Forum der Vereinigung der Sternfreunde

Dear all,

I open here a thread for all discussions of the new campaign with technical content, like discussions about the telescope and spectrograph requirements. So we can the professionals who are more interested in the scientific discussion, relieve them of the many emails about problems of AMs.

_________________
Herzliche Grüße / best regards

Lothar

https://lotharschanne.wordpress.com/

Hi Lothar,

Great idea.

So I would like to ask:

¿ What would be the minimum requirement of telescope Aperture and Spectrograph ?

... in order to get the asked for data.

OK, I know the dispersion depends of the Pixel size in microns of the CCD camera and that there are a huge amount of possibilities.

Nowadays I guess the most available CCD cameras in amateur hands vary from 5.4µ to 9.0µ being the 5.4µ, 6.8µ and 7.4µ the most common, from my point of view

Maybe a simple excel spread sheet where one could input the own available setup parameters and see what comes out ?

I know there is SimSpec.xls and I have played with it. The biggest hurdle for me has always been to find the correct parameters for the Spectrographs. All other parameters are more or less easier to find in the camera producers pages, etc.

Maybe I already answered my message by myself

This also would help to make a decision if one should invest more time in this project when not reaching the minimum requirements and better invest time in other projects where the equipment is able to deliver the needed info.

I know that my setup is by far not yet enough but investing some money in a spectrograph is a feasable idea, if the telescopes are OK. If the Telescopes are the problem then better I just forget it

I also know I just started in March if this year but there is still time to learn more until Mid Year 2013

_________________
Grüsse Rainer www.rsfotografia.com

Hello Rainer and others,

i will try the combination Lhires III with a 50 um slit width, 1800 g/mm grating and my C14 telescope. CCD = KAF 1603ME.

I had measured WR140 (6.9 mag) also with a 2400 g/mm grating and 35 um slit, so I think and hope to get useful spectra of a 8.3 mag star with the above combination (S/N > 100, R ca. 5000, resolution 1.3 Angström).

Perhaps I will need a exposure time of more then 1 h (2 or 3 ?).

_________________
Herzliche Grüße / best regards

Lothar

https://lotharschanne.wordpress.com/

Hi Rainer,

It is important that we do not get hung up on dispersion. We can easily chose the desired the dispersion with the LHIRES for example by changing the grating. The important factor is resolution.

Pixel size does not matter unless we have less than 2 pixels/ image of the slit width at the camera, which is normall not a problem.

The key factor is to collect enough photons to give the required SNR. To get 200 SNR at 1A resolution in 1 hour we need to collect 200^2 = 40000 electrons per hour in each 0.5A region of the spectrum at the camera. (ignoring camera noise) This will decide the aperture needed. (~0.5m is my guess for a typical spectrograph and camera efficiency but Lothar and Thierry's tests with 350mm aperture will give us more information on this)

The star size (which, for a given focal ratio, depends on the aperture and seeing ) will decide the required slit width. Once we have the slit width (50um for example) we can then chose the dispersion so that we get the desired resolution (In this example, 1A/50um)

Note that Lothar's LHIRES is not standard. It had been modified with larger components so it can work at lower focal ratio than the standard f10. This gives an advantage here as he can run a 50um slit and collect most of the light. A standard LHIRES will need a larger slit width and so higher dispersion.

Cheers
Robin


----- Original Message ----- From: Rainer Ehlert (fg-spek-convento@vds-astro.de)
To: fg-spek-convento@vds-astro.de (fg-spek-convento@vds-astro.de)
Sent: Tuesday, December 13, 2011 10:16 PM
Subject: [fg-spek] Re: Technical meeting point



Hi Lothar,

Great idea.

So I would like to ask:

¿ What would be the minimum requirement of telescope Aperture and Spectrograph ?

... in order to get the asked for data.

OK, I know the dispersion depends of the Pixel size in microns of the CCD camera and that there are a huge amount of possibilities.

Nowadays I guess the most available CCD cameras in amateur hands vary from 5.4µ to 9.0µ being the 5.4µ, 6.8µ and 7.4µ the most common, from my point of view

Maybe a simple excel spread sheet where one could input the own available setup parameters and see what comes out ?

I know there is SimSpec.xls and I have played with it. The biggest hurdle for me has always been to find the correct parameters for the Spectrographs. All other parameters are more or less easier to find in the camera producers pages, etc.

