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Not sure if these should be here as they are a first go at using the SA seriously. I have still some work to do to establish an instrument response and calibration that I am happy with but this is what I have managed to date. The image scale is ~10.5 A/pixel and I have used a linear calibration base...

Ken - If I rember correctly (and it is a very long time ago) the band gap of Si is too wide for these low energy photo to excite photo electrons. This puts you into the use of Ge, PbSe or InSb which are specialist and I suspect expensive (see here http://www.pacer.co.uk/products/lasers-and-detectors...

Hi I am trying to process some Tau DR spectra and have go to the point to plot the result out. However, ISIS V5.1.4 says it has written the file but it is not there! Once I have done it once the polt commands don't seem to work any more. I have gnuplot v 4.6 and win 7 64bit Home Premium. The directo...

Robin (or others) - I was wondering if you had agreed with Darryl yet on the details of the use of the Star Analyser in this study? Specifically have you agreed the "in field" references stars and the preferred position angle (PA) of the spectra with respect to the target stars? Is there a...

Robin and others - I notice that Robin continues to just use a SA driect in the converging beam without the improvments of a wedge prism and/or a UV/IR cut filter as popularised bt Christian Buil. I was jus wondering why.

Thanks Andrew

Robin - The answer is in your comment about a slit spectroscope. What you want is the FF that would have been created has a slit been in place at the location of the zero order image but this is imposible! So the question is what obtainable FF best approximates this ideal?

Regards Andrew

As an extreme test it might be interesting to deliberately add a severely vignetting field stop before the grating. Thinking about it, and taking it to the extreme, this is what a slit spectograph is. A flat taken without the grating would definitely not do the job in this case :lol: Robin Quite ri...

[quote="Robin Leadbeater As far as I can see, using a flat taken without the grating in which the light drops off at the right hand edge due to vignetting before the grating would definitely not give the right answer as the light from the star would not have been affected by vignetting in that ...

Hi Robin – I have had a look at the reference you gave and also at this http://www.stsci.edu/hst/acs/documents/isrs/isr0502.pdf which gives more details on how the flat fields (FF) were created. It seems to me that the flat cube is more about removing the wavelength dependant pixel to pixel response...

Thanks Robin - I will study and come back after due consideration! Regards Andrew