Bandpass Expectations:
0.7Å users will find that prominences are easily
visible and very well-pronounced with a 0.7Å fil-
ter. Surface structure is not very contrasted, but
it is possible to see mottling on the surface and
large flares, plages and active regions.
0.5Å users will see prominences but not quite as
broad as with a 0.7Å due to wing shift in the
prominence. Surface detail will be much
stronger with a 0.5Å, revealing more detail in
active regions, filaments, spicule, and all other
features.
0.3Å users will see only very thin, hairline promi-
nences, but surface contrast will be very
defined and sharp. Soft chromosphere will
appear in highest detail with .3Å.
A word about daytime seeing and limiting resolution:
During the daytime, radiant heating from the sun affects seeing significantly.
Characterized by turbulence or shimmering as seen over a hot street, seeing
can cause significant impact on quality of solar observations.
Bad seeing is caused by air of different temperatures mixing. This typically
happens within the lowest 10 feet of air. It occurs most often over pavement,
dark objects, rooftops and sometimes trees.
High cirrus clouds or “scuz” will cause scattering of sunlight in the high atmos-
phere which often makes for bad viewing conditions. A classic sign of high
cirrus clouds is the inability to achieve focus, or the need to “chase focus”.
A jet-stream moving overhead can also hurt seeing conditions even on a
clear day.
While many of these conditions are beyond our control, observing in an area
with ideal conditions without pavement in the direction of viewing and on
days with no high cirrus will offer best results. Grass is the best environment for
daytime seeing stability.
The SolaREDi 60mm has a limiting resolution at 6562.8 of approximately 2.8
arc seconds. Over-magnification of the image will have resolution limitations
in which features can not be resolved. Also note that the sun’s limb in hydro-
gen alpha is soft, with a fuzzy layer of chromosphere surrounding the surface.
Using eyepieces higher than 12mm in power, it is challenging to achieve
focus on the limb. For users who are interested in higher magnification, we
suggest one of our other models of T-Scanner or Quantum DayStar filters
which can mount to your existing telescope and be used up to 6.5” in clear
aperture.
Features of the Sun in Hydrogen Alpha
By observing the sun with a narrow bandpass filter tuned to 6562.8Å, we can
observe the behavior of the Sun's
Chromosphere
. The chromosphere is like a
shell of gas around the Sun's
photosphere, always moving
and changing. The chromos-
phere's structure behaves differ-
ently in active regions than quiet
areas, where magnetic field
lines are stronger. Thought to be
tied to the photosphere, the chromosphere is governed by magnetic forces
and, yet it still has its own IntraNetwork (IN) of material oscillating every 5 min-
utes.
On the limb, even a rather wide
filter of 1Å or more will show
prominences
, a detail of the
chromosphere projected
against the dark black contrast
of space. To observe the details
of chromosphere on the face of
the sun, we need a narrower fil-
ter to eliminate more off-band light of the photosphere and continuum. We
need a filter less than 1.0Å. The narrower the filter's bandpass, the more con-
trast we will see - down to 0.4Å, where prominence structure is reduced due
to high velocity and subsequent wing shift.
Spicules
dominate the chromos-
phere in non-active regions and
have been studied exhaustively.
They are barely visible, last only
about 15 minutes, and resemble
a "burning prarie". Some jets
can be seen shooting 10,000 km
up from the Sun's limb at velocities of about 30km/sec. Studied exhaustively,
they present a number of observing challenges, as they are too small to
resolve and move so quickly as to present wing-shift challenges.
Field Transition Arches (FTA's)
connect P and F spots - ele-
ments of opposite polarity.
Inside an active region, where
sunspots are originally linked by
a FTA, a shear boundary forms.
Field Transition Arches are differ-
ent from filaments in that they
are thin and not very dark. The
FTA usually has plage or granular
structure underneath.
