[Aavso-photometry] [vsnet-alert 11010] Re: Observe the hot disc of R CrB in the I band

[arne]

Eric Broens wrote:
> Following observations have been obtained during May 2008.
> The observations are transformed to the standard system.
> The values given are averages from 3 images in each filter, the standard
> deviation is given in parentheses (least significant digit).
> 
> The comparison stars used are labeled 122, 126, 129 and 142 on AAVSO
> chart 1072knh.
> For the observations on JD 2454594.42 comparison star 122 has not been
> used.
> The values for the comp stars are taken from the photometry table for
> this AAVSO chart.
> Please note that the photometry for these comp stars comes from various
> sources (ASAS, TASS, SDSS, CMC14)!
> The V-Rc data is based on comp star 142 only. For the other comp stars
> no Rc data is available currently.
> The observations will be revised and submitted to the AAVSO database as
> soon as the field is calibrated.
> 
> 
> JD          V         V-Rc      V-Ic 
> 2454594.42  14.30(2)  +0.37(6)  +1.04(3)
> 2454595.41  14.32(2)  +0.41(3)  +1.05(4)
> 2454599.41  14.25(1)  +0.36(3)  +1.00(3)
> 2454607.41  14.29(4)  +0.35(4)  +1.05(1)
> 
> 
> Arne, is this fading not monitored at SRO as intensively as Z UMi's
> fading?
> 
I've updated the VSP/VSD photometry, based on a 3-night calibration
from SRO.  This will give you BVRcIc magnitudes for all of the sequence
stars from 122 through 151.

We put Z UMi on the SRO program, and have monitored it nearly every night
for 4 years.  We chose that R Coronae Borealis star because it was
circumpolar at SRO and stayed within the saturation range, even at maximum.
R CrB itself gets a bit too bright for comfort at SRO.  It would always
be nice to monitor each of these stars every night, but we just don't
have enough telescope time.
Arne