(CCD image by Giancarlo Ubaldo Nappi, image on the day of the discovery.
(CCD image by Giancarlo Ubaldo Nappi, image on the day of the discovery.
Data: telescope: Newtonian 1260mm FL f/7 Camera: MX 916 Time:2seconds exposure Local: Belo Horizonte (Brazil))
IAUC No. 7692 announced the visual discovery of a nova in Sagittarius by Alfredo J. S. Pereira (Cabo da Roca, Portugal).
Position (J2000.0) 182446.04 -300041.1 (G. Nappi) 182446.06 -300040.9 (A. Hale) YYYYMMDD(UT) mag observer 20010826.866 76 (A. Pereira) discovery 20010826.913 73 (A. Pereira) 20010826.930 74 (A. Pereira) 20010826.940 74 (A. Pereira) 20010826.967 72 (A. Pereira) 20010826.996 72 (A. Pereira) 20010827.000 95 (G. Nappi) 20010827.100 64 (C. Scovil) 20010827.100 66 (J. Griese) 20010827.100 7.29V (M. Mattei (from IAUC)) 20010827.180 74 (A. Hale (from IAUC)) 20010827.340 6.47I (P. M. Kilmartin) 20010827.340 6.93R (P. M. Kilmartin) 20010827.340 7.30U (P. M. Kilmartin) 20010827.340 7.46V (P. M. Kilmartin) 20010827.340 8.01B (P. M. Kilmartin) 20010827.350 6.50I (P. M. Kilmartin) 20010827.350 6.96R (P. M. Kilmartin) 20010827.350 7.33U (P. M. Kilmartin) 20010827.350 7.51V (P. M. Kilmartin) 20010827.350 8.07B (P. M. Kilmartin) 20010827.369 6.54I (P. M. Kilmartin) 20010827.369 7.02R (P. M. Kilmartin) 20010827.369 7.38U (P. M. Kilmartin) 20010827.369 7.58V (P. M. Kilmartin) 20010827.369 8.13B (P. M. Kilmartin) 20010827.380 6.55I (P. M. Kilmartin) 20010827.380 7.03R (P. M. Kilmartin) 20010827.380 7.39U (P. M. Kilmartin) 20010827.380 7.59V (P. M. Kilmartin) 20010827.380 8.15B (P. M. Kilmartin) 20010827.380 80 (A. Jones) 20010827.815 79 (M. Reszelski)
No spectroscopic confirmation was reported at the time of the IAUC announcement.
V4739 Sgr (Nova Sgr 2001-2) spectroscopic confirmation by Fujii
M. Fujii (Fujii Bisei Observatory) took the spectrum of V4739 Sgr on Aug. 28.44 UT. Both H-alpha and H-beta were seen in broad emission (FWHM of the H-alpha is 4700 km/s). There was little evidence of Fe II lines, and Fujii suggested a He/N-type nova.
The spectrum is given at:
http://www1.harenet.ne.jp/~aikow/v4739_sgr.gif
Fujii also pointed out similarity of the spectrum with that of the
recurrent nova U Sco during the 1999 outburst
(cf. http://www1.harenet.ne.jp/~aikow/u_sco.GIF)
Fujii's line identifications:
N III 4640A
H-beta
He I 5015A
N II 5679A
He I 5876A
Na I 5892A (weak absorption)
5912A
6170A (weak, broad emission)
H-alpha
He I 7065A
Relayed from M. Fujii.
Dear all -
Regarding the new Nova Sgr 2001-2:
Broadband-V photometry with CCD by Wm. Liller, Vina del Mar, Chile: Aug 28.048 UT, V(bb) = 8.55; 28.116, 8.20 (through clouds).
Nothing brighter than magnitude 12.0 appears at the position of the nova on films taken by him on Aug 18.04.
A low-dispersion CCD objective prism spectrogram taken through clouds at Aug 28.111 with a 0.20 m Schmidt shows H-alpha in emission at more than twice the brightness of the surrounding continuum. H-beta is also clearly seen.
My sincere heartiest congratulations to Don Alfredo Pereira for his discovery, especially since it was (1) a visual discovery and (2) made at an altitude much lower than it would have been here in Chile!
All the best to all, Bill Liller
Image of Nova Sgr 2001#2 plus spectrum [H-alpha+beta etc prominent] posted at
http://home.freeuk.com/m.gavin/nsgr01_2.htm
Maurice Gavin - Worcester Park Observatory-UK www.astroman.fsnet.co.uk m.gavin@freeuk.com
NOVA SAGITTARII 2001 No. 2
The USNO-A2.0 star closest to this nova (which will presumably receive the variable star designation V4739 Sgr): R.A. 18h24m46.062s Decl. -30o00'39.64" (J2000.0) r= 17.5 b= 19.4 This star is 1.4" north of the nova position. On the DSS-2 red image a very faint star (mag 20?) is visible 1" SW of the USNO-A2.0 star. The prenova???
Regards,
Patrick
P.S.:
Yes, that's Alfredo's second nova discovery. On 1999 Dec. 1 he found Nova Aql 1999 No. 2 = V1494 Aql. Congratulations to him!!!
