Constellations & Asterisms
How to draw your own
Ok, this page contains the exact
steps you will need to create your own line drawings (constellations,
asterisms, pointer stars, nebulae,
and so forth).
In the Data | User-Defined
Data area choose the option "Snap to: Nearest star"
as highlighted below. This way when you use a CONTROL+Left Mouse Click
anywhere on a star it becomes your anchor point and a line is drawn to
the star.
Initial settings
Data | Add User-Defined Data
Choose the correct settings!
Choose the Data class: Lines/Polygons as shown
along with Object type: "Constellation Figure". Actually
you can make the lines ANY object type you want but Constellation Figure
makes sense in this example.
The comment field is not necessary.
Pick a filename for your version of the constellation lines. Here
I chose the drive and folder "D:\my-constellations.txt"
for the file.
This text file will be compiled into an SDB that will plot the lines you
have created.
Label the stars if you find this helps. Also turn
off the fainter stars to avoid confusion. A setting of Stars
Visible to about 4th or 5th magnitude is usually about right when
drawing constellations or asterisms. This will keep you from
inadvertently clicking on fainter stars.
View
| Display Explorer | Star Properties. See below limiting the stars
to only 4th magnitude and brighter.
Shut off fainter stars
Avoid confusion
Turning on the Constellation Boundaries will also help you see what stars are
found within the constellation you are working. See boundary marking Ursa Major below.
Constellation Boundaries
help you see the limits of the constellation
Now Ready to start drawing!
First
you must designate the first star in the sequence. This is done by using
CONTROL+SHIFT+Left Mouse Click
which creates an initial "Move To command".
WARNING!
It appears that nothing has
happened when you use the CONTROL+SHIFT+Left Mouse Click issuing the
Move To command.
The Move To command lifts the pen off the chart cleanly and drops an
anchor. Again nothing happens when the Move To command is used! Failure to
include an initial and final Move To command will cause your lines to all be
interconnected!
Now, pick the star Alkaid.
CONTROL+SHIFT+Left Mouse Click
on this star.
It appears that
nothing has happened!
However, in the Data | User-Defined Data area you now have a "MOVE TO" command
with the coordinates of Alkaid. The Move To command is simply placing
the pen on the first star in the sequence. If you don't start with a "Move To" you will
have lines connected that you don't intend. You should always end with a
Move To command also, that is
CONTROL+SHIFT+Left Mouse Click
on the last star in the sequence.
CONTROL+SHIFT+Left Mouse Click
on the
first star
Note: Command: MOVE TO
The first star stamped here for you
After placing your initial
anchor (Move To) next
CONTROL+Left Mouse Click on the
star Mizar. If you accidentally hit Alcor instead of Mizar you can
remove the line by pressing F4 then try again. F4 will continue to
DELETE lines as long as you press it. That is you can REMOVE as
many lines as needed by pressing F4 over and over again.
NOTE: If you press F4 too many
times you will also remove the initial anchor you had created by using
the first
CONTROL+SHIFT+Left Mouse Click!
If you have DELETED all of the entries in the User-Defined Data area
go back and start again!
CONTROL+Left Mouse Click on the second Star
F4 DELETES lines that are mistakes!
Next
CONTROL+Left Mouse Click on the star named Alioth.
CONTROL+Left Mouse Click on next star
See how simple!
Now when you have the
Big Dipper asterism
done if you wish to connect the other stars you will have to use the
CONTROL+SHIFT+Left Mouse Click
on the very last star in the sequence. If you don't use an initial and
final anchor (Move To) additional stars added will be connected!
See below. The line is drawn from Megrez not cleanly from Dubhe to
the next star. Press F4 DELETE once and the line disappears.
Use the CONTROL+SHIFT+Left
Mouse Click to anchor on Dubhe first. Now you can
CONTROL+Left Mouse Click on the next star and the line will be drawn
from Dubhe correctly. Watch the animation below!
