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THE ASTRONOMER Electronic Circular No 2116      2005 May 28 20.10UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise,  Basingstoke,
Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074
INTERNET: GUY@TAHQ.DEMON.CO.UK             GMH at AST.STAR.RL.AC.UK
WORLD WIDE WEB                         http://www.theastronomer.org
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NN DEL - 2005: CALL FOR AN INTERNATIONAL CAMPAIGN
Ivan L. Andronov, Ukraine e-mails:

There is an interesting newly (Hipparcos) discovered Algol-type star 
with 99.27 day period and highly eccentric (e=0.517) orbit - NN Del = 
SAO 126201
http://www.astrogea.org/var2/nn_del.htm

The approaching minimum will be on 2005 May 31, centred on 15:25 G.M.T., 
total duration 21.2 hours (17.3 hours for another minimum).

To observe this minimum completely, inter-longitude observations
starting in Japan or Korea, continued in China, India, Iran and then 
Europe are needed.

Next secondary minima (like that on May 31) will be centred on
September 7 (22 G.M.T) and December 14 (05 GMT). Next primary minima 
will be on August 20 (06 G.M.T.) and November 26 (13 G.M.T.), as 
intervals between the minima are 18.69 and 80.59 days (depth 0.54 and 
0.49 mag, respectively).

Because of the brightness and long minimum, it is an excellent target 
for multi-colour CCD observations with changing filters for all the 
night on May 31. Besides, it will be very fruitful to make some colour 
brightness estimates outside minima.

The closest star of comparable brightness is SAO 126199 (8.6, K5),
although SAO 126187 (6.9, A0) is much better according to the spectral 
class and colour index.

Please send results on the international campaign "NN Del - 2005" (which 
is a part of the largest project "Inter-Longitude Astronomy) to the 
e-mail of the Ukrainian Association of Variable Star Observers: 
uavso@pochta.ru

Results will be used for determination of the more precise ephemeris and 
of the system parameters.

Guy M Hurst