Image Link and Map
Walk before running...that is before Automapping
Here is how to use Image Link
technology
to accurately MAP the telescope using
TPoint modeling software
for Windows. Image Link is very accurate - limited
only by your
scale in arcseconds/pixel. Image
Link and Map is a good technique to
use when modeling the scope using TPoint.
Before you continue you
must be intimately familiar with Image Link already! Make sure you
are able to Inage Link your CCD images on a regular basis before trying to use
Image Link and Map or the automated mapping procedure.
First, take a
short CCD exposure in
CCDSoft (say 8
to 10 second exposure), then Edit | Copy and Edit | Paste
the CCD image directly into TheSky where it is to be Tools | Link
Wizard - Image Linked. After analyzing the CCD image and finding a match using the
stars in TheSky's datasets Image Link will then set
the scale to match your CCD camera and telescope very
accurately. That is because the scale is computed based on the
actual image not by computing a theoretical scale. Small
discrepancies in manufacturing/mounting of hardware are then
accounted for so you may not get exactly what you expect or compute
manually!
When "mapping" a
set of Alt/Az coordinates using
TPoint
the point is the Image Link coordinates are not necessarily on the object's
coordinates you slewed to but rather the exact center of the CCD image regardless of pointing
errors or other offsets like catalog errors. See below for details
on mapping the Image
Link coordinates.
To demonstrate. The
following image was randomly taken from the Digitized Sky Survey
data. The image does not have any stars in the center of the field.
This is where the telescope was after the slew. It is accurate and
the position is computed by using the stars in the field.
1.7 arcseconds/pixel
centered on
coordinates - RA:08h 28m 53s and Dec: +22°40'31"
Right Mouse
Click on the above Image and choose Copy
Use the "Copy" to
Clip Board option
Then you can try this image yourself
Edit | Paste into TheSky and Link!
Tools Image Link |
Link Wizard (Ctrl+D)
Image Link!
Or you can also use the
Image Link Tool Bar. View | Tool Bar Setup and Check Image Link. See
below.
Enabling Image Link
Tool Bar - See below
Image Link Tool Bar!
Use the wand on right
Or after using "Save Picture As" on
the above image and loading it into
CCDSoft or
PhotoShop or Paint (whatever you prefer)
Edit | Copy the image to the Clip Board so you can Edit | Paste
it into TheSky for linking.
But FIRST using TheSky you must center on the
coordinates RA:08h 28m 53s and Dec: +22°40'31".
Use Orientation | Move To then enter the coordinates here,
Center on the
image coordinates first
Move To dialog with coordinates
Now just use TheSky's Tools | Image Link
| Link Wizard to find the match for you!
Successful Image Link.
Image
Link data
Computed from image
When an Image Link
is successful you will see the above. The
Image Link Coordinates
are what you are mapping not where you slewed the scope!
Next you will be
asked
Choose Yes!
Image Link
Coordinates shown on image
Image Link Information showing
center of field
Mapping is done on the
Image Link Coordinates see below
The Image
Link position is
shown by the RED telescope Cross Hair! Again, this is where the
telescope is ACTUALLY pointing not where it was told
to go!!! And there do not have to be any stars in the center of the
field either.
I can't get this
to work!
Now just left mouse
click anywhere on TheSky display, no need to be accurate, to bring
up the Object Information dialog to access the Image Link
information. See this below.
Left Mouse Click on
TheSky Display anywhere
Use the Down Arrow on the right of
Object:
to access the Image Link information
Now you will use the
Telescope tab to "MAP" the very accurate
Image Link coordinates. The Image Link coordinates are the actual center of the CCD image,
regardless of what you slewed to. Also, no re-centering, or jogging
of the telescope is required. Very handy and efficient.
Map the telescope on the
Image Link coordinates
Use the RED BULLS-EYE highlighted
above to Map
the true center of the image!
Now you can slew, image
link, and map as many points as you like. When this technique has been
mastered you are ready for completely automated mapping using
Orchestrate,
Automapper II or the
Auto-Mapping VB script provided by Software Bisque.
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