The description below was prepared many years ago for the old
"US Naval Observatory (USNO)" graze predictions generated by IOTA up
to 1993. Since then, the predictions have instead been generated
with Eberhard Riedel's Grazereg program. The Grazereg limit
predictions are very similar in form to the USNO predictions,
containing almost exactly the same information that is described
below. But, for example, the exact lines of the heading where
particular data are given are different, so the line numbers given
here should be ignored. See grazer60.txt for Riedel's less detailed
description of the 1999 Grazereg version 6.0 predictions, but which
describes the newest features of the predictions.
6.1 GRAZING OCCULTATION LIMIT PREDICTIONS
__________________________________________
The grazing occultation limit prediction data are provided as ta-
bles of longitude, latitude, and time for the predicted path,
with the Moon's altitude and azimuth and the Sun's altitude also
indicated. Each graze prediction has a heading section, which
gives information on the star and the graze rating. The lo-
cations of other observers selected to receive a particular graze
prediction are given at the end of the tabular data. Starting in
1994, IOTA plans to use a different computer program for graze
predictions. The format will be a little different from that
given here, but most of the same information will be given.
6.1.1 HEADING DATA
___________________
LINE 1 These include the name; super standard station letter(s);
city; country, state, or province; and maximum travel
radii of the observer. For the purpose of graze predic-
tions, much of the world has been divided into super-
standard station regions, each 1000 miles (1609 km) in
diameter. Different computors (volunteers who run the
computer programs to do the actual predictions) calculate
and distribute predictions for the different regions.
Observers whose maximum travel radii cover more than one
super-standard region receive more than one set of pre-
dictions, one from each region their maximum travel ra-
dius covers.
LINE 2 The distance in miles of the closest point in the pre-
dicted limit to the posiiton specified by the observer as
his location, the Universal Time (UT) of central graze at
that point, and the graze rating are given here. When
the program computes these quantities, it terminates the
path at low Moon altitude or when the Sun is above the
horizon. It may be that the actual path will be closer
to the observer than the number specified as the closest
point, but low altitude or daylight may make observation
impossible at the true closest point. Twilight and low
Moon altitude are not considered in computing the rating
(except for spectacular events), but interference by
sunlit lunar features and daylight are considered.
LINE 3 The third line is normally blank, but sometimes a special
message appears here, giving information such as the
computor's address, spectroscopic binary data, or a lunar
eclipse message.
LINE 4 This line gives the star's name (if any), Durchmusterung
(BD or CD) number, USNO reference number (X, ZC, K, C,
etc.), Smithsonian Astrophysical Observatory Catalog
(SAO) number, and visual magnitude, followed by the UT
date. The USNO reference number and the SAO number are
the numbers that should be entered on observation re-
ports. SAO numbers less than 17 are not true SAO num-
bers, but are error codes for stars in the Third
Astronomische Gesellschaft Katalog (AGK3) that are not in
the SAO catalog. The name includes a proper name, Greek
letter, Flamsteed number, variable-star designation, and
other catalog numbers, in that order of preference, and
depending on which, if any, are available. The other
catalog numbers, indicated by the letters B., H1., G. and
H. (for Bode, Heis, Gould, and Hevelius, respectively)
should not be confused with the more commonly used
Flamsteed numbers. The number immediately following "BD"
or "CD" is the "zone" number, and is the star's approxi-
mate declination in degrees.
LINE 5 The line starts with the percent of the Moon's disk illu-
minated by the Sun, where 0 is new moon, 100 is full
moon, 50 is first or last quarter, 1 to 49 is crescent
moon, and 51 to 99 is gibbous moon. If the Moon's appar-
ent diameter is considered to be 100 units, the termina-
tor crosses the Moon's equator at a point "percent
sunlit" units measured along the terminator from the
bright limb. The equator here is not the Moon's actual
equator, but is usually very close to it; it is really
the diameter line through the Moon's center pointing in
the direction of the Sun. The term WAXING following the
percent sunlit shows that the percent sunlit is increas-
ing (between new moon and full moon), while WANING indi-
cates decreasing percent sunlit (full moon to new moon).
