Trouble with Spectrum Wavelength Calibration

NGC 5139 · Post by **NGC 5139** » Sat Jul 30, 2005 2:55 pm

Hello,

I am working on a school project to observe the spectrum of Venus but have found myself stuck. I am using the Visual Spec software to calibrate my .pic file (converted from jpg using Christian Buil's IRIS software), but have hit a dead end on how to calibrate the wavelengths of the absorption lines. I do not have enough practical experience in this area of spectroscopy.

May I ask on how would be the best way to do so for a lay person like me?

Have a nice day
Omega

ChaosKnight · Post by **ChaosKnight** » Sat Jul 30, 2005 7:11 pm

You could try burning an element with absorbtion lines that are well defined and photographing it using your existing system.

Then get hold of a database that contains the spectra info of the element and match the wavelengths there with your absorbtion line spectra. You can then get a calibration.

If i'm not wrong sodium gives off strong lines. So does tungsten and iodine. You could try these elements.

Similarly, if you haven't got elements to burn, you could photograph the sun. Then pull the spectra info off google for a match.

kingkong · Post by **kingkong** » Sat Jul 30, 2005 11:24 pm

ChaosKnight wrote:Similarly, if you haven't got elements to burn, you could [highlight=red]photograph the sun[/highlight]. Then pull the spectra info off google for a match.

warning!
this can be real bad to your eyes and/or damage your digital camera if you don't know what you are doing.

gchew · Post by **gchew** » Sun Jul 31, 2005 9:14 am

Hello,

You could try taking the spectra of a mercury vapour lamp (or sodium, or neon, or whatever else). Your school lab might have these. You'd then do calibration by matching the strongest lines using data from NIST:

http://physics.nist.gov/PhysRefData/Handbook/index.html

The same information can be found in the CRC handbook of Chemistry and Physics.

Hope this helps!