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PostPosted: 11. December 2007, 16:22:40 PM 
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Hello,

Here is a low resolution (R ~ 800) WR140 from last night.
LHIRES III 150 l/mm 200mm Vixen VC200L ATIK 16IC

It is wavelength calibrated using neon standard and corrected for instrument response using Altair. It is scaled to the "continuum" at 5540A but the continuum has not been removed.

I plan to buy a 600 l/mm grating to use for this project. Do you have a standard calibration procedure and format for the data?

Thanks
Robin


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PostPosted: 11. December 2007, 18:19:34 PM 
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Hello,

Robin Leadbeater wrote:
Quote:
Hello,

Here is a low resolution (R ~ 800) WR140 from last night.
LHIRES III 150 l/mm 200mm Vixen VC200L ATIK 16IC

It is wavelength calibrated using neon standard and corrected for
instrument response using Altair. It is scaled to the "continuum" at
5540A but the continuum has not been removed.
This is a nice spectrum, although I am not sure that the resolution is
high enough to see interesting variations. You may be interested in
Berthold Stober's recent spectra of WR 140:

http://stahl.homelinux.org:8000/otmar/specdb/
Quote:
I plan to buy a 600 l/mm grating to use for this project. Do you have a
standard calibration procedure and format for the data?
For professional astronomy, FITS is THE standard data format.
Quote:
Thanks
Robin
Kind regards,
Otmar


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PostPosted: 11. December 2007, 23:00:25 PM 
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Thank you Otmar,

My spectrograph will give R ~3000 with the 600 l/mm grating. For example
http://astro2a.mysite.orange.co.uk/spectra_32.htm
Will this resolution be good enough? (I could use a 1200l/mm but my CCD is small so the wavelength will be limited. Also 100+ S/N could be difficult with 200mm aperture.)

Yes I can produce fits files. What wavelengths should be concentrated on and have any wavelengths been decided to define the continuum?

Thank you for the database link. Is it planned to put all validated amateur WR140 spectra here?

Best Regards
Robin


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PostPosted: 12. December 2007, 10:46:17 AM 
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Hi Robin,

Robin Leadbeater wrote:
Quote:
Thank you Otmar,

My spectrograph will give R ~3000 with the 600 l/mm grating. For example
http://astro2a.mysite.orange.co.uk/spectra_32.htm
Will this resolution be good enough? (I could use a 1200l/mm but my CCD
is small so the wavelength will be limited. Also 100+ S/N could be
difficult with 200mm aperture.)
Yes, I think R=3000 will be high enough to see variations. The following
link will show you what you can expect to see:

http://cdsads.u-strasbg.fr/cgi-bin/nph- ... e=PDF_HIGH

The S/N should be high enough to allow a good radial velocity
measurement of the faint O star absorption lines on top of the WR
emission lines. The HeII5411 absorption (and probably other lines) is
already visible in your spectrum with R=800, I think.
Quote:
Yes I can produce fits files. What wavelengths should be concentrated on
and have any wavelengths been decided to define the continuum?
I am not really involved in this project. May be Thomas can comment?
Quote:
Thank you for the database link. Is it planned to put all validated
amateur WR140 spectra here?
Everyone is welcome to send me spectra! The spectra should be in FITS
format, wavelength calibrated and contain at least date and time.
Quote:
Best Regards
Robin
Best regards,
Otmar


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PostPosted: 12. December 2007, 15:30:50 PM 
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Hi Robin, that is great work. Congratulations!

Even with this small resolution you should be able to see variability in the 5700 CIII line. I strongly recommend to read the paper of Marchenko et al. Then you will understand more and there you will find their chosen regions for rectification, too. And read the stuff within our WR 140 page including the faq. Keep in mind that you can average nightly spectra to find residuals during periastron. The central wavelenght could be this CIII line as Merchenko and Berthold showed. But, if we find more partners we could go to other lines within the spectrum. Remember, there are mainly emission lines from the WR wind. Nobody made a multi-wavelength campaign yet. Who knows, what else is there...but a 600 l/mm grating should be best...if I am right...

I strongly suggest to make many observations in advance to learn for the final event.

Data reduction as usual: Flat, bias, dark and so on. Rectification acc. to Marchenko, probably with a three order spline. You should try.

Yes, I recomend to send the final and properly reduced data (you should carefully document your reduction procedures - we want to work together with the pro´s).

S/N should be > 100. But in fact, Berthold reached more than 200 with a C14. So, if you expose for about 2 h (in winter is difficult, I know), this should be sufficient. Try it NOW!!!

Wow, it`s great that you are on board!!! Keep running and asking. I will do my best to answer.

Cherio, Thomas


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PostPosted: 12. December 2007, 15:38:24 PM 
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Hi Robin,

I will use the next opportunity my 600 g/mm grating in LhiresIII to take a spectrum of WR140. Then we will see the result.

