Last updated: 14 October 2010

Adding Comets

Subject:	AutoStar Update Vers 2.4
Sent:	Thursday, July 12, 2001 21:59:13
From: (Fernando Pertuz)
Well, using the Drag & Drop approach I finally managed to get correct
comet LINEAR A2 data into the AutoStar.  Keep in mind that this rather
cumbersome method only bypasses the problem (a bug in Meade's AutoStar
Update program version 2.4) and doesn't fix it.

In a nutshell this is what I did.

In the "AutoStar Update" page of Meade's website there is a link at the
bottom of the page that retrives comet data.  I got the file and saved
it as MYCOMETS.TXT.  This file is already in the .CMT format required
but saving it as .TXT makes it easier to use Window's NOTEPAD to edit
it.  It contains umpteen comets, some of them not even HUBBLE can see!

Using NOTEPAD, I erased all but the comets I wanted to put in the
AutoStar (almost ALL of them) and saved the reduced file as MYCOMETS.CMT

In the EPHEMERIDES sub-folder within the MEADE folder (bottom level) I
deleted a file named LIBCOMET.ROM

After connecting the ETX & AutoStar to the PC I started Explorer,
resized it to about an eight of the screen size, displyed the folder
that contained MYCOMETS.CMT and moved Explorer's window off to the left
leaving only the displayed list of files.

Without closing Explorer, I started the AutoStar Update Program and
moved its window to the right of the screen such that I could see
Explorer's window.

Now using the mouse I click over the file MYCOMETS.CMT and WITHOUT
RELEASING THE MOUSE BUTTON, I move the mouse (drag) over the "COMET"
button in the Updater's window and release the button (drop).  (This
procedure creates a new LIBCOMETS.ROM file.)

Clicking the COMET button confirmed not only that the comets were there
but all were tagged to be sent to the AutoStar handbox.  DO NOT click on
an individual comet as the Updater may change the epoch date and render
that data useless.

I then proceeded to download the efemerides data to the handbox.

Testing the result was another story, the overcast is NOT on my side so
I started the scope, faked an allignment, connected it to the PC,
started up SkyMap and using the handbox I slewed to Linear A2 and was
glad to see that it pointed to the exact same location calculated by

By the looks of it, my sighting of Linear A2 is destined to be a comet
icon on a SkyMap display or pictures of the darned thing.

Fernando Pertuz
Subject:	A2.4 versus Comet Epochs...
Sent:	Thursday, July 12, 2001 22:13:51
From: (richard seymour)
Personally, i key in individual comets via the Autostar keypad.
But drag-and-drop -does- seem to work.

One MAJOR difference in v22eR compared to previous is *much* 
improved Comet tracking.  If you played with 22eH, you'd find that
it occasionally predicted -retrograde- motion over the course of 
a day (at least with Linear A2).  With 22eR A2 appears within my
ETX90's 26mm eyepiece 8 times out of ten, and the other two times
it's within one "spiral search" cycle...

You might just try only doing a [send firmware to Autostar]
when you update (but do a [get ephemerides from autostar] first!

Sometimes the User Data survives the update.

The Training, etc, has to be replaced because their assigned locations
-change- from version to version... there's no good reason for it,
but they do.
Feel free to send notes to requesting that those
values ("in the EEprom") survive from version to version.

have fun

Subject:	How to Enter A Comet to the Autostar... the complete example
Sent:	Wednesday, April 24, 2002 21:05:46
From: (Richard Seymour)
How to add a Comet to the Autostar (without using the Updater)
for how to do it -with- the Updater)

Select > Object > Solar System > [enter][scroll up] Comets [enter]
You're now seeing:

Now press [scroll down] and you're seeing:

Press [enter]
it asks for a Name.

Use the scroll up/down keys to cycle thru letters and numbers,
the big <- and ->  slew keys to move from space to space,
and press [enter] when you're happy.

It will now ask for Epoch date:
23.5-Mar-2002 [enter]

Perihelion Distance:  (how close it gets to the sun, in AU (earth orbit radii)
Eccentricity: (how round the orbit is)
Arg. of Per.: (argument of Perihelion, the RA of closest sun approach)
Lon Asc Node: (RA where it heads above the equator)
Inclination: (tilt of orbit compared to equator)
Absolute Magnitude (how bright it would be at a fixed distance)

That's it... the Autostar can now predict where the comet will be.
Since these are -early- numbers, expect them to change over the
next few weeks... so don't plan to use this set in late May 2002.

If you scroll -up- from Comets/Select, you'll reach Comets/EDIT
which lets you easily tweak the data already stored for a Comet.
Try playing with it (just keep pressing [enter]) with a Comet
already in your Autostar.

have fun

For reference, here's the line from Meade's Comets reference link:
C/2002 H2 (LINEAR)  |2000|20020323.461  | 1.63562  |1.00000  | 20.445  |269.011 
|110.478  |10.5 |10.0 | MPEC 2002-H40

Subject:	addendum for the Adding Comets to the Autostar
Sent:	Sunday, November 14, 2004 12:55:27
From:	Richard Seymour (
In the April 24, 2002 section of
[this page] I describe entering Comet data into the Autostar
from the one-line descriptors provided by the link on
Meade's Update page to Harvard's Smithsonian data.
( )

But many people fall across the individual comet's data page,
namely (for example) something like:

On that page, there's a link to "forms suitable for loading..."
and from -there- you can reach the Autostar-flavored "Smithsonian"
 page cited above.

But we've nevere covered precisely how to dissect the individual
 page's data:
C/2004 Q2 (Machholz)
Epoch 2005 Jan. 30.0 TT = JDT 2453400.5
T 2005 Jan. 24.9146 TT                                  MPC
q   1.205088             (2000.0)            P               Q
z  +0.000413       Peri.   19.5023      -0.3200531      -0.7142006
 +/-0.000015       Node    93.6269      +0.7651382      -0.5823175
e   0.999502       Incl.   38.5891      +0.5586855      +0.3883604
into the constituent parts.

The same data, in the format i recommend, is:
C/2004 Q2 (Machholz) |2000|20050124.9146 | 1.205088 |0.999502 | 19.5023 | 93.6269 |
38.5891 | 5.5 |10.0 | MPC 52905

In the order the Autostar (and ASU) wants them is/are:
20050124.9  is Jan (01)  24.9 2005 expressed year-month-day-fractionalDay
q  is perihelion distance (1.205088)
e  is eccentricity  (0.999502)
Peri  is Arg of Perihelion (RA of closest approach) (19.5023)
Node  is Long of Ascending Node (RA as it rises north of ecliptic) (93.6269)
Incl  is the angle of inclination (38.5891)

Interestingly enough, the "detailed" page doesn't show the
absolute -magnitude- (the 5.5 in the one-liner).

have fun

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