The term ECLPNG indicates that a lunar eclipse is in
progress. During a lunar eclipse, the percent sunlit is
the percent of the Moon's diameter not in the umbra at
the central graze time given in the second line, so that
0 would imply totality. Note that the percent sunlit
changes rapidly during the partial phases of an eclipse.
The position angle of cusp is geocentric and only approx-
imate; it is meaningless during an eclipse. DELTAT is
the difference, Ephemeris Time minus Universal Time, a
quantity with which observers are likely never to be con-
cerned. Finally, it is noted whether the path is a
northern or southern occultation limit.
LINE 6 This line gives the error of the star's declination, and
the phase of the Moon. The PROBABLE ERROR is a measure
of the uncertainty in the star's position. There is a
50% chance that the star will actually be between the
star's catalog declination + the error and the catalog
declination ¯ the error. It should be used with the pre-
dicted profile for determining the distance from the
limit line for positioning observers.
LINE 7 The SPECTRAL CLASS indicates the star's color. Stars of
class O and B are blue; A, bluish-white; F, white; G,
yellowish-white; K, orange; M, N, S, and C, red. The Sun
(and therefore the Moon) is G2, yellow. Bright-limb
grazes are easier to see if there is good color contrast,
as for B and M stars. B, A, and F stars have the highest
probability of being double. The POSITION SOURCE gives
the catalog from which the star's position and other in-
formation were taken.
LINE 8 Extra lines in the heading usually are for double-star
data, including the separation(s) and position angle(s)
for secondary and possible tertiary (third) components
from the primary. If the star is listed in Aitken's
double-star catalog, this is indicated, since his desig-
nations are often used in double-star work. If the
statement "THE POSITION SOURCE MUST BE CONSULTED FOR PO-
SITION USED" appears, the position of the primary has
usually been used for the prediction, unless the sepa-
ration is less than about 3", and the secondary is nearly
as bright as the primary. In this case, a mean position
( probably the center of light of the system) has been
used. Offsets for mean position are computed by the pro-
gram that produces the profiles. During lunar eclipses,
a message describing the umbral distance is printed.
6.1.2 COLUMN DATA
__________________
Twelve columns of data are given at regualar intervals of longi-
tude along the graze path. The longitude is measured westward
(negative numbers indicate east longitude) from Greenwich.
WEST LONGITUDE The longitude in degrees and decimals of degrees.
The intervals are usually 0.125 deg.in longitude,
or 7.5', so they are at the margins of 7.5' USGS
topographic maps. Data at 2.5', 5.0', and 10.0'
intervals are also available. Below are
listed the fractions of degrees at 0.125 and
their equivalents in minutes and seconds for ref-
erence with the topographic maps.
+--------------+-------------+
| 0.875 | 52' 30" |
| 0.750 | 45 00 |
| 0.625 | 37 30 |
| 0.500 | 30 00 |
| 0.375 | 22 30 |
| 0.250 | 15 00 |
| 0.125 | 07 30 |
| 0.000 | 00 00 |
+--------------+-------------+
Table 1. Fractional Degree
Equivalents
NORTH LATITUDE The degrees and minutes of geodetic latitude
where the predicted sea level limit crosses the
longitude meridian of WEST LONGITUDE. Minutes of
arc are probably easiest to use with topographic
maps; if desired, the seconds of arc can be de-
termined by multiplying the decimal part of the
minutes by 60.
UNIVERSAL TIME The coordinated universal time (UTC) of central
graze as seen from the longitude and latitude.
This is the time when the star is closest to the
center of the Moon as seen from that location.
MOON ALTITUDE Altitude of the star being occulted. The alti-
tude is zero at the horizon and 90d at the zenith
and is equal to 90d minus the zenith angle. At-
mospheric refraction is not considered in the
calculation of the altitude.
MOON AZIMUTH Azimuth of the star being occulted. The azimuth
is measured eastward from due north, so that 90d
is due east, 180d is due south, and 270d is due
west.
