Comparison Lamp Spectra

MMTO F/9 Top Box Comparison Lamp Spectra

The f/9 topbox has a variety of comparison lamps observers may use to calibrate their spectroscopic data. The following lamps are available without any special preparation:

Fe-Ne (hollow cathode)
He-Ar (AC glow discharge)
Neon (low pressure discharge)
Hg-Cd – attenuated longward of 4000 Å with a U-330 filter.
Incandescent (`Bright’ and `Dim’)
`Dome’ Incandescent lamps
Etalon – several spacings are available.

Note that these lamps can be on simultaneously for added flexibility. The HgCd lamp takes time to warm up; the recommended time to warm up and stabilize this lamp is 300 sec. There is also the option for observers to use a ThAr lamp, but they must notify observatory staff well in advance of their run as these lamps are mounted in place of the standard HeAr lamps (so both cannot be used during the same run). Below are spectra of MMT HeNeAr lamps with wavelengths of the prominent lines marked. The linelist used is available here. All indicated wavelengths are in air. In all but the Echellette spectra, the normalization shows the counts per second per pixel on the CCD after bias subtraction, but no gain or flat field corrections have been applied. Note that the binning used is either 1×1 or binned by 2 in the spatial direction (1×2 for blue channel, 2×1 for red channel); the binning used is shown in the title of each plot. Please contact Joannah Hinz if you require more information or have questions.