[vsnet-alert 12537] R CrB started to end its fading episode

Tue Dec 28 21:42:13 JST 2010

Hello

The assumption of John Toone back in October was IMO confirmed.
It definitly looks like as R CrB started to brighten up significantly just
before the start of the seasonal gap 2010/2011.

R CrB started its current fading episode in July 2007.
http://adsabs.harvard.edu/abs/2009JBAA..119..107P

It got very slightly brighter already for the last one and a half year since
its historic record minimum in March/April 2009 (means: 15.1 mag V,
14.9 mag vis).
<http://www.aavso.org/lcg/plot?auid=000-BBW-575&starname=R%20CRB&lastdays=&start=2454800&stop=2455200&obscode=&obscode_symbol=2&obstotals=yes&grid=on&visual=on&r=on&unknown=on&uband=on&iband=on&bband=on&v=on&unvalidated=on&pointsize=1&width=800&height=600&mag1=&mag2=&mean=14&vmean=7>
JOHN TOONE - R Coronae Borialis in 2009 - Faintest Fully Substan-
tiated Fade in BAA.VSS CIRCULAR No 140, June 2009
<http://www.britastro.org/vss/VSSC%20140c.pdf>

The faster rising magnitude values and especially the increasing
color indices (= its getting brighter in the redder bands first) since
October 2010 does support that the "dust" gets thinner.
<http://www.aavso.org/lcg/plot?auid=000-BBW-575&starname=R%20CRB&lastdays=&start=2455200&stop=2455600&obscode=&obscode_symbol=2&obstotals=yes&grid=on&visual=on&r=on&unknown=on&uband=on&iband=on&bband=on&v=on&unvalidated=on&pointsize=1&width=800&height=600&mag1=&mag2=&mean=7&vmean=7>

It would be good to get some early moring (multicolor) measurements
as soon as possible in January to confirm this and to see how bright
it already has gotten. As common with RCB stars, it might fade again
several times before its returning to normal brightness for a longer time.

Data references:

[vsnet-obs 69231] CCD observations by Kis (2010 Nov.)
> object         YYYYMMDD(UT)   mag      code
> CRBR           20101124.835   13.55V   Kis.VSOLJ
> CRBR           20101124.834   12.12Ic  Kis.VSOLJ
> Observer: Seiichiro Kiyota (Ibaraki, Japan)

[vsnet-obs 68639] CCD observations by Mhh (Oct. 10)
> CRBR           20101010.40133 14.34V   Mhh.VSOLJ
> Observer: Hiroyuki Maehara (Kyoto, Japan)

vsnet-obs 68749] CCD observations by Kis (2009 Sep.)
> object         YYYYMMDD(UT)   mag      code
> CRBR           20100909.150   14.36V   Kis.VSOLJ
> CRBR           20100909.151   13.42Ic  Kis.VSOLJ
> Observer: Seiichiro Kiyota (Ibaraki, Japan)

[vsnet-obs 68661] CCD observations by Kis (2008 Aug.)
> object         YYYYMMDD(UT)   mag      code
> CRBR           20100826.184   14.41V   Kis.VSOLJ
> CRBR           20100826.185   13.33Ic  Kis.VSOLJ
> Observer: Seiichiro Kiyota (Ibaraki, Japan)

