(Kiyota-san's Rc-band image, showing both V4444 Sgr and V4006 Sgr)
Possible Nova in Sgr
IAUC No. 8113 reports the discovery of a possible nova in Sgr by Hideo Nishimura (Kakegawa, Shizuoka, Japan). The approximate position reported by Nishimura is:
18h 07m 19s
-27o 24' 20"
(J2000.0)
The magnitude were as follows (using the tentative object's notation):
SGRnova2003 20030325.81 <110p Nmh SGRnova2003 20030327.81 109p Nmh SGRnova2003 20030330.80 <110p Nmh 120? SGRnova2003 20030405.80 104p Nmh SGRnova2003 20030408.792 98p Nmh According to the same IAUC, Kushida and Kushida reported astrometry of a bright object on an unfiltered CCD image: 18h 07m 20s.38, -27o 24' 31".6 (J2000.0). However, this position almost perfectly coincides with a bright 2MASS star (likely a very red star) located at 2MASS 180720.388 -272432.27 (2000.0) 6.039 0.000 0.000 = MSX5C_G003.7266-03.3729 at 180720.6 -272431 (This 2MASS identification has been also independently communicated by John Greaves). This identification indicates that either the object was misidentified by Kushida and Kushida, or that the object is less likely a nova, if the identification was correct. [There is still a small possibility that a red star underwent an unusual outburst, though.] It would be interesting to note that there are a number of variable objects near the original position reported by Nishimura. Many of them are OGLE2 variable stars, which have been classified as "transient-type" variables. These objects are, however, very faint. 180718.9 -272420 (2000.0) OGLE2-BUL-SC18-V1565 16.692I (0.304) trans 180719.1 -272425 (2000.0) OGLE2-BUL-SC18-V1566 14.877I (0.114) trans 180719.2 -272413 (2000.0) OGLE2-BUL-SC18-V1769 12.733I (0.017) trans 180719.2 -272420 (2000.0) OGLE2-BUL-SC18-V1567 13.576I (0.046) trans 180719.3 -272426 (2000.0) OGLE2-BUL-SC18-V1569 15.320I (0.200) trans 180719.4 -272417 (2000.0) OGLE2-BUL-SC18-V1593 14.018I (0.081) trans 180719.5 -272422 (2000.0) OGLE2-BUL-SC18-V1595 14.496I (0.138) transThere are also 2MASS stars, but not as bright as the above object most likely measured by Kushida and Kushida. The brightest one near the Nishimura's position is:
2MASS 180719.244 -272420.37 (2000.0) 11.924 10.492 10.299 (= GSC 6850.4355)There is also a GCVS (position still uncertain) star V4006 Sgr
180715.3 -272535 (2000.0) SGRV4006 M 11.6 <14.4 P 37846 281 -
This Mira star is sufficiently bright, but has not been yet properly identified (although the discovery finding chart would suggest the GCVS location is correct) with a very conspicuous 2MASS counterpart at the reported position (either on 2MASS public images and catalogs). The brightest 2MASS object in this field is the star measured by Kushida and Kushida. It may have been possible that the original paper (by L. Lukas) somehow provided an incorrect chart, or the original type classification was wrong. If V4006 Sgr was truly a Mira-star, it may have been possible that Nishimura "recovered" this variable. It would be still worth persuiting for the exact location of this supposed Mira-star, too.
Precise measurement of Nishimura's photograph, other comteporaneously taken photographs and images, and further examination of the identity are strongly encouraged.
Regards, Taichi Kato
According to vsnet-chat 1860, Mati Morel suggested the following identification for V4006 Sgr:
18h 07m 22s.17, -27o 24' 42".85 (J2000.0)
based on its red color in USNO A2.0. However, this star does not seem to be particularly bright on 2MASS. Given all the uncertainties claimed in the past, the exact location of V4006 Sgr probably needs to be more closely examined.
Regards, Taichi Kato
Kushida communicated that it was mag about 8.5 on this image. Compared with the photographic magnitude by Nishimura (98p on 8.792 UT), the new object is rather red source, which is less likely a typical nova in the rising phase.
Sincerely Yours, Hitoshi Yamaoka, Kyushu Univ., Japan yamaoka@rc.kyushu-u.ac.jp
It is near by Nova 1999 Sgr = V4444 Sgr. It will be valuable to check the images of the old nova in 1999. We the MISAO Project also have some images of this field. I will investigate it later.
