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 Betreff des Beitrags: WR 140 29.12.07 600 line grating
BeitragVerfasst: 01. Januar 2008, 19:45:09 PM 
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Registriert: 25. Oktober 2006, 23:43:13 PM
Beiträge: 741
Wohnort: Cumbria England
Here is my first try with the LHIRES III and 600 line grating. Conditions were poor and the exposure was only 40min so the S/N is only ~50. I also used a narrow (15um) slit to help the resolution (R~3000)

The spectrum is corrected for the continuum but only two of the Marchenko fit zones could be used because of the small size of the CCD.

I have also plotted Jose's recent result. The comparsion is quite good except for a small ( ~ 0.5-1A) wavelength calibration difference in the zone 5750-5850 A I cannot explain this. My fit to the neon calibration lines at 5764.41 5804.45 and 5820.16 are all correct to better than 0.1A

New Year Greetings
Robin


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wr140_29dec07_21-05.png
wr140_29dec07_21-05.png [ 11.55 KiB | 2625 mal betrachtet ]
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BeitragVerfasst: 02. Januar 2008, 10:40:16 AM 
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Registriert: 31. Juli 2006, 16:43:32 PM
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Hi Robin! Happy new year from Bonn!

As I can estimate, you and José have a fairly solid set-up and repeat results quite nice. In addition, the differences in the red line peak of CIII and all over CIV should be real. That are stochastic variations due to clumping in the WR wind. Congratulations! However, the interstellar lines around 5890 have diferent depths... I do not know the reason. Any idea?

I stopped placing new results into our project page because Otmar designed a database already. But if you want it to be placed, give me a message.

Cheers, Thomas


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BeitragVerfasst: 02. Januar 2008, 18:01:38 PM 
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Registriert: 25. Oktober 2006, 23:43:13 PM
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Hi Thomas,

Yes it looks like this setup will work OK. The span is rather small though (400A) Do you think the range I have chosen is Ok or should I move more towards the blue?

I think the differences in the Na lines are because of Jose's higher resolution (he is using a 1200 grating). If I measure the EW of the lines in the two spectra, they are the same within a few percent and if I low pass filter Jose's spectrum the Na lines look very similar.

I have attached a fits file to go into the database.

Best Wishes
Robin


Dateianhänge:
Na_intensity_comparison.png
Na_intensity_comparison.png [ 7.4 KiB | 2595 mal betrachtet ]
Dateikommentar: fits file
wr140_29dec07_21-05_contindiv.zip [3.18 KiB]
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BeitragVerfasst: 03. Januar 2008, 09:26:45 AM 
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Ok, Robin, I'm convinced. That looks pretty nice! The continua match perfectly as if rectified at this very same wavelength. That is how the result should be. Now Berthold and you showed the real variability within the line peaks.

Just today I got the following meassage from Tony Moffat in Montréal. He made some quick calculations.
Zitat:
Assuming the length of the observable night is ~12h at Teneriffe on Jan 25 (the worst night to be observing WR140!), then the hour angle is +6h and increasing at the beginning of the night and -6h and decreasing - but the sky is getting bright! - at the end of the night. [On the best night, July 25, one has HA = -4h and +4h, resp.]
So, one will have to observe WR140 at HA = +/- 6h at this time of year. Of course, as you go off this date, things get better slowly at first. Anyway, HA = +/- 6h corresponds to airmass X = 3.0, increasing to 5.9 at HA = +/- 7h.
This means that you don't have much time to grab a spectrum on Jan 25, maybe 30 minutes or so. One way around this would be to observe more into twilight, although at this high airmass, the sky is already significantly brighter than at lower airmasses.

Bottom line: NOW is the time to make some tests (i.e. between say early January and mid February), to see how good the spectra will be, ready for next year when it really counts. Can you get your troops on it now?
Cheers, Thomas


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 Betreff des Beitrags: WR 140 29.12.07 600 line grating
BeitragVerfasst: 06. Januar 2008, 10:20:16 AM 
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Registriert: 17. Dezember 2006, 15:08:21 PM
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Hi Robin and all,

Happy new year to all!

Robin Leadbeater wrote:
Zitat:
I have attached a fits file to go into the database.
This spectrum will go into the database (I assume the time in the
header is UT?), as soon as I find the time (I was in vacation until
yesterday). In the future, everybody who wants to send spectra to the
database, please use the email address found here:

http://shurl.org/QMxqZ

which is also linked now at the database site:

http://stahl.homelinux.org:8000/otmar/specdb/

The first time you send a spectrum, please also add a brief description
of your instrumentation (telescope, spectrograph, detector) as e.g. in:

http://stahl.homelinux.org:8000/otmar/s ... %20Schanne

Best regards,
Otmar


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