These two sequences of stars of intermediate brightness lie within a degree of Nova Sgr 2001 No. 2, and may be useful in calibrating wide-field images of the nova as it fades below the Tycho-2 limit.
\Brian
Name RA (2000) Dec GSC V B-V NGC 6624 9 18 23 33.2 -30 22 06 7393-0184 11.47 0.60 NGC 6624 h=8 18 23 50.3 -30 22 12 7393-0326 12.07 1.27 NGC 6624 10 18 23 32.4 -30 22 06 7393-1031 12.93 0.66 NGC 6624 5 18 23 32.3 -30 22 35 7393-0644 13.00 1.31 NGC 6624 11 18 23 51.0 -30 23 18 13.35 1.36 NGC 6624 3 18 23 34.7 -30 22 51 13.87 0.48 S457-B 18 28 58.5 -29 35 43 6869-0779 10.31 0.26 S457-C 18 28 47.9 -29 53 57 6869-1057 11.71 0.73 S457-U 18 28 46.0 -29 51 52 13.18 0.98 S457-W 18 28 56.3 -29 52 42 14.12 0.72
Nova Sgr 2001 #2 Discovery Story:
I had just started another searching session at 2043 UT. The Moon was starting to interfere but I still could see my memorized patterns well. I started scanning near M7 as usual, and 3 minutes later immediately saw the very bright 7.6 mag object within my 8th mag star patterns. It completely disturbed my binocular constellations. I waited a minute or so and saw it was no satellite. It was white-yellowish in contrast to V1494 Aql that was orange to my eyes at discovery.
I quickly estimated the mag, and rushed into the house with a sketch of its position. As usual I had the computer turned on with GSC7 in red star mode to save dark adaptation. I quickly got the position with the mouse and I did careful checks (asteroids, variables, etc). I typed the data into the e-mail template I always have ready to go. Then I went out to see the object one last time before sending the mail. Back in the house again, 12 minutes after first seeing the object I had the mail out to CBAT.
Then I went on observing my other Milky Way fields, while keeping an eye on the nova and e-mailing CBAT with follow-up magnitude estimates. After the object set, I started looking for the time when it would be night-time in several places around the world, as confirmation took quite a while. It was an even more painful wait than with V1494 Aql. I nervously walked a lot back and forth in the house.
Between my discoveries in Aql and Sgr, 149h 20m of search time elapsed. The grand total since I started binocular patrol on a significant enough scale (back in June 1991), is 614h 01m. At the current pace I typically search ~3h each clear night regardless of the Moon, broken cloud, thin cirrus, low altitude or twilight. As long as conditions allow me to see my memorized patterns, I search. Before 1996, there were frequent gaps when for a few months (mainly due to social and logistical reasons) I did not search. By 1998 I was searching some 1.5h each night whether permitting. Then in late 2000, again came a 7 month gap, but afterwards the pace has step-like increased to 3 hr/night.
I use 9x34 and 14x100B's. My search area is ~3000 square degrees, with several thousand stars memorized, and includes parts of the following constellations: Sgr, Sco, Oph, Sct, Ser, Aql, Her, Lyr, Sge, Vul, Cyg, Cep, UMi, Lac, Cas, And, Aur, Gem, Tau, Ori, Pup, and Pyx. Generally I search down to mag 7.5-8.0, but in Sgr/Sco/Oph//Sct/Aql, I try to go deep to mag 8.5 using 14x100B's (occasionally a rich-field 15-cm f/4 L @ 26x).
Miras and asteroids are usually picked up when in the mag 8.3-8.7 range, but the location of the object within memorized patterns is important. Pallas easily caught up in Pup at mag 8.5, later when at mag 7.5, there were occasions when its position "disguised" it a bit. More recently, I overlooked V2275 Cyg at mag 7.0. According to my notebook, I swept the nova's field with 9x34B's in the course of two sessions on Aug. 18.93- -18.95 UT and 19.08-19.11 UT. I suspect that I mistook the 7th mag nova for a nearby 8th mag star (in turn disregarded as a faint non-memorized star).
Optimizing the design of one's asterism patterns is not easy, because of different field orientations and variable seeing limit. Collins [JAAVSO vol 23, 1, p. 64, 1994] swept right around N Her 91 at 5th mag! I think that the observer has a natural tendency to move from asterism to asterism, and the gaps may not get properly checked, and a bright nova be missed there. I always try to have this present and make an effort to go check those gaps. Often I sweep the same area with both binoculars plus the naked eye (to mag 4.5-5.0) during a single night.
I've always been prepared to be beaten by weather or other friend observers, but after passing right over a 7th mag nova twice, I tried to understand what went wrong, and think of improvements in search method. I was feeling a bit frustrated because the next chance was likely to be years away. Now less than two weeks later, I certainly feel rewarded by having persisted. Visual patrol may have its flaws, but has the advantage of an extremely prompt alert, and I am very happy that my swift reports on two occasions, provided the opportunity for very early stage observations.
Alfredo Pereira
Charts with Hipparcos/Tycho magnitudes:
Chart by Reinder Bouma/Edwin van Dijk
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