SOHO Intercalibration Joint Observing Program
Updated: 26 November 2003

SOHO/CALSO-6 Cross Calibration & Co-Measurements

The SOHO CELIAS/SEM has operated continuously since its activation December, 1995. The next underflight calibration of the CELIAS/SEM instrument is scheduled December 5, 2003.

Calibration underflights for SOHO and Solar Atmosphere Investigations (CALSO-6) is a multi-year program to provide the absolute solar irradiance in the extreme ultraviolet (EUV) wavelength region. The data obtained will provide verification of the Solar Heliospheric Observatory (SOHO) Solar EUV Monitor (CELIAS/SEM) calibration.

To supplement the SEM data, and the SOHO inter-calibration, the spectral emissions from key solar EUV lines and continuum will be measured on the CALSO rocket by an Optics Free Spectrometer (OFS). All instruments on the CALSO-VI rocket payload make full disk observations and include the following instruments in addition to the ROCKET/SEM.

1. Rare gas ionization cell used to obtain a direct measurement of the absolute integral flux shortward of the ionization limit of the rare gas of interest (neon < 57.5 nm).

2. Double ionization cell used to obtain a direct measurement of the photoionization rate of in-flowing interstellar helium (< 50.4 nm).

3. Silicon photodiodes with aluminum and titanium filters used to continuously monitor and characterize the solar EUV flux as a function of payload altitude.

Operational Scenario

Launch is currently scheduled for December 5, 2003, at 19:30 UT.  This is a dual-launch coordinated with the launch of the EIT CalRoc II payload.

ICAL Instrument teams will have access to launch day activities real-time via live web cast of the mission.

SOHO Instruments:

CELIAS/SEM will provide continuous measurements at full resolution (15s) through the complete mission. There are no mission specific requirements for the CELIAS/SEM.

EIT - EIT synoptic sets (full-resolution, full-field of view images in all four wavelengths) before, during, and after the rocket flight will be scheduled (3 synoptic sets requested, two minimum). NRT commanding will be necessary to allow for a launch slip in the rocket program.

CDS - Program operation USUN_6 is requested to be run during the planned coordinated observations. USUN_6 will begin at T-6 hours to be centered around the planned launch of the dual sounding rocket mission. The observation will run for 13 hours. No real-time commanding is required during the sequence. There are no plans to change the CDS observation schedule in the case of minor delays of the rocket launch.

TIMED Instruments:

- TBA -