Maybe I already answered my message by myself

This also would help to make a decision if one should invest more time in this project when not reaching the minimum requirements and better invest time in other projects where the equipment is able to deliver the needed info.

I know that my setup is by far not yet enough but investing some money in a spectrograph is a feasable idea, if the telescopes are OK. If the Telescopes are the problem then better I just forget it

I also know I just started in March if this year but there is still time to learn more until Mid Year 2013



Grüsse Rainer

" Wenn es funktionert, sollte man es nicht reparieren "

www.rsfotografia.com

Hi Robin,

Thanks. I will keep reading this topics and then after more information decide what to do.

So far if I keep reading telescope aperture of 350mm or even more I will have to pass

_________________
Grüsse Rainer www.rsfotografia.com

Hi Gang!

To disentangle the discussion I open this new technical thread. The one "New ProAm campaign in 2013" becomes longer and longer and it becomes difficult to keep it usable.

Thomas

Hi,i began to explore the results of my Dec 12th observing session.
Here is a presentation of the HeII 4686 lines extracted from one order of a eshell spectra at different exposure. Conditions were perfect, 80°high, good seing, easy to guide. The prelimary conclusion are that my echelle setup (C14, ST10XME, eshell, R10000 disp 0.1A), cannot reach SNR200 in 1H. It is more near 20 for 2H40 exposure.
 But the line is well resolved, easy to spot, the continuum is intense and so, such SNR should not be required for a Rv study. Small change in the profile should be evident too. It would be usefull, for better setup choice, to explain why such SNR is required ?
http://gabalou.canalblog.com/archives/2 ... 66856.html
Cheers
Thierry

2011/12/14 Rainer Ehlert <fg-spek-convento@vds-astro.de (fg-spek-convento@vds-astro.de)>

_________________
Thierry Garrel
Observatoire de Fontcaude, Montpellier, France
SpectroBlog http://gabalou.canalblog.com/

Hi Thierry! As you have seen in the webpage, we want to detect and trace CIRs and clumps. These features are very small in contrast and, hence, need good S/N. In addition, CIRs come and go periodically or not (we want to find out). And to find out we need enough signal of the respective line features so that we can perform a good periodicity analysis. And wind turbulence seen as line clumbs might be even harder. It might well be that we need to compromise between S/N and exposure time but we can only judge if we have first results. It might also be that this parameter combination fails. Then we have to make up our mind.

Salut, Thomas

Thanks Thomas,
Are the features optically thin or thick ?
Do you have such examples to show ?

T

_________________
Thierry Garrel
Observatoire de Fontcaude, Montpellier, France
SpectroBlog http://gabalou.canalblog.com/

Hi Thierry

Because of your dispersion of 0,1 A/pix you could binn by factor 5, and if you do this also perpendicular to the direction of dispersion you will get a factor of 25^0.5 = 5 in SNR (maybe) . . .

If the detector is oversampled you will not lose much resolution but I think it is only an resolving power of 5.000 needed.

_________________
Daniel P. Sablowski

https://www.kunstmann.de/buch/axel_hack ... 42000/t-2/
https://dpsablowski.wordpress.com
https://github.com/DPSablowski
https://www.aip.de/mitglieder/dsablowski/

Yes indeed,

Thierry, try resampling your spectrum at 0.5A/bin and see what SNR you get. (Binning vertically will not help much because the pixels are already summed vertically, just a small improvement if it is done in camera due to the reduced number of read noise doses but this is very marginal)

Cheers
Robin

----- Original Message -----
From: Daniel Sablowski (fg-spek-convento@vds-astro.de)
To: fg-spek-convento@vds-astro.de (fg-spek-convento@vds-astro.de)
Sent: Wednesday, December 14, 2011 7:55 PM
Subject: [fg-spek] Re: ProAm campaign in 2013 - Technical aspects



Hi Thierry

Because of your dispersion of 0,1 A/pix you could binn by factor 5, and if you do this also perpendicular to the direction of dispersion you will get a factor of 25^0.5 = 5 in SNR (maybe) . . .

If the detector is oversampled you will not lose much resolution but I think it is only an resolving power of 5.000 needed.



