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WHATSNEW.DOC
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1991-07-05
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INTRODUCTION
This file is a supplement to the original SOLAR
documentation. It is intended to list the major
changes to the program from version 1.30.
SETUP MENU
-------------------------------
Local Coordinates
With version 1.40 two new features have been added!
First, a Universal Time offset has been added
so the times calculated by the local circumstances
routine can be displayed in your local time.
Second, you can now add your city's location data
to the accompaning city database file. You must first
select option "S" to search the database. Type in
the name of the city and press [ENTER]. The program
will then search the database and find all possible
matches. If your city is not in the file, figure 1
will be displayed.
Figure 1.
├────────────────────┤
╔═══════════════════════════════════════════════════════╗
║ City Search [San Jose del Cabo Airport ] ║
║ CURRENT SELECTION: ( 850) ║
║ Would you like to add this city to database? (YES/no) ║
╚═══════════════════════════════════════════════════════╝
║ CITY: South Gate, California ║
If you wish to add the city to the database, press
the [ENTER] key to accept the default. You will then be
asked to enter in the city's geographical data. There
will be another question to confirm the accuracy of
your data. Make sure that your data is correct. If it
isn't, press any other key and you will be able to make
the corrections, otherwise, press [ENTER]. The program
will automatically save your data to the file.
If you do not wish to add the city city to the
database file, simply press any other key and you will be
returned to the Local Coordinates screen.
Eclipse Selection
The only changes in this section is the addition
of a default for each question asked. Press [ENTER] to
accept the defaults or any other key if not.
TABULAR MENU
-------------------------------
All the data input routines that are used have been
modified to reduce extra keystrokes and forces the user
to use the [ENTER] key to complete a choice.
Local Circumstances
More data has been added to the local circumstances
routine. The positional angles of the center of the moon
listings have been improved to clarify the symbols used in
version 1.30. The biggest change in this area is the
addition of the obscuration percentage of the eclipse at the
selected site.
The obscuration percentage is the true amount of the
Sun's disk that is hidden from view by the Moon. It is NOT
the same as the magnitude of an eclipse, which is defined
as the maximum diameter of the Sun that is obscured by the
Moon.
If at the selected site, the eclipse is total or annular,
a length of totality or annularity will be displayed. This
is a handy feature if you quickly wish to know how long
totality will last at a certain location. Figure 2 shows
how the eclipse will look like at Mexico City.
Figure 2.
Mexico City, Mexico
1991 JUL 11
POSITION ANGLES OF
LOCAL SUN'S CENTER OF MOON
PHASE TIME ALTITUDE NORTH ZENITH
─────────────────────────────────────────────────────────────
Eclipse Begins 10:54:01 +78° 28' +292° 32' +191° 30'
Totality Begins 12:20:55 +80° 32' +282° 46' +27° 08'
Maximum Eclipse 12:24:12 +79° 48' +205° 34' +308° 35'
Totality Ends 12:27:29 +79° 03' +128° 22' +230° 12'
Eclipse Ends 13:47:35 +60° 35' +117° 23' +28° 06'
─────────────────────────────────────────────────────────────
Length of Totality: 06:33
Magnitude = 1.031 Ratio Moon/Sun = 1.0796
Obscuration = 1.000 Delta T = 57.8 Sec.
Saros # 136
«« - Previous Day »» - Next Day
The contact times are defined as follows:
First Contact:
This is the time when the eclipse begins at the
selected site.
Second Contact:
The time when totality or annularity begins. If
an eclipse is partial then this area will be blank.
Maximum Eclipse:
The time when the eclipse at the selected site is
at a maximum. In other words, the highlight of
the spectacular show!
Third Contact:
The time when totality or annularity ends. If an
eclipse is partial, then this will be blank.
However, for those fortunate people who witnessed
totality, this contact marks the time when the Sun
again reappears and the rest of the eclipse is
rather anti-climatic.
Fourth Contact:
This is the time when the eclipse ends.
GRAPHICS MENU
-------------------------------
Simulation Mode
Version 1.40 now supports Hercules, EGA, VGA, and MCGA
graphic adapters for the simulation mode. Two new additions
have been made with this release. 1) North View Mode, and
2) Zenith View Mode.
There has been a great deal of confusion relating to
the positional angles calculated by SOLAR. These two angles
depict the direction of the center of the Moon compared to
the Sun. In the simulation display, you now have the option
to view either mode.
North View Mode:
The North Position Angle is defined as the direction of
the center of the Moon measured from the North point of the
solar disk towards the East. This north point is constant
and therefore, the motion of the Moon is fairly linear. This
angle, however, doesn't truely show how the Sun will look at
a particular location.
Zenith View Mode:
The Zenith Position Angle is defined as the direction of
the center of the Moon measured from the zenith (vertex) point
of the solar disk towards the East. This angle varies with
the altitude of the Sun. As the Sun rises in the morning,
its' altitude is constantly increasing. It will reach a point
in the sky where its altitude is at a maximum. This occurs
around local noon time. After this point is reached, the
Sun's altitude will be decreasing.
The zenith angle in turn is not very constant however.
Around local noon time, the zenith angle is changing the most.
After noon has passed, the zenith angle has effective made a
reverse turn. This is mathematically correct and is rather
difficult to visualize. Consider the appearance of the Moon
around First or Last Quarter. When the Moon rises, its'
appearance is different than when it is setting. It has
effectively rotated 180 degrees during the course of the
night. This is exactly the behavior that the zenith angle
describes, and therefore, it is how the Sun will look
during the eclipse.
Quick Map
Version 1.40 also introduces a new graphic option. Have
you ever selected an eclipse and only wanted to know the
general area of where it is visible, but you had to wait
until the world graphics plot was completed? Well, now you
don't have to wait anymore.
This mode is only activated for EGA, VGA, and MCGA
computer systems. It is the default mode of the CGA
display systems. Hercules is not supported at this time.
Upon selection of this option, the screen will
immediately load in a binary file of the world. This process
is very quick. As a comparison, the loading process is
faster than a 386, 20-MHz computer plotting the World data
points manually.
CONCLUSION
-------------------------------
Those are the changes for this version of Solar. I
am pleased with the tremendous response and interest from
the users of the program. It is only from your comments
and suggestions that I can continue to improve the program.
So, please keep those suggestions coming!
I have one request from those who view the upcoming
July 11th eclipse. Make a drawing of the Sun and Moon during
the progress of the eclipse and compare that with the displays
from the simulation mode. I am very interested as to how well
SOLAR accurately depicts the image of the Sun.
May you have clear skies!
Matthew Merrill
1991 July 5th