NGC 3516 Seyfert galaxy

Science Spectroscopy
1

Hi,
Yesterday I tried my luck on the NGC 3516 a Seyfert galaxy. The difficult thing here was it is quite low in the North where I have some strong light pollution. It was just at 36.5° altitude and it is about 168 mly away. I made a total of 16 images with 300s exposure time.I realize that my telescope aperture with 130mm f5.34 is not enough for this magnitude.
The spectrum below is processed with 6X Binning. My redshift is about 0.008230 and according to ned/ipac page it is 2649 km/s. So calculating 0.008230 x 300.000 gives me a redshfit of 2469 km/s which is a difference of 7.3% ¿?
I did not response correct this spectrum. Next time when I get a better clear sky.

Ha @ 6616.820Å minus 6562.81 Å = 54.01 / 6562.81 = 0.0082297 x 300.000 = 2,468.9119 km/s

NGC_3516_080426_21h34m_300s_16_6XB_
NGC_3516_080426_21h34m_300s_16_6XB_2887×1132 53.3 KB

2

Below the spectrum of NGC 3516 from 3 days with a total of 4 hours 50 minutes. The spectrum is the sum of these 3 days and is binned 6x. It was response corrected using a nearby A2 star.

NGC_3516_Sum_08-10-13_300s_6XB
NGC_3516_Sum_08-10-13_300s_6XB3235×1217 61.5 KB

Anybody can tell me what is the hump on the left side of the two O III emiision lines? I asked ChatGpt and it told me it could be an Iron Multiplet ?
Rainer

3

Looks like nobody knows and after many searches I found a paper about NGC 3516 which answers my question. Interesting is that in my spectrum the OIII lines are less pronounced compared to the papers spectrum.
It is a broad H-beta emission line.
Rainer
https://articles.adsabs.harvard.edu/pdf/1977ApJ...212...37B