The SWAN data consist of a series of more than 3000 FITS files containing the SWAN intensity background maps in rayleigh units.
The information necessary to study the data are given in the headers of the fits files.
The beginning and end time of each observation are given by OBSSTART and OBSSTOP Each map was obtained roughly over a period of 24 hours.
The observation is performed for a position in the solar system given in spherical coordinates (ecliptic J2000) (keywords RSOHO, SOHOLON and SOHOLAT).
The data are given in Rayleigh (taking into account the official calibration factor).
They consist of arrays computed on a grid of 360 ecliptic longitude by 180 latitude. The longitude goes from 0.5 to 359.5 degrees by step of 1.0 degree. The latitude goes from -89.5 degrees to +89.5 degrees by step of 1.0 degrees.
The median dark current level is given by the keyword MEDCPS26. If this keyword value is larger than 20, it means that the data are contaminated by dark counts caused by solar events and should be used with precaution.
Example of the important keywords:
| OBSSTART | '2009-01-09T20:52:25' | Observation start date |
| OBSSTOP | '2009-01-10T20:50:52' | Observation stop date |
| TELESCOP | 'SOHO ' | |
| INSTRUME | 'SWAN ' | |
| WAVELENG | 121.560 | |
| MEDCPS26 | 11.9170 | Median counting rate of SU+Z pixel 26 |
| COORDSYS | 'Heliocentric ecliptic coordinate' | |
| COORDUNI | 'Degrees ' | |
| RSOHO | 0.97331880 | Distance of observer to Sun center in AU |
| SOHOLON | 109.90522 | Longitude of the observer |
| SOHOLAT | -0.041080601 | Latitude of the observer |
The FONDUE (Fully ON-Line Datacenter for Ultraviolet Emissions) Web Service
| Last updated on Fri, Mar 30, 2012 | EQ |