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Re: CH Cyg 2018

PostPosted: Fri Jul 20, 2018 5:00 pm
by Vincent Bouttard
Hi all,

Please find my contribution to this topic with a low resolution spectrum taken during the last OHP workshop.
20x30s with Alpy600 spectrograph on 250 mm F/4 Newtonian telescope.


Re: CH Cyg 2018

PostPosted: Thu Jul 26, 2018 7:50 am
by Vincent Bouttard

CH Cyg last night. 20 x 30s with Alpy600 on 250 F/4 Newtonian telescope (I've made a mistake on the title of this image about the exposure time).

CH_Cyg_20180725_882.png (5.25 KiB) Viewed 2136 times

Re: CH Cyg 2018

PostPosted: Thu Jul 26, 2018 5:14 pm
by Francois Teyssier
CH Cyg returns to its previous luminosity
CHCyg2.PNG (6.77 KiB) Viewed 2111 times

Last Echelle spectra:
CHCyg3.PNG (40.55 KiB) Viewed 2111 times

Of course, we undergo high cadency monitoring until the return to previous state


Re: CH Cyg 2018

PostPosted: Thu Jul 26, 2018 7:14 pm
by Peter Somogyi
Hello Francois,

I think the H-beta is considerably affected by the B component's flux level - hence can be mixed by a similar absorption that's prominent clearly in the UV:

The green line is my new observation, unfortunately got bad weather here and can't shoot for 1-2 weeks.
What I suspect, the jet in the line of sight is precessing towards the 0 km/s vrad (maybe approached it by now).

I'd rather recommend looking at the sudden EW(H-alpha) drop happening since 07.12 - that's what the daily spectra show in the database, just cannot graph so many data.


Re: CH Cyg 2018

PostPosted: Mon Sep 03, 2018 2:38 pm
by James Foster
Here is what I got on CH Cyg last week using the LhiresIII with a 1800 l/mm grating with 35 micron slit:
I'll try getting it at CaK and Hb when the clouds go away!

Sincerely Yours,

James Foster
Los Angeles, CA

Re: CH Cyg 2018

PostPosted: Sun Sep 16, 2018 12:20 pm
by Peter Somogyi
CH Cyg went into a blue minima again (see aavso).
By fortune with yesterday session, I've got 2 spectra close by 1 week showing high & low state having their own flux (using the wide slit, ref.: Vega/calspec):
chcyg_high_and_low_20180915.gif (54.33 KiB) Viewed 1852 times

Included my spectrum on 2018.07.07 which was in the middle of the earlier minima.
I am curious what is causing these events.

Re: CH Cyg 2018

PostPosted: Mon Sep 17, 2018 9:48 am
by James Foster
To: Peter,

RE:"...I am curious what is causing these events."
Not sure about this myself, but here is my LhiresIII CaK data using the 1800 m/ln grating and 35micron slit (08Sep18) in the same near UV region:


Here is a 2D i did to more clearly see the processed Isis 2D _CH CygCaK.fits file via PS motion blur filter.


Let me know if you see anything strange here, as the short end of the spectrum sometimes does not "line-up" with the H-lines like the center and high end do.


Re: CH Cyg 2018

PostPosted: Mon Oct 01, 2018 7:33 pm
by Peter Somogyi
This lucky weekend (3-days serie) allowed to follow the rise after this 2nd dip again, presenting within the whole month:

Each spectra flux calibrated (ref: Vega), using the wide slit.


Re: CH Cyg 2018

PostPosted: Sun Nov 18, 2018 11:17 am
by Peter Somogyi

Just reporting a sudden flux drop of CH Cyg in the 3860-4000A range from OCT.30 to NOV.11, comparing to the previous low states:

It was extremely hard, switched to 20 minute to get real photons at low ADUs (with clouds in between).
The flux capture with the wide slit was yet at good sky conditions (Alpy Lyr + 2 x 5 minute CH Cyg), but had to do atmospheric correction (10% lower level than without the correction). The emissions with similar integrated flux amount confirming the continuum drop.
With pink color, showing hd207076 that I've scaled it via a rough human eye estimate (that when I subtract, then emission features become symmetric).
I'd assume, it should be a must for the Alpy owners to follow the decrement, and observers should make sure the low level in the UV is properly exposured.

During october, the flux level was flickering between low- and medium level (of 2018):

The emissions flux level were a kind of constant, except 1-2 observations.

- Peter