Last updated 19 March 2002
A few people have expressed an interest in the format used in files such as STARTUP.MAR ("mark files"). Usually, they're working on scope control projects or have some sort of research interest.
The .MARs are ASCII files where each line consists of a number, a keyword, and one or more settings. The keywords are actually irrelevant, except to merely human viewers; it's the numbers in the beginning that Guide uses to interpret a given line. As you may have already figured out, you don't need to have all the lines in a given .MAR; for example, the "May 1994 eclipse" mark resets your date and time, and your lat/lon, and recenters you on the sun at a level where you can see the eclipse. But irrelevancies such as what printer is set up aren't included.
The following documents most of the lines I think people would actually use; I've not had time to go through and document all the lines. Please feel free to ask me if you think it would help for me to add documentation for some of them.
The very first two lines were added in Guide 6, and will be ignored by any older version:
999 name Gervase occ. in 1180 998 created 2450721.124664 601
Despite the numbers, these appear at the top of a .MAR file. Line "999 name" is used to give a proper description in the list box, instead of showing a meaningless GERVASE.MAR. It is omitted for STARTUP.MAR; Guide already knows to call that one "Initial Position". Line 998 contains the Julian Day the .MAR was last modified, plus a version number. (Shortly after Guide 6 was sent to be replicated, I decided to start playing with improvements. As of 21 Dec 1998, the version number was up to 605; with Guide 8, it's moved up to version 702.)
1 ra 51.044208
2 dec -17.406833
3 level 6.000000
These lines tell Guide that the chart is centered at RA=51.044208
degrees, dec=-17.406833 degrees, at zoom level 6. The RA/dec is
always in J2000, even if the default epoch was set elsewhere to be
something else.
The RA is in decimal degrees running opposite of the usual
convention: that is, an RA of 50 degrees would correspond, not to
3h20m, but to 20h40m. This is an unfortunate legacy of the early days
of Guide. I thought of RA as resembling an x-coordinate, which would
"obviously" increase from "left to right". Guide is therefore peppered
with places where the sign of the RA has to be flipped.
4 mag0 106
Stars are being shown to magnitude 10.6.
5 markings 6607
6 automark c607
The above are hexadecimal values. A marking is turned on if its
bit in line 5 is set; it's on "auto display" if the bit on line 6
is set. The following bits are used:
Crosshair at screen center 0x0001 *(No auto)
Border around chart 0x0004 (No auto)
SAO numbers on stars 0x0008
Bayer (Greek letters) 0x0010
Flamsteed numbers 0x0020
HD (Henry Draper) numbers 0x0040 *
HIP (Hipparcos) numbers 0x0080 *
HR (Yale BSC) numbers 0x0100 *
PPM numbers 0x0800
GSC numbers 0x1000
Common star names 0x2000 *
Legend 0x4000 (No auto)
For "no auto" markings, the corresponding bit in automark is
ignored; that marking is either on or off (for example, there's no
"auto" setting for the legend). The five asterisked markings are
new to 6.01.
11 lat/lon -69.900000 44.010000
Specifies longitude West 69.9, North 44.01 (in this case,
Bowdoinham, Maine: Project Pluto corporate headquarters.)
12 zenith 0
0=north at top of chart, 1=zenith at top of chart, 2=ecliptic
north at top and 3=galactic north at top.
13 strfmt 77 12
These numbers give the formats for RA/dec and lat/lon, respectively.
The first number is the sum of the following values:
0 for declination in decimal degrees
1 for declination in degrees/minutes
2 for declination in degrees/minutes/seconds
4 for use of +/- instead of N/S
8 for use of leading zeroes
32 to leave out the 'hms' letters in RA and ' and " in dec
0 for RA in decimal degrees
64 for RA in hours/minutes
128 for RA in hours/minutes/seconds
1024 for RA in decimal hours
...with 16, 256, and 512 having been either left out or obsoleted.
So, the above example value of 77 (=64 + 8 + 4 + 1) would indicate
RA in hours/minutes, with leading zeroes, and +/- used on declinations
instead of N/S. And the declinations should be in degrees and minutes.
It may be simpler to go into Guide's Formats dialog (inside the
Settings menu), set the format you want, exit, look at STARTUP.MAR,
and say, "Ah... that must be the string format number I want to use."
