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What instruments do amateur astronomers use in their ground based telescopes in order to avoid atmospheric absorption/telluric contamination? For example, when an astronomer observes a celestial body like a distant star or an object, what do they do in their spectrometer to avoid telluric contamination (atmospheric absorption of wavelengths), as space telescopes have a great advantage in it? Because the atmospheric humidity is variable and that may affect the telluric absorption, so how do the telluric correction softwares like ISIS (Thanks, EdV!) cope up with the variable humidity?.

Thanks in advance!

Arjun
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  • Please read the last paragraph in the response here: https://groups.io/g/RSpec-Astronomy/message/12064?p=%2C%2C%2C20%2C0%2C0%2C0%3A%3Arecentpostdate%2Fsticky%2C%2CTelluric%2C20%2C2%2C0%2C94222533. Basically, the telluric lines are known/tabulated and compensation can be performed. – Ed V Sep 08 '23 at 14:19
  • @EdV Thanks a lot!, " Telluric lines can easily be identified from standard Telluric catalogues and even removed if necessary using templates in programs such as ISIS but they are all at the red end from NaD lines upwards and are not found in the regions traditionally used for spectra classification." was very insightful!. So amateur astronomers identify the telluric contamination and then analyze the spectral data, and minus out the data from the catalogue? – Arjun Sep 08 '23 at 14:37
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    Yes. There are lots of example of stellar spectra at the linked site and a great deal of useful information. The person who posted the answer there is an actual expert amateur who is very knowledgeable and helpful when people have questions. I am just a member there and likely the only one with no telescope! But I do spectroscopy, like this: https://astronomy.stackexchange.com/a/49116/45954. – Ed V Sep 08 '23 at 15:36
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    @EdV Thanks a lot, it solved almost all of my doubts!. – Arjun Sep 08 '23 at 15:44
  • @EdV detected any telluric tellurium lines yet? :-) (strictly humor) – uhoh Sep 10 '23 at 02:45
  • @uhoh No, but there are some interesting tellurium facts even aside from the intense body oder issue, e.g., the gold miners during one of the Australian gold rushes tossed aside some heavy rocks in their frenzied search for gold. Turns out the rocks were gold telluride, which they discovered when some of those rocks were used around a campfire and gold was released by the inadvertent processing. ;-) – Ed V Sep 10 '23 at 11:16
  • @EdV Oh, amazing; I did not know there were gold minerals! But I should have guessed it because there is of course a lot of gold in telluride. – uhoh Sep 10 '23 at 12:01
  • @EdV Thank you for the answer again. I have one more doubt, how do the telluric absorption correction softwares know which bands of the electromagnetic spectrum are absorbed the most, since the water vapour amount or the wind speed varies, do they first measure the humidity via hygrometers? Thanks in advanced! – Arjun Sep 10 '23 at 14:37
  • Good question! I don’t know the answer. The people who actually correct for the telluric bands presumably rely upon their experience. I doubt wind speed matters much, but I have no direct experience with telluric band compensation. Sorry! – Ed V Sep 10 '23 at 14:42
  • @EdV No problem at all! Thank you for your assistance! – Arjun Sep 10 '23 at 14:48

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