Daniel Sablowski

Das Gegenteil einer jeden Wahrheit ist falsch, das Gegenteil einer tiefen Wahrheit ist wieder eine tiefe Wahrheit.
[Bohr]

www.hobbysternwarteploesen.de
www.sternwarte.uni-erlangen.de/new

re sampling to 0.5 does not support the resolution anymore, it is conditions of  under sampling spectra. You don't know what your spectra would show.The HeII line is quite large and support a strong undersampling with some profile modification, like tiny features may disappear or not depending of the loss of point of profile. With the 1h exposure, SNR get from 17 to 24 by re sampling the dispersion of a factor 4, at 0.4A (R=0.5A at 4686). I don't like it  much and no significant advantage in term of SNR.
Cheers
T
2011/12/14 Robin Leadbeater <fg-spek-convento@vds-astro.de (fg-spek-convento@vds-astro.de)>

_________________
Thierry Garrel
Observatoire de Fontcaude, Montpellier, France
SpectroBlog http://gabalou.canalblog.com/

Comparison between under sampled spectra and original. Not very confident on what under sampled spectra will show.

2011/12/14 thierry Garrel <fg-spek-convento@vds-astro.de (fg-spek-convento@vds-astro.de)>

_________________
Thierry Garrel
Observatoire de Fontcaude, Montpellier, France
SpectroBlog http://gabalou.canalblog.com/

Hi Thierry,

The required resolution is only 1A, not the eShel native resolution so we can resample at 0.5A and still match the required resolution (or alternatively filter the original spectrum) I checked the SNR in your 6x1200 sec spectrum in the region 4721-4739A (after removal of the "continuum" and got SNR 48 before resampling and 90 after resampling.

Robin

----- Original Message -----
From: thierry Garrel (fg-spek-convento@vds-astro.de)
To: fg-spek-convento@vds-astro.de (fg-spek-convento@vds-astro.de)
Sent: Wednesday, December 14, 2011 9:15 PM
Subject: [fg-spek] Re: ProAm campaign in 2013 - Technical aspects



re sampling to 0.5 does not support the resolution anymore, it is conditions of under sampling spectra. You don't know what your spectra would show.The HeII line is quite large and support a strong undersampling with some profile modification, like tiny features may disappear or not depending of the loss of point of profile. With the 1h exposure, SNR get from 17 to 24 by re sampling the dispersion of a factor 4, at 0.4A (R=0.5A at 4686). I don't like it much and no significant advantage in term of SNR.
Cheers
T
2011/12/14 Robin Leadbeater )vds-astro.de (fg-spek-convento(==>)vds-astro.de ([email]fg-spek-convento(==>)vds-astro.de[/email]))>
: Yes indeed,

Thierry, try resampling your spectrum at 0.5A/bin and see what SNR you get. (Binning vertically will not help much because the pixels are already summed vertically, just a small improvement if it is done in camera due to the reduced number of read noise doses but this is very marginal)

Cheers
Robin

----- Original Message -----
From: Daniel Sablowski (fg-spek-convento(==>)vds-astro.de ([email]fg-spek-convento(==%3E)vds-astro.de[/email]))
To: fg-spek-convento(==>)vds-astro.de ([email]fg-spek-convento(==%3E)vds-astro.de[/email]) (fg-spek-convento(==>)vds-astro.de ([email]fg-spek-convento(==%3E)vds-astro.de[/email]))
Sent: Wednesday, December 14, 2011 7:55 PM
Subject: [fg-spek] Re: ProAm campaign in 2013 - Technical aspects



Hi Thierry

Because of your dispersion of 0,1 A/pix you could binn by factor 5, and if you do this also perpendicular to the direction of dispersion you will get a factor of 25^0.5 = 5 in SNR (maybe) . . .

If the detector is oversampled you will not lose much resolution but I think it is only an resolving power of 5.000 needed.




Daniel Sablowski

Das Gegenteil einer jeden Wahrheit ist falsch, das Gegenteil einer tiefen Wahrheit ist wieder eine tiefe Wahrheit.
[Bohr]

www.hobbysternwarteploesen.de
www.sternwarte.uni-erlangen.de/new










Thierry Garrel
Observatoire de Fontcaude, Montpellier, France
SpectroBlog http://gabalou.canalblog.com/

Attached is the continuum removed region, raw (SNR 48) and with a 5 sample running mean filter (SNR 100). The problem is improving from 100 to 200 SNR will need at least 4x the number of photons ie 4 hours exposure even without the extra camera noise.