TANZ The tangent of the zenith angle of the star. It
is also the cotangent of MOON ALTITUDE and is
used with MOON AZIMUTH to compute the amount the
sea level limit must be moved for heights signif-
icantly above mean sea level. This correction
should be performed when the observer's height is
more than 200 meters (aproximately 600 feet)
above sea level. This is explained in "Elevation
Correction" on page 35.
SUN ALTITUDE The Sun's altitude in degrees and tenths of a de-
gree. It is negative when the Sun is below the
horizon and positive when above. Atmospheric re-
fraction is not taken into account, so 0.6 deg.
should be added when the altitude is within a
degree of the horizon. Astronomical twilight be-
gins when the Sun reaches -18d, nautical twilight
begins when the Sun's altitude is -12d, and civil
twilight when the Sun reaches -6d.
PA OF GRAZE The position angle of central graze in degrees
and tenths, measured eastward along the Moon's
limb from north. North on the Moon's disk is de-
fined to be from the right ascension meridian
passing from the center of the Moon to the cur-
rent (apparent) North Celestial Pole (NCP).
CUSP ANGLE The angle measured in degrees around the limb
from the cusp to the point of central graze,
where N or S indicate whether it is from the
north or from the south cusp, respectively. A
negative number indicates that the point of cen-
tral graze is on the sunlit limb of the Moon,
while a positive number indicates the dark limb.
The cusp is the intersection of the terminator
with the Moon's limb, 90þ around the limb from
the direction to the Sun from the center of the
Moon. High mountains beyond this theoretical
cusp often catch sunlight. During lunar
eclipses, the cusp angle is meaningless and is
replaced by the UMBRAL DISTANCE, the distance of
the star from the center of the umbra, expressed
as a percent of the radius of the umbra. U dis-
tinguishes the umbral distance from the N or S
given with cusp angles.
6.1.3 ENDING DATA
__________________
Following the columns of data are statements indicating the ver-
sion of the prediction program used, the prediction data source,
and the name of the computor who ran the program. The last in-
formation given is a result of the observer scan, indicating
which other observers have been selected to receive these predic-
tions, if any. In the scan, the observer's specified travel
radii are given in miles after the latitude. An asterisk follow-
ing the spectacular radius signifies those who expect to organize
expeditions more often than join expeditions set up by others.
The super standard station, in which the observer's position is
located, is given after his name. The time of closest approach
is in hours and decimals of an hour.
Some, but not all, versions of the graze prediction programs gen-
erate a one-page summary of all grazes. The observer's station
coordinates are given in the heading. The summary includes cir-
cumstances at the point of closest approach, including the longi-
tude and latitude of the closest point given in the main list.
6.1.4 ELEVATION CORRECTION
___________________________
MOON AZIMUTH and TANZ can be used to make corrections for ele-
vations above sea level. If the elevation above sea level is h
(in feet or meters), the magnitude of the correction to be ap-
plied, d, is given by the formula
d = (TANZ)h
, where d is applied in the direction of the Moon's azimuth. If
the limit is plotted and its direction or azimuth is measured,
the distance, x, that the limit should be shifted, x measured
perpendicular to the limit, is given by the formula:
x = sin (D) d = sin (D) (TANZ) h
where D is the difference of the Moon's and the limit's azimuth.
When the altitude of the star is small, TANZ is large, and D is
small (the azimuth of the limit is nearly equal to MOON AZIMUTH).
For grazes north of latitude +31d, note that shifts are always
southward (unless the elevation is below sea level).
International Occultation Timing Association, European Section
Dr. Eberhard Riedel Schuberstr. 7
D - 80336 Muenchen November 1999
GRAZEREG Version 2000 (GRAZREG0.EXE)
----------------------------------------
The GRAZEREG 2000 program, that is now named 'GRAZREG0.EXE', was designed
to cross-reference between yearly grazing occultation binary data and any
ASCII file of station data to produce output files containing all grazing
occultation events for the specified observers within the given region
including profile plots. The use of former versions of GRAZEREG has become
obsolete with version 2000.
The improvements of GRAZEREG 2000 that observers will notice are:
- The SAO-number was added to the headlines of each event.
