robin_astro

Hi Louise,

Using the video mode is good to start with as it helps with focusing. Choose a main sequence A or B type star to start with (type Av/Bv) There is a list of bright stars with their spectral type in the back of the manual.  Check you have the grating orientated with the star on the left and the brightest spectrum horizontal across the  field  (There are spectra on both sides of the star image, one is much brighter). Focus first on the zero order star image to start with, then reduce the exposure until the spectrum looks on the under exposed side all the way along the spectrum and then wind the focuser in a touch until you see a dark absorption line appear sharpest about 1/3 the way along the spectrum (The Hydrogen beta line) You should then be able to other Hydrogen lines crowding together towards the blue end nearest the zero order. ( It is a good idea to always start an observing session this way as this star can be used to both wavelength calibrate and adjust your spectrum for the response of your instrument.)  

Once you are in good focus you can move to other targets. Perhaps try a cool M type star for example, noting the broad molecular bands and an emission line star like Gamma Cas for example, looking for the bright spot  towards the right hand end of the spectrum which is Hydrogen alpha emission from the disc around this star, or later in the year, P Cygni, a luminous blue variable supergiant which shows  Hydrogen and Helium emission lines. Wolf Rayet stars, although fainter show spectacular emission lines too in the stellar wind. You can  get an idea of what the raw spectra should look like here. (Yours will be clearer as these were taken with a smaller camera sensor so the spectrum is not very long)

 http://www.threehillsobservatory.co.uk/astro/spectra_12.htm

http://www.threehillsobservatory.co.uk/astro/spectra_14.htm

Cheers

Robin