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At 19.8 g/17.8 r (SDSS) and a redshift of 4.315, this is the faintest and most distant object I have measured using my modified ALPY200.
My spectrum (red) is shown overlaid on the reference spectrum (grey). The Lyman alpha emission redshifted from 1216A is clear. More details on my BAA page here
https://britastro.org/observations/obse ... 4be2035d42

Cheers
Robin

Superb spectrum, very impressive. Bravo Robin. With Etienne, you are really pushing the limits.

The lyman forest is also impressive. It seem there is a broad absorber at 5100, and maybe others at various z along the line of sight (large neutral H megaclouds ?). It is like the quasar is acting as a beacon across the Universe, allowing to probe the intergalactic medium !

JP Nougayrede wrote:With Etienne, you are really pushing the limits.

Yes it is a close race Etienne's PSS J1458+6813 (with a standard ALPY600 ) is almost the same redshift.
http://www.spectro-aras.com/forum/viewt ... 752&p=8310

Can we get any further I wonder ?

Cheers
Robin

JP Nougayrede wrote:Superb spectrum, very impressive. Bravo Robin. With Etienne, you are really pushing the limits.

It seem there is a broad absorber at 5100, and maybe others at various z along the line of sight (large neutral H megaclouds ?). It is like the quasar is acting as a beacon across the Universe, allowing to probe the intergalactic medium !

Yes the (Lyman damped?) absorption at ~5100 is very strong. Perhaps like the gravitationally lensed APM 08279+5255 here in an early spectrum using the Star Analyser which shows something similar at z=3.07 ?
http://www.threehillsobservatory.co.uk/ ... tra_22.htm

Cheers
Robin

A couple more from the PS1-ELQ catalogue at even higher redshifts. The one at z=4.564 is g mag 20.2 r mag 18.4
(the spectra in grey are from the literature. Click on the image to see all three full size)

Hello Robin, Bravo for this result, it's superb!
On the other hand you are more advantaged than me because you observe from England which is closer to the quasar on the line of sight lol LOL

I'confirm the most difficult is for find the source many catalog and many name for a source, where do you find it ?

For a catalog of quasar that you can parse and download in your favorite spreadsheet:
https://heasarc.gsfc.nasa.gov/W3Browse/ ... iquas.html

For example here is a list of all quasars brighter than mag 15 (way two close and bright for you Robin and Etienne !)

etienne bertrand wrote:
I'confirm the most difficult is for find the source many catalog and many name for a source, where do you find it ?

Hi Etienne

These came from the PS-ELQS catalogue
which is a good list of distant but relatively bright QSO with reference spectra
https://vizier.u-strasbg.fr/viz-bin/Viz ... 3/5/table7
but there are almost 2 million to chose from in the MILLIQAS catalogue
https://vizier.u-strasbg.fr/viz-bin/Viz ... 83/catalog

Cheers
Robin

JP Nougayrede wrote:For a catalog of quasar that you can parse and download in your favorite spreadsheet:

Hi JP,

I see that is a later version than v6.3 in Vizier. Do you know why later versions are not found in Vizier ?

Cheers
Robin

Hello Robin, I don't know. We can guess that the authors of the Milliqas catalog did not submit yet their latest version to Viziers, or it has yet to be preocessed by the Strasbourg data center..
Jean-Philippe