- The observed data used by ACLPPP was updated and adjusted to better
fit the GRAZREG0 profile data. So an extra run of ACLPPPIN will not
be necessary in this respect. Within the Cassini regions no Watts
profile data is shown anymore, since it has led to some confusion
in the past. This is a consequent step due to the fact that there
actually does not exist any such data for these regions.
Some computors still find the use of the ACLPPP program important after
the prediction run with GRAZREG0. The only ACLPPP items not covered by
GRAZREG0 are:
- Empirical corrections to the Watts data. These are considered not to
be very reliable and therefore only sometimes yield an improvement of
the profile. GRAZREG0 rather relies on observed and affirmed profile
data. [Note added by D. Dunham: The Grazreg0 profiles now agree
with the ACLPPP profiles to within about 0.1", in any case to less
than the approximate 0.2" best accuracy of the profile data, for
about 80% of the grazes. For the rest, differences larger than 0.5"
are rare.]
- Plotting of extra profile heights for double/multiple stellar systems
(a few cases only where this can be plotted with the scale used).
Since GRAZREG0 uses and shows three distinct sources for profile data
a plotting similar to ACLPPPIN cannot be accomplished. But with the
numerical data given for stellar components an estimation is always
easy.
[Note added by D. Dunham: Especially for the last reason generation of
ACLPPP profiles is recommended. For single stars, we will be
interested in knowning which profiles, Grazreg0 or ACLPPP, give a
better match to the observations when the two profiles have significant
differences.]
Every prediction file can be copied on a diskette or a printer to be
mailed to the observer. In case the observer wants a printout, the prin-
ter format must be set first.
The lines in the prediction files never exceed a length of 78 characters.
So if paper measuring 8 inches horizontally is used, the printer must be
set to 12 characters per inch (cpi), if it has 12 inches across
instead, also 10 cpi are possible. If adjustable, 80 or 90 lines per
page should be selected. Furthermore letter quality print and sanserif
characters are suggested.
THE OUTPUT
----------
1. The observers heading
------------------------
The first two lines give the year of the calculation, and name, place,
geographic position of the observer and his travel radius.
2. Graze Overviews
------------------
The prediction list for every single observer is preceded by a summary
list that gives an overview on all occultations within the observer's
travel radius. If graze events of bright stars outside of the observer's
travel radius are included, there is also a second overview list normally
showing all grazes of stars brighter or equal 4.5 mag. that occur within
the complete Super Standard Region. Sometimes though the limiting stellar
magnitude may be chosen brighter and/or the area covered may be decreased
to reduce the amount of data.
The column 'H/P/S#' contains the position source catalog number of the
star. If the number is preceeded by an 'H' it is the Hipparcos catalog,
'P' is a star from the PPM catalog and 'S' is a SAO-star. There is no
place for Tycho numbers in this column.
The column 'D(KM)' resp. 'D(MI) has the least distance to the graze path
in kilometers or miles, and the 'UT' refers to this very location of the
path.
In the column 'CUSP' the Cusp Angle is given as the absolute difference
between the position angle of the cusp and the position angle of graze.
The letter 'D' after the angle denotes a graze on the dark lunar limb,
the letter 'B' one on the bright side. 'T' marks a graze close to the
terminator of the geometrically dark lunar limb within 1 degree or less
of the geometrical terminator.
3. The graze path prediction
----------------------------
The heading for each graze shows three columns
named 'EVENT', 'STAR' and 'MOON'.
The field for the star number now generally first gives the number of the
catalog that was used as the position and proper motion source. The obser-
vers should be advised to only report this number to ILOC. Of course at
present this is not possible in all cases, but ILOC will hopefully change
the format real soon.
The format of the Tycho numbers (4 digits, 5 digits and 1 digit) leaves
leading zeros or blanks away in the output. The stellar magnitude is
'visual' unless followed by 'B' (B magnitude).
In case of a graze during a lunar eclipse no position angle of cusp is
given and the percentage of the sunlit Moon refers to the fraction of the
Moon's diameter outside of the umbra.
