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I recently purchased a new Lhires III mounted on a C-11. vv Ceph is my 1st target. Unprocessed the data looks good, but I am getting unexpected results. I had except to see the Ha line fall somewhere within the double hump. Instead it fell outside and to the right using the predefined mode 2400 grooves/mm (3 lines). I then tried using 2 lines and found 6562.8 to the left of the double hump. I've played some with the neon lines using averages and individual lines without much change.
As tuned the third line in just on the edge of the field of view, so tuning the micrometer may help, but unfortunately I will be able to do much for a couple months as the clouds have arrived and monsoon rains are forecast to arrive tomorrow.
Questions 1. Should 6562.8 fall within the double hump?
2. Is a three line calibration preferred over a 2 line calibration?

Al,
so far I can see, the blue edge of your spectrum is oriented on the right and the red edge vice versa. It would be better to change that, in sense of comparability with other spectra.
I assume your difficulties in calibration has to do with the choise of wrong wavelenghts of the reference lines. Basicly a calibration with three reference lines would be better, because of a higher accuracy for calculation of the radial velocity of the central absorption core.
You have to know that I am very intersted on your spectrum.

Ernst

Albert Stiewing wrote: Questions 1. Should 6562.8 fall within the double hump?

Not exactly, because VV Cep has a proper motion about of -18,7 km/s and there is also the heliocentric velocity includ in the spectrum (depending on the date and time and the observation location of VV Cep about +/- 30km/s)

But as Ernst said, the spectrum must be right oriented with the blue part on the left and the red on the right and you have to use 3 calibration lines for best wavelengths calibration.

Ernst and Oliver,
Thanks. I mirrored 1 neon and 1 vv ceph and got the expected results using 3 line calibration even though the 6506.52 line was at pixel 3. I assume if I mirror all the images the results will be acceptable?
I see two action items at this point
rotate the camera 180 degrees
adjust the micrometer to shift the data to the red to get 6506.52 off the edge.
Thanks again
Al

Albert
To check calibration do not use the star line, as mentionned above the h-alpha has lot of reasons to not be at exact laboratory wavelength: heliocentric earth motion, doppler...
The best is to use the earth atmosphere telluric lines. You can superimpose them with ISIS, VSpec... it is the easiest and most realiable way to check calibration. Usually with my Lhires I'm good at 0.1 ang or less.
Valerie