Measuring redshift change as earth spins

[Physics_dude]

Hi, I'm thinking of getting into astronomy, I'm a science nerd hehe. I have three questions:

1. Has anyone ever measured the spectrum of a star and noticed it's redshift change slightly over hours /days/years due to earth's spin and orbit? 

2. What equipment would you recommend to measure 0.1 0.001 A resolution spectrums? (Say $10,000 US budget probably can't afford it)

3. I've heard iodine gas cells can be used to create reference marks in a spectrum. Are there other good techniques?

I'm trying to figure out how to track a star through the night and see the subtle changes in redshift due to the earth, I think that'd be fun. 

Edited January 19, 2021 by Physics_dude
modified mistakes in numbers

[andrew s]

If you are new to Astronomical spectroscopy try look at this site http://www.astrosurf.com/buil/index.html

Regards Andrew 

[Physics_dude]

Thanks for the post, I had actually discovered this very website earlier and was reading it for hours and then saw your post lol. This is exactly the kind of stuff I'm looking for. On this page of the website it appears Christian has measured the "final tau Bootis phase diagram" with about +/- 100m/s error bars, and the corresponding redshift resolution is ~0.002 Angstroms. So this is about the redshift detection limit of what skilled individuals can do? If I understand this correctly, Earths rotation is ~460m/s at the equator, so we'd be looking to see a change of ~2x400m/s = 800m/s over one night (ignoring orbital motion).  So we'd expect a redshift change of a close star about the same (about 0.16 A peak to peak over the night) than what the final tau bootis made (0.17 A peak to peak or 850m/s change). I'd like to measure a cleaner curve than the Tau Bootis curve, so looks like I'll need to find better redshift measuring equipment, if it exists? <0.001 A resolution (<50m/s velocimeter spectrometer). Ideally I'd want a 10m/s velocimeter to measure stars relative speed, but I doubt I could buy/make one....

Have I made any silly mistakes in my reasoning?

Edited January 19, 2021 by Physics_dude
fixed mistakes in numbers

[andrew s]

At a glance that looks right but if you are not on the equator it will drop off as you approach  a pole.

 

There is some good stuff here http://www.threehillsobservatory.co.uk on Robin's site.

Regards Andrew 

[Physics_dude]

Nice! Another interesting link. 463 m/s spin speed at equator, ~320m/s in France, and the radial velocity due to Earth's spin for the Tau Bootis star (DEC 17,27',24") as observed from France would be +/-305 m/s. I'm actually working on a fun mini project to theoretically calculate the exact redshift shift for any latitude/longitude/altitude + UTC time/date + any star DEC/RA & speed. I'm looking for data to test how the model compares to the real world. I've attached a screenshot to show the graph and input code.

   One sub goal is to understand what equipment could measure this radial velocity change. So sounds like I'd need to detect a 0.001 Angstrom shift (50m/s resolution on velocimeter) to clearly detect the Earth's spin in France when measuring the Tau Bootis redshift. I think?

Edited January 19, 2021 by Physics_dude