Latitude and Universal Time:
----------------------------
The graze path coordinates and time values are corrected for the chosen
local geodetic datum and for refraction. The only possible offset of the
graze path is therefore caused by the lunar limb profile and by mostly
neglectable height differences of geoid contours of the International
Reference Spheriod.
These corrections make it possible to plot highly precise graze paths
into the maps available to the local observer. Small shifts may only
sometimes occur near the edges of a geodetic datum region due to some
overlapping areas.
Since the path values refer to mean sea level, the path has to be shif-
ted to the elevation of the observing site towards the lunar azimut
using TANZ.
Cusp Angle:
-----------
The Cusp Angle and the letter describing the illumination of the lunar
limb (D, B or T) only show the geometrical situation. Thus a bright limb
event at crescent phases may very well occur on the dark limb and vice
versa. A better idea of the situation is provided by the profile predic-
tion.
A few grazes are included occurring on the bright limb with their central
graze angle (and are unobservable there) but have a possible event at a
different position angle where the Watts Data yield a mountain in dark-
ness so at least one dark limb disappearance and reappearance of the star
can be suspected.
The rightmost column in the graze path prediction has a 'T' in the head-
line and gives letters 'A', 'B' or 'C' for the required telescope aper-
ture. 'A' means 4-inch telescopes are sufficient, 'B' denotes apertures
up to 6 inches, and 'C' suggests telescopes well above 6 inches.
Lunar Eclipses:
---------------
Instead of a Cusp Angle a value of the 'Umbral Distance' in degrees and
decimals is given. Umbral distance in this case means the distance of
the grazed star from the edge of the umbra, not from its center.
Used Geodetic Datum and Star Catalog:
-------------------------------------
Directly following the graze path data the geodetic datum for the longi-
tude/latitude values and the used stellar catalog is stated.
Credit Line:
------------
Below that the GRAZEREG version number and the computor's name(s) are
given in a credit line.
4. Observer Scan
----------------
All other observers within the same Super Standard Region, that have the
same event inside their travel radius are listed with their location and
distance and time of their closest approach.
5. Profile Plot
---------------
If requested, each graze path prediction within the observer's travel ra-
dius (not outside of it) is directly followed by the profile plot of that
event. It is always plotted for the location and time of the observer's
closest approach to the graze path, centering the corresponding position
angle of graze in the headline 'PA' and the central Watts angle in line
'WA'.
The mean lunar limb always agrees with the 0 km-line, which is the predic-
ted limit, at central graze, because the graze path data already includes
the shifts due to geodetic datum and refraction. The mean lunar limb is
plotted with the letters 'D' for the dark limb and 'B' for the bright
limb. During a lunar eclipse the mean lunar limb is given with letter 'E'.
The terminator is shown with 'T's and is given at its geometrical posi-
tion for lunar phases between 21 degrees and 339 degrees. At crescent
phases the terminator is plotted at a decreased position angle allowing
for the retreat of the cusp. A 'Worst Terminator' is not included in the
plots, instead the letter 'W' stands for the worst case of lunar limb il-
lumination referring to possible mountains of a height of 2 arc seconds.
The worst limb is geometrically a dark limb and always starts where the
terminator hits the limb.
The lunar profile is continuously plotted with 'o's, 'x's and asterisks (*)
thus making use of three separate data sets:
- The Watts data (with corrections according to Yoshio Kubo, Tokyo) are
identified by an
'o'.
- All observed limb data also given with ACLPPP as '3' or '4' are
identified by an
'x'.
- All observed limb data now published as MOONLIMB data are identified by
an
'*'.
The MOONLIMB data set is rather small yet so only a few plots show those
values. On the other hand the MOONLIMB data was checked for consistency,
so only the most reliable data was adopted.
When all of these three data sets are shown together in one profile the
plots sometimes look a little crowded. It is not always possible to connect
the profile points by a smooth line. Sometimes the coverage is so dense,
that with the poor resolution of the profile plots there is more than one
symbol of that limb data in one column, and sometimes there are wide gaps
in the observed data. Any connection between limb structures of different
symbols is not recommended.