Best regards, Seiichi Yoshida
As reported in another list by Mati Morel, the object measured by Kushida and Kushida is in my field photometry file for V4444 Sgr.
It is given there as
RA (J2000) DEC V B-V
18:07:20.41 -27:24:32.6 13.247 1.490
with large photometric error indicating variability. Coupled
with the 2MASS bright detection, this is most likely a Mira.
I don't know if it is the same object thought by Nishimura
to be a possible nova.
Arne
I noticed that Minoru Wakuda reported in the past a photographic detection of a variable star (WSV89) in the proximity of V4006 Sgr. Although neither accurate identification nor precise position was reported by Wakuda, this detection most likely (agreed within Wakuda's typical positional error) correponded to V4006 Sgr. Wakuda-used a photographic films adjusted to V-band. All the circumstances suggest that V4006 Sgr is a Mira-star which also becomes relatively bright in the visual wavelengths (not an extremely red "infrared" Mira). The most likely candidate for the correct V4006 Sgr thus seems to agree with the star Kushida and Kushida measured.
Regards, Taichi Kato
The variability of this object is easily detected with the DSS2 R images taken on 1991, 1992, and 1996. It is quite dim on DSS1 Bj images (1987.705 and 1987.590), which I guess Kushidas referred.
Sincerely Yours, Hitoshi Yamaoka, Kyushu Univ., Japan yamaoka@rc.kyushu-u.ac.jp
K. Kanatsu (Matsue, Shimane, Japan) just reported the following photographic estimates (with f200mm lens and T-Max400(120) film + PO0 filter) of the object reported in IAUC 8113. (Kanatsu gave the GSC number rather than the possible nova designation; the decision is preserved in the following data). The object was bright in 2002 summer, indicating that the object is likely a Mira-star, which can be identical with V4006 Sgr. Kanatsu did not detect other different variable star canditates near the nominal position of V4006 Sgr.
Photographic magnitude estimates by VSOLJ members object YYYYMMDD(UT) mag code GSC6850.4355 20020413.811 <113p Knk.VSOLJ GSC6850.4355 20020520.682 <113p Knk.VSOLJ GSC6850.4355 20020606.640 <113p Knk.VSOLJ GSC6850.4355 20020706.599 113:p Knk.VSOLJ GSC6850.4355 20020711.591 111:p Knk.VSOLJ GSC6850.4355 20020805.570 110:p Knk.VSOLJ GSC6850.4355 20030313.830 <113p Knk.VSOLJ GSC6850.4355 20030405.760 107:p Knk.VSOLJ GSC6850.4355 20030405.762 107:p Knk.VSOLJ (Comparison stars: GSC 6850.3011, GSC 6850.1358, GSC 6850.2166) Regards, Taichi Kato
So, it is likely that Possible Nova in Sgr is a Mira variable identified with:
= V4006 Sgr 18h07m15s.39 -27o25'35".1 Mag(max):11.6 Mag(min):<14.4 MagSystem:P Type:M Epoc h:37846 Period:281 = OGLE2-BUL-SC18-V1606 18h07m21s.13 -27o24'21".8 Type:trans = MSX5C G003.7266-03.3729 18h07m20s.69 -27o24'32".0 InScanError:2.2" CrossScanError:1.5" Flux(A):3.8583 F lux(C):2.5987 Flux(D):1.9344 Flux(E):3.1353No I-band magnitude is recorded for OGLE2-BUL-SC18-V1606, probably too bright I guess.
Best regards,
Seiichi Yoshida comet@aerith.net
K. Haseda (Aichi, Japan) just reported the following photographic estimates (with f400mm lens and T-Max400(120)). The notation follows that by Kanatsu. Haseda's observation clearly indicates that the variable shows recurring maxima consistent with the Mira-type classification. (Haseda reported that the brightenings of the object has been noticed several times in the past; the detection has not been reported because of a presumed assumption that the object is identical with V4006 Sgr).
