My repeat spectra are still inaccurate round H alpha

Home Forums Spectroscopy What wavelength error is acceptable with an Alpy? My repeat spectra are still inaccurate round H alpha

#580152
John Coffin
Participant

Last night’s specrum of Pi Andromeda (HD 00369) was still about 3 A out at H alpha but very accurate from H beta to epsilon. 

If this is an error due to undersampling why would it only affect H alpha?

If undersampling is the issue, can I calibrate the dispersion of a spectrum collected binned x 2 using a reference star that was not binned?