Central Bureau for Astronomical Telegrams
IAUC 8832: V5558 Sgr = N Sgr 2007
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Circular No. 8832
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
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URL http://www.cfa.harvard.edu/iau/cbat.html ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)
V5558 SAGITTARII = NOVA SAGITTARII 2007
S. Nakano, Sumoto, Japan, reports the discovery by Yukio
Sakurai (Mito, Ibaraki-ken) of a possible nova (mag 10.3) on two
20-s CCD exposures taken on Apr. 14.777 UT with a Fuji FinePix S2
Pro Digital camera (+ Nikon 180-mm f/2.8 lens), giving the position
for the new object as R.A. = 18h10m18s.4, Decl. = -18o46'51"
(equinox 2000.0). Sakurai adds that nothing is visible at this
location on an image taken on Apr. 9.8 (limiting magnitude 11.4).
Nakano provides the following position end figures for his own
measurement of Sakurai's discovery 'jpeg' image: 18s.47, 52".0.
On Apr. 19.712, Nakano obtained his own unfiltered CCD frames of
the new object (at mag 10.2) with a 0.25-m f/4.8 reflector,
providing the position end figures 18s.19, 50".9 (but apparently
involved with a nearby 12th-magnitude star). Nakano adds that K.
Itagaki (Yamagata, Japan) obtained an unfiltered CCD image on Apr.
19.745 showing the new object at mag 9.8, with Itagaki measuring
position end figures 18s.27, 52".1; Itagaki adds that the closest
star on the same frame has position end figures 18s.03, 46".1 (mag
12.1). Neither the USNO catalogue nor the Digitized Sky Survey
indicates any precursor at the position of the new star. R. Koff
(Bennett, CO, U.S.A.) reports the following position end figures
18s.21, 51".8 and magnitude V = 9.8 for the apparent nova from CCD
images obtained with a 0.25-m f/10 reflector on Apr. 20.4, adding
that it is blended with the star GSC 6272-0182, which is just
northwest of the new object.
H. Yamaoka, Kyushu University, writes that, following posting
of this object on the Central Bureau's unconfirmed-objects webpage,
K. Haseda (Toyohashi, Aichi, Japan) has located several
prediscovery images of the new star with a Canon EOS-5D digital
camera (+ 120-mm-f.l. f/3.5 lens), providing the following
estimated magnitudes: Apr. 7.780 UT, [11.8; 11.792, 11.2
(correction to date given on CBET 931); 13.793, 10.8; 14.777, 10.4.
Yamaoka adds that Y. Nakamura (Kameyama, Mie, Japan) obtained an
unfiltered CCD image with a 135-mm-f.l. f/2.8 camera lens on Apr.
19.803 that showed the apparent nova at mag 9.9, and the new star
was evidently not present on an image taken by Nakamura on Apr.
9.792.
N. N. Samus, Institute of Astronomy, Russian Academy of
Sciences, informs us that this nova has been given the designation
V5558 Sgr.
(C) Copyright 2007 CBAT
2007 April 20 (8832) Daniel W. E. Green
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