articolo su periodico|