[vsnet-chat 692] (fwd) Re: [vsnet-alert 1421] Fading of EsB365

[Taichi Kato <tkato>]

For further hot discussion on the cool subject, EsB365, hereby I have
collected messages beginning to disseminate over the whole(!) VSNET lists.

From owner-vsnet-alert@kusastro.kyoto-u.ac.jp Fri Jan  9 12:29 JST 1998
Date: Fri, 9 Jan 1998 12:29:19 +0900 (JST)
From: Taichi Kato <tkato>
To: vsnet-alert
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Subject: [vsnet-alert 1419] Fading of EsB365
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Fading of EsB365

   The suspected R CrB-star, EsB365 (Cru), is reported to be fading (but
I can't find its position -- hope someone can comment).

  YYMMDD(UT)   mag  observer
  970622.699    88  (B. Monard)
  970720.699    87  (B. Monard)
  970729.458    91  (M. Mattiazzo)
  970802.700    89  (B. Monard)
  970810.699    89  (B. Monard)
  970831.699    89  (B. Monard)
  971123.000    91  (B. Monard)
  971226.000    93  (B. Monard)
  980104.950   106  (B. Monard)
  980107.590   108  (M. Mattiazzo)

Regards,
Taichi Kato

From owner-vsnet-alert@kusastro.kyoto-u.ac.jp Sun Jan 11 18:48 JST 1998
Subject: [vsnet-alert 1420] (fwd) re EsB363 / vsnet-alert 1419
From: "PETER F WILLIAMS" <PFWILLIAMS@onaustralia.com.au>

The following may be of interest re EsB363.

This is a deep reddish carbon star which lies only 2.4 arcmin at pa 260
degrees from the brilliant white star Beta Crucis (mag 1.2 and slightly
variable).  It is well known to many southern hemisphere amateurs for its
colouring.

It is listed as GCCCS2031 and GCCGCS3284 in C.B.Stephenson's (1) General
Catalogue of Cool Carbon Stars, Publ Warner & Swasey Observatory Vol 1 No4
(1973); and (2) General Catalogue of Cool Galactic Carbon Stars, Publ
Warner & Swasey Observatory Vol 3 No2 (1989), respectively.

Both these list give an epoch 1900 position RA 12h 41m 33.8s Dec -59deg 08'
45" but there is some question as to the accuracy of these co-ordinates.

Alternative designations given there are Westerlund 79-2 and Hen 183
(Rybski).  A spectral classification N was given by Thackery (1949).

EsB363 was apparently first noted for its colour by John Herschel and was
later listed by Rev. T.E.Espin & J.Birmingham in their 1883 catalogue of
orange/red stars, hence EsB363.  It is not listed in either the GCVS4 or
NSV catalogues but, being a carbon star, variation of some kind would not
be unexpected.

In recent years it has been mentioned in several Australian amateur club
newsletters.  Attention was directed to EsB363 in 1991 when it was reported
to have faded to near 13th magnitude (visual) but these observations were
made near its lower culmination and this event apparently passed 
unconfirmed.  In 1992 it reportedly 'flared' to visual magnitude 5.0, but
again this passed unconfirmed.  Also reported is a visual magnitude range
of 9.0 to 10.7 with a 17.5 day period.

All this seems a little confusing but if these unconfirmed observations
represent genuine variations then EsB363 is certainly an exceptional star!

The late David Allen of the Anglo Australian Observatory was going to
attempt a detailed spectrum of this star following the 1992 report but I do
not know if this was actually obtained.

Visual observation of EsB363 is exceedingly difficult through small
telescopes due to its strong red colouring, its relative faintness and
close proximity to Beta Cru and extreme care must be exercised by the
visual observer.

I hope the above is of some interest to vsnet readers

Regards

Peter Williams

From owner-vsnet-alert@kusastro.kyoto-u.ac.jp Sun Jan 11 22:52 JST 1998
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Date: Sun, 11 Jan 1998 15:41:04 +0200
From: Berto Monard <lagmonar@csir.co.za>
To: tkato@kusastro.kyoto-u.ac.jp, vsnet-alert@kusastro.kyoto-u.ac.jp
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Subject: [vsnet-alert 1421] Fading of EsB365 -Reply
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Hi,

I respond late because I have been 'out' for a while, playing golf and
doing other things I am not so good in....

