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NOTcam spectroscopy: calibration unit

In April 2004 we purchased an Argon and Xenon lamp from LOT-Oriel. The lamps were mounted experimentally in the baffle of the primary mirror. The Argon lamp was put into a conical reflector. In this way, the light from the lamp does unfortunately not fill the f/11 telescope beam, and hence inside the spectrograph the lamp light only traverses through the central (i.e. close to on-axis) part of the optics.

Below are the test images of the lamp light detected with NOTcam in spectroscopy mode. The images show that it is feasible to mount the lamps at this distance to the slit: enough light is coming in to secure good wavelength calibration spectra within acceptable exposure times.


Argon lamp spectrum with J band and 128-micron slit. Cuts: 0 - 4000 ADU. Exposure time: 10 secs.



Argon lamp spectrum with H band and 128-micron slit. Cuts: 0 - 4000 ADU. Exposure time: 5 secs.



Argon lamp spectrum with K' (left) and K band and 128-micron slit. Cuts: 0 - 2000 ADU. Exposure time: 10 secs.

Flat field lamp

In the baffle of the primary there is a blue-bright flatfield lamp originaly put there for ALFOSC spectral calibrations. Also with NOTcam it can be used to obtain spectral flats. Note that for the frame command (ramp sampling) the minimum exposure time is too long to be able to obtain flats in the K band: too much light. The 5 dome tungsten lamps are too faint to get a decent spectral flat in K. For the exp command proper flats can be obtained in K with the baffle lamp.

John Telting (jht)

Back to top Last modified: 08-Jul-2004