Seen some impressive spectrae in the files and photos section. How large a scope is needed to produce informative spectra of 3rd or 4th mag stars? How about...
Hi Jim, ... 4th mag stars? Well it depends on your camera and somewhat on the dispersion you use (How far you mount the grating from the CCD) but with low...
Hi Jim, it's nice to see you evolving your interest into spectroscopy. It seems to be the "natural" evolution after doing pretty picture astronomy. I think you...
Hi Richard Actually, the interest in spectroscopy is an expansion of my off and on work in photoelectric photometry; eruptive variables. As for the 'pretty...
Most informative, Robin. Thanks. How does seeing conditions; specifically turbulance, affect resolution of spectral lines? Cheers, Jim Livermore CA ... or ......
... Hi Jim, With a slitless setup (The simplest configuration) the resolution is dependent on the size of the star image, so seeing (and guiding if you are...
Hi Jim, what you can see for a given exposure with an Ha filter is typical of the Ha brightness in a spectrum. That should give you some idea of what the...
Hi Richard, I will be most interested in hearing about your experiments with the PIN diode. I too have experimented with them, but have found the amplifier...
Hi Jeff, thanks for the information. I had considered using a photomultiplier, but was concerned with the high voltages, magnetic field effects, and risk of...
... some ... Hi Richard, That depends very much on the distribution of light across the spectrum. To take an extreme example, Wolf Rayet stars have ...
... Well it is definitely OT since we have now even moved away from spectroscopy ;-) I would suggest continuing off list or moving the subject to a more ...
Hi Robin, ok, back to SA spectroscopy, but another harebrain thought? I wonder if it would make any sense to use high transmission RGB filters to increase the...
No, it won't. Why should it ? They just block light in and out of band that could be used for increasing the SNR of the spectra. The only usefull applications...
Hi Richard, Wolfgang, It is rare for me to disagree with Wolfgang ;-) but in fact pre filtering does have a potential advantage with slitless spectroscopy in a...
Hi Robin I thought about light pollution too. But using a filter helps then just if the filter excludes all the major local light pollution emission lines. But...
Hi Robin, thanks for the reply and information. That was my sense for maximizing seeing deep by increasing the S/N and using a more sensitive mono camera than...
Hi Richard, One limitation of imaging RGB filters would be that they do not have sharp cut offs so the sensitivity is dropping away from the centre wavelength....
Hi Robin, as a extension of the increased S/N result by narrowing the bandpass, is there any useful astro LRS spectrometry application to see dimmer object's...
Hi Robin, BTW, I forgot to add in my last post that interference type RGB filters do have sharp cutoff, see: http://panther-observatory.com/Baader_LRGB.htm ...
Hi Robin, well, you made it home safely as I can see. You got an efficiency curve for the SA in the files section. Could you let me know how you actually did...
Hi Dieter, Yes we had a great time meeting everyone at the spectroscopy conference in Heidelberg and later, touring that area of the country. I had to dig into...
Hi Robin Thx for showing us your work. Have you thought about using an other long pass filter that starts at a shorter wavelength ? e.g. the 495 or the 570 nm...
Hi Wolfgang, "why should it?" Let me walk you though the issue. Let's assume that a certain sky condition limits the maximum exposure time for a given object...
Hi Robin, I think that trying a light pollution filter like the Baader UHC-S for PNs may have merit? They would pass all the useful emission lines while...
Hi Robin, I agree, I wasn't thinking beyond ~700nm. All the LPRs I have spectrophotometer tested have erratic behavior beyond ~700nm. However, in the visible,...
Hi Robin Thx for your instructive explainations. ... With HPS dominated LP one longer than ~ 620 nm (even ~ 650 nm if one wants get rid of nearly all of it,...
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