But even with a rough connection of the profile points there is a good
chance to estimate the favorable location for an observation. The observed
data ('*' and 'x') always has to have priority, and is the only data shown
in the Cassini regions, where Watts data does not exist.
The table below the profile gives the time and location for which the pro-
file is valid and the angles of libration used here. The 'VERTICAL SCALE'
value corresponds to the former VPS-value, but is calculated in a diffe-
rent way from the actual topographic situation. All corrections to obser-
ving locations derived from this value always have to be made perpendicu-
lar to the graze path heading (see value 'HEADING', which is the azimut
direction of the lunar motion on the earth's surface).
The value 'LUNAR VELOCITY' is equal to the former HPS-value and gives the
rate of lunar motion per minute relative to position angles on the lunar
limb.
Any graphic display of secondary or tertiary stars was left away to leave
an easy estimate to the observer using the separations and position angles
given in the path predictions.
Eberhard Riedel
6.2.1 PROFILE EXPLANATION (for ACLPPP profiles)
__________________________
PROFILE HEADING DATA The following information is found in the
heading:
LINES 1-2 These are the scale in Watts an-
gles. The values on the scale
are printed in one-degree inter-
vals from the Watts angle of
central graze.
LINE 3 This is the time from central
graze in one-minute intervals.
Vertical bars are generated for
each minute through the plot,
with the one for central graze
so labeled. Negative numbers
indicate minutes before central
graze, and positive numbers min-
utes after central graze.
PROFILE PLOT Horizontal bars are drawn across the plot
at regular intervals to help in scaling the
distance from the predicted limit. One of
the lines is the predicted limit, and is
labeled as "PREDICTED LIMIT" on the right
side, and "0" on the left side. The verti-
cal scale on the right side is the number
of miles or kilometers from the limit,
while the scale on the left side is seconds
of arc from the limit. A negative value is
south of the limit and a positive value is
north of the limit.
The actual profile data are a series of
letters, numbers, and asterisks that can
look busy and bewildering. Some observers
have found that drawing smooth curves
through the points for the limb and for the
predicted profile help in understanding the
plot. There are at least two curves re-
presented on each plot, and sometimes more.
Each plot has a curve for the smooth mean
limb of the Moon, and a more jagged plot
for the predicted profile. In addition,
the terminator may appear on the plot, if
it is near the central graze. If the star
is double, and both components will graze,
the profile for the secondary (and terti-
ary, if there is one) component will also
be provided.
The codes for the limbs and terminators
are:
D dark limb of the Moon
B bright limb of the Moon
T terminator
W "worst" terminator, where two-mile
(3-km) high lunar mountain peaks can be
sunlit. Areas enclosed by W's will usu-
ally be sunlit at the south limb, where
high mountains are common, and will usu-
ally be dark at the relatively smooth
north limb
The codes for the profile points are:
* good limb correction, typically accurate
to 0.15"
1 fair limb correction, accurate to 0.3"
2 meaningless limb correction, either ex-
treme librations or in the Cassini re-
gion (see "The Lunar Profile" on page
8).
3 good limb correction from previously ob-
served graze data, accurate to 0.4"
4 poor limb correction from previously ob-
served graze data, accurate to 1"; most
of the Cassini regions have been crudely
"mapped" with previously observed
grazes, so 3's and 4's usually dominate
the profile when a graze occurs in these
regions
5 good limb correction with an empirical
correction applied (* [or 0] + 5)
6 fair limb correction with an empirical
correction applied (1 + 5)
7 meaningless limb correction with an em-
pirical correction applied (2 + 5)
P shifted limb of the primary component of
a multiple star (when the star is not at
the position used for the limb predic-
tions, which is often the case when a
center-of-light, or mean position, is
used)
S shifted limb of the secondary component
of a multiple star
R shifted limb of the tertiary component
of a multiple star
When drawing curves through the plotted
points, the following groups should be con-
nected together. A different color pen for
each group makes the profile more readable.