14 defepoch J2000.000000
The letter can be J=Julian, B=Bessel, D=epoch of date, and is
always followed by the default epoch year. (For D=epoch of date, the
year is meaningless and ignored.)
15 timezone -5.00
Specifies difference in hours between local time and UT. I'm set up
for EST, with a five-hour difference.
16 currtime 2450537.124028
Specifies Guide's time when the .MAR was written. When Guide first
starts up, it ignores this time in favor of that provided by the PC
clock.
17 zonename 1
Look in the file STRINGS.DAT in your Guide directory, and you'll
see that lines 156-164 contain the time zones Guide knows about. (In
some of the foreign language versions of STRINGS.DAT, such as
DEUTSCH.DAT, the zones and numbers are modified to correspond to
European zones.) Zonename=1 tells Guide that you selected line
156+1=157, or "EST". It needs that information to know what text to
append to time values. (The simple '-5.00' from the '15 timezone'
isn't enough; it could mean either EST or CDT.)
51 language d
This can currently be e=English, d=Deutsch (German), f=French,
i=Italian, or s=Spanish (e for Espanol was already taken), or
a=Japanese, b=Dutch, c=Russian, k=Chinese, j=Czech.
18 drive f:\
Specifies the CD drive letter. It's only used when Guide first
starts up.
19 julian 0
It used to be that this could only be 0=Gregorian calendar,
1=Julian calendar. Now, however, the following values can be
added in to specify the format in which dates and times are
displayed:
add 0 to show time to tenths of seconds
add 2 to show time to full seconds only
add 4 to show time to .01 seconds
add 6 to show time to .001 seconds
add 256 to show time to minutes only
add 0 to show Day/Month/Year
add 8 to show Month/Day/Year
add 16 to show Year/Day/Month
add 24 to show Year/Month/Day
add 32 to show date only with no HH:MM:SS
add 128 to show months as two-digit numbers, not three-letter abbreviations
20 home 3
Specifies your home planet; 0=sun, 1...9=Mercury...Pluto,
10=Earth's moon, 11...14=Io...Callisto, 15...22=Mimas...Japetus,
23...27=Miranda... Oberon, 28=Phobos, 29=Deimos. (Obviously,
3=Earth is the most common value!) Values extend up to (at present)
96 = S/2000 J 11, the most recently-discovered satellite of Jupiter.
If you specify an observing position in Guide such as a comet,
asteroid, artificial satellite, or probe, then additional text
specifying that object will follow. For example, set your location
to be the ISS and you'll get
20 home 3 ISS
indicating that you're observing from the ISS, an object orbiting
object #3, a.k.a. "the Earth".
21 inversn 0 0.000000
The first number can be 0=uninverted chart, 1=completely inverted,
2=flipped left/right, 3=flipped top/bottom. In addition to these
sorts of flips, the second number specifies an arbitrary rotation in
degrees. (It's almost always zero, but some people want to put North
to the left or some such.) All these things are usually controlled
through the Inversion Dialog.
22 printer 0 0 ! PRN 0 0
Specifies several aspects of printing behavior in DOS (Windows
users can ignore it). In order, the fields specify landscape vs.
portrait (0 or 1), resolution (0=lowest resolution, 3=maximum), the
printer driver selected ('!' indicates none selected), the output
file name (PRN indicates printing directly to the printer), and two
fields that _may_ get used soon, if I have time to implement printing
through GhostScript (right now, leave 'em both set to zero).
24 testflag ffff
You may recall that Guide 5 had a "test flags" menu, used to
control assorted things that were not quite ready yet (bitmapped
planets, RealSky display, etc.) It may have some use in Guide 7
eventually, but right now, leave it set to hex ffff=all bits set=no
test flags used.
25 marking 0 1 1 0 J2000.000000 125000.000000 100000.000000 15 131.62
(The final '131.62' is new to Guide 6.01.)
Guide provides eight of these 'marking' lines; they specify (in
order) how ticks, grids, hatches, side labels, an unused marking,
the horizon, the ecliptic, and the galactic equator are to be
drawn. After the first number (a simple index running from 0 to 7),
it is specified whether the marking is on auto spacing (1=yes,
0=no); its type (0=off, 1=tick, 2=grid, 3=hatch, 4=side label,
5=equator); its coordinate system (0= RA/dec, 1=alt/az,
2=ecliptic, 3=galactic); its epoch; its spacing in each axis, in
units of .00001 degree; its color index (15=white); and (in 6.01 and
later) a number indicating, for auto mode, the frequency at which
marks are to be ideally made (in the above case, Guide strives to
have ticks at 131.62-pixel intervals.)
