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
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)