Nova Sgr 2001 = V4643 Sgr
CCD image by S. Kiyota
(vsnet-alert 5713 = vsnet 2076)
Possible nova in Sgr
Date: Sat, 24 Feb 2001 16:58:06 -0500
From: "W.Liller"
Subject: [vsnet 2076] Possible nova in Sgr
Hola everyone -
Surely someone else will have discovered this bright intruder already, but
here is what I found:
There is an apparent nova (mag 7.7) on Technical Pan photographs taken on
Feb. 24.3687 and 24.3709 UT with an 85mm camera (+orange filter). The
approximate location of the star is R.A. = 17h 54.7m, Dec. = -26d 14'
(equinox 2000). Nothing brighter than mag 11.0 appears at this location on
photographs taken on Feb. 14.
Confirmation is kindly requested. The star is approx. 3.0' east of GSC
6845 565. I will try for a more precise CCD position and magnitude tonight
-- and a spectrogram if possible.
All the best to all, Bill Liller
Confirmation
(vsnet-alert 5721)
Kia ora everyone,
Clouds clearing.
Nova Sgr 2001
2001 February 25d15h04m UT Magnitude (visual) 8.9
Comparison stars Vj from Guide 7 CD ROM
Cheers,
Albert Jones
(vsnet-alert 5722)
Visual magnitude estimates by VSOLJ members
object YYYYMMDD(UT) mag code
SGRnova2001 20010225.838 91 Mhh.VSOLJ Seq. H/T
Observer: H.Maehara (Saitama, Japan)
Instruments: 20L
(vsnet-alert 5730)
Nova Sgr 2001 observation by K. Hirosawa
object YYYYMMDD(UT) mag code
SGRnova2001 20010225.835 90 Hsk.VSOLJ
Observer's code:
Hsk: Kenji Hirosawa (Aichi, Japan) Instruments: 28cm SC
Independent detection
(vsnet-alert 5734)
Nova Sgr 2001: independent detection and prediscovery records by H. Nishimura
Hideo Nishimura (Kakegawa, Shizuoka, Japan) has reported he had detected
the presence of the object on two photographs taken on Feb. 24 (see below
for the details). The object was barely seen at the limit of detection
on two photographs taken on Feb. 17.831 and 17.833 UT.
The data:
2001 Feb. 17.831 UT detected at the limit exposure=40s
17.833 detected at the limit exposure=50s
24.833 photographic magnitude 7.5 exposure=50s
24.834 photographic magnitude 7.5 exposure=50s
Instruments: 105mm F/5.6, T-Max 400 unfiltered
Relayed from Murai (Hamamatsu, Japan)
Spectroscopic confirmation as a nova!
(vsnet-alert 5723)
Dear colleagues,
We, K. Ayani and T. Kawabata (Bisei Astronomical Observatory) obtained
a low-resolution spectrum (instrumental FWHM = 0.6nm; range 470-800nm)
of possible nova Sgr 2001 at Feb. 25.88 UT with the Bisei Astronomical
Observatory 1.01-m telescope. Strong and broad H-alpha and H-beta
emission lines and broad emission feature at 784nm (O I 777.3 + Mg II
789.0 ?) are prominent. Fitting a gaussian, the equivalent width and
FWHM of the H-alpha line are estimated to be 45nm and 4700 km/s,
respectively. This object is truly a nova.
Best regards,
Kazuya Ayani
Bisei Astronomical Observatory
Prediscovery negative data
(vsnet-alert 5738)
Nova Sgr 2001 prediscovery negative observation by Takamizawa
Dear William,
Congratulations on your discovery!!
This is a first galactic nova in 21th century.
The SASS(Saku All Sky Survey) image which was
taken 5-min T-Max 400 film exposures on 2001
Feb. 19.831UT shows no object to mag 13.7 at
the location Nova Sgr. 2001.
Best wishes,Kesao
Kesao Takamizawa
SASS(Saku All Sky Survey)
Saku-machi, Nagano, 384-0502 Japan
Astrometry and identification
(vsnet-alert 5724)
Dear Colleagues,
Possible nova in Sgr: astrometry
2001 02 25.82760 UT
R.A.=17h54m40.42s Decl.=-26d14'15.2" (J2000.0)
12 reference stars from GSC-ACT. Mean residuals: 0.08" in R.A., 0.09" in Decl.
