Problem was an orientation issue caused by similar star patterns of comparison stars.
Visual observation of T CrB, I am a beginner. I found something weird.
I used:
- 180mm MakCass f/15 and 38mm 2" Erfle.
- 2024-04-30T23:30:00+02.00, Germany, Lat. 51.25°N
- AAVSO Chart: X36498BEJ
- Faintest star in my bright city sky in this sky area: 12m0 ± 0.2
The comparison star UCAC4-581-05220 (10m6) in the chart appears much fainter, fainter than UCAC4-580-052241(11m2), approx 11m5-11m8. All other comparison stars appeared in plausible magnitudes.
Even T CrB appeared in 11m3 ± 0.2. When I looked in the current light curves and tabular data of my observing date and time almost all visual observers transferred around 10mag to AAVSO.
I observed these stars over an hour, so no clouds or parts of it or Sahara dust (we suffer from it right now in Europe) could be the cause. I also triple checked my position and star identification.
Unfortunately the weather got worse and I have not the opportunity to verify it the next days.
Do any of you have an explanation or made similar experiences?
PS: Unfortunately I cannot upload an image with the marked star