Coordinates of EsB 365 as per my docs via F Farell:
(2000)  12 47 25  -59 42
a very reddish star (like RV Cen), very close to B Cru, one cannot
miss it...  

It was F Farell who noticed the fade and asked me to check it out.
Fraser, wake up man!
my most recent observation of EsB365 Cru: Jan 08.00  10.5

Regards,


Berto Monard,
Pretoria

From owner-vsnet@kusastro.kyoto-u.ac.jp Tue Jan 13 01:06 JST 1998
To: <vsnet@kusastro.kyoto-u.ac.jp>
From: Fraser Farrell <fraserf@dove.net.au>
Date: Tue, 13 Jan 1998 01:36:25 +0930
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> 
> The suspected R CrB-star, EsB365 (Cru), is reported to be fading (but
> I can't find its position -- hope someone can comment).
> 

G'day all,

EsB 365 is also listed as CCCS 2031 and GSC 8659.01394.  The GSC
position is 12h47m24.6s -59o41'41" -- only 2.4 arcminutes west of Beta
Crucis.  As a very red carbon star, it makes a fine colour (and
magnitude) contrast with Beta; which earns it a mention in Hartung's
"Astronomical Objects For Southern Telescopes".

I have been watching EsB365 for a number of years, suspecting it to be a
RCB or RV-type variable; and had assistance from some of my proteges in
this task.  Observed visual range is 8.6 to around 12th mag. I did post
a long list of observations to VSNET a while back but I don't recall the
message number.  Observations would also be available from the VSS RASNZ
archives.

AFAIK nearly all the observers of EsB 365 are in the southeast of
Australia -- and tend to get clouded out at the same time. I encourage
observers elswhere to emulate Berto's efforts to improve our coverage;
and help pin down the true nature of this star.

I have posted a suitable chart at the following URL:
http://vsnet.dove.net.au/~fraserf/vss-rasnz/esb365.zip

Beta's proximity makes EsB 365 a difficult target to _observe_; but so
easy to _locate_  ;-)  Good luck!


cheers,
Fraser Farrell

http://vsnet.dove.net.au/~fraserf/  email: fraserf@dove.net.au
traditional: PO Box 332, Christies Beach, SA 5165, Australia

From owner-vsnet-obs@kusastro.kyoto-u.ac.jp Tue Jan 13 02:21 JST 1998
To: <vsnet-obs@kusastro.kyoto-u.ac.jp>, <lagmonar@csir.co.za>
From: Fraser Farrell <fraserf@dove.net.au>
Date: Tue, 13 Jan 1998 02:53:24 +0930
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X-Sequence: vsnet-obs 9340
Subject: [vsnet-obs 9340] Re: [vsnet-alert 1421] Fading of EsB365
   >It was F Farell who noticed the fade and asked me to check it out.
   >Fraser, wake up man!
   >my most recent observation of EsB365 Cru: Jan 08.00  10.5
Sender: owner-vsnet-obs@kusastro.kyoto-u.ac.jp
Content-Type: text
Content-Length: 973

G'day Berto,

I would love to be observing this event.  But tell that to the
many thunderclouds passing over my place all this month.  And predicted
to continue for several more days... :-(

My most recent EsB 365 obs (forgot to mention them in earlier
message) are:
Dec 29  16:25 UT     mag 10.9
Dec 31  15:08            11.1

In response to Peter William's posting: I have received many anecdotal
reports of this star's activities since the 1970's.  Unfortunately, all
the witnesses assumed EsB 365 was a known variable and didn't bother to
note observations in detail! Frank Bateson at the VSS RASNZ is searching
plate archives to extend our historical record.

The glare of Beta Cru hides EsB 365 on typical "nova patrol" photos; and
most of the detailed photography I've seen has been of the nearby NGC
4755 cluster.




cheers,
Fraser Farrell

http://vsnet.dove.net.au/~fraserf/  email: fraserf@dove.net.au
traditional: PO Box 332, Christies Beach, SA 5165, Australia

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