First Anchor on Dubhe
(CONTROL+SHIFT+Left Mouse Click on Dubhe)
Then a normal CONTROL+Left Mouse Click on the next star
So get it!? Keep
CONTROL+Left
Mouse Clicking on the stars you want to include lifting the PEN where
needed. F4 DELETES lines you don't want. When you are
satisfied with the end result make sure you do a final
CONTROL+SHIFT+Left Mouse Click on the very last star issuing a Move
To!
Each constellation starts with the
anchor MOVE TO (CONTROL+SHIFT+Left Mouse Click) and ends up
with another MOVE TO (CONTROL+SHIFT+Left Mouse Click) on the very
last star in the sequence.
Don't forget to start with the Move To and
then end with another Move To (CONTROL+SHIFT+Left click). Failure to include
the "Move To" commands will result in lines being drawn where you don't
want them. Remember "F4" DELETES unwanted lines.
This is how it is done!
See how simple?
Mistake made, No Problem
- F4!
Whoops! Better use F4 (DELETE) and get rid of
that line!
1)
Setup the User-Defined Data (Data
| User-Defined Data)
section correctly
2) Find the first star of the constellation and anchor on
it using
CONTROL+SHIFT+Left Mouse Click creating a MOVE TO command
3) CONTROL+Left Mouse Click on each star you want connected with
a line
4) Use F4 to DELETE lines that are mistakes
5) Re-anchor the pen wherever necessary. CONTROL+SHIFT+Left Mouse
Click
avoiding bad or unwanted lines.
6) Finally Anchor again CONTROL+SHIFT+Left Mouse Click on the
very last star in the sequence.
When satisfied with the
drawing use the EXPORT button to save the data. You can also SAVE
the document file using File Save As BEFORE you DELETE the User-Defined
Data. I recommend saving a document for each constellation as you
go. Then you can add them all together into a single text file!
When Done Export the text file!
This Text file is then made into and SDB
Once you have your text file created it can then be
compiled into an
SDB. Use Data | Import and Browse your computer for the text
file and press Compile
Data | Import
Here is the default Ursa Major
definition as found in the Constellation Figures.txt file.
21 MOVE TO HIP 67301 13.79233056 49.31325000 30.00 Ursa
major
22 LINE TO HIP 65378 13.39877753 54.92533732 30.00
23 LINE TO HIP 62956 12.90050072 55.95981118 30.00
24 LINE TO HIP 59774 12.25711412 57.03262557 30.00
25 LINE TO HIP 58001 11.89719332 53.69477247 30.00
26 LINE TO HIP 57399 11.76748865 47.77943745 30.00
27 LINE TO HIP 56034 11.48447316 39.33698916 30.00
28 LINE TO HIP 55219 11.30798009 33.09433621 30.00
29 MOVE TO HIP 57399 11.76748865 47.77943745 30.00
30 LINE TO HIP 54539 11.16105143 44.49845643 30.00
31 LINE TO HIP 50372 10.28492488 42.91431758 30.00
32 MOVE TO HIP 54539 11.16105143 44.49845643 30.00
33 LINE TO HIP 50801 10.37214221 41.49955423 30.00
34 MOVE TO HIP 58001 11.89719332 53.69477247 30.00
35 LINE TO HIP 53910 11.03069891 56.38246424 30.00
36 LINE TO HIP 48402 9.86843169 54.06435365 30.00
37 LINE TO HIP 46853 9.54750763 51.67670569 30.00
38 LINE TO HIP 44471 9.06042002 47.15646323 30.00
39 LINE TO HIP 44127 8.98674392 48.04158759 30.00
40 LINE TO HIP 46853 9.54750763 51.67670569 30.00
41 MOVE TO HIP 48402 9.86843169 54.06435365 30.00
42 LINE TO HIP 48319 9.84977927 59.03856708 30.00
43 LINE TO HIP 41704 8.50438801 60.71804967 30.00
44 LINE TO HIP 46733 9.52549205 63.06189055 30.00
45 LINE TO HIP 54061 11.06210886 61.75099407 30.00
46 LINE TO HIP 53910 11.03069891 56.38246424 30.00
47 MOVE TO HIP 54061 11.06210886 61.75099407 30.00
48 LINE TO HIP 59774 12.25711412 57.03262557 30.00
49 MOVE TO HIP 59774 12.25711389 57.03263889 30.00 end Ursa major
Your constellation text file for Ursa Major
should resemble the above.
