ABSOLUTE RADIOMETRIC CALIBRATION OF THE EUNIS-06 170-205 A CHANNEL AND CALIBRATION UPDATE FOR CORONAL DIAGNOSTIC SPECTROMETER/NORMAL-INCIDENCE SPECTROMETER

Journal Article · Mon Feb 01 04:00:00 EST 2010 · Astrophysical Journal, Supplement Series

DOI:https://doi.org/10.1088/0067-0049/186/2/222; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21301330

Tongjiang, Wang; Brosius, Jeffrey W ^[1]; Thomas, Roger J; Rabin, Douglas M

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1. Department of Physics, Catholic University of America, 620 Michigan Avenue NE, Washington, DC 20064 (United States)

The Extreme-Ultraviolet Normal-Incidence Spectrograph sounding-rocket payload was flown on 2006 April 12 (EUNIS-06), carrying two independent imaging spectrographs covering wavebands of 300-370 A in first order and 170-205 A in second order, respectively. The absolute radiometric response of the EUNIS-06 long-wavelength (LW) channel was directly measured in the same facility used to calibrate Coronal Diagnostic Spectrometer (CDS) prior to the Solar and Heliospheric Observatory (SOHO) launch. Because the absolute calibration of the short-wavelength (SW) channel could not be obtained from the same lab configuration, we here present a technique to derive it using a combination of solar LW spectra and density- and temperature-insensitive line intensity ratios. The first step in this procedure is to use the coordinated, cospatial EUNIS and SOHO/CDS spectra to carry out an intensity calibration update for the CDS NIS-1 waveband, which shows that its efficiency has decreased by a factor about 1.7 compared to that of the previously implemented calibration. Then, theoretical insensitive line ratios obtained from CHIANTI allow us to determine absolute intensities of emission lines within the EUNIS SW bandpass from those of cospatial CDS/NIS-1 spectra after the EUNIS LW calibration correction. A total of 12 ratios derived from intensities of 5 CDS and 12 SW emission lines from Fe X to Fe XIII yield an instrumental response curve for the EUNIS-06 SW channel that matches well to a relative calibration which relied on combining measurements of individual optical components. Taking into account all potential sources of error, we estimate that the EUNIS-06 SW absolute calibration is accurate to {+-}20%.

• OSTI ID: 21301330
• Journal Information: Astrophysical Journal, Supplement Series, Journal Name: Astrophysical Journal, Supplement Series Journal Issue: 2 Vol. 186; ISSN 0067-0049; ISSN APJSA2
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
99 GENERAL AND MISCELLANEOUS
CALIBRATION
EMISSION
EXTREME ULTRAVIOLET RADIATION
SPECTRA
SPECTROMETERS
SUN
WAVELENGTHS