View Full Version here: : Quasar and spectroscopy
28-02-2012, 01:21 PM
Has anyone tried to get a spectrum for a quasar?
For my SAO course, I can do a project on the cosmological redshift and Quasar. In short, an image of a quasar is taken, its spectrum analysed and the effects of the expansion of spacetime assessed from the redshift.
I have a an RC8 on an EQ6 which will be up to the task of imaging a few quasars. However, I only have access to a Star Analyser difraction grating ie no spectroscope. I suspect that this won't have the precision necessary to get a meaningful result.
Has anyone else tried this?
The logical answer is - get outside and give it a go. Sadly, the clouds are everywhere at the moment in Sydney and I need to select my project in the next 2 weeks.
Alternatively, does anyone have access to a spectroscope that I could use? Happy to hire or discuss buying.
28-02-2012, 06:22 PM
Maurice Gavin was the first amateur to successfully record the spectrum and red shift of a quasar back in 1998.
He used a Star Analyser grating on his 12" Lx200 to determine the redshift of the 13th magnitude quasar 3C273.
(This is detailed with a illustration of the results in "Astronomical Spectroscopy for Amateurs", p119)
28-02-2012, 08:49 PM
What you would like to do is outlined here
28-02-2012, 08:56 PM
Now that is an inspiration! I have ASforA - picked it up just after my SA arrived about 6 months back. So far I've only used it to extract spectra for some bright stars.
Off to study up
28-02-2012, 08:57 PM
Thanks Terry - that is a useful site.
28-02-2012, 09:46 PM
OK I'm convinced I can do this now.
Just found this website
with some excellent instructions and some useful links too.
Will let you know how I go.
I must confess I am blown away by this - being able to observe a quasar is one thing (never tried that - for 3C 273 at V mag 12.5 it shouldn't be that hard) - but to determine the cosmological redshift from it from suburban Sydney - that would be seriously cool.
23-04-2012, 06:18 PM
As I type this, I am keeping an eye o the clearing sky outside as I have yet to nab 3C 273.
Assuming I am successful, what next? I need another quasar for y SAO project. I have reviewed everything on the following list:
but they are skewed to the northern hemisphere or too dim for me - I particularly like the look of 3C 279 but at mag 17.75 it would be a serious push for me.
Does anyone know how to access a list of quasars by constellation that is suitable for the southern hemisphere. I found one list that looked really useful till I realised that there is nothing on it south of -20.
23-04-2012, 06:44 PM
Check this one out.
(Edit: Just noticed the -20 limit - this is probably the list yu looked at!)
The seventh list of the Calán-Tololo Survey is presented. It contains information for 100 southern quasars with a B magnitude in the range 16 ≤ B < 19.5; only 20 quasars are brighter than B = 18.
23-04-2012, 08:48 PM
I had another review of the first list you suggest - it suits the bill well. If I can get down to mag 14, I should have a few alternatives.
23-04-2012, 08:58 PM
Sending you a spreadsheet of Quasars from the Large Quasar Astrometric Catalogue
There are 113,000 to choose from in RA order from 0-360, Dec from -85 to +88 with lots of astrometric data.
Its just under 20mb
There should be one suitable for you !
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