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Service observations with ISIS
ISIS offers a wide variety of observing setups as it allows the user to choose the central wavelengths, slit width, dichroic, on-chip binning and detector readout speeds, and it offers distinct observing modes such as long-slit spectroscopy and spectro- and imaging-polarimetry, with a choice of standard and electron multiplying, frame-transfer detectors. Therefore to manage overheads of multiple setups during service-mode observing the number of setups offered is restricted. Nevertheless, non-default settings involving dichroics, central wavelengths, slit width, read speed and binning are allowed if their need is justified scientifically in the service application. Additional overheads involved in such non-standard setups will be accounted to the programmes requesting them.
Imaging polarimetry and observations requiring the QUCAM electron multiplying, frame-transfer CCDs are in general excluded from the ISIS service programme because of the greater overheads involved and the limited opportunity to carry out such observations.
Spectropolarimetry observations, however, can be requested. They will be attempted whenever (1) a spectropolarimetry-trained observer is rostered, and (2) there is enough time to carry out the extended day-time set-up. The latter condition may not be satisfied e.g., on winter service nights when ISIS has just been mounted on the telescope. The probability of completing spectropolarimetry proposals is therefore not as high as for normal ISIS service proposals.
2. ISIS default settings
The following settings are the default for service observations:
Exceptions to these default settings will be considered if justified in the service proposal.
The tables below list the gratings and central wavelengths offered in the red and blue arms on service nights, along with spectral dispersions and wavelength ranges. Notice that the response of the system+dichroic should also be taken into account (wavelength ranges in parentheses).
Basic calibrations (biases, tungsten flats and CuAr-CuNe arcs) will be obtained by default in the afternoon/morning for each observing setup used during the service night, as well as one arc per target during the night. Additional calibrations (e.g., flux standards, radial velocity standards solar analogue stars, more frequent arcs) should be requested explicitly in the proposal, and they will be accounted to the total time requested.
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