JOP No 130 Solar Maximum equatorial slow wind. Responsible Scientists : E. Antonucci and A. Gabriel Version updated 18.10.2000 Participating : S. Giordano, F. Bely-Dubau, C. David, A. Fludra, P. Lemaire, etc, ... Scientific rationale During the Maximum, the simple dipole configuration of the Sun is destroyed by the migration of local field dominant field polarities towards, what will become at the next solar minimum, a dipole configuration with a reversed polarity. The detailed evolution of this migration is not well understood. For the present we assume that the higher multipole components become increasingly important and that we can view the Maximum configuration approximately as a random distribution of local monopoles over the surface of the Sun. During the Minimum, the origin of the slow solar wind is believed to be associated with the equatorial streamers. Recently, UVCS has succeeded in observing some radial velocities associated with such structures, which opens up the possibility to measure onset regions of the slow solar wind by Doppler dimming methods using the oxygen VI lines. Also during the minimum; CDS with SUMER have measured the electron temperature gradients in equatorial streamers, during a practice run of the JOP 2 observation, carried out at the equator before S/C rotation. The aim of the present JOP is to try to identify and measure the equivalent of such closed field/streamer configurations, as they will appear at the solar maximum. It is essential for the UVCS to work outside of the limb. For CDS/SUMER, it is also desirable to work outside of the limb. We will not know in advance, where to find such configurations at the limb. We therefore adopt the strategy of observing one portion of the limb during 7 days. This enables us to look at some 90 degrees in longitude as the Sun rotates, (as long as we are near the equator). If we take into account the fact that CDS and SUMER slits are oriented N-S, and that a preferred position, for technical reasons, for the SUMER slit is just above the E limb, we converge towards the solution of an equatorial E-limb for the target of this JOP. Scientific objectives We need to measure the electron temperature, the different ion kinetic "temperatures" and the radial outflow velocity, as a function of the height, above the probable slow wind origin structures, during the solar maximum. Specifically, for each instrument : CDS/SUMER. These will perform a modified version of the sequences developed for JOP 2 (as run at the equator during the JOP 2 practice run). For CDS, we will modify the earlier JOP 2 sequences to suppress the limb crossing part, thereby avoiding the risk of over-exposure which caused some worries for the CDS engineers. We aim to cover effectively from 1.02 Ro to 1.3 Ro, that is, down to 20 arcsec above the limb, but with shorter exposure times to allow for the brighter coronal emission. For SUMER, we are today unable to scan in the x-direction. A fixed height of 20 arsec above the E limb has been negotiated for the SUMER slit. This will allow an overlap with CDS measurements, but will necessitate some extrapolation of the of the same lines : O VI, and Lyman Beta, observed with the UVCS. To establish the 173/1032 line ratio, required for Te measurement, as a function of height, we will use the UVCS to extrapolate the SUMER single-point 1032 intensity. UVCS. We will observe in offset mode from 1.2 to 1.5 Ro and then in normal mode up to 4 Ro. It will measure O VI for Te diagnostics and then the ratio 1032/1038 for the radial velocity. In addition we will measure ion kinetic velocity for O VI, Si XII and H I. TRACE is requested to measure loop structures in the corona at the E-limb, by observing locally in 171 A band. EIT should support this aim and also survey the importance of nearby active regions by its normal CME Watch full-disk images in 195 A. MDI can assist in evaluating the active regions, using its synoptic magnetogram images. Since this is less efficient near the limb, use will be made of the magnetograms obtained during the following several days after the JOP 130 runs. LASCO images over the complete solar rotation are important for establishing the streamer geometry, but these can be obtained in the normal synoptic program. Solar conditions Contingency If good streamers are not found at the equator on the E limb, but are found up to +/- 20 degrees latitude, we will modify the pointing to take these into the fields of view. This involves rotation offsets for the UVCS and a change of y coordinates for the CDS and SUMER observations. Such sequences will effectively move the CDS and SUMER observations to a point higher above the limb, but at a cost of loss of height resolution for the CDS (GIS) observations. Nevertheless, it will be an advantage to do this at least once during the 7 days of observations, since this offers the possibility of observing the same point and thereby cross-calibrating between SUMER and UVCS for the O VI lines. Spacecraft/Operational Requirements. No S/C roll manoeuvre is required. UVCS will need real-time commanding access. Observations will be made during normal working hours at the EOF. Scheduling The first runs are proposed during the MEDOC 6 campaign, week 6 - 12 November 2000. In order to reduce possible conflict with MEDOC/Tenerife observations, it is proposed to use some of the intervals between 18:00 and 24:00 UT each day for 7 days.