For the epoch, see comments about line 14 ("defepoch") above.
If you are using the current Guide 8 software, the "15"
in the above line will be replaced by a six-byte hexadecimal number
giving the color (RGB) to be used for this marking. That change was
made as part of an effort to allow a full selection of colors and
line styles throughout Guide. (You may get a seven-digit hex number,
with the leading digit indicating a line style.)
With the "original" Guide 8, or any earlier version, the color will
instead be indicated by a number ranging from 0 (black) to 15 (white):
0 Black
1 Bright Green
2 Orange
3 Cyan
4 Yellow
5 Red
6 Brown
7 Purple
8 Blue
9 Magenta
10 Dark Green
11 Middle Green
12 Bright Green
13 Dark Gray
14 Light Gray
15 White
26 ap dia 0.000000
Specifies the diameter in degrees of the aperture circle
controlled in the Measurement Markings dialog. 0=off.
An undocumented feature: you can specify multiple apertures one
right after another. For example, "26 ap dia .5 1 5" would get you
30', 1-degree, and 5-degree concentric circles.
27 mark2 cf
This is another hex value. It would appear that lines 5-6
would handle all markings, and that some bits are even still
available. At one time, all bits were used and a second
"markings 2" had to be added on. In the past, more bits in
mark2 were used; but now, only three have any meaning:
Show GSC "non-stars" 0x0001
Show the CCD frame 0x0010
Show the Telrad 0x0020
28 altitude 100.00
Specifies a 100-meter altitude above the ellipsoid.
29 mag rang 100
Specifies that a range of 10 magnitudes is shown (as
controlled in the Star Display dialog box.)
30 az convn 0
Default of zero defines the "normal" convention where azimuth is
specified as north=0 degrees, east=90, south=180, west=270.
Four possible bits added to 'az_convn' have the following meanings:
Bit 1 resets to the "astronomical" convention, with south=0,
west=90, north=180, and east=270. This is used more frequently
in French-speaking countries, though even there, it's not
all that commonly used.
Bit 2 resets azimuths from 180 to 360 to run from -180 to 0.
Azimuths from 0 to 180 are unaffected; azimuths from 180 to
360 have a full 360 degrees subtracted from them. Combine these
bits, and there are four possible values for 'az_convn':
value = 0: N=0, E=90, S=180, W=270
value = 1: S=0, W=90, N=180, E=270
value = 2: N=0, E=90, S=+/-180, W=-90
value = 3: S=0, W=90, N=+/-180, E=-90
Bits 3 and 4 reset the conventions used for display of hour angles
in the Legend area. By default, these run from -12:00 to +12:00.
Bit 3 resets this to run from 00:00 to 24:00. Bit 4 is intended for
people taking telescopes across the equator; in this situation, it can
be helpful to "flip" the convention so that (for example) an
hour angle of 3:15 is displayed as 20:45.
Thus, a value of (say) 6 would tell Guide to have hour angles run from
0 to 24, and azimuths from -180 to +180, with north equal to az=0.
31 margins 50 50 600 50
Print margins in .01 inches: left, top, right, bottom.
32 rescale 1.000000
Part of the "printer kludge" solution listed in the manual...
specifies that the print output in DOS should be unstretched. Some
Panasonic printers turned out to be slightly nonstandard, and
required that this value be reset to 1.125 or .8889 before they
would give round stars and an undistorted chart. Under Windows,
it doesn't mean anything.
33 sizes 0 648000000 324000000 162000000 72000000 36000000 18000000
7200000 3600000 1800000 900000 480000 240000 120000 60000 30000 15000
8000 4000 2000 1000
(Wrapped around for clarity) Specifies level sizes in milliarcseconds.
The first number specifies a size for level 0, which doesn't exist;
after this, level 1 is set to be 648000 arcseconds = 180 degrees;
level 2 is set to be 324000 arcseconds = 90 degrees; and so on,
down to level 20 being a mere one arcsecond.
