CI Aql = Recurrent Nova Aql 1917,2000

(CCD image by Yasuo Sano)

(CCD image by Katsura Matsumoto, May 1)

(Spectrum taken by Makoto Uemura and Taichi Kato on Apr. 29 UT, Okayama Astrophysical Observatory)

Dear Colleagues,

We have received the following detection of a possible new nova or the first-ever recurrence of the old "nova" CI Aql (1917). Although Takamizawa's object is less than 1 arcmin different from the cataloged CI Aql position, it may be the recovery of the true CI Aql. At the position of the literature CI Aql, an eclipsing binary showing He II and C III/N III lines was discovered (IBVS 4338, 4232). The identity od this object with Takamizawa's should be checked. If the identity of the He II-emitting object is confirmed, CI Aql may be a non-classical nova (such as V4641 Sgr). Confirmatory observations, field imaging, accurate astrometry, photometry, and potentially X-ray pointing observations are most urgently requested.

From: Kesao Takamizawa 
Subject: Possible Nova or CI Aql?
To: dgreen@cfa.harvard.edu, tkato@kusastro.kyoto-u.ac.jp

Dear Sirs,

I have found possible nova (mag.10.0) near CI Aql on unfiltered T-Max 400 films taken on Apr. 28.669UT and 28.673UT (each five minutes exposures) with 0.10-mf/4 twin patrol cameras. I have checked for known minor planets, but nothing is on there. The position of possible nova as R.A.=18h52m02s.0 Decl.=-01d28'14" (equinox 2000.0). No star is present at this location on 110 previous patrol films taken from 1994 May 12 to 2000 Apr. 11.

Could you confirm this object?

Best wishes,
Kesao Tkamizawa 
(Saku-machi,Nagano,Japan)

(vsnet-alert 4696)

Dear Colleagues,

The event has been independently detected by Minoru Yamamoto (Aichi, Japan). He reported the object as "CI Aql" (with a comment that V1346 Aql also lies close).

   2000 Apr. 28.694 UT  mag = 9.8 (seq H/T)
   instruments:f200mmPO0 + Tmax400

Regards,
Taichi Kato

(vsnet-alert 4697)

Dear Colleagues,

>    The event has been independently detected by Minoru Yamamoto (Aichi,
> Japan).  He reported the object as "CI Aql" (with a comment that V1346 Aql
> also lies close).

This variable star commented should read V1364 Aql (185201.9 -012638, J2000), type M, 6.5-8.0 H, which is too far from Takamizawa's position. This variable is unlikely related with the presently erupting object.

Regards,
Taichi Kato

(vsnet-alert 4698)

Updated information from Takamizawa:

From GHA07243@nifty.ne.jp Sat Apr 29 22:41 JST 2000
Date: Sat, 29 Apr 2000 22:41:22 +0900
From: Kesao Takamizawa 
Subject: Possible Nova or CI Aql?
To: dgreen@cfa.harvard.edu, tkato@kusastro.kyoto-u.ac.jp

Dear Dan and Kato-San,

I have mistook to add limiting magnitude.

Best wishes,
Kesao Takamizawa 
(Saku-machi,Nagano,Japan)

(vsnet-alert 4699)

Dear Colleagues,

Congratulations to Takamizawa-san and Yamamoto-san! The spectrum taken at Okayama Astrophysical Observatory (M. Uemura and T. Kato, Kyoto University) clearly shows the presence of strong H-alpha and (weaker) H-beta emission lines. The object is indeed a nova (probably not an X-ray nova). A more detailed description of the spectrum will be reported by Uemura-san within an hour. We are still looking forward to hearing whether the nova is a recurrece of the suspect nova CI Aql in 1917.

Regards,
Taichi Kato

(vsnet-alert 4700)

Dear Colleagues,

A quick-look spectrum (no calibration yet) is placed at

/vsnet/ftpfile/Novae/nova_aql00/ciaql.gif

The red line represents the present nova (by Takamizawa and Yamamoto), the green line V1494 Aql. The strongest line is H-alpha, H-beta is the strongest in the blue region (left). The spectra of these two objects are remarkably similar, suggesting that the similar evolutionary stage of the nova outburst.

Regards,
Taichi Kato and Makoto Uemura

(vsnet-alert 4710)

Dear Dr. Green

We would like to report the following result about spectroscopy on possible nova Aql 2000 to IAU Circ.

Regards
Makoto Uemura and Taichi Kato

----------

NOVA AQUILAE 2000 = CI AQUILAE ?

M. Uemura and T. Kato, Kyoto University, report: "We obtained low-dispersion spectra (430-730 nm) of possible nova Aql 2000 on April 29.6 UT with the Okayama Astrophysical Observatory 1.88-m telescope. H-alpha emission, whose FWHM is about 2300 km/s, is prominent and H-beta is also detected. The spectrum is similar to those of fast novae a few week after their maximum. The balmer lines show no P-Cyg profiles. These spectral features indicate the outbursting object is a fast nova at the slightly evolved stage."

(vsnet-alert 4719)

CI Aql = recurrent Nova Aql 2000: spectrum by Fujii

Mitsugu Fujii reports the following nova spectrum taken on Apr. 29.7 UT.

http://www1.harenet.ne.jp/~aikow/n_nova.gif

Regards,
Taichi Kato
Makoto Uemura
and the VSNET collaboration team

(vsnet-alert 4721)

Dear Colleagues,

My heartfelt congratulations to Takamizawa-san (Kesao) and Yamamoto-san (Minoru) ! I missed this one... On April 28.260 UT, I photographed it clearly with an 85mm f/2.0 lens with orange filter and hypersensitized Kodak Technical Pan film. Its magnitude was 9.8. I will begin CCD photometry of it beginning tonight (~April 30