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Apparent Motion Readout

I use Sky Safari Pro 5 on MacOS and iOS and find the apparent motion display somewhat useless for planning imaging of fast moving objects like comets at sidereal tracking rates. Rather than have separate readouts for apparent motion in RA and Dec a single value showing the total apparent motion in degrees/day or arcsec/min or arcsec/sec would be better. Then we imagers can compare this value to our imaging scale in arcsec/pixel and quickly know how long an exposure we can take before significant blurring occurs (when not auto guiding on the moving object itself). Also, if this value can be expressed in a user friendly format, that would be a bonus: Instead of 5389.6 "/day just say 1.50 deg/day or 3.74 arcsec/min.

Thanks for these great tools,

Arlo Reeves

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5 comments

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    Bill Tschumy

    I assume you are referring to the apparent motion data that is in the Object Info?  I can look into reporting a single total apparent motion.

  • 0
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    Cockypops

    Exactly. The Object info provides lots of useful information and the number imagers need for comets can be gleaned from the RA & Dec apparent motion, but why bust out a calculator...?!

    Thanks,

    Arlo

  • 0
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    Bill Tschumy

    Arlo,

    We have implemented your request.  Here is the info for 41P/Tuttle-...

    We scale the units depending on how quickly the object moves.  This is reporting in arcsec/day.  I might be able t talk Tim into different units.  Seems like this should be arcsec/min perhaps.  Thoughts?

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    Cockypops

    This is great! Most imagers know their "image scale" in arseconds/pixel so having a readout in "/min or "/sec is handy (the latter conveniently being equal to degrees/hour). For example at 200mm my Canon 550D has 4.4" pixels so if a comet's apparent motion is 8.8"/min I know I can keep the nucleus within a pixel using a 30sec exposure (or 60sec if I downsample by 2).

    I don't see a need for more than 4 significant digits as used for the Az & Alt values above; these values are often varying so having seven 7 digits is unnecessary IMO.

    Thanks again - this is something I've wanted for some time.

    Arlo

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    Stoian L M

    Hi all

     

    About these comets (and satellite) motion, is there a way (is it feasible) to include a "Track"  option, beside the Center and Orbit?  To slew the mount to the current position and "track" along the trajectory?  For instance if I want to have ISS in the FOV and watch it for a longer period (during a star party for childrens, they all want to see, and I cannot move the mount every 5-10secons to a new position). Something like this may be usefull, I think. Also for filming ISS/satellites or other fast moving objects.

     

    Thanks.

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