34 colors 7 15 4 4 1 2 3 15 15 15 14 15 15 3 15 0 0 0 0 0
This line defines color values for (in order) planet symbols,
planet disks (when done with the line artwork of Guide 5.0... somewhat
obsolete now), asteroid Xs, deep-sky objects, constellation lines,
constellation boundaries, constellation labels, a no-longer-used
marking, Greek letters and common names, Flamsteed numbers,
SAO/HD/HIP/GSC/PPM numbers, the chart border, the aperture circle,
planet trails, and the CCD frame. There are a few other items
reserved for future use... thus the trailing zeroes.
The color indices range from 0 to 15. For their meaning, look above
to the discussion for "25 marking".
35 legend 2075 0
The first number describes what items are shown in the legend; the second
describes its "layout". Both are written in decimal format, though they
really ought to be in hex (since it is the individual bits in them that are
significant).
For the first number, each bit specifies whether a particular part of
the legend is shown, as follows. Notice that in three cases, a bit set
indicates that this part of the legend is shut _off_.
Time 1
Lat/lon 2
Caption 4
RA/dec 8
Field of view/zoom level 0x10
Object key _off_ 0x20
Star size key _off_ 0x40
Compass _off_ 0x80
Sky Atlas 2000 page 0x100
Uranometria page 0x200
POSS plate (not used yet) 0x400
Alt/az 0x800
Ecliptic coordinates 0x1000
Galactic coordinates 0x2000
Hour angle 0x4000
Millennium Atlas page 0x8000
In the example given, 2075=2048+16+8+2+1, indicating that the time,
lat/lon, RA/dec, field of view/zoom level, alt/az, object key, star
size key, and compass are being shown.
Bits in the second number have the following meanings:
1 Horizontal style (legend items are stacked left/right, not up/down)
2 Legend is centered
4 Legend is moved to right-hand side of screen
8 Legend is at top of screen
In the example, this number is zero, leaving the legend in the vertical
style at the lower left corner (the default situation).
37 Frame 0.979206 0.751226 1.500000 1.000000 3.019420 0
This line specifies, in order, the CCD frame center RA and dec (in
radians); its width and height (in degrees); its rotation (in radians);
and a Boolean describing if it is nailed to the center of the chart (1 if
it is, 0 if it isn't).
40 view off 0.000000 0.000000 0.000000
This is part of a (pretty clumsy) way of specifying viewpoints other than
those on planets. Right now, it's almost always (0, 0, 0), meaning a
planetocentric viewpoint (topocentric if your home planet is Earth). The
only way to get other viewpoints (right now) are the somewhat user-abusive
systems described at
http://www.projectpluto.com/useless.htm#Viewpoints
http://www.projectpluto.com/useless.htm#odd_viewpoints
Eventually, I'll figure out a reasonable way of managing this feature.
The three numbers specify an offset, in J2000 coordinates, from the
planetocentric or topocentric position.
41 ast a li 0 2147483647
The "Asteroid a (major axis) limits" store the values set (in the DOS
software only) for limiting values of major axes. These can be used to
require that, for example, only Trojan asteroids be shown... or only
those venturing within 1 AU of the sun... or only distant minor planets.
The limits are in units of 1/100 000 000 of an AU. The values given above
indicate that no limits are currently set (all asteroids are shown,
regardless of their minor axes.)
42 lx200 pr 0
Specifies the serial port for the LX200 or Sky Commander. 0=neither of
these devices is hooked up.
43 track fr 2
Specifies that planet trails should have cross-marks at every second
position. Thus, if you had made a trail with 5-day intervals, cross-marks
would be added at 10-day intervals.
44 col spec 0
1=stars are colored by spectral type; 0=stars are not colored by type.
45 dpi, inv 300 300 0 1
(DOS software only) Indicates a resolution in DPI (in this case,
300x300), whether the chart is inverted in color (0=black stars on a
white background, 1=white stars on a black background), and the number
of copies to be made each time. (Normally, you would only print one copy
of a chart, but DOS Guide provides an option to print multiple copies.)
46 data 4 0 4 0 7 0 4 0 5 0 7 0 4 0 5 0 4 18 28 26 4 30 1807 0 487 54 7 3
47 anim spd 0.000347222
48 outlined 1 1 31 164 0 1
A B C D E F
Call the six numbers on line 48 A, B, C, D, E, and F. A = 1 if stars
are outlined; A = 0 if they are not. E = length of the 'proper motion vector'
attached to stars, as set in the Star Display dialog; it defaults to zero.
F = the 'fuzziness' set in the Star Display dialog.
