FOR OBSERVERS
We call for a new observation campaign of variable star EE Cep which will be held in 2020 during the next eclipse (Epoch E = 12). The beginning of the ingress will take place around the 7th of March (JD 2458916), the mid-eclipse is predicted on the 3rd of April (JD 2458943.2) whereas the end of the egress is expected on the 21st of April (JD 2458960). It is recommended to start observing at least two months before the mid-eclipse and continue at least two months after the mid-eclipse. All photometric optical (UBVRI) and especially infrared (JHK etc.) data and spectra will be useful.
Special attention should be paid also about one year later, around ϕ = 0.2 of the orbital phase, i.e. 20th of May 2021 (JD 2459354). In the previous epochs at this point of the orbital period, an increase of the near-infrared IC flux was observed (Pieńkowski et al. 2020). We recommend to carry out the observations between December 2020 and November 2021. Observing in Johnson-Cousins RCIC system with accuracy of 0.01 magnitude or higher is advised. Near-infrared J, H, K photometry would be particularly usefull.
The details for the expected photometric data are the same as during three previous campaigns (see e.g. Gałan et al. 2014). There you can find also the finding chart. As a reference star, “a”, BD+55ᴼ2690 is recommended. Observing stars ”b" GSC-3973:2150, “c” BD+55o2691, and “d”GSC-3973:1261 is also advised as the check stars to verify the variability of these stars.
Before the ingress one or two measurements during the night will be useful, whereas during the eclipse we count on the highest possible time resolution of observations.
Spectroscopic observations with high resolution (R~10000 or higher) are also recommended. Observing Hα, Hβ and Hγ lines and ion Na I doublet for analysis of line profiles will be useful. In the case of spectrographs with low-resolution flux calibration will be essential to make them useful in analyses.
Please send the reduced data to Dariusz Kubicki (kubickid@gmail.com). Please attach information about your institution and photometry or spectroscopy systems. You may also sent the data to AAVSO International Database.