|Frequently Asked Questions|
Here we try to answer all frequently asked questionsquestions about the system and our campaign. More questions will be answered in our discussion forum.
When should I observe WR 134 and WR 135?
As often as possible. It is always a good idea to start a "training" far in advance. The first good opportunity is in summer/fall 2012 when the system is high in the sky, then during the campaign period 2012. Most important, we should know what we can expect in S/N for which exposure time and resolving power.
The spectrum should be centered in what wavelenght? What bandwidth is adviced?
Due to their nature as WR stars we only see emission lines. They are all of great interest and deliver worthy insights in the physics of the system. We mainly focus on the HeII 5411A line in WR134 and the CIII 5696A line in WR135.
What kind of spectrograph is necessary?
Any reliable and stable spectroscopic system is feasible. However, broadband Echelle WR spectra are very difficult to reduce. Standard spectrographs are preferred.
What wavelength interval should be observed?
As we need highly mechanically stable systems and a reliable setup for highest accuracy we will allocate specific wavlength regions for each observer. Then it is neither necessary nor intended to "touch" the measurement system for the whole campaign anymore.
Can I use my private observatory for other observations during the campaign?
Highest quality is achieved by dedicating your observatory/instrumentation to the whole campaign. Hence, we would highly appreciate if you would not change grating position or spectrograph connection to the telescope. A stable temperature would be perfect but that might be impossible.
What calibration images/spectra are needed?
We definitely the whole range of calibration images. Flat, dark and bias fields are essential, as well as accurate wavelength calibration spectra for the respective wavelength range.
Should I perform a complete data reduction?
No! As we want to leave the final data reduction in one single hand (PhD thesis) we need the raw data and can not take privately reduced data into account for later publication. But of course, we recomment a data reduction for private use so that amateurs can compare their performance with the professional one.
What calibration lamp must be used?
Each lamp with sufficient emission lines for calibration plus catalogue in the respectively observed wavelength reagion is fine. Special note: As we go for the green wavlength range, Neon calibration might be a problem. Other lamps with lines in the respective band are better.
No real continuum? How can I estimate the Signal-to-Noise-Ratio then?
By using two spectra one can estimate S/N by deviding one spectrum by the other. The lines will then be eliminated. If the two spectra have the same exposure time the S/N of the quotient is sqrt(2) of that of the single spectrum. The S/N of the sum spectrum is then better by a factor of two than the quotient.
What S/N is sufficient?
The more the better. But S/N should be about 200 at least.
I do not reach S/N > 100. What should I do?
Just increase your exposure time. However, we define a critical limit of 1h exposure time.
When doing photometry, do I need to take additional data?
Yes! To guarantee maximum photometric reliability you need to measure photometric standard stars as often as possible.
Is it necessary to perform photometric observations other than in the V-band?
No! Visual variability is fine. If you have specific filters, though, then discuss that with the experts in the forum.
How long should I observe the star during the campaign?
Four months are ok. But if you can cover a longer time interval, the better. Keep in mind that we want to investigate potential stellar wind periodicities and, hence, need to cover the campaign as much as possible. Don't do other stars during that time.
What happens to my data?
After the campaign we will collect all worldwide data and give them to a single scientist to do science with it. This will probably a PhD student using them for his PhD thesis.
What is my personal benefit?