The middle group of three numbers, '1 31 164', or 'B C D', specify
how isophotes are shown. B has the following meanings:
B = 0: filled isophotes, but turned off
B = 1: filled isophotes, turned on
B = 2: outlined isophotes, but turned off
B = 3: outlined isophotes, turned on
C and D give intensity levels for the dimmest and brightest isophotes,
in the range 0 to 256. Thus, C=31 causes the lowest isophote to appear
at 31/256 of the distance from "background" to "foreground" color. (In
"normal mode", "background" is black and "foreground" is white, so
C=31 corresponds to a dim shade of gray.) D=247 would cause the brightest
isophote to be almost white.
If you switch to red mode, where "background" is black and "foreground"
is red, you'll see that the isophotes swap to shades of red. And in
"realistic" mode, where the foreground is blue in the daytime, you'll
see isophotes in shades of blue, and so on.
Eventually, the plan is that you'll be able to click on an isophote
and get the usual "OK", "More Info", "Next", "Display" dialog. The
Display dialog will let you turn isophotes off and on, and the Options
dialog will have
[X] Show isophotes as outlines
[ * ] Contrast
[ * ] Brightness
...with the last two being slider controls, just as for planets. The
underlying code is in place, but I've not had a chance to figure out how
to hook up the interface.
49 lx delay 15 400 9600 0 2400
Indicates that Guide waits 15 seconds for a reply to an LX-200 command,
and that once it does get a reply, it waits 400 milliseconds before
sending another command. Communication runs at 9600 baud.
The following number is zero by default, indicating that the scope
sends and receives LX-200 commands in the short-precision format. If
it's 1, it indicates that the LX-200 is using the "long format". As
described at the above link, Guide determines the format in use by
looking at the coordinates returned by the "Slew Guide" command.
The final number indicates the baud rate used for Sky Commander or
Sky Tracker systems. The default value of 2400 will almost always work,
but some of the later versions of these gadgets can run at higher baud
rates. (The advantage of this is a little doubtful, though.)
Users of "real" LX-200s won't have to modify any of this, but some
builders of LX-200 "clones" may have different timing or baud rate
requirements.
50 enc syst 0
Indicates what sort of scope control you're using. 0=LX-200, 1=Sky
Commander, 2=Tech 2000 Dob Driver (reserved for future use), 3=Mel
Bartels' ALTAZ system.
53 curs rdt 1
Set to 1 if coordinates in the legend are updated as the mouse moves.
This is the default behavior. Otherwise, it's set to zero.
54 starsize 5 300
Indicates that stars range from a radius of .5 pixels (smallest, dimmest)
to 30.0 pixels (largest, brightest). This is combined with "29 mag range",
and stars within that range are scaled logarithmically.
55 mag text 0
Indicates to what level stars are labelled by magnitude; for example,
if this value were 150, then all stars brighter than mag 15.0 would be
labelled by magnitude. 0=no mag labels shown.
56 ast labe 0 0
57 video 3
Current video mode. This is only used by the DOS software.
58 gsc ppm 150
This was used in Guide 5 to indicate that, if a GSC star was within
15.0 arcseconds of a PPM star, they were to be considered the same star.
It has no meaning at all in Guide 6 or later.
59 gal size 20 9
Indicates that galaxy symbols should be 20 pixels wide, 9 high.
Also indicates that other symbols such as boxes for nebulae, circles
for open/ globular clusters, etc. should be 20 pixels across.
60 GRS lon 62.000000
Indicates that the user has set the Great Red Spot to be at Jupiter
System II longitude 62 degrees.
61 quickinf -1 110 150 1 0 0
The first number, '-1', is a bitfield ('-1'='all bits set'),
describing which parts of Quick Info should be shown. Right now,
it's not recommended that you change this number; it's really
reserved for future use.
The next number, '110', indicates that Quick Info should list all
asteroids brighter than magnitude 11.0. Resetting it to zero shuts
off the list completely.
The third number, '150', indicates that Quick Info should list
all comets brighter than magnitude 11.0. Resetting it to zero shuts
off the list completely.
The fourth number, '1', indicates that Quick Info should list
one set of lunar phases. (Given the way phase data is lined up in
columns, Guide has to bump that up to an even number of lunar
months.) Resetting it to zero shuts off the list of phases
completely.
The fifth number, '0', indicates that Quick Info should list
zero days worth of Galilean satellite events. If you changed this
to, say, 13, then Guide would show 13 days worth of data.
