Forum der Vereinigung der Sternfreunde

Hallo,

Have some graphics from the VV Cep. The changes are subtle.

A question to all observers, is there someone who has recent observations of this star?

There are currently many stars to watch and it seems that telescopes are needed.

Regards, Joan.

Hi,

How long is your exposure time? What S/N do you have?. It could be useful for others if you would provide your spectra for downloading.

Do you have any experience with crosscorelation to find radial velocities ?

Cheers Berthold

Hi Joan and Berthold,

from time to time I take spectra from VV Cep. So I have a reduced (to get more practice in ESO-MIDAS) spectrum from July the 26. 2017.

6x300sec with C5, equipped with Lhires 1800 l/mm, ATIK 428.

Viele Grüße und CS
Christoph

Joan,

there is a signifcant difference between our normalisation to 1. Your intensity is higher. Maybe too high? Or am I too low? Do you know enough about the physics of this system that you can say what would be better?

Viele Grüße und CS
Christoph

Schönes Spektrum, nur sind 3 Angström zur S/N Bestimmung sehr wenig, 10 sollten es mindestens sein, meine ich zumindest.

Berthold

Hello everyone,

First, I apologize to all of you for my delay in answering you.


Berthol,

The exposure time varies a lot, depending on weather conditions and seeing conditions, there are usually 8 integrations between 150 and 300 seconds. I try to get the Halpha peak to reach half the histogram.

I also send a graph, (_vvcep_20170727_849_JGF.fit), which is the closest observation to that made by Christoph.

My experience is reduced to the observation, these graphs, automatically calculated by PLOTSPECTRA, by Tim Lester, https://1drv.ms/f/s!AvXqhKI5kEGRjEhdaQ6jaj8AHx_L.



Christoph,

Yes, I see that there is a significant difference, but at this moment I can not give you a specific answer.

If you look good, you can pass me your Fits, and I can see it. I only prepare my comments and send them to analysts. Sorry, but I have never analyzed (maybe I could not do it), but I do not have time to observe, reduce data and always have the material ready to build spectroscopes.

I also do not know how MIDAS works ...

I can expose the problem to the ARAS SPECTROSCOPY FORUM.



To all,

I also think it would be very beneficial, that there be a good connection between the VdS and the ARAS SPECTROSCOPY FORUM, (they are now two isolated worlds that seem to be mutually ignorant), everyone would win.

Now we are losing all of us.

I have been dedicated to spectroscopy for almost twenty years, until last year, I did not know the existence of VdS.

Friendly, Joan.

Hi,

Berthold, ja das Problem ist, dass da ja nicht wirklich ungestörtes Kontinuum vorhanden ist, um das SNR vernüfntig messen zu können.


Joan, the fits-Header of your fts say, that you used ISIS for data reduction. But there are no operations done by ISIS listed. It seems, that you dont set your zoom into Ha to 1. If you do so, our data fit.

MIDAS is a command-line driven programm, developed and used by pros. It runs in Linux. If you are willing to learn something new, I can recommend it to you! One of the advantages of this programm is that it is transparent. So you know what happend to your data.

I attached also my .fit. By the way, the forum allowed not .fts. Does anyone know why?

Viele Grüße und CS
Christoph

Hello Christoph,

Comparing your graph with that of other observers, there is a strong shuffle in the wavelength.

Could you check your calibration data?

At the moment I have not thought of changing software, the ISIS works very well and the results are very well accepted by professional analysts. This year, as a co-author, there is an article in Icarus and another in Astronomy & Astrophysics and another one about to publish. I do not say it with a spirit of arrogance. I say this to reaffirm the good quality of ISIS.

Friendly, Joan.

Hi Joan,

you are right!

My calibration wasn't good . I've corrected it. I use usually the water lines (because normally its more precise than the three neon lines) for calibration and not experienced in reduction of "late type stars". (And I'm still learning MIDAS. Mistakes are not excluded!)

Do you know, if ISIS or PLOTSPECTRA correct your data for the temperature of the star? Is there generally a difference for Echelle spectrographs?

Gratulation to your co-autorship!
Its okay if the software work fine. I think there is a good match in our data quality. For me its a problem, if the software is a black box. Therefore I decided to learn MIDAS.

I attach two graphs. The first show our spectra without setting yours to 1. And the second with normalisation of your spectrum. There is a little differnce. Maybe an error of my subjective choice of points for the spline or intrinsic origin?!
Viele Grüße und CS
Christoph

This is very good news ! I think it is impressive to get that good agreement between two observers with very different types of spectrograph and using different software.

For me the VV Cep campaign has a problem because there is no professional astronomer PI to explain what is happening and what measurements are useful.

Robin

Hi Christoph!
I believe your S/N is significantly higher then about 120.

Hi Joan! I presume your great observations and your carefull data reduction is the reason for your success having a co-authorship. I guess we all can congratulate und you have all reason to be proud!
I can only agree but have no solution for that. We twice hold our conference close to France and only in Freiburg we had participants from Alsace. Maybe it is a different focus approach - more observational in France, more technical in Germany. At least that is what Christian Buil said when I once talked to him. And perhaps a different attitude triggered by socialization - but I am not sure.