Robin


----- Original Message ----- From: Robin Leadbeater (fg-spek-convento@vds-astro.de)
To: fg-spek-convento@vds-astro.de (fg-spek-convento@vds-astro.de)
Sent: Wednesday, December 14, 2011 9:43 PM
Subject: [fg-spek] Re: ProAm campaign in 2013 - Technical aspects



Hi Thierry,

The required resolution is only 1A, not the eShel native resolution so we can resample at 0.5A and still match the required resolution (or alternatively filter the original spectrum) I checked the SNR in your 6x1200 sec spectrum in the region 4721-4739A (after removal of the "continuum" and got SNR 48 before resampling and 90 after resampling.

Robin

----- Original Message -----
From: thierry Garrel (fg-spek-convento(==>)vds-astro.de ([email]fg-spek-convento(==>)vds-astro.de[/email]))
To: fg-spek-convento(==>)vds-astro.de ([email]fg-spek-convento(==>)vds-astro.de[/email]) (fg-spek-convento(==>)vds-astro.de ([email]fg-spek-convento(==>)vds-astro.de[/email]))
Sent: Wednesday, December 14, 2011 9:15 PM
Subject: [fg-spek] Re: ProAm campaign in 2013 - Technical aspects



re sampling to 0.5 does not support the resolution anymore, it is conditions of under sampling spectra. You don't know what your spectra would show.The HeII line is quite large and support a strong undersampling with some profile modification, like tiny features may disappear or not depending of the loss of point of profile. With the 1h exposure, SNR get from 17 to 24 by re sampling the dispersion of a factor 4, at 0.4A (R=0.5A at 4686). I don't like it much and no significant advantage in term of SNR.
Cheers
T
2011/12/14 Robin Leadbeater )vds-astro.de (fg-spek-convento(==>)vds-astro.de ([email]fg-spek-convento(==>)vds-astro.de[/email]))>
: Yes indeed,

Thierry, try resampling your spectrum at 0.5A/bin and see what SNR you get. (Binning vertically will not help much because the pixels are already summed vertically, just a small improvement if it is done in camera due to the reduced number of read noise doses but this is very marginal)

Cheers
Robin

----- Original Message -----
From: Daniel Sablowski (fg-spek-convento(==>)vds-astro.de ([email]fg-spek-convento(==%3E)vds-astro.de[/email]))
To: fg-spek-convento(==>)vds-astro.de ([email]fg-spek-convento(==%3E)vds-astro.de[/email]) (fg-spek-convento(==>)vds-astro.de ([email]fg-spek-convento(==%3E)vds-astro.de[/email]))
Sent: Wednesday, December 14, 2011 7:55 PM
Subject: [fg-spek] Re: ProAm campaign in 2013 - Technical aspects



Hi Thierry

Because of your dispersion of 0,1 A/pix you could binn by factor 5, and if you do this also perpendicular to the direction of dispersion you will get a factor of 25^0.5 = 5 in SNR (maybe) . . .

If the detector is oversampled you will not lose much resolution but I think it is only an resolving power of 5.000 needed.




Daniel Sablowski

Das Gegenteil einer jeden Wahrheit ist falsch, das Gegenteil einer tiefen Wahrheit ist wieder eine tiefe Wahrheit.
[Bohr]

www.hobbysternwarteploesen.de
www.sternwarte.uni-erlangen.de/new










Thierry Garrel
Observatoire de Fontcaude, Montpellier, France
SpectroBlog http://gabalou.canalblog.com/

48*5^0.5 = 107

90/48 = 1,88

so, the theory for best SNR fits nur exactly (85 %, this is noise).

_________________
Daniel P. Sablowski

https://www.kunstmann.de/buch/axel_hack ... 42000/t-2/
https://dpsablowski.wordpress.com
https://github.com/DPSablowski
https://www.aip.de/mitglieder/dsablowski/

HeI 5876 presentation, much better SNR as the ccd sensitivity is better.http://gabalou.canalblog.com/archives/2 ... 68638.html
No change of intensities of the lines during the exposure, while HeII seems more active in my spectra.

_________________
Thierry Garrel
Observatoire de Fontcaude, Montpellier, France
SpectroBlog http://gabalou.canalblog.com/

Yes it is all fitting together as expected. Meeting the required specification is going to need ~0.5m aperture. If we are to get many amateurs participating we will either need a relaxed specification or, as Fil suggested, the results of several (typically 4) observers combined.

