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Altering the Tracking Rates
to track non-sidereal objects - Paramount ME
Working Examples:
For our example we will use the
Paramount ME to track on Comet 9P/Tempel. First use your Internet
connection to obtain the most recent orbital elements for the comet. This is best done the same day you will be imaging if and whenever possible. For objects with very stable orbits you need not be so concerned, i.e.
the brighter more stable minor planets..
In TheSky use the option Data | Comets & Minor Planets and choose the
"COMETS" tab as shown. First REMOVE any
existing comets that are already listed! Those listed (if
any) will most likely
have out-of-date orbital elements! Best to start with a
"clean" slate by removing any listed here first. See
below.
A page with details on what sources
TheSky uses
for current
"orbital elements" can be found here!
Drag the entire list of existing comets
and choose the "Remove" button on the Comets and Minor Planets dialog as
shown.
Remove any existing comets
Wipe out any that are listed!
You will be asked for a confirmation. Once the existing comets
have been removed choose the
button "Observable" under From the web as shown. Choose the Observable button
Data | Comets and Minor Planets
Found under the link "From the Web."
You are now presented with a list of comets that are
considered currently visible. You can either choose to DRAG the
entire list with your mouse or simply click on the one(s) that you want. If you use CONTROL+Mouse Click you can individually select more than
one.
Select more than one
CONTROL+Mouse Click
Pick the ones you want, or highlight all of them with a
mouse drag down the entire list then press OK to add them to
TheSky.
NOTE: Keep in mind that many of these
comets are very faint and may not be visible with your equipment. BECAUSE the magnitude does not exist until it has been computed by
TheSky using the orbital element data
TheSky cannot simply filter out
the faint ones for you yet. Once downloaded into
TheSky you can
use the filtering option to set any magnitude range you like. Use
the Display Explorer to "name" the comets and also set a filter to hide
the fainter ones.
View | Display Explorer
Enter COMET in the GOTO box!
By typing in "COMET" in the GO to: box you are taken
directly to the entry for COMETS. The Display properties allows
you to enter a magnitude cut-off. Actually you can "FILTER" them
by the starting magnitude and the
Display Properties for Comets
Pick a realistic Faintest magnitude here
(example 18th as shown)
Now only the brighter comets will be displayed greatly
cleaning up the display. Next Label the comet with either the
"name" and/or magnitude to make it easy to see. Under the Display
Properties for Comet check mark Common Name and/or magnitude as shown.
Check name
and/or magnitude
Make sure that you have the Common Names set to visible
or they will not show. Use View | Labels and make sure that Common
Names is checked as shown.
Turn on Common Name labeling
Check Mark Common Names
Now the comets will be labeled on the display.
Comet Labeled with magnitude
Common names set to visible
In order to Find Comet 9P/Tempel in our example choose
Edit | Find then use the Find dialog. You can either go down under
Solar System | Comets to see the entire list (only a few shown here for
clarity) OR you can enter the name in the find as in Find "9P/Tempel"
without the quotes.
NOTE: By choosing the comet from the list you will not have to enter the
name manually which assumes you know the spelling. By entering a name in the find dialog you will have
to know how the comet is labeled and enter this correctly. Using the list is not prone to
input errors when searching for you query!
Use the Find dialog
Find it on the list or manually type it
Now that you have the orbital elements loaded in
TheSky can accurately compute the tracking rates for both RA and DEC for
the given date and time! After you have slewed the telescope to
the object use the Telescope Tab on the object Information dialog to set
the tracking rates. There is a button "Set Tracking Rates". When this is clicked you will be shown the current RA and DEC rates in arcseconds/second. This is a great reality check
WARNING: These
computed rates are completely dependent on the Site information in
TheSky (Data | Location) AND the accuracy of the orbital elements used. Basically
garbage in garbage out. ALWAYS check the site information along
with the DATE and TIME!
Example for Table Mountain Observatory
As found in TheSky's
list of observatories
Also make sure your date and time along with the
daylight option have been properly set! Choose the wrong daylight
option can cause an error of 15 degrees or 1 hour.
Let TheSky compute the tracking rates from the
orbital elements
Set the telescope's tracking rates to match the comets motion
As a reality check take a long exposure or several 1 to
2 minute exposures over say 15 minutes. If the tracking rate is
correct the comet will stay fixed and the stars will trail slightly
because of the rate change!
Minor Planet tracking is almost identical to tracking
comets. First you want to get the most recent orbital elements you
can. This can usually be done from directly within TheSky! Use Data | Comets & Minor Planets and choose the Minor Planets tab. The following shows how to get a list of the MPC's "Distant" minor
planets. You can also pick from the "Critical" and or "Unusual"
list as well.
Data | Comets & Minor Planets | Minor Planets
Click on Distant
Next just grab the minor planet(s) you are interested in
just like the comet example above. You can drag the mouse over the
entire list or simply CONTROL+Mouse Click on the individual ones you are
interested in. Once the minor planet has been added you can use
the Find dialog to search for it by name or by clicking on the list. See below example for Chiron.
Find Dialog
Find and Slew to Minor Planet
Once TheSky has found the minor planet for you after you
have slewed to the object you can have the Paramount track at the minor
planet rate. Use the option Set Tracking Rate as found on the
object Information dialog.
Set rates to match minor planet
Note rates computed by TheSky
To track on a satellite first issue a Slew To when you
have found it or clicked on it in TheSky then use the option "Track Satellite"
on the telescope tab. See below.
Tracking satellite
Track on satellite set rates to match
NOTE: Tracking a satellite is not as
simple as a planet, comet, or minor planet. It will take one or more slews to
get the object in the field then it TheSky will attempt to micro-slew to the
object based on the ever changing rates in RA and DEC.
Note rates are displayed
Satellite tracking dialog
The star symbol in the center represents the
center of the field and the smaller circle where the scope is relative to the
target. When the two are coincident the object is being precisely tracked!
You can also use a spiral search using Start
Search whereby the scope will attempt to find the object if it is no where in
the field. If the object is in the field but offset from center you can
mouse click inside the square box and the object will be offset from the current
position in the opposite direction. Takes practice! This way you can manually center the satellite provided it is in your
field. If not try to search for it a second time and make sure you are setting
the rates to match the bird. Good luck!
Before trying to nail a fast moving bird first
make the tracking work with a Geosynchronous orbit satellite. Why? Because they
hardly move at all! These are quite easy and fun. In fact you can actually just
turn the tracking off completely and these satellites will remain in the field. Even in very small CCD fields. See below image.
4 Geos all in a row!
Sample image 15 arcminute field
Weather satellites are also a very
good for a first try since they too move very slowly.
This Iridium 10 flare CCD
imaged with C-14 and Paramount ME using an ST-9E. First attempt!
The option to "Track Satellite was used and a 67 second exposure was
taken. Note the trailing stars on the left of the image. You can see the
satellite is moving reasonably fast!
Tracking on Iridium 13
Through the flare!
ST-9E C-14 image of
flare
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