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Spectra of Quasar 4C 11.69

PostPosted: Tue Dec 20, 2016 5:38 pm
by Franck Boubault

This is a spectra of the 4C 11.69 quasar, obtained the 14 th of december, 2016.
My setup is composed of a C8 telescope + LISA spectrometer + Atik 414 camera.
Apart the telluric bands, no emission or absorption lines are visible.

Franck Boubault

Re: Spectra of Quasar 4C 11.69

PostPosted: Tue Dec 20, 2016 8:56 pm
by etienne bertrand
Hello Franck,

Nice r├ęsults.
What is the extension of your file .7z ? Is it not a .fit ?

Re: Spectra of Quasar 4C 11.69

PostPosted: Tue Dec 20, 2016 9:44 pm
by Peter Somogyi

I'm glad you opened this topic, so that these fits are gathered somewhere to learn!

Here is my 1 hour result, caught a bit low (it was unplanned, just received the alert):
cta102_20161204_812_pso.png (8.17 KiB) Viewed 4295 times


Fits file in the zip:
(10.33 KiB) Downloaded 176 times

I think the Na I 5890 is measurable at least (it's non-telluric), but will compare your fits (uncompressing the .7z) to see what is common very soon.


Re: Spectra of Quasar 4C 11.69

PostPosted: Tue Dec 20, 2016 10:43 pm
by Franck Boubault
Hello Etienne,

My spectra is a compressed fit file with using the seven-zip freeware, that you can freely download.


Re: Spectra of Quasar 4C 11.69

PostPosted: Tue Dec 20, 2016 11:10 pm
by Peter Somogyi

I did compare now the 2, I think the best result is to make an average of both (did it on my laptop, so far the best...).
Got uncertain about my Na I 5890 statement (interstellar absorption used to be there - an expert's confirmation needed), but not able to find it on yours.
There are some differences between our continuum (mine is more straight), that's either because different processing technique (, etc...) or it's a real change.
Certainly need a 3rd observation.


Re: Spectra of Quasar 4C 11.69

PostPosted: Thu Dec 29, 2016 12:24 pm
by Peter Somogyi
These days this object got even brighter, attracted enough to try a 2nd reproduce:

cta102.png (37.31 KiB) Viewed 4230 times

Exposure composition: 3 x 20 min caught the object in good quality (but windy conditions), + 2 x 20 min weighted as 0.5 for being the object low. (All with bin 1x1, just to make the noise level really visible.)

The Na I 5890 absorption seems definitely there and continuum slope matching with previous, but there might be a (missing?) feature of Mg II 2700A redshifted to 5700A according to 1606.07836.pdf.

See: - there is a large emission of Mg II ~ 5700A from 2012 and 2015, if I read the page 3.3 correctly! (fixme)

And an older event, with no emission:

Explanation would be appreciated about why to see Mg II emission sometimes, and not in the other cases.

Attaching result spectra with and without sky background removal (to see where can be pollution).
(20.67 KiB) Downloaded 179 times

Re: Spectra of Quasar 4C 11.69

PostPosted: Sat Dec 31, 2016 12:23 pm
by Peter Somogyi
After being curious of the IR part, I've just made an experiment of a 4 x 20 minute on this object (while shooting other stars and learning how the LHires + 150/mm grating + ccd behave in this region).

Being just an experiment while learning, used no order filter. The setup effort was not minimal, had to adjust all the 3 focuses (incl. guide cam).

Here is the outcome:
cta102_result_ir.png (86.86 KiB) Viewed 4199 times

What I can observe on it:
* spectral range here: 7635 - 10562. At 7635A end, every star I shoot (from type A-M) all have a hole there, should be the end of telluric band at 7605.
* validity check: the 10562A is still meaningful, as an M-type star still gives matching signal with Pickles.
blue end recover: I estimate the 2nd half of Balmer serie (blue-UV part) contaminating this region - in case of A and B type stars. Was a bit surprised how good quality.
flat was internal tungsten lamp, it should be OK since it has no real signal below 4000A (other than reflection - checked it's still usable to remove dusts on the ccd).
Wavelength calibration is real and easy, found 7 lines from Ar with RMS 0.1 order 2. Found the Ca II triplet on F-M stars easily.
* for response curve, I used an M1 star "55 peg" with very low order curve in ISIS (I know this is speculative; but finally was unable to use A or B stars due to their blue end contamination)
* features: no big emission anywhere, just a W hump around 9210A (or maybe something from the blue end) - that might be real, or needs an extra observation in the blue end.

I wish a brighter cta 102 (with emissions) to everybody in the new year!


Re: Spectra of Quasar 4C 11.69

PostPosted: Tue Jan 10, 2017 6:43 pm
by Joan Guarro Flo
Hi to All,

Is the Quasar 4C 11.69, on the night 20170106.

Regards, Joan.

Re: Spectra of Quasar 4C 11.69

PostPosted: Sat Jan 14, 2017 8:32 pm
by Franck Boubault

This is my second spectra of 4C 11.69, obtained the 7 th of January, 2017.
I've also made a superposition of this spectra with the one that I made the 12 th of december, 2016.
Except a variation on shorter wavelength, no obvious evolution can be noticed.
The quasar was low on the horizon during the acquisition of my last spectra, this could explain the variation on the blue wavelength side.