next up previous contents
Next: 5.4 Mailing Addresses and Up: 5 Other Information Previous: 5.2 Regional Data Analysis

5.3 Calibration Recommendations

Determination of the best calibration for IUE data is an ongoing process. Due to the stability of the cameras, absolute calibrations derived early in the mission are still in use. During the last few years data have been obtained for new absolute calibrations for all three operational cameras. Announcements of calibration improvements are published in the IUE Newsletters. RDAF users will find the absolute calibrations used in the software to be current. A summary of present calibrations follows, with further discussion given in the IUE Data Analysis Guide (Grady and Taylor 1989).

Low-Dispersion Calibration:

LWR and SWP Holm et al. 1982
LWP Cassatella, Lloyd, and Gonzalez-Riestra 1988

High-Dispersion Calibration:

Spectra processed before
November 10, 1981 (GSFC) Cassatella, Ponz, and Selvelli 1981
March 11,1982 (VILSPA)

Spectra processed subsequently Cassatella, Ponz, Selvelli, and Vogel 1990
to the present (all cameras)

Large Aperture Size for Trailed and Extended Sources:

LWSW
Trail length (arc seconds) 21.3±1.0 21.4±0.4 Oliversen 1987;Crenshaw and Park 1989
Trail width (arc seconds) 9.3±0.1 8.9±0.3 Panek 1982b
Area (square arc seconds) 203.±6. 200.±5. Panek 1982a

Exposure Length: LWP, LWR, and SWP:

t(actual) = 0.4096 · INTEGER(t[commanded]/0.4096) - R/F time

R/F time = LWP 0.127±0.003 Schiffer 1980b
SWP 0.129±0.005 Gonzalez-Riestra et al. 1990
LWR TBD


next up previous contents
Next: 5.4 Mailing Addresses and Up: 5 Other Information Previous: 5.2 Regional Data Analysis

Last updated: 23 July 1997
jrc