JOP164 Quiet Sun Magnetic Carpet Study

Authors:  Robert Close (St Andrews), Clare Parnell (St Andrews), Richard
Harrison (CDS), Joe Gurman (EIT), Sarah Gregory (MDI), Karel Schrijver


January 28, 2003             First draft
January 29, 2003             Version 1 
March 6, 2003                Version 2 Differences

Observing Period: 26th-30th March (if Sun activity permits)

OBJECTIVE: Multi-wavelength observations of the magnetic carpet and
the atmosphere above to correlate magnetic changes modelled from MDI
maps with transient activity detected in EUV/UV.

high-resolution field as near to central meridian as possible.
Minimum instrument involvement: MDI, and at least one of CDS, EIT or
TRACE - preferably all three.

SCIENCE CASE AND SCHEME: The modelling of coronal magnetic fields from
MDI maps has provided information on the temporal changes of coronal
fields. The aim is to attempt to correlate these changes with
small-scale transient activity and structure in the solar atmosphere
detected in the EUV and UV wavelengths (chromosphere through to
corona). In this way, we can identify the magnetic ?events? which
drive transient activity and assess the drivers and impacts of such
events in a global picture. To do this, we require a long series of
MDI high-resolution maps, and EUV imaging and spectroscopy from within
the MDI high-resolution field, from CDS, EIT and TRACE.  To ensure
good statistical significance, each observation run must be many hours
in duration - 6 hours minimum, 48 hours ideal. Two such runs are
envisaged. The only difference between the runs would be in the
spectroscopic observations, which for one would use an ?open slit?
technique, and for the other full spectral capability would be
used. This allows good spectral, i.e. plasma diagnostic coverage, and
good temporal capabilities for a range of temperatures. The two runs
do not need to be made following on from one another; they can be made
in the same week or even a month apart. Both should be made on a quiet
Sun region.

high-resolution field of view. CDS and TRACE fields must be
co-centred, and CDS must be fully within MDI high-resolution
area. Solar X: CDS and TRACE (centre of FOV) pointing to start 1
arcminute inside eastern edge of the high-resolution MDI field of
view. Solar Y: TRACE northern and southern FOV boundaries must be
within MDI FOV. See figure below:

Relative FOV of TRACE, CDS & MDI at
the beginning of the observation sequence
OPERATING DETAILS: (i) MDI We require high-resolution (0.625 arcsec) magnetograms with a cadence of 1 minute, over a minimum of 6 hours. However, the ideal duration would be 48 hours. This applies to each of the two runs of the campaign. The area covered must be the full 10 arcmin in the E-W direction (to cover rotation compensation of CDS and TRACE), and at least 8.5 arcmin in the N-S direction to encompass the TRACE field of view. It has been agreed that hr_m1_v2 best suits our needs giving full high-resolution magnetograms, 2x2 binned dopplergrams at 1 minute cadence. (ii) CDS RUN 1: For the duration of the MDI observation, CDS should run an open slit (90x240 arcsec) sequence using the lines He I 584 Angstrom, O V 629 Angstrom, Mg IX 368 Angstrom, with an exposure time of 20 s (TBC). CDS should run rotation compensation or feature tracking. RUN 2: For the duration of the MDI observation, CDS should run a raster sequence with following details: 20s exposure time, 4x240 arcsec slit, 30 locations (Field of view 120x120 arcsec.), cadence about 12-15 minutes. Use the following emission lines (30 pixels across each?): He I 584, He II 607, O III 599, O IV 554, O V 629, Ne VI 562, Ca X 557, Mg IX 368, Mg X 624, Fe XVI 360. CDS should run rotation compensation - i.e. update of pointing at start of rasters, not during rasters, using mirror. (iii) EIT For the duration of the MDI observation, for each run of the campaign, make full-Sun images at 195 Angstrom approximately every 12 minutes. It is expected that synoptic observations in the other three wavelength bands will be taken every 6 hours. (iv) TRACE For the duration of the MDI observation, make 8.5 arcmin x 8.5 arcmin images in 173 (if possible, also in 195 Angstrom) and 1216 Angstrom images with cadence of the image set (e.g. 173 and 1216 or 173, 195 and 1216 - TBC) at about 5 to 6 minutes, co-pointed with CDS. Quiet Sun exposure times of about 2 minutes are required for 173 and 195. Exposure time for 1216 TBD. Feature tracking by updating pointing between image sets is needed. Note: details still to be confirmed.