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TOOLS MENU
Modeling
Under Tools Menu there are 3 choices for the GTOCP5: Modeling, PhotoTimer, and
Bookmark.
Select 2 = Modeling to bring up 3 modeling choices - Point&Track, Drift and Ortho
models. Depending on the setup and software available, the user can employ the
Drift and Ortho routines with just the keypad or the full Point + Track model for all-sky
modeling.
Point + Track Model
Point + Track model can be used for both precision pointing and for precise tracking of an object’s path across the sky
for unguided imaging. The model can store up to 8 data points along a series of 16 declination lines on both sides of the
meridian. It is easiest to do this with an external planetarium program where the user simply slews to any number of stars
whose positions are precisely known. Then using a crosshair, the star is simply centered exactly and the data is entered
into the control box memory. Once enough data points are stored, the model can be turned on for precise pointing, and the
tracking rate can be set to Custom for precise tracking over time. It is not necessary to be precisely polar aligned for the
pointing and tracking to be improved with modeling. However, the more precise the polar alignment, the more precise the
model will be for long time exposures.
The upper right corner of window 5211 displays the number of data points that have been added for any particular Dec
line. A new declination data line is created when a star is entered 10 degrees from the original. Dec lines are created at 10
degree intervals from -90 to +90 degrees. Each Dec line is a corridor that includes any star that is within 5 degrees of the
first one. Up to 8 stars can be measured and entered as data points on any one of 16 declination lines in the model. The
first declination line will have numbers from 1 to 8. The second Dec line will have numbers from 11 to 18, the third will have
numbers from 21 to 28 and so on. As an example, a number 64 means that the 7th Dec line has 4 data points in it, and the
user can add 4 more before that line is full.
Pointing Model
The easiest way to do the modeling is to follow one declination line on your planetarium program. For example, you could
pick several stars near Decli30 Deg that are within the +- 5 degree envelope. A star at +26 Dec and a star at +33
Dec would be sorted into the 30 degree corridor. A star at +36 degrees would be sorted into the +40 degree corridor and
would therefore be registered as the first star in the second Dec line. All stars’ motions and positions would be calculated
properly according to their actual RA and Dec coordinates and proper offsets be applied, even if they are not exactly on the
actual Dec center line.
The east and west models are independent. All mapped points are remembered through power cycles, available for
correction in subsequent sessions, until you create a new model.
Pointing
For good pointing over the entire sky, a minimum of 3 stars are needed for each Dec. line on both sides of the meridian.
Start a model run by choosing a reference star near the zenith after centering and doing a Recal (Sync) on it.