Photographic magnitude estimates by VSOLJ members object YYYYMMDD(UT) mag code GSC6850.4355 20000313.813 104p Had.VSOLJ GSC6850.4355 20000822.513 <124p Had.VSOLJ GSC6850.4355 20010319.788 <106p Had.VSOLJ GSC6850.4355 20010922.469 106p Had.VSOLJ GSC6850.4355 20020223.000 <134p Had.VSOLJ GSC6850.4355 20020319.826 <134p Had.VSOLJ GSC6850.4355 20020412.793 <134p Had.VSOLJ GSC6850.4355 20020502.648 126p Had.VSOLJ GSC6850.4355 20020511.688 <124p Had.VSOLJ GSC6850.4355 20020521.640 <134p Had.VSOLJ GSC6850.4355 20020609.643 <124p Had.VSOLJ GSC6850.4355 20020710.648 105p Had.VSOLJ GSC6850.4355 20020714.560 106p Had.VSOLJ GSC6850.4355 20020731.524 106p Had.VSOLJ GSC6850.4355 20020805.556 110p Had.VSOLJ GSC6850.4355 20020809.558 114p Had.VSOLJ GSC6850.4355 20020813.535 114p Had.VSOLJ GSC6850.4355 20020827.540 115p Had.VSOLJ Regards, Taichi Kato
loking at my images archivied I found the object on two images taken in July 2002.
You can see the images at my address
http://digilander.libero.it/infosis/homepage/novasgr2003.htm
I am loking on other images taken at the same time to verify the presence of the object.
Best regards, Toni Scarmato[magnitudes]
Kadota's astrometry of the past images is shown below. The object was recorded bright on CCD images. S. Kiyota (Tsukuba, Japan) confirmed the variability on the past CCD images.
=== 1999 04 29.69188 UT 18 07 20.39 -27 24 32.7 (equinox 2000.0) 0.16-m f/3.3 reflector + CCD. K. Kadota, Ageo, Saitama, Japan. 10 GSC-ACT reference stars. Mean residuals: 0.15" in R.A., 0.15" in Decl. 1999 05 07.73164 UT 18 07 20.40 -27 24 32.6 (equinox 2000.0) 12 GSC-ACT reference stars. Mean residuals: 0.12" in R.A., 0.13" in Decl. 0.18-m f/5.5 reflector + CCD. K. Kadota, Ageo, Saitama, Japan.
By those elements, this star should be at maximum on JD 2452739... tonight.
These elements also agree well with Kanatsu and Haseda's observations of the previous maximum, in July, 2002. The previous maximum by the above elements would have been on July 2, 2002, JD 2452458.
Jim Bedient
The POSS I digitized image (thanks to USNO Flagstaff) taken on 1958.5257 with 103aO (Bj) shows this object much brighter than in other Bj images, such as POSS I Bj taken on 1958.2957. Thus this object has also a large amplitude in photographic band, which is consistent with the description of V4006 Sgr, and the reports by Haseda-san and others.
Sincerely Yours, Hitoshi Yamaoka, Kyushu Univ., Japan yamaoka@rc.kyushu-u.ac.jp[comment]
180407. -272600 (B1950.0) V4006 Sgr (taken from GCVS online) 180412.0 -272457 (B1950.0) processed from 180720.388 -272432.27 (J2000.0)If the position was given only in 0m.1 and 1' accuracy, they are well consistent.
And, extrapolating the periodicity, the expected maximum would occur around 1958.65, near to the epoch when it cought brighter in POSS I image (vsnet-alert 7701). It is also valid for the most recent maximum, suggested by Jim Bedient (vsnet-alert 7700).
The nominal position of GSC 6850.4355 is about 17" away from the suspected object, and around this nominal position there are some crowded stars. I guess it should be avoided to call this object as GSC6850.4355 in further reporting. Please specify the appropriate name, Taichi ?
Sincerely Yours, Hitoshi Yamaoka, Kyushu Univ., Japan yamaoka@rc.kyushu-u.ac.jp
I have successfully recognized that the chart is "south is up". Then the position marked on this discovery chart closely corresponds to the infrared/variable object currently in question. We should call the object V4006 Sgr, and quit vsnet-alert and vsnet-discovery-nova in further discussion.
Regards, Taichi Kato
Please have a look at http://www.astrouw.edu.pl/cgi-asas/asas_variable/180720-2724.5,asas3,0,500,0,0
or go to http://www.astrouw.edu.pl/~gp/asas/asas.html
and click on Photometric_Catalog_Search:V-band enter 180720-2724.5 click on Search click on 180720-2724.5 (in lower left window)Please note that "upper limits" are not yet properly programmed - They tell only that photometry for a given object on a given frame is not available at the moment. The value of a "upper limit" is always a few percent below the faintest available measurement.
Without colors I'd say: UGem, but high amplitude Mira is also possible.
Grzegorz Pojmanski, ASAS
Kushida's image, taken upon notification from Nishimura.
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