High precision RV of Deneb using LHIRES III

[Robin Leadbeater]

I have been measuring the pulsations of Deneb for the ConVento BRITE campaign
http://www.spectro-aras.com/forum/viewt ... ?f=6&t=840
The quasi-periodic pulsations of Deneb are clearly detected (currently ~ 12.5 days period ~6 km/s pp).

The variations are only a few km/s so a nice challenge for the LHIRES. By superimposing the lamp lines in the same exposure as the star (A "Filly " lamp mounted in front of the aperture) a long term precision of 0.5km/s 1 sigma was achieved based on measurements of Vega as a reference star,
but there is probably a small +1-2 km/s systematic error based on an initial comparison of lamp and solar spectra (to be confirmed).

Some of the residual scatter appears to be from the measurement of the line centres (2 Si II lines were used, measured using VSpec) so it may be possible to improve the precision using the cross correlation technique. The lamp lines would need to be carefully subtracted though to avoid interference.

Cheers
Robin

[Christian Buil]

Excellent result Robin!
Fine initiative to use simultaneous calibration lamp.

(Could you precise the wavelength region used ?)

Christian

[Robin Leadbeater]

Hello Christian.

I used the two Si II lines at 6347 and 6371 recommended for the campaign. They are nicely surrounded by Ne lines but they do not interfere with them. I also tried removing the lamp lines by subtracting the background. It is not quite perfect but perhaps good enough try the cross correlation technique to see if that reduces the residual errors further.

Cheers
Robin