Study 000329:

ACRONYM: YKK_EqCH_02w

This study is one of the two studies designed for measuring temperatures,
densities, velocities, and abundances  in and at the boundary of equatorial
and low-latitude coronal holes. To improve the signal in weak lines,
2 long exposures are taken at each position in the raster.

TARGET: Coronal Hole
EXPOSURE TIME: 150s x 2 (2 exposures per raster position)
RASTER: Scanning
SLIT: 1"
STEP SIZE: 1"
FOV: 50"x400"
RASTER DURATION: 4h 32 m25s
COMPRESSION: DPCM
VOLUME: 121 Mbits

Pointing:
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An equatorial or low-latitude coronal hole (within 40 degrees to the
solar equator) during its passage across the central meridian.
Polar coronal hole extensions can also be a candidate of study if
it extends to below 40 degrees in latitude.

The slit field-of-view should at least cover the solar equator or, 
if the coronal hole does not reach latitude zero, the lowest latitude
that the coronal hole covers.

Use/Instructions to planners:
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The objective of this study is the variation in physical properties
(temperature, density, velocity, abundances)  along the longitudinal
extent of an equatorial or low-latitude coronal hole that may correspond
to different  footpoints of the fast to slow solar wind. Therefore the
longitudinal coverage is essential.

This raster is used in combination with another study YKK_EqCH_02n
to complete a set of observations on
the coronal hole and its EAST boundary. A default set of study is as follows.

1) run twice the study YKK_EqCH_02n, one near the center of the coronal hole,
the other in between the center  and the EAST coronal hole boundary.  
2) run one time this study YKK_EqCH_02w at the EAST boundary of the
coronal hole, partly covering the 'visible' coronal hole, 
partly covering the neighboring active region or quiet Sun at its east. 
3) followed by one context raster (400"x400") covering the FOV of the
above raster runs.

Alternatively, two `slot shots' before and after the above raster runs
are OK too as long as it covers the FOV of the above raster runs.

The two studies (YKK_EqCH_02n and YKK_EqCH_02w) can be used in various
combinations depending on coronal size or planning restrictions. At least
three raster runs like the above default set on the same day are requested
in order to meet the objectives of the study.  If not possible, the priority
is:

1) east coronal hole boundary,
2) in between the center and the EAST coronal hole boundary,
3) center of the coronal hole.

The pointing of multi raster runs should be made in a sequence that is
toward the east. 

Warning:
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None.