[vsnet-rcb 689] Re: [AVSON] UX ANT Possible Fade

[Peter F Williams]

Hi Georgio and All,

Any decline of UX Ant will be most interesting as it appears to be one of
the least active RCB stars with just 3 recorded fades in the past 20 years.
My most recent observation last night show it now clearly fainter than its
normal visual range and at the level I would consider as reporting a
possible decline onset:

ANTUX    20070310.505    126    WPX
ANTUX    20070313.465    122    WPX
ANTUX    20070315.461    121    WPX
ANTUX    20070323.418    125    WPX
ANTUX    20070328.437    129    WPX

The year 2000 decline was interesting for its step nature in what appeared
to be 50-odd day intervals.  Based on my own observations of this event I
submitted a brief paper to the AAVSO asking the question if this was another
example of the pulsation cycle phase being linked to decline onset.  The
data was, however, rather sparse and the paper essentially (and
understandably so) rejected.  At the referee's suggestion I looked at
combining observations by all other visual observers to look for firm
evidence of this 50-day cycle but the resulting light curve simply showed
too much scatter to be next to useless when looking for such small
variations.  Also, the ASAS3 data of the 2000 and 2002 events seems to have
gone missing.

It would be interesting to see if your photometry does show evidence of a
50-day cycle in the lead up to this current event.

UX Ant is certainly a star to watch with interest in the coming weeks.

Best wishes.

Peter Williams
Heathcote NSW



  -----Original Message-----
  From: AVSON at yahoogroups.com [mailto:AVSON at yahoogroups.com]On Behalf Of
lgtcdiscala
  Sent: Tuesday, 27 March 2007 5:06 PM
  To: AVSON at yahoogroups.com
  Subject: [AVSON] UW CEN and UX ANT


  Hi all;

  UW CEN photometry for JD: 2,454,186.00347 showed the star to be at V =
  9.90 and B - V colour holding steady at 0.83.

  UX ANT photometry for JD: 2,454,186.00625 showed the star is fainter at
  v = 12.27 0.11 magnitudes fainter than about 3 days earlier. It's
  colour index at this time was 0.56. Both stars are displaying normal
  colours at this stage however colours won't change much in the early
  stages of a decline.
  UW CEN is probably not in decline at this stage however UX ANT may well
  be in the early stages of a decline since this is the faintest I have
  measured this star in more than 1 year of regular observations. Both
  stars are well woth keeping an eye on.

  Regards: Giorgio.



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