[vsnet-sequence 60] Nova Sagittarii 2001 information and sequence

["Bjorn H. Granslo" <b.h.granslo@astro.uio.no>]

...05...10...15...20...25...30...35...40...45...50...55...60...65...70..
Norwegian Astronomical Society - Variable Star Section

***** Nova Sagittarii 2001 information and sequence *****

1748-26  NOVA SGR 2001 [R.A. = 17h54m40s.4, Decl. = -26o14'15" (2000)]

W. Liller has detected an apparent nova of mag. 7.7 on two exposures
from Feb 24.47 UT using an 85-mm camera, Techical Pan film and an
orange filter. No new object was present on Feb. 14 to a limiting
magnitude of 11.0. [vsnet 2076].

The discovery has been confirmed by other observers. Observations by
A. Jones, R. Stubbins and H. Maehara indicated mv=8.9-9.1 during
Feb. 25.628-25.838 UT [vsnet 2077, vsnet 2078, vsnet-alert 5722].

Spectroscopic observations by K. Ayani and T. Kawabata confirm that
the object is a nova. They found Doppler broadened emissions from H
and possibly O I and Mg II [vsnet-alert 5723].

K. Kadota reports the following accurate position [vsnet-alert 5724]:
R.A. = 17h54m40s.42s, Decl. = -26o14'15.2" (J2000.0). A USNO-A2.0 star
(with magnitudes B=17.4 and R=15.8) and a 2MASS object is located
very close to this position. The position end figures of these
identifications are 40.41s, 15".4 and 40s.42, 15".5, respectively.

I have prepared a sequence based on astrometry and photometry from the
Hipparcos (HIP) and Tycho-2 (TYC2) catalogues. This sequence is
primary intended for visual observers, mainly due to the limited
accuracy of the HIP/TYC2 photometry (with decreasing brightness from
0.02 to about 0.10 mag.). In order to minimize systematic differences
between the Johnson V and visual magnitudes I have only included stars
that are bluer than B-V = +1.0. In order to obtain V and B-V from the
BT and VT magnitudes in TYC2 the standard transformation formulae have
been used. B. Skiff (private communication 2001) has, however, pointed
out that better results can be obtained by using the relations of
M. Bessell in Publ. Ast. Soc. Pacific, 112, 961 (2000).

For more accurate photometry one may use the GSPC sequence prepared by
Skiff [vsnet-alert 5710].

The numbers in last column refer to identifications (V magnitudes in
units of 0.1 mag.) on the chart compiled by R. Bouma and E. van Dijk
at http://www.shopplaza.nl/astro/vs-charts/nsgr2001.htm
[vsnet-alert 5719].

-------------------------------------------------------------------
Id   R.A. (2000.0) Decl.  Star Name      V-mag   B-V   Ref   Bouma
    h  m   s    o  '  "                                      chart
-------------------------------------------------------------------
A  17 56 24.4  -26 46 24  HIP 87824       7.39  +0.61  HIP    74
B  17 56 15.2  -25 40 22  HIP 87809       7.87  +0.06  HIP    79
C  17 54 30.1  -26 37 56  HIP 87679       8.55  +0.76  HIP    86
D  17 54 18.4  -25 57 44  HIP 87661       9.00  +0.60  HIP    90 
E  17 55 09.7  -26 18 11  TYC 6849-1798   9.13  +0.08  TYC2   92
F  17 56 41.0  -26 12 03  TYC 6845-0880   9.76  +0.75  TYC2   97
G  17 56 55.2  -26 07 06  TYC 6845-0562  10.14  +0.14  TYC2  102 
H  17 54 23.1  -26 42 58  TYC 6849-0872  10.28  +0.16  TYC2  103
I  17 55 10.4  -26 15 14  TYC 6849-1114  10.97  +0.78  TYC2  108
K  17 54 37.5  -26 16 36  TYC 6849-1825  11.06  +0.56  TYC2  ...
-------------------------------------------------------------------

Acknowledgement:
For this study I have made extensive use of the VizieR service of CDS
(http://vizier.u-strasbg.fr/cgi-bin/VizieR) and I wish to thank CDS
for this service.

                                    Yours sincerely,
                                    Bjorn H. Granslo
                                       (NAS.VSS)

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