Guide to Spectrograms John Menke john@menkescientific.com 082818 AZCas is about mag9 and is an eclipsing binary having an M0 cool giant and a B0 star (about mag11). Period is approximately 9 years in highly eccentric orbit (0.55). Primary eclipse was on approx 011213 Black-Averaged AZCas spectra from 031818. Provides a reference for all spectra. Wide absorption at 6495 used as initial wavelength calibration Red-Target AZCas spectrum. This spectrum shows occasional large changes which are the subject of the study. Most spectra shown are averages of 25-50 spectra. Yellow-Wavelength reference spectrum from nearby (7 a-min) star SAO11931 B0. After May 2018, a reference spectrum is taken after every 9 AZCas spectra. 6563-Nominal Ha line 6495 Distinctive group of iron lines used for rough wavelength calibration 6475 Weak line in common with AZCas and Spectrometer is homebuilt R=2-3000 on N18 telescope. Spectra shown are normalized over region 6470-6480 A.

Note: AZCas schematic is taken from the Cowley 1977 paper with approximate phase markings added by Menke. Calculations of phase dates above are by Menke.

Note: This slide shows 080618. Yellow is approximately one hour exposure early in evening. The system continued unattended, but lost guide star for approximately one hour, then automatically re-locked on star, yielding the red curve.

Second Group—2018ff.