Dome Calculation

Diagram of a side-by-side set-up.
Figure 1: Diagram of a side-by-side set-up.
Soon an article by me on the dome azimuth calculations for a side-by-side set-up will be published in the Astronomy Technology Today magazine. The article discusses the maths involved in the proper calculation of the dome slit position for a side-by-side set-up. This page here is to support programmers in testing their implementation of the algorithms. Currently the algorithms are available to a limited group of beta-tester, the calculations below are for REV06 of the manuscript.

- X-axis: runs north-south, north is positive;
- Y-axis: runs east-west, west is positive;
- Z-axis: runs vertical, upwards is positive.
- Lateral offset: + when OTA is east of centre at park position with the scopes pointing towards Polaris and the counterweight in the direction with an azimuth of 0 degrees.
- GEM offset: always positive.

The latitude-axis and intersection of the RA- and DEC-axis of a mount.
Figure 2: The latitude-axis and intersection of the RA- and DEC-axis of a mount.

All linear measurements can be given in any unit of length as long as the same unit is used for all of them.
All linear answers are in the same unit of length as provided.
Changing any of below parameters will automatically recalculate the outcome. The pier-side is changed automatically for azimuths between 0░ and 180░ (pier-side = west) and between 188░ and 360░ (pier-side = east), but can be changed at will.

Latitude [degrees]
Offset from dome centre to base mountXm
Offset from base mount to latitude axis (see figure 2)Xla
Distance D from latitude axis to RA/DEC axis intersection (see figure 2)

Dome radius (not diameter!)
Target altitude
Target azimuth


Dome azimuth calculations

If you have any questions and/or remarks please let me know.

Home Geodesy Navigation Astronomy Literature
InFINNity Deck... Astrophotography... Astro-Software... Astro Reach-out... Equipment...
ASCOM Generic UPS driver ASCOM Envir. SafetyMonitor ASCOM File SafetyMonitor ASCOM SafetyMonitor Hub Astronomical Twilight Log10mGrabber MountCMD MountMonitor Dome Calculation