Stellar aberration measurement

[jk1956]

Hi everyone,
I am interested in measuring stellar aberration as a challenge to myself; I am more of a physicist than an astronomer. I have a fair knowledge of telescopes and imaging. I would appreciate if somebody can give me instructions or point to some references on: which star to select, what time at night to conduct measurement, how often to measure etc. My goal is to obtain better than 1" accuracy. I intend to use a stationary telescope with a DSLR camera, with the recorded images analysed to determine position shift.

I am in the southern hemisphere, Sydney, Australia. I could not find a description of stellar aberration measurement procedure in my searches, except Bradley' original paper. Thanks for your interest.
Regards,
Joseph

 

[mfb]

My goal is to obtain better than 1" accuracy.

Will be hard to see anything if you don't reach that. Alpha Centauri has the largest parallax at 750 milliarcseconds (not counting the slightly nearer but much dimmer Proxima Centauri).

Nearby bright stars, with more distant bright stars nearby as reference (ideally in the direction of parallax shifts), should be the best targets.
More measurements give better accurary, so does a longer timespan (probably go for a year, otherwise it is hard to separate the small parallax from the proper motion).

I don't know the best time of the night. Atmospheric turbulences should be as weak as possible.

 

[davenn]

which star to select, what time at night to conduct measurement, how often to measure etc.

I don't know the best time of the night. Atmospheric turbulences should be as weak as possible.

Hi Joseph
welcome to the Physics Forums
I am also in Sydney ( inner west)

cool winter nights are the best for lowest atmospheric turbulence ( summer not so good).
Also use Alpha Centauri as mfb suggested and when it is highest in the sky so you are looking through the least amount of atmosphere.
measuring 6 months apart will give the greatest difference in parallax measurement and you would want to do multiple measurements at each of those 6 monthly intervals to get a good avg measurement at those times

cheers
Dave

 

[jk1956]

Hi mfb and Dave,
Thank you very much for your replies. Based on your suggestions, I may try Alpha Centauri, when it is highest in the sky.

May I clarify that I am planning to measure stellar aberration, which I believe, is around +/- twenty arc second over the period of an year. My understanding is that the much smaller parallax is superimposed on stellar aberration, but with a 90 deg phase shift. Also, parallax will depend on the distance to the star being measured, whereas stellar aberration, arises solely due to the motion of the observer (earth in our case). Unfortunately, one cannot depend on any 'reference stars', as all stars will exhibit stellar aberration to the same degree.

Any suggestions on stable telescope mounting techniques for the long period of measurement needed is appreciated.

Dave, I live in the suburb of Pennant Hills and work in the inner west; is there any place or gathering of professional/ amateur astronomers in Sydney where I can ask for some tips?

Regards,
Joseph

 

[mfb]

Oh, somehow I read parallax. Aberration is a different challenge, the effect is larger but you cannot use other stars as reference, right.

 

[davenn]

Oh, somehow I read parallax. Aberration is a different challenge, the effect is larger but you cannot use other stars as reference, right.

eeekkk ... We both did, mfb

Apologies Joseph

I might have to read up on that.
I thought stellar aberration was to do with oscillations due to orbiting planets ... apparently that must have another name

http://www.colorado.edu/physics/phys2170/phys2170_fa06/downloads/stellar_aberration.pdf

OK I have some learning to do LOL

Dave, I live in the suburb of Pennant Hills and work in the inner west; is there any place or gathering of professional/ amateur astronomers in Sydney where I can ask for some tips?

just up the hill from me in West Ryde

The ASNSW ( Astronomical Soc of NSW) meet at Macquarie Uni
I am a member but haven't been to a meeting for yonks

http://www.asnsw.com/cheers
Dave

 

[jk1956]

Hi Dave and mfb,
No worries.

Dave, thanks; I will check out ASNSW.

Regards,
Joseph