National Aeronautics and Space Administration

The Vela-5B Archive

Experiment	Lightcurves	Raw Data
All Sky Monitor	FITS, GIF	FITS

The Vela-5B lightcurves can be obtained via the database Vela5b available from Browse. Lightcurves and the raw data can be directly retrieved from the Vela-5B FTP area at the HEASARC archive.

High level Products : Lightcurves have been extracted for 99 known X-ray sources. The lightcurves for 35 sources in unconfused areas of the sky were generated both in a natural binning format (roughly 56 hours) and with the original 1 second time resolution. The lightcurves generated by deconvolving source contributions from crowded regions are in 112 hour bins. The lightcurves are available in the 3-12 keV and 6-12 keV energy band.

Raw data: There are two sets of Vela-5B raw data, one ordered by time and the other by coordinates. The FITS layout consists of one extension bintable containing the scientific data, pointing information and other parameters. A small portion (~0.1%) of the Vela-5B raw data was corrupted during transfer from a Cyber 725 to VAX computer at Los Alamos labs in 1986. The complete list of corrupted points is available in the file all_bad.dat (~8 Mb) in the Vela-5B FTP area at HEASARC.

Time ordered data The corruption-free time ordered data is available in FITS format on the Legacy computer in the Vela-5B raw data area. Files cover the entire ten year mission and have been split so that a single file covers five mission days. These files have also been ingested at the National Space Science Data Center (NSSDC).

Coordinate ordered data The corruption-free coordinate ordered data are available in FITS format on the Legacy computer in the Vela-5B raw data area. The celestial sphere has been divided into approximately 12,000 boxes, most containing roughly a 2 deg x 2 deg area of sky.

Software: The software package Vela5b , distributed with the FTOOLs, includes 5 tasks which allow to extract lightcurves from the raw data files. The fvelalc generates a pair of light curves (one for each of the two detectors, usually referred to as Channel 1 and Channel 2) for a specified source which is in an unconfused region of the sky. For previous users of the raw binary data, fvelalc replaces the programs SVELA and BINIT. The velabox determines which raw data files are required.
The fvelmap and fvelgallc programs combined perform the comparable function for crowded fields. Fvelmap computes a binned map of the region around the source of interest, fvelgallc uses this map to subtract the contributions of neighboring sources to the lightcurve. For previous uses of the raw binary data, fvelmap replaces NOD2D and FVELGALLC replaces NUSRC. The velamap determines which raw data files are require.