Quote:
Originally Posted by Terry B
Interesting.
My image is a stack of 5x300sec exposures in each region using a VC200L, 600l/mm grating with the minimum width slit that the L200 has and a ST9E with 20um pixels. Clearly more exposure time is the key here.
I am using a guide scope and seem to be able to keep the star on the slit reasonably well with this.
I would like to keep monitoring eta Car. How often do you think is reasonable to take exposures to potentially show any change?
It clearly takes time to do so with limited clear weather and other objects that I monitor.
I haven't tried other areas of the spectrum due to the crappy weather. I will see what I can do.
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Given that you have a 20um pixel (the ST-9 isn't the bast match for higher res work) and that you need a two pixel coverage to meet the Nyquist criteria, you won't gain any resolution by using a slit narrower than 40um ... which will also give better throughput.
Normally you don't need to monitor eta Car more than once a month.