Hi Robin! I read this at ARAS Yahoo and agree. I even would say that a professionable publication is not granted. A single amateur without thorough science education and ongoing experience in the community won't be too successfull. At least I couldn't do this.
Cheers, Thomas

Hallo Christoph,

Do not worry about making a mistake, this comes within normality, I've done dozens, and most seriously, and I have not done the last.

In ISIS, if you can correct the data for the temperature of the star, (it can also be done with the VSPEC), as long as you have observed a pattern star on the same night. The echelles are a world apart, I have seen "terrible" graphics obtained with echelles, (both professional observatories and amateurs). In order to get good results in the curve of a star they must be single-order spectroscopes, the Lhires and those with low resolution.

See the animation of Umberto Sollecchia, Aug 01 2017 8:48 pm, http://www.spectro-aras.com/forum/viewt ... 4&start=70.

In my case, I compare the entire spectrum of the echelle with a low resolution (see graph), of course this is not useful for all stars, (RRLyr, Novas, etc.). Your second graph adjusts a lot to reality.


I really like to have this change of views with you, we must keep in touch.

Hi Robin,

I agree with you, we all have to explain more things, those dedicated to spectroscopy are a very small family, in this world of astronomy and we have many things to learn. The VV Cep is a star that has been watching since 2009, http://www.astrosurf.com/aras/Aras_Data ... /VVCep.htm, (the head of this section is Olivier Thizy and not the has updated). There are also current data for the Aras Spectroscopy Forum.

Hello Thomas,

Thanks, however, I do not do great work, I do not consider it a success either. I am lucky to live in a place where it is used, (not always), to make good weather to observe, and that if, I observe, I work. In the case of errors ..., you know one of my during the last WR140 observation campaign. As an excuse, I can always say, on my disclaimer and according to UNESCO, that I am cataloged in the group of Analfabets of the Second Degree. I do not have the Certificate of Primary Studies, (I guess it should be noted). If I did mention, it was in defense of the ISIS. Do not do too much of the written letter is too serious and hard.

I have noticed this difference between the two Conferences, but I still think that they could be complemented, we are few people and the contacts should be more normal.

OK that ARAS is an amateur world, but it's a job, I think that, apart from feeding the Be Data Base, where you collaborate with the Paris Observatory, you collect an amount Very important observations of all kinds of stars. A very important aspect of our work is the ability to monotourise, a small example of the last campaign of the WR140.

Sincerely yours, Joan.

Hi Joan, I understand your point and highly appreciate your modesty. But I and possibly all of us fully disagree with your low rating of your spectroscopic achievement. In addition, we do not focus on a persons disabilities but in his/her abilities. This forum and the VdS spectroscopy section is for people who like to talk to colleagues who also love the topic. I do not bother if you have problems with reading/writing (obviously not) or if you only have one eye, so to speak. We want you as our partner for the benefit of all and to have fun together. That’s it!

ARAS & VdS:
To bring both groups closer together a personal meeting on a joint conference would be a good idea, I suppose. OHP is probably too far away from Germany. Even our national meetings suffer from distances. We have to accept that nobody from France joint us on our Swiss conference although the distances were smaller than for many in Germany. Maybe there is no real need to do more, I do not know. But maybe we are already together without seeing it. At least I sometimes read the Yahoo list and it is possible for everybody to see our discussions here. And international campaign contributions already exist, anyway.

Next year we have our conference in Frankfurt with extremely easy and cheap rail & air travel access. Registration is already open. Perhaps you and some other colleagues from abroad will joins us. Would be great!

Cheers, Thomas

No more evolution since my last spectrum taken the 28th july.

Here's a comparison between 28th July and 4th August (corrected from heliocentrique velocity).



And the full spectrum

Hi Robin,
Yes, I think this will be very usefull for Pro-Am campaigns! And it shows, that the amateur programs work very well (if my reduction in MIDAS is good, but I hope so).
A reason why there isn't a big interest from my side. I'm looking for more than only take spectra without to know for what it is usefull.


Hey Thomas,
I think you are right! Günter give me a hint for an other way to estimate the SNR. I will try it if there is time



Hi Joan,
Its absolute okay for me to make mistakes and earn positive criticism to learn from it.
Okay! Therefore the missunderstanding. I'm used to remove the continuum and set it to one. Isn't that the most common way used by Pros?
The animation from Umberto is really impressive! I wonder if it is really possible to amatuers to make a absolute calibration?! And how work it to use photometry data?
Yes! And I there is already a thing we are working together on !
And I'm going with Thomas you do really great work (thinking i.e. on your self-build Echelles...)!


To the topic ARAS & VdS: Maybe there is a possibility to unite the forums?

Viele Grüße und CS
Christoph

Hallo Thomas,

As you say, you do not have to force the situations, forced friendships do not work, but a type of exchange ..., only that there was a direct link on the ARAS page to go to VdS, and a VdS link to jump to ARAS, everything would be different. You're right with the lack of assistance, (at ARAS I saw your ads from the ASpekt 2017), it's hard to get out of the comfort environment ...

