next up previous contents
Next: Appendices Up: node4.html Previous: Photographic plates - Obsolete

Astronomical exposures - Warning, needs to be updated

Astronomical exposures are straightforward compared with the setting operations.'

NEEDS TO BE UPDATED The loaded plateholder should be mounted onto the instrument and positioned ready to receive the first exposure. The good pointing of the telescope in combination with the versatile TV system enables objects within the magnitude range of the Spectrograph to be easily acquired, Although the comparison arc/direct view configuration of the A&G unit enables a larger field of sky to be viewed, the pointing is such that slit viewing imaging system is adequate for acquisition. The 2,mm apertures of the dekker correspond to 27 arc seconds at f/15 focus.

NEEDS TO BE UPDATED During stellar exposures, image trailing will be required. At this time the details of the trailing facility have not been finalised. Telescope focus and guiding are performed from the Console.

OBSOLETE, uncorrected The duration of comparison arc exposures can either be timed or 'counted' on. the exposure meter. At commissioning the hollow cathode source was unstable (old tube) a-,id the exposure meter method was preferred.'

The duration of the astronomical exposure can be estimated from the data in Appendix 4, but observers will have to modify their exposures to match their measurement goals.

OBSOLETE, uncorrected After use, the dummy plateholder should be mounted to protect the vulnerable field flattener. Unlike the plateholder, the dummy can he mounted in two orientations.

manuals store
Tue Aug 5 00:46:52 BST 1997