How far away is Quasar 3C-273?

Dave Grennan knows...

In what I think is an astonishing piece of work, Dave captured a spectrum of a quasar, calculated its redshift and came up with an approximate distance. This sets yet another bar of accomplishment in Irish Amateur Astronomy.

Dave, I thought you would never surprise me again - but this is just incredible.

I'm just totally amazed that this could be done by an amateur astronomer. Next thing, you'll discover a supernova and couple of asteroids. Oh wait...

"Congratulations" really doesn't cut it but I can't think of anything else to say.

All the best
Dave McD

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Hi All,

Last evening (or should I say this morning, Sun. 15 April) I set about capturing a spectrum of quasar 3C-273 (in Virgo). Rather that write a lengthy post about it here, I wrote it all up including how the spectrum was used to calculate its redshift and thus provide an approximation as to its distance. Please see here for the article.

www.webtreatz.com/index.php/articles/34-...asuring-the-redshift

Best Wishes,

Dave.

Thats impressive! To put this in context, radio sources had identified objects like this since the 50's but 3c-273 was the first optical component to be associated with the radio source. In 1963 using a 5M scope at the Palomar observatory the redshift was measured and it was found to lie far far far beyond the milky way.

It's visual magnitude is 12.9 so it would be a struggle for many amateur telescopes to see it, never mind produce a lightcurve that could pick out the Ha line to within about 30angstroms of the accepted value!

Very impressive.

3C-273 is the most distant object I've seen.

Michael.

Dave,
That was a great read very interesting. I can hear the bar ringing while it’s rising great work.

Good result Dave!

One query - in your report on your web page you state that you take the Doppler effect "into account" (red or blue shift due to proper motion).
I don't see that one can take it into account - but it can probably be ignored.

Your cosmological red-shift will surely also be influenced by proper motion. However, I would expect the cosmological red-shift to dominate and I would expect any Doppler effect can be neglected at such a distance as it is probably very small in comparison to the recessional velocity due to Hubble expansion.

Please correct me if I'm off-the wall or missed something.

But a very nice piece of work.

Mark C.

Mark: You are of course quite correct about the erroneous reference to the doppler shift. This has no relevance at all and I will remove it from the text. It was really just lazy thinking on my part.

Anyway, Thanks Dave Mc for posting this, I'm really flattered that you thought this worthy to post. Isn't it really exciting that we amateurs can do some serious science like this. Only a few short years ago this sort of thing was just a facet of my wildest astro dreams. I really hope that a few others may look at this and realise that anyone can do it if you want to.

I have now just finished a little write up about how this instrument (which I now call the "G300") was built. It is certainly a project which I think many could undertake.

Here's the construction write up;

www.webtreatz.com/index.php/articles/34-...he-g300-spectroscope

I think the fact that amateurs can do this sort of thing nowadays is really down to the revolution which mass produced CCD's brought. We really are living in a golden age of amateur astronomy.