Measuring parallax with Celestia

[Imagined Horizons]

Celestia displays stellar parallax beautifully and is excellent as teaching aid. What would be really useful is a scale bar in angular units (minutes, seconds of arc) so that parallactic ellipses could be measured and distances to stars found. The existing FOV information at the bottom right of the screen is a bit vague (does it mean top to bottom, side to side or diagonally acroos the screen?).

Has anyone built this add-on already or does anyone want to try? Apologies, but I'm not a programmer!

[Christophe]

The FOV is top to bottom, you can see it adjusting when changing the window's height. It varies so that the zoom factor stays constant. The zoom factor is based on the actual angle the window occupies in your field of view calculated from your screen's dpi and distance to screen (which is set to 40cm by default.)

Code: Select all

fov(zoom) = 2 * atan(height / (screenDpi / 25.4) / 2. / distanceToScreen) / zoom

I'm not sure an angular scale is doable as an add-on, that probably needs to be done at the code level.

[Imagined Horizons]

Thanks for that. Knowing which way to measure the window/screen is a useful start.

Keith