Robin


----- Original Message ----- From: Daniel Sablowski (fg-spek-convento@vds-astro.de)
To: fg-spek-convento@vds-astro.de (fg-spek-convento@vds-astro.de)
Sent: Wednesday, December 14, 2011 10:00 PM
Subject: [fg-spek] Re: ProAm campaign in 2013 - Technical aspects



48*5^0.5 = 107

90/48 = 1,88

so, the theory for best SNR fits nur exactly (85 %, this is noise).



Daniel Sablowski

Das Gegenteil einer jeden Wahrheit ist falsch, das Gegenteil einer tiefen Wahrheit ist wieder eine tiefe Wahrheit.
[Bohr]

www.hobbysternwarteploesen.de
www.sternwarte.uni-erlangen.de/new

Hi Thierry,

I think the difference in intensity between the three He 4686 spectra could be small scaling errors when normalising. This was a big problem for me to start with in the WR140 campaign. Very small errors in normalisation or in dark/background subtraction can give big errors at the top of the emssion line.

Cheers
Robin


----- Original Message ----- From: thierry Garrel (fg-spek-convento@vds-astro.de)
To: fg-spek-convento@vds-astro.de (fg-spek-convento@vds-astro.de)
Sent: Wednesday, December 14, 2011 6:54 PM
Subject: [fg-spek] Re: ProAm campaign in 2013 - Technical aspects



Hi,i began to explore the results of my Dec 12th observing session.
Here is a presentation of the HeII 4686 lines extracted from one order of a eshell spectra at different exposure. Conditions were perfect, 80°high, good seing, easy to guide. The prelimary conclusion are that my echelle setup (C14, ST10XME, eshell, R10000 disp 0.1A), cannot reach SNR200 in 1H. It is more near 20 for 1H40 exposure.
But the line is well resolved, easy to spot, the continuum is intense and so, such SNR should not be required for a Rv study. Small change in the profile should be evident too. It would be usefull, for better setup choice, to explain why such SNR is required ?
http://gabalou.canalblog.com/archives/2 ... 66856.html
Cheers
Thierry

2011/12/14 Rainer Ehlert )vds-astro.de (fg-spek-convento(==>)vds-astro.de ([email]fg-spek-convento(==>)vds-astro.de[/email]))>
: Hi Robin,

Thanks. I will keep reading this topics and then after more information decide what to do.



Grüsse Rainer

" Wenn es funktionert, sollte man es nicht reparieren "

www.rsfotografia.com










Thierry Garrel
Observatoire de Fontcaude, Montpellier, France
SpectroBlog http://gabalou.canalblog.com/

Hi Robin,
These spectra are not normalized. Just re-scaled to fit the continuum at 1.
But it could be a continuum dimming effect, very intense in these part of the spectrum, as i stopped observation just below airmass 2. Note, i'v done the same observation on del sco far below airmass 2 without notice it, but the continuum is not so intense.
But the literacy report a short term variation of 4686, 1.8d, http://www.stsci.de/wr134/pdf/morel1999.pdf . Well could be real, need a pro.
In this publication, spectra are from multiple meters size telescope at a max SNR of 160 for nearly same resolution as required.
My experience on faintest star pro am programs like FS cma group or A type supergiant, stars of mag 10+, is that there is not a tremendous gain of SNR between a 0.35m and a 0.5m. Need much more larger to have significant gain in 1h.
Amitiés
T

_________________
Thierry Garrel
Observatoire de Fontcaude, Montpellier, France
SpectroBlog http://gabalou.canalblog.com/

Hi Gang!

Your general concern not to reach the requirements is reasonable and I see some necessary input of the pro's here. However, keep in mind that the noted requirements (S/N, exp. time, resolution) are not like a bible. Remember, the WR140 campaign where we used data from OHP, Mons, others, as well as amateurs with smaller aperture. ALL data have been useful for the system analysis. Remi Fahed then wheighted the data points with respect to telescope aperture, S/N, etc. and used them for the orbit calculation. This is how science goes. You take every available information and squeeze it out. So, if we only use 10m-Keck we would get superb data but only them. If we accept small telescopes, then we possible get, say, 100 observers resulting in large statistics and, hence, quality increase. And if we take all, as we presently try it, the better.

Overall, if you have a spectrograph but do not fullfil the announced requirements, then just go ahead and try the best you can. In the meantime we discuss what to do, to circumvent potential problems. Fil already proposed a solution by combining some single observations (well, if we have more observers - Thierry, maybe you can encourage our french colleagues again). I am not familiar with such a technique but it is an important input for our discussion.