The last positive R CrB measurements in the AID are:
http://www.aavso.org/ql/results?auid=000-BBW-575&startjd=2455465
R CrB  2455508.19203  2010 Nov 07.6920  13.117 R  SJAR  0.023
R CrB  2455508.19084  2010 Nov 07.6908  13.979 V  SJAR  0.019
R CrB  2455508.17304  2010 Nov 07.6730  13.091 R    SJAR  0.014
R CrB  2455508.17184  2010 Nov 07.6718  13.989 V    SJAR  0.024
R CrB  2455501.34200  2010 Oct 31.8420  14.06 V  PYG  
R CrB  2455499.34300  2010 Oct 29.8430  14.13 V  PYG  
R CrB  2455496.33800  2010 Oct 26.8380  14.14 V  PYG  
R CrB  2455487.50099  2010 Oct 18.0010  14.24 V  DKS  0.03
R CrB  2455486.36500  2010 Oct 16.8650  14.34 V  PYG  
R CrB  2455480.36652  2010 Oct 10.8665  14.556 V  SDI  0.005
R CrB  2455479.55156  2010 Oct 10.0516  14.306 V  PWD  0.089
R CrB  2455478.58063  2010 Oct 09.0806  14.303 V  PKV  0.032
R CrB  2455476.36085  2010 Oct 06.8609  14.574 V  SDI  0.002
R CrB  2455476.22503  2010 Oct 06.7250  13.103 I  SJAR  0.038
R CrB  2455476.22381  2010 Oct 06.7238  15.138 B  SJAR  0.087
R CrB  2455476.22259  2010 Oct 06.7226  13.763 R  SJAR  0.024
R CrB  2455476.22136  2010 Oct 06.7214  14.378 V  SJAR  0.030
R CrB  2455474.58075  2010 Oct 05.0808  14.306 V  PKV  0.030
R CrB  2455472.56684  2010 Oct 03.0668  14.225 V  PWD  0.118
R CrB  2455471.32827  2010 Oct 01.8283  14.346 V  ATE  0.03
R CrB  2455471.32617  2010 Oct 01.8262  14.344 V  ATE  0.03
R CrB  2455471.32405  2010 Oct 01.8241  14.357 V  ATE  0.03
R CrB  2455471.32195  2010 Oct 01.8220  14.365 V  ATE  0.03
R CrB  2455471.3036  2010 Oct 01.8036  14.367 V  ATE  0.03
R CrB  2455471.25070  2010 Oct 01.7507  13.223 I  SJAR  0.045
R CrB  2455471.24948  2010 Oct 01.7495  15.091 B  SJAR  0.074
R CrB  2455471.24826  2010 Oct 01.7483  13.805 R  SJAR  0.024
R CrB  2455471.24704  2010 Oct 01.7470  14.323 V  SJAR  0.029
R CrB  2455469.38201  2010 Sep 29.8820  14.555 V  SDI  0.055

BTW:
The mentioned two obs in 2009JBAA..119..107P of 14.5 mag vis
(re-reduced with the new sequence to 15.2 mag vis) by a single
observer are IMO not yet confirmed sufficiently by other vis obser-
vers or CCD measurements. Therefore I wouldn't claim that the
1962-1967 fading episode of R CrB was the faintest ever observed
minimum of R CrB before a similar re-reduction was also done for
the numerous obs in the AID for JD 2438570 to 2438920.
<http://www.britastro.org/vss/gifl/00107.gif>
<http://www.aavso.org/lcg/plot?auid=000-BBW-575&starname=R%20CRB&lastdays=&start=2437600&stop=2439600&obscode=&obscode_symbol=2&obstotals=yes&grid=on&visual=on&r=on&unknown=on&uband=on&iband=on&bband=on&v=on&unvalidated=on&pointsize=1&width=800&height=600&mag1=&mag2=&mean=14&vmean=14>
<http://www.aavso.org/lcg/plot?auid=000-BBW-575&starname=R%20CRB&lastdays=&start=2438450&stop=2439050&obscode=&obscode_symbol=2&obstotals=yes&grid=on&visual=on&r=on&unknown=on&uband=on&iband=on&bband=on&v=on&unvalidated=on&pointsize=1&width=800&height=600&mag1=&mag2=&mean=14&vmean=14>
IMO a single swallow doesn't make a spring yet. This time there were
vis obs with the new sequence down to 15.3 and even 15.5  mag vis
while others saw it at 14.5 mag and the majority around 14.9 mag.)

A happy new year  and clear skies
 Wolfgang

-- 
Wolfgang Renz, Karlsruhe, Germany

>> ----- Original Message -----
>> From: John Toone
>> To: baavss-alert
>> Sent: Sunday, October 18, 2009 9:10 AM
>> Subject: [baavss-alert] R CrB - Hint of a Slight Recovery
>>
>> > As R CrB gets lower in the sky and the sun passes through the ecliptic
>> > area to the south, it is worthwhile keeping our eyes and CCD's on it
>> > because it seems to me to be showing a hint of a slight recovery. By
>> > my reckoning it is now brighter than comparison BB for the first time
>> > in over a year.
>> > Selected recent observations follow:
>> >
>> > 12 Sep 2009 2056GMT BB(1)V(4)NN 15.0 C14
>> > 26 Sep 2009 2020GMT BB-2 15.0 C14
>> > 11 Oct 2009 1927GMT =BB 14.8 C14
>> > 16 Oct 2009 1943GMT AA(5)V(1)BB 14.7 C14
>> >
>> > John Toone
>>
>> PS I should have added that it's still varying between about 14.7 and
>> 15.1 in a matter of a few tens of minutes!