- #1

Daniel P

- 3

- 0

Hi

I have a question about "proper motion of stars".

At this page (http://www.astronexus.com/a-a/motions-long-term) there are a lot of examples how you can measuring the proper motion of stars.

But at "Point 4 - Turn these velocities into Cartesian velocities" i have some different results.

vR = -5.19 Km/sec

vTA = -58.3 Km/sec

vTD = -106.6 Km/sec

α = 14.2612

δ = 19.1873

===========================================================================

should!

vx = ( vR * cos δ * cos α ) - (vTA*sin α ) - (vTD * sin δ * cos α ) =

vy = ( vR * cos δ * sin α ) + (vTA * cos α ) - (vTD * sin δ sin α ) =

vz = vR * sin δ + vTD* cos δ =

===========================================================================

My results: vx = +54.1, xy = +37.5 and xz = -102.4

You can see the results one and two don't agree with my calculation, the result three agrees (depents on the accuracy of "my" data!)

Can anybody help me, please?

Thank you very much,

DANIEL

I have a question about "proper motion of stars".

At this page (http://www.astronexus.com/a-a/motions-long-term) there are a lot of examples how you can measuring the proper motion of stars.

But at "Point 4 - Turn these velocities into Cartesian velocities" i have some different results.

vR = -5.19 Km/sec

vTA = -58.3 Km/sec

vTD = -106.6 Km/sec

α = 14.2612

δ = 19.1873

===========================================================================

should!

vx = ( vR * cos δ * cos α ) - (vTA*sin α ) - (vTD * sin δ * cos α ) =

**-57.7 Km/sec**vy = ( vR * cos δ * sin α ) + (vTA * cos α ) - (vTD * sin δ sin α ) =

**+31.5 Km/sec**vz = vR * sin δ + vTD* cos δ =

**-102.3 Km/sec**===========================================================================

My results: vx = +54.1, xy = +37.5 and xz = -102.4

You can see the results one and two don't agree with my calculation, the result three agrees (depents on the accuracy of "my" data!)

Can anybody help me, please?

Thank you very much,

DANIEL

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