Cherio, Thomas

Small absorption are evolving on a time series at the top of the HeII 5411A line of WR134, and transient emsision appears on the right, near 2200km/s. It would be great if these features are DAC and CIR that we are looking for. Need a pro comment.
Note SNR is relatively high, 110, at R12000, well i think that this question of SNR is depending on how to calculate it. So i let it down.
Resolution seems to be a good advantage to detect, if so, these small features.
As this star is relatively bright, it could be a good idea to increase required resolution, it could balance loss of SNR in the detection of these features.
Ref:http://www.stsci.de/wr134/pdf/moffat2000.pdf

http://gabalou.canalblog.com/archives/2 ... 86755.html

Waiting for a pro.
Cheers
T

_________________
Thierry Garrel
Observatoire de Fontcaude, Montpellier, France
SpectroBlog http://gabalou.canalblog.com/

Hi (the other) Thierry,

Very nice spectra. Difficult to tell by eye whether there are indeed
significant variations between the three exposures at the top of the line.
Concerning the feature at 2200 km/s, to me it looks as an artifact. The
fact that the profile is highly asymmetric is likely to be due to CIRs.
The profile does not seem to evolve much during the ~2-3 hrs of
observations because this only corresponds to 0.04 in phase (period ~ 2.25
days). I am pretty sure that if you observe it once again within the next
few days then the profile will be substantially different. To me obtaining
such high-quality spectra over a long time span is exactly what this
campaign is about and so I would warmly encourage you to carry on!

Cheers,
Thierry

Dear All,
I am Marco Leonardi (Milan-Italy). I know already some of you but this is my first post at Spektroskopie Forum-The Convento Group and I think it is important to introduce myself. I am a spectroscopy amateur since September 2010 when I bought my first SA100, the I "falled in love" for this science and I decide to buy the Spectra-L200 KIT (Ken Harrison) and so I have assembled my first Littrow spectroscope. It has 600 lines/mm + 30 microns fixed slit. I also bought a C9.25 + a new mount EQ6Pro. I am using EQMOD to manage all observatory. As software I use AA4 + PHD to guide. My spectroscope has not reflective slit so I guide using a guide scope. I am a member of BeSS and almost each month I upload some B star spectra, mainly I am monitoring kap Dra.

Even if my experience is quite short (+one year) and my setup is a typical low level amateur set up, and the project specification are severe, I decided to partecipare to this campaign for the following reasons:

1) the campaign will start on summer 2013 and during this time frame I will have the opportunity to do a lot of tests, to growth up and to define my limits and my real possibilities.
2) I am optimistic that the campaign's organizers will find a way to use the data coming from amateurs as me.

Then, if I will have no chance to give my contribute, never mind, however it will be a very good opportunity to learn more and to increase my experience on spectroscopy, which will be a great benefit.

I am trying to convince others italian friends with more experience than me, to partecipate and I hope some other amateur from Italy will partecipate to this very interesting discussion, as a member, here.

About the Campaign: the first test I will do will be to train myself to make spectra of a 8-9 magnitude star. I have plain of time to do a lot of tests and to check the real resolution and SNR I am able to reach. As soon as I will have some result I will post here so that we can discuss with real experimental data in hands. I am also thinking to install a 50 microns slit to gain more signal....and other ideas mainly related with setup investment/improvements.

Cheers,
Marco Leonardi

Hallo,

sollte ich die Mag 8 mit ausreichenden S/N erreichen, bin ich auch dabei!

Viele Grüße
Siegfried

Very well, Siegfried! But it is not only the S/N for 8 mag but also the necessary resolution. Just try it and keep us informed. And don't forget, the ConVento Group is an english discussing community. Or we all accept learning Italian, French, Spanish, German, ...

Cherio, Thomas

Well sure, as I could!

Many Thanks Thierry, the other, not me , for your warn full comments;
So i join the campaign with this setup and will encourage, french, collaboration by the same way.
i will try to catch another spectra until the end of the Cygnii observing season, but i'm involved in this part of the sky on the seek of rare blue super-giant stars that does not allow much left time this year.
We didn't have discussed about photomety requirement.

Cheers
T (original one)

_________________
Thierry Garrel
Observatoire de Fontcaude, Montpellier, France
SpectroBlog http://gabalou.canalblog.com/