B AND T enclose bright area of the Moon
D encloses dark mean limb
W encloses area where sunlit peaks
may exist and cause observing dif-
ficulties ("worst" terminator)
*,1-7 the predicted limb for mean star
position
P the predicted limb for a primary
star not at the mean star position
S the predicted limb for a secondary
component
R the predicted limb for a tertiary
component
At the bottom of the profile are seven
lines of additional information about the
profile and the star.
LINE 1 The date, UT hour and latitude
libration of the graze is given.
LINE 2 The star number in the ZC or X
catalog, the version of the USNO
profile prediction program that
generated the data for the plot,
and the longitude libration of
the graze are given.
LINE 3 This line gives the limit
(northern, southern) of the
graze and the vertical profile
correction (VPC) in seconds of
arc (north is positive).
LINE 4 The Watts angle of central graze
(for the point in the limit
closest to the observer), graze
height (of the predicted limit
from the mean limb in seconds of
arc, with positive values indi-
cating a shift away from the
center of the Moon), the cusp
angle, and the name of the per-
son running the profile program
are given.
LINE 5 The horizontal profile scale
(HPS) in minutes of time per
degree of Watts angle, the pos-
ition angle for the point in the
limit closest to the observer,
and the person for whom the pro-
file was produced are given.
LINE 6 The vertical profile scale (VPS)
in seconds of arc per mile or
per kilometer, the distance of
the observer to the limit line,
and the observer's home location
are given.
LINE 7 The empirical corrections ap-
plied are identified.
LINES 8-9 Additional information is given
if the star is multiple. The
type (double, triple), the dis-
tance of the primary from the
mean position, the magnitude,
separation, position angle, and
the vertical and horizontal
shift in the profile for each
component are listed. Vertical
shifts are given in miles (or
kilometers) and seconds of arc,
horizontal shifts in time. In-
formation is given for compo-
nents that do not show on the
plot.
Below is a description by Eberhard Riedel concerning the improved
profile plots generated by GRAZEREG. Good luck for 1999.
GRAZEREG 5.0 shows more features on the lunar limb by utilizing all
available data from observed grazes. This option so far was only
possible by making an extra run with D. Dunham's 'ACLPPP'-program
during the last years, also using Mitsuru Soma's reduction work.
Furthermore some extra lunar limb data has been published by Dietmar
Buettner and Reinhold Buechner, Germany, after another thorough
reduction work, giving highly reliable limb data. Their 'MOONLIMB'
data only improves some northern lunar limb regions at present, whereas
southern regions will be added in the near future.
Compared to ACLPPP the only thing NOT being considered by GRAZEREG
profiles is a limb correction for double stars. Neglecting this the
use of ACLPPP can be abandoned by the computors. GRAZEREG will con-
sider double stars in the future in accordance with a revision of the
available double star data.
GRAZEREG 5.0 now takes into account the internationally agreed conven-
tion concerning geographical longitudes:
longitudes west of Greenwich go from 0 to -180 degrees,
longitudes east of Greenwich go from 0 to +180 degrees.
THE PROFILE OUTPUT
------------------
Since two more sets of limb data are being used now besides the common
Watts data, two more signs can be found in the profile plots for precise
distinction.
- The Watts data (with the Kubo correction) are no longer identified by an
astrisk, but by an
'o'.
- All observed limb data formerly also given with ACLPPP are identified by
an
'x'.
- All observed limb data now published as MOONLIMB data are identified by
an
'*'.
The MOONLIMB data set is rather small yet so only a few plots show those
values. On the other hand the MOONLIMB data was checked for consistency,
so only the most reliable data was adopted.
When all of these three data sets are shown together in one profile the
plots sometimes look a little crowded. It is not always possible to connect
the profile points by a smooth line. Sometimes the coverage is so dense,
that with the little resolution of the profile plots there is more than one
symbol of that limb data in one column, and sometimes there are wide gaps
in the observed data. Any connection between limb structures of different
symbols is not recommended though.
But even with a rough connection of the profile points there now is a much
better chance to estimate the favorable location for an observation. The
observed data ('*' and 'x') always has to have priority, especially con-
cerning the Cassini regions.
Eberhard Riedel