[Aavso-photometry] CI Cyg Comparison stars

[arne]

françois teyssier wrote:
> Hello!
> 
> Doing time serie photometry on CI Cyg, I've got a problem with the 
> magnitude of reference star Label 88 (000-BCJ-157), 8.831 according to 
> Henden, which gives me only approximative mesures for check stars 115 
> and 117, with a 0.2 mag difference.
> 
> I've found that both Brian A. Skiff and Skopal use a different magnitude 
> mesure  for star 88, about 0.2 mag brigther
> 
> IAUD 	Label 	Name 	V Henden 	V Skiff 	V Skopal
> 000-BCJ-157 	88 	HD 226041 	8.831 	8.588 	8.60
> 000-BCJ-223 	108 	GSC 2677-1273 	10.837 	10.673 	
> 000-BCJ-202 	115 	GSC 2861-0298 	11.548 	11.56 	
> 000-BCJ-186 	117 	GSC 2861-1332 	11.715 	11.722 	
> 000-BCJ-177 	125 	J195019+3539.5 	12.535 	12.52 	
> 000-BCJ-181 	135 	J195022+3541.1 	13.456 	13.42 	
> 
> 
> Using 8.588 for star 88 (Skiff) gives me quiet good results for the 
> check stars 115 and 117 (resp.  11.55 and 11.71). Note that for fainter 
> stars, Henden and Skiff mesures are in good agreement.
> 
> Have other observers the same issue or perhaps I'm wrong?
> 
My exposure times were 8sec for V on the 1.0m telescope, and the
88 star is overexposed.  I would trust Skiff more here.
Report your photometry using 8.588 and give a comment regarding
the change in magnitude.  As for the 108 star (000-BCJ-223),
that is more of a question.  That comes from TASS, not Henden
(it was outside of my field of view). Note the large error
associated with that value (0.092mag).
Here again, I'd trust Brian and use 10.673 for its magnitude.
The other stars are properly exposed on my frames, and I'd use
the photometry table values for those.

We'll modify the comparison star table to reflect the changes to
the 000-BCJ-157 and 000-BCJ-223 values in the next day or so.
Arne