When comets are set in "Data Shown.." on "Auto", decrease the stars
magnitude to the point where a comet is about to disappear, its position
changes about a magnitude before the event. After the disappearance,
increasing the magnitude reverses the process, when the comet reappears
it will move when magnitude is further increase by one.

If one creates a track as the comet appears and then decreases the field
which increases magnitude the comet changes position and the track
become invalid.

We tried on 3 different computer systems and replicated the error with
more than one comets. Guide version is from 17 June 2013.

This only append when a comet is about to disappear or reappear.

Hope this is clear enough explanation to find a fix.

Denis

On 14/08/2013 8:24 AM, Bill Gray wrote:
> Hi Pierre,
>
> There's a standard magnitude formula, using H (absolute magnitude, the
> magnitude the asteroid would have if it were one AU from the sun as seen
> from the sun itself) and G (the 'slope parameter', which roughly describes
> the magnitude as a function of phase angle).
>
> The absolute magnitude H essentially combines the diameter and albedo to
> say "this is how much light the object reflects". It's what you actually
> observe when you point a telescope at the object: you can't tell if it's
> a really big object covered in black paint, or a small object covered in
> mirrors. (You can put a lower limit on the object's diameter based on the
> assumption that it reflects 100% of the incoming light. It might be
> twice as big if the albedo is really 25%, or five times as big if the
> albedo is actually 4%. Or a truly massive alien artifact cleverly disguised
> as a small asteroid, covered in black paint.)
>
> The IAU standard magnitude formula is :
>
> mag = H + 5 log(r * delta) - 2.5 log((1-G)phi1 + G * phi2)
>
> phi1 = exp[ -3.33( tan( beta / 2) ^ 0.63)]
> phi2 = exp[ -1.87( tan( beta / 2) ^ 1.22)]
>
> ...in which logarithms are to base 10, r = the distance between the
> asteroid and the sun, delta = distance of the asteroid from the observer,
> and beta = phase angle.
>
> If an asteroid has been observed for a while over a wide range of phase
> angles, then the slope parameter G can usually be determined. But for most
> objects, a default value of 0.15 is assumed. I don't know what that value
> corresponds to in a physical sense.
>
> -- Bill
>
>
> ------------------------------------
>
> To unsubscribe from this group, send an empty email to:
> guide-user-unsubscribe@egroups.comYahoo! Groups Links
>
>
>
>