Cherio
Lothar


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PostPosted: 12. December 2007, 19:01:53 PM 
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Hi,

in all my wr140 spectra, I used a grating with 1200 lines/mm.

cheers
Berthold


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PostPosted: 12. December 2007, 23:16:20 PM 
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Thank you Thomas, Lothar,

I took another one last night and corrected both of them for the continuum using the windows shown in Marchenko fig 5. With more care taken with focussing and an increased exposure to 36min, last nights result has a S/N of 150. I also compared my results with the spectrum from 28 Nov in the database.

I am quite pleased with the repeatability (apart from a small 1 pixel wavelength shift which I need to look into) The result is very dependent on the exact fit chosen for the continuum though.

I have ordered the 600 grating

Cheers
Robin


Attachments:
wr140_28nov_10dec_11dec07.png
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PostPosted: 13. December 2007, 09:59:37 AM 
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Hello Robin,

Robin Leadbeater wrote:
Quote:
Thank you Thomas, Lothar,

I took another one last night and corrected both of them for the
continuum using the windows shown in Marchenko fig 5. With more care
taken with focussing and an increased exposure to 36min, last nights
result has a S/N of 150. I also compared my results with the spectrum
from 28 Nov in the database.

I am quite pleased with the repeatability (apart from a small 1 pixel
wavelength shift which I need to look into) The result is very dependent
on the exact fit chosen for the continuum though.
The repeatability in your spectra is indeed very satisfactory. It
worries me, however, that Berthold's spectra show much stronger lines.
This cannot be due to the difference in resolution, I suppose. Any idea
where this comes from?
Quote:
I have ordered the 600 grating

Cheers
Robin
Best regards,
Otmar


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PostPosted: 13. December 2007, 10:12:32 AM 
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Hallo Robin,

if you look the wr140 spektra in the database, you can see some fine variations in the emission line aubout 5700 from one spectrum to the other. These variations are rather quickly. some hours are enough, to see these variations. On your spectra, I don't see any variation. Perhaps, the resolution is not high enough. I would recommad, to take a grating not with 600 but one with 1200 l/mm.

cheers
Berthold


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PostPosted: 13. December 2007, 18:30:59 PM 
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Hi Otmar, Berthold
Quote:
The repeatability in your spectra is indeed very satisfactory. It
worries me, however, that Berthold's spectra show much stronger lines.
This cannot be due to the difference in resolution, I suppose. Any idea
where this comes from?
I think the difference in the intensity of the narrow lines is caused by the lower resolution (For example I cannot split the Na D lines at this R ~ 800. )
There are some differences in the size of the broad emission lines from spectrum to spectrum in Berthold's results (the broad lines from 28Nov are more intense than previously. Mine are more like the spectrum from 24Nov where the CIV line peaks at ~ 4.3)

1200 lines is difficult for me as the wavelength range is so small with such a small CCD (640x480) but the pixels are small (7.4 um) and I can close up the slit to get a bit more resolution. Also SN>100 could be tough with only 200mm aperture. I should soon get the 600 grating so we will see what that gives. I checked last night that at least I will be able to see past the trees at Periastron :)

Robin


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PostPosted: 14. December 2007, 01:29:15 AM 
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Hi WR gang! Just for quick information. I am not regularly available yet and check the forum only temporary. Starting in monday I can support better.

Yes, the problem in CIV is definitely not due to resolution power. The Marchenko paper gives no clear answer because there the CIV line at 5800 has an intensity of about 4.4 x continuum. Robin and Berthold, please check your setup and compare again. I must admit I am more with Berthold but we never know...I am not sure. Yes, Berthold is right, the variability is within some ours and perhaps you, Robin, could see them. If not, clumping is resolution sensitive and I wouldn't care if it is not visible. The global stuff during periastron is different, though.

Greetings from an impressed and delighted Thomas


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PostPosted: 14. December 2007, 10:39:18 AM 
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Hi Robin,

Robin Leadbeater wrote:
Quote:
I think the difference in the intensity of the narrow lines is caused by
the lower resolution (For example I cannot split the Na D lines at this
R ~ 800. )
Ok. The difference in narrow is easily explained by the difference in
resolution.
Quote:
There are some differences in the size of the broad emission lines from
spectrum to spectrum in Berthold's results (the broad lines from 28Nov
are more intense than previously. Mine are more like the spectrum from
24Nov where the CIV line peaks at ~ 4.3)
In the meantime, I have also seen the differences between the emission
line strengths in Berthold's spectra. I assume this an effect of the
normalization of the spectra, which is very critical for WR stars. A
peak value of ~ 4.3-4.4 in CIV (which most of Berthold's spectra also
show) seems to be about correct. The spectrum from Nov. 28 has a much
stronger peak.

