Quasar Spectra 3C273

[Terry B]

Dear all
3C273 is the brightest quasar and it is currently reasonably high in the north in the evening in Virgo. It ha a mag of 12.9 so is easily found for reasonable size scopes visually.
I took a spectra of it to demonstrate it's redshift.
The spectra is a stack of 5 x 300sec exposures through a C11 with my LISA spectrograph.
The attached graph is an overlay of the spectra of a standard A2V star that has nice hydrogen absorption lines for comparison.
The quasar demonstrates hydrogen emission lines and Ha, Hb, and Hg are easily identified. They are all redshifted and when I measure the shift it gives a calculated redshift that is pretty close to the professionally measured redshift.

Cheers
Terry

[sjastro]

Excellent Terry.

Regards

Steven

[sheeny]

Great work Terry!

Al.

[Merlin66]

Well done!
Good to see some spectroscopic results.
Your LISA and the C11 seem to work well together.

[pvelez]

Great job Terry

I did the same thing with my LISA and RC8 last year. My results were z = 0.142 - 0.148. I still had my L plates on when processing with ISIS and was using the EQ6 at the time. I plan to give it another go in the next week or 2.

Pete

[madbadgalaxyman]

Terry

Very interesting for you to replicate the work of Maarten Schmidt in his very famous 1963 paper in Nature, when the true meaning of quasar spectra was finally revealed.
(the entire story, from the positional determination of this object at Parkes through to Schmidt's insight , is described in a webpage which can be accessed from the recent 'Occultation' thread in the Science Forum)

That is certainly good accuracy, certainly very adequate for getting redshifts of quasars and other high-surface brightness galaxies (e.g. powerful starbursts) at significant redshift.

It seems to me that it must be significantly easier for amateur spectroscopists to get redshifts of decent accuracy, than to do other things such as calibrating spectra so as to get accurate Line Intensity Ratios and suchlike. Would I be correct in saying this?

This sort of redshift measurement work might be useful for a quick initial determination of the redshift and distance of a newly discovered object.
How faint could you go with your equipment, when doing this sort of redshift determination?

I personally think that there are still some highly unusual undiscovered objects at recession velocities of >10,000 kilometres per second;
this is just a hunch really, because I turned up a very large number of morphologically unusual objects in a two month search for peculiar FUV-emitting objects in the imaging data from the GALEX satellite.

cheers,
Robert

[Merlin66]

Robert,
Just for the record...Maurice Gavin (UK) was the first amateur to record the Redshift of 3C273 back in 1998. (See "Astronomical Spectroscopy for Amateurs", p 120)
The issue with recording faint objects is getting a good resolution combined with an acceptable SNR.
This usually demands large telescope apertures and fast f ratios combined with low resolution spectrscopes/ gratings.

[Rob_K]

Fantastic work Terry! :thumbsup: Just amazing what you can do, from your own backyard!!!

Cheers -