SIMBAD references

We present spectroscopic observations of the four planetary nebulae TaWe1, HDW6, HDW7, and A8. The first of them is confirmed for the first time. The spectra reveal that the four objects are of low excitation, and remarkably showing strong [O III] but week H-alpha emission. Furthermore, for the two objects TaWe1 and HDW7 the [S II] emission lines have not been detected. The [S II] I(6717)/I(6730) line ratio indicates a very low electron density for the planetary nebulae HDW6 and A8, showing that the two objects are in an advanced stage of evolution. Interstellar extinction, total Hbeta flux, and excitation class are calculated using the average spectra. The distances of the all objects have been estimated using Shklovsky method.