Just wanted to show an other simple method in order to calibrate low resolution spectra with the Neon lmap available with LISA and LHIRES3.
- First of all, take a short (typically 0.3 s) exposure spectrum of the lamp in order to get red Neon lines;
- Take a long exposure (typically 15 s, be aware with remanance!) to get blue lines;
- Merged 2d spectrum with the background unified (red edge of long exposure was set to 0, see Juanary SpcAudace release):
You get the best of the two worlds!
Then, the lines profiles with identified main lines is made for you:
(Figure updated on 2012/01/29)
I recommand you to select widespreaded lines in order not to favour the red edge or blue edge.
- The following lines seem working fine for a deg 3 polynom:
4065.65, 4348.06, 5400.56, 5852.49, 6402.25, 7032.41 and 7245.17
Which lead to a rms of 0.6 A where the dispersion is here 2.57 A/pixel, so an accuracy of 1/5 pixel.
- With a deg 4 polynome and the following lines:
4065.65, 4348.06, 4710.06, 5400.56, 5852.49, 6402.25, 7032.41, 7245.17, 6143.06, 6678.28 and 6929.47,
the following dispersion law was found: Lambda=3917.50781533+2.43491203042*(x-1)+0.000230671871345*(x-1)^2+-1.61973682859e-07*(x-1)^3+4.63971559225e-11*(x-1)^4 with RMS=0.293443870835,
So a linear law described by: 3917.50781533+2.56720166243*(x-1).
Enjoy,
Benji