Frankfurt is much more affordable for me, I promise to attend the ASpekt. Barcelona and Frankfurt are very well connected by plane.

Sometimes I have the impression that in VdS, issues and issues that have already been resolved by someone within ARAS are raised. Possibly the solutions or answers, they do not like absolutely. But these solutions or answers are always a good starting point. It's not that the ARAS is perfect.



Hallo Christoph,

Here you will find the answer to many of your questions,

Http://www.astrosurf.com/buil/spectrographs.htm, section, Reviews, evaluations and techniques

The C.Buil website is the result of many years of work, it is very extensive and usually tells the questions very didactically.

The construction of an echelle, the Mussol and now the Linx, have been the result of the "need", (the commercial ones are very expensive), Antoni Jové, helped me build my echelles. Now he has built several hoods of the echelle spectrograph and the tracking module, they are for anyone who wants it.

The ARAS and the VdS have their own personality, I do not think they should join, maybe it should be more normal, that their respective members regularly enter the two Forums and gradually participate. In the end, we are the people who hold the institutions.

Friendly, Joan.

Hi Joan! For many years there is a top link to the ARAS mailing list in our website. And at "Links" you can find the ARAS website as a "First Class Link". Unfortunately I have never seen such a VdS-Link in ARAS.

Well, who's perfect? Might well be that certain problems are already solved in other groups. But that is valid for all discussions, I suppose. It is a matter of bringing discussions onto one single platform. Some years ago VdS unsuccessfully tried to solve this. Frankly, I have no idea how to do this, especially because our spctroscopy forum is part of the main VdS forum. And I guess our French colleagues are not too eager.
Cheers, Thomas

Hello Joan,

Ernst Pollmann is coordinating an international VV Cep campaign. Pls contact him for details directly - if not done yet.
E-mail: ernestospec@hotmail.de
Website: http://www.astrospectroscopy.de/projects.html

I think he is very interested in collecting high quality data all over the eclipse.

Regards,
Thomas

Hallo Thomas,

We may have to give time in time, that new people and new ideas are emerging, the most important thing is that everyone is doing and trying things without being afraid to make mistakes. In this sense, the VdS is very dynamic, I am happy to be in this Forum.

Hallo Thomas Hunger,

Thank you very much for this link, it is one of the two where I send the data of the VV Cep.

Sincerely yours, Joan.

Hi Thomas,
As you know, when performing the Mons and IAC80 campaigns at Teide in 2009 and 2012 we carefully prepared everything together with our professional colleagues. The same happened, e.g., for the ARAS Nova Del and the SASER campaigns on gamma Velorum, zeta Puppis and eta Carinae in the south. We discussed the science goals in the forum, all necessary observation parameters as well as supportive amateur backyard observations and brought all this to the amateur community in form of detailed websites (http://stsci.de/wr140/index_e.htm and http://stsci.de/wr134/index.htm). Unfortunately the VV Cep description texts lack such basic information as a whole. These question must be addressed:

• What is the scientific goal of the approach?
• Are there more approaches than simple EW measurements, e.g., line profile analysis?
• Who will interpret the data and in what respect?
• Will the results be published in a professional journal? If yes, which one?
• Who will be the publication PI?
• Is he/she familiar with top level publications?
• Are co-authorships granted to all observers?

A very important point is the missing scientific PI (not only Robin mentioned this). I was the campaign organizer for the two above runs at Teide but it was always clear to me that I could not bring the campaigns to a success without a professional science PI (SASER and ARAS agree with that). My experience is that at least one willing professional including his/her student(s) is required to lead such a campaign. Before investing (or even wasting) significant time into this, I recommend to properly answer these reasonable questions to all potential participants. You can certainly do this on behalf of the present amateur PI.
Cheers, Thomas

Hi all,

some of the answers Thomas is missing, can be found here

http://astrospectroscopy.de/media/files/SAS_2015.pdf

Best regards

Michael

Thank you, Michael! So, my first question is somehow answered. For my second question I only read that EW, V/R and RV measurements are requested, no line profile analysis (the authors call EW measurements line profile analysis which isn't). Why RV with Halpha remains a mystery, though. All other and from my point of view very important questions remain unanswered. By my experience, the questions of publication and co-authorship are important because this was often neglected by the present 'PI' (to express it mildly). Just my two cents...
Cheers, Thomas

Hi,
last night I could take my first spectrum of VV Cep.
Cheers Christian

Can somebody explain, why the blue wing in all the spectra is higher than the red one or point me to an article on the web?

cs
günter

_________________
Im längsten Frieden spricht der Mensch nicht so viel Unsinn und Unwahrheit als im kürzesten Kriege. (Jean Paul)

Attached are a series of spectra of VV Cep covering 3800-4150A at R ~2500 (variable 3000-1500 across the range due to LHIRES chromatism)

Note the loss of H Balmer emission, broadening of the Ca II H K lines and relative drop in continuum flux below ~4000A, particularly noticeable in the latest spectrum recorded 2017-09-26

This is the same pattern as seen with AZCas (Except that there is no H alpha emission)
http://www.threehillsobservatory.co.uk/ ... tra_43.htm

Robin