Spectroscopy

A task to put 2 stars on the slit was developed for the sequencer. The plan is to also make other post-processing tasks sequencer tasks, in general those that are directly related to observing (like `slitoffset'), where tasks that are to further analyse a resulting image can/should be post-processing tasks.

We still need to define and update the efficiencies and amount of fringing with CCD#8. The vertical 0.5 arcsec slit was scratched and will be replaced. Also, an inventory will be made of all calibration lamps to see if sufficient spares are available.

Vallery Stanishev (Stockholm University), who regularly uses ALFOSC for a ToO program on SNe, has quantified the 2$^{nd}$-order contamination when using grism 4 without an order sorter filter. Based on this he has developed an empirical method to correct low-resolution astronomical spectra for second-order contamination. For SNe, which have broad spectral features, this method works very well. The results have been published in `Astronomical Nachrichten' and a copy of the paper is provided on the ALFOSC web page.