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The 2.1-m GoldCam spectrometer has proven to be one of the most popular spectroscopic instruments at Kitt Peak. While one cannot go as faint with it as one can with the 4-m on stellar sources, many programs simply need more observing time than can typically be accommodated during short 4-m runs. The total system throughput (telescope + spectrograph + CCD) is 15-18% under typical seeing conditions with a nominal slit width (24% peak throughput under excellent seeing conditions). GoldCam offers resolutions from 300 to 4500 using a variety of gratings. The detector in GoldCam is a Ford 3K x 1K CCD with 15m pixels and fairly good cosmetics. The full 5.2 slit projects to 400 rows, and so only half of the chip is used. The camera design does not give good focus over the entire 3K length, although we find that the central 2000 pixels are in relatively good focus. A TV camera views the slit, and guiding is accomplished using a second TV which is moved around the xy axis outside of the instrument field of view.
It is possible to rotate the slit to specific position angles at the 2.1-m, but doing so requires moving the telescope to zenith and must be done manually by the telescope operator. Allow a minimum of 10 minutes of overhead for each rotation.
The following table lists the available gratings and wavelengths coverage.
|2.1m GoldCam Gratings|
Notes: (a) Based on 2.7 pixels FHWM corresponding to 100 m slit (1.3 arcsec). Resolution will degrade to 3 pixels at 150 m slit (2 arcsec). (b) Spectral coverage limited by overlapping orders. (c) Spectral coverage limited by grating efficiency and atmospheric cut-off.
The grating efficiencies have been measured in the laboratory and are shown in Fig. 5
Figure 5: The efficiencies of the various GoldCam gratings are shown in this figure.
There are a variety of order-separation filters available for use in GoldCam. These filters are listed below and their transmission curves are shown in Fig. 6 and Fig. 7.
|Blocking Filters for GoldCam|
|Long cut-off||Short cut-off|
Figure 6: The transmission curves for the various GoldCam long- cut-off filters.
Figure 7: The transmission curves for the various GoldCam short- cut-off filters.