0.18-m f/5.5 reflector + CCD.
K. Kadota, Ageo, Saitama, Japan.
Best regards,
K. Kadota
(vsnet-alert 5725)
There appears to be a USNO-A2.0 star at this position with magnitudes
B = 17.4 and R = 15.8.
Yours sincerely,
Bjorn H. Granslo
(vsnet-alert 5727)
I note that Kadota-san's position is 0".4 from a moderately-bright
USNO-A2.0 star (which looks real on the DSS image) at:
17 54 40.413 -26 14 15.38 (2000)
When reporting astrometry from CCD images, it would be best if several
images were used to make the determination, particularly if the target were
moved somewhat between frames, so that the reference net would also be
shifted. The scatter in say three or four measurements would give a much
better idea of the true uncertainty in the position than would a single
frame using only the error in the fits to the reference stars.
\Brian
(vsnet-alert 5728)
Dear all,
>Immediately neighbourhood of this position, an USNO_A2.0 star
>(position end figures 40s.414, 15".40, rmag = 15.8, bmag = 17.4)
>exists, which is the plausible counterpart at quiescent.
This star is really seen on DSS2R image. There seems to exist an dim
(rmag about 18) star 2"-3" northeast of this USNO star, and no other
object can be seen in 5" radius.
Sincerely Yours,
Hitoshi Yamaoka, Kyushu Univ., Japan
yamaoka@rc.kyushu-u.ac.jp
(vsnet-alert 5729)
Using K. Kadota's position of the new nova in Sgr (vsnet-alert 5724), the
VizieR catalogue service at CDS Strasbourg returns the following potential
precursor:
USNO-A2.0 0600-29446361 J2000 position RA 17 54 40.413, Dec -26 14 15.38
Blue plate mag 17.4 Red plate mag 15.8
2MASSI J1754404-261415 J2000 position RA 17 54 40.42, Dec -26 14 15.5
Jmag 12.950 +-0.050 Hmag 12.561 +-0.036 Kmag 12.268 +-0.067
Aloha,
Jim
=======================
James Bedient
bedient@hawaii.rr.com
Meteor Group Hawaii
(vsnet-alert 5733)
Nova Sgr 2001: revised astrometry by Kadota
K. Kadota, Ageo, Saitama, Japan has provided the following updated
astrometry of Nova Sgr 2001. The position may be more accurate than
the one previously reported (vsnet-alert 5724), which may have been
affected by the image saturation.
2001 02 25.83346 UT
R.A.=17h54m40.43s Decl.=-26d14'15.7" (J2000.0)
12 reference stars from GSC-ACT. Mean residuals: 0.12" in R.A., 0.13" in Decl.
0.18-m f/5.5 reflector.
K. Kadota, Ageo, Saitama, Japan.
(vsnet-alert 5735)
Nova Sgr 2001: astrometry by Torii
K. Torii, NASDA, Japan has provided the following astrometry of
Nova Sgr 2001. The position and error were estimated from 15 frames.
Reference: USNO A2.0, software: Pixy-1
2001 02 25.826 UT
R.A.=17h54m40.41s Decl.=-26d14'15.7" (J2000.0)
Error: 0.2" in R.A, 0.3" in Decl. (1-sigma)
0.2-m f/4 reflector + 1.4x teleconverter
Comparison star sequence
(vsnet-sequence 60)
***** 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)
Charts
(vsnet-alert 5719)
Following Liller's report of a possible nova in Sagittarius [vsnet 2076]
we have prepared a chart (2.5 x 3 degrees) for visual observers, with
comparison stars from Hipparcos/Tycho down to magnitude 10.8 and placed
it the following URL:
http://www.shopplaza.nl/astro/vs-charts/nsgr2001.htm
Reinder Bouma/Edwin van Dijk
(vsnet-alert 5720)
For those not quite familiar with Sagittarius, we now have placed a
finderchart (12x15 degrees) for the possible nova, with a few bright
comparison stars down to magnitude 8.6, at:
http://www.shopplaza.nl/astro/vs-charts/nsgr1fnd.htm
VSNET light curve (requires Java)
Light curve
VSNET data search
Search!
Return to HomePage
Return to the Powerful Manager, Daisaku Nogami
vsnet-adm@kusastro.kyoto-u.ac.jp