What is an
asterism? <-- Click here for details and complete list provided by TheSky
OK. Now that you know how to draw your own constellation lines let's
consider making an asterism within a constellation. In order to accomplish
this you will need to use two different object types in order to differentiate
between them. By using Constellation Figure then say Reference Line you
can have two different attributes. Better yet make a new object type
called Asterisms first using the View | Display Explorer. In the Goto: box
type in User and you will be taken directly to the User-Defined object types.
See below.
Create new Asterism Object Type!
Use Display Properties on Type 1
Pick a different line type and/or color for your asterisms.
Different line type
And color
Change the Data | User-Defined Data section to use the newly
created object type Asterism as shown. Also use a new file name for the
asterisms!
Asterisms use new object type!
And new name!
So you draw the stars that make up the
asterism using object type asterism and the constellation using object type
constellation figure. Below the green dashed lines are the asterism "The
Big Dipper" and the red lines the constellation lines for Ursa Major.
How about a new group called Pointers.
This can be another line type and turned on and off accordingly. Be
creative!
Pointer Stars
Here is how you can add the
"summer triangle" asterism. Set up the Add-User Defined Data area
as per the above instructions first.
Next find the first star, in this
case we will use Altair. CONTROL+SHIFT+LEFT MOUSE click on the star
Altair creating a Move To. Using SHIFT KEY plus the left mouse click sets the starting anchor.
Then CONTROL+Left Mouse Click on the next star, Deneb in the example. A
line is drawn connecting the two using a Line To command. CONTROL+Left Mouse Click on the star Vega in
the example below, another line is drawn. Lastly, CONTROL+SHIFT+Left Mouse
Click again on Altair dropping the anchor and lifting the pen so-to-speak.
See below.
Summer Triangle
Example
Done!
Again, also best to
make a new line type to differentiate
the "Asterism" from the constellations lines as per the above instructions.
Then just compile the text file
into an SDB file. Here is the text created by TheSky for this example.
;Copyright, Software Bisque, Inc.
>LABEL 1,30
>ALIAS 19,35
>RAHOURS 37,47
>DECDEGREES 49,60
>CATALOG CLASS=LINES
>LOADMEMORY
>IDENTIFIER Summer Triangle <---- CHANGE ACCORDINGLY!
>OBJECT TYPE 70 <----------------- First User Defined Object Type See Below
1 MOVE TO
Altair
19.84644722 8.86894444 30.00
2 LINE TO Deneb
20.69053333 45.28033333 30.00
3 LINE TO Vega
18.61567500 38.78413889 30.00
4 LINE TO Altair
19.84644722 8.86894444 30.00
5 MOVE TO Altair
19.84644722 8.86894444 30.00
NOTE: Object Type 54
is object type "Reference Line". Refer to TheSky manual
for a complete list of object types. The object type used must be
set to visible to see them. If you use some other object type just
make sure the object type used is set to visible
using View | Display Explorer and find it listed there.
HINT: Just type in the
name in the Go to: field and you will be taken directly to that object
type there is no need to go digging for it.
If you are
using your own object type
these are accessed starting at Object Type "70" in the header definition above
and the numbers go up from there. See examples below showing
custom object types I have created.
User-Defined
Object Types
First entry "Simbad" = Object Type 70
You can also just just change this upon
compiling the data using the Import dialog. Also make the
Identifier field clear here. See below.
Compile the text into
an SDB file
Note the name here and object type!
(Use Identifier field to name the SDB)
Can I draw something more
than just lines? You bet. Consider the following examples.
Taurus the Bull
drawing
Courtesy Brian Rickard
Drawing of the Veil Nebula
region in Cygnus done by me.
Wow, 25,000
points, nearly a full day of drawing!
Not for the faint at heart ;)
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