Best regards,
Otmar


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PostPosted: 15. December 2007, 03:19:03 AM 
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I plotted all Berthold's results from the database and superimposed my result from 11 Dec. (Red) It is low but still just inside the "snake"

Robin


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WR140_all_BS-RL11Dec07.png
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PostPosted: 15. December 2007, 13:57:44 PM 
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Hi Robin,

Robin Leadbeater wrote:
Quote:
I plotted all Berthold's results from the database and superimposed my
result from 11 Dec. (Red) It is low but still just inside the "snake"
This is a nice plot. The rather large scatter in the peak intensity of
Berthold's spectra probably indicates that the spectral range which he
covers make it difficult to normalize the spectra reliably.
Quote:
Robin
Best regards,
Otmar


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PostPosted: 15. December 2007, 16:15:39 PM 
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Hm, this is indeed a large scatter. However, the intervals for rectification are actually well defined. I have no explanation for the variability. I would try to go for a stable setup und would continue as long as possibel to find the reason.

Thomas


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 Post subject: WR 140 20071215
PostPosted: 16. December 2007, 17:32:54 PM 
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Hallo,

A measurement result of last night. C14, Lhires III 600 g / mm, 40um slit, 8 x 10 min = 80 min exposure time, sigma 1603E in 2x2 binning, darkcorrogated, sum, sky background correction, calibration with Vspec with neon lines (linear). S / N 140 (600 -610 nm).

Normalization in the field of 600 to 601 nm (no real continuum).
Dispersion: 1,467 Angstr. / pix (18um x 18 um pixel)
FWHM Na-Linien (D1, D2) = 3 Pix = 4.4 Angstrom.
Na-D1 and D2 well separated.

I will send the spectrum to Otmar for the database.

Ask Thomas: Is the resolution to the bumps to see (if an
y)?

Hallo,
hier ein Messergebnis von letzter Nacht. C14, Lhires III 600 g/mm, 40 um slit, 8 x 10 min = 80 min Belichtungszeit, sigma 1603E im 2x2 binning, darkkorrigiert, summiert, Himmelshintergrundkorrektur, Kalibrierung mit Vspec mit Neonlinien (linear). S/N 140 (600 -610 nm).

Normierung auf den Bereich 600 bis 601 nm (es ist kein Sternkontinuum auszumachen).
Dispersion: 1.467 Angstr./pix (18 um x 18 um pixel)
FWHM Na-Linien (D1, D2) = 3 Pix = 4.4 Angström.
Na-D1 und D2 gut getrennt.

Spektrum schicke ich Otmar für die Datenbank.

Frage an Thomas: Reicht die Auflösung, um die bumps zu sehen (falls vorhanden)?

Viele Grüße
Lothar

PS: Vorsicht, das Spektrum ist wahrscheinlich durch unterschiedliche Empfindlichkeit der Pixel in Abhängigkeit von der Wellenlänge beeinflusst. Siehe mein Beitrag von heute unter "Datenreduktion"


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PostPosted: 16. December 2007, 23:47:41 PM 
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Thank you Lothar,

I will have 0.6A/pixel with my camera so that looks encouraging.

Also your maximum value of the CIV line is similar to mine if I normalise to 600-601nm

Is your spectrum corrected for instrument response?

Robin


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PostPosted: 17. December 2007, 10:49:41 AM 
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Quote:
Is your spectrum corrected for instrument response?
Hello Robin,
no, it is not corrected for instrument response. See http://spektroskopie.fg-vds.de/forum/vi ... =8765#8765.
I will do that the next time (by standard star)

Best regards
Lothar


Last edited by Lothar Schanne on 17. December 2007, 11:11:25 AM, edited 1 time in total.

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PostPosted: 17. December 2007, 11:10:55 AM 
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Hi Gang!
Quote:
Ask Thomas: Is the resolution to the bumps to see (if any)?
I assume that you mean the clumps. Note that sub-line events like clumping and global-line events like shock-cone variability are two different things (see also our WR 140 page). Lothar, for clumps your dispersion of about 1.5 A/pixel (what is the resolution) will nit be sufficient. But for global line variability like periastron shock-cone variations it should be fine. Wy? Well this affects the whole line and if the whole line is detected, this should be visible.

Please, read the WR page plus the faq and at least the Marchenko paper!

Generally, we have to be sure about the correct and proper data reduction. A major difference in line strength between different observers is not acceptable.

Cherio, Thomas


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PostPosted: 17. December 2007, 11:18:58 AM 
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Quote:
Lothar, for clumps your dispersion of about 1.5 A/pixel (what is the resolution) will nit be sufficient.
Hi Thomas, chairman of the WR 140 Gang :wink:,

Ok. I will install my 1200g/mm grating the next time.

best regards
Lothar


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PostPosted: 17. December 2007, 11:47:39 AM 
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Wait, Lothar, if you want to detect stochastic clumps you also need sufficient S/N. It is a good idea to try and I want to encourage for this idea. Go for it but don't be surprised if you do not see stochastic clumps moving away in time from the line center.

Thomas


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