The sixth number isn't used yet.
62 datacols 4 4 4 4 4 4 4 4 7 7 15 15 15 15 4 4 4 4 4 4 7 7 4 4 5 4 14 4
63 real CD k
Normally, this letter matches that of your Guide CD (specified
on "18 drive"). But this can be used if you have Guide on one
drive and are putting RealSky and A1.0 CDs in a different drive.
For example, I have copied Guide to drive F: and put RealSky and
A1.0 CDs in drive K:.
64 line var 0.000
Length of the line of variation shown for comets and asteroids,
in days. 0=no line of variation shown.
65 cometcrc eab73d1b
A value computed by Guide and used to determine if the COMETS.DAT
file has been changed. (In Guide 5, people sometimes modified
COMETS.DAT to include new comets and were puzzled when they didn't
necessarily show up right away. The reason was that Guide 5 didn't
recognize that it should recompute which comets were visible. The
sole purpose of this line is to cause Guide 6 and later to think,
"There's a new COMETS.DAT... it's time to check out comets again.") I
can't think of a good reason someone would want to modify this line.
66 color mo 0 0 ffffff 000000 000080
These five values all pertain to settings in the Backgrounds dialog.
The first value is 0 for 'normal' colors, 1 for 'chart mode', 2 for
'red mode', 3 for 'flashlight mode', and 4 for 'realistic mode'.
The second value is 1 if the ground is shown filled in (the 'Show
Ground' checkbox), 2 if the horizon objects are shown, 3 if both
are shown, 0 if neither are shown.
The remaining three values are RGB colors, giving the color of the
background in chart mode, in normal mode, and the color of the ground.
The above examples specify white, black, and a "half-way", dark red.
67 projecti 4
This value is 2 if you've set an orthographic projection, 3 for
gnomonic, 4 for stereographic, and 5 for equidistant.
68 planets 0
This value is 1 if you've selected "Use Full Precision" (for
planets) in the Data Shown dialog; 2 if you've selected "Label
Planets by Name" (instead of symbol); and 3 if you've selected both.
It's zero if you've selected neither (the default).
69 TLE name bright.tle
The logical meaning: this line specifies the name of the file
containing satellite elements, and is altered when you use the
"TLE=" feature in the Settings menu.
70 encoders 8192 8192
Specifies that the JMI/NGC-Max/MicroGuider III/Ouranos encoders
(if any) have a resolution of 8192 steps _in both directions_ (alt
and az, or RA and dec for an equatorial).
71 ephemer 403f -600 0
73 temp/hum 20.00 20.000000 1.000000
Indicates: temperature (in degrees C), humidity (as a
percentage), pressure (in bars). I realize that, in theory, there
ought to be settings for each planet. But right now, only the
Earth makes use of this data. Computing refraction from, say,
Venus (pressure=90 bars, temp=500 C, humidity=0) is beyond the
scope of this software at present. (Though computing refraction
from the Moon, pressure = 0 bars, shouldn't be too tough...)
75 panning 0.500000 7.000000 0
First number indicates that cursor keys pan half a screen (that
is, hit left-arrow and you recenter on the center of the left side;
hit Num-7 and you move diagonally to the upper left corner; and so
on).
Next number indicates that at fields of view smaller than 7
degrees, Guide switches to its more "detailed" deep-sky and
variable star data. Above that limit, it shows no variables
and only NGC and IC deep-sky objects.
The reason behind this is that Guide shows a _lot_ of DSOs. If
it had to puzzle through all the DSO data to cover a 180-degree
field of view, you would have to be very patient indeed. So
above a somewhat arbitrary level (defaulting to seven degrees),
it drops back to NGC and IC objects only. You can raise that
level, and thereby get Guide to (say) show all variable stars
in a given hemisphere. But you will have to be a little patient;
it will take time for them all to appear.
81 disp lim 18.00 181.00 0.00 1.90 0.00 40.00 0.00 18.00
The first two numbers indicate that Milky Way isophotes are to
be shown at fields of view between 18 and 181 degrees. The next
two indicate that DSS and RealSky images are shown at fields of
view between 0 and 1.9 degrees. The next two numbers indicate
that, on eclipse charts, city names are shown at fields of view
from 0 to 40 degrees. The last two numbers indicate that nebula
isophotes are shown at fields of zero to 18 degrees (i.e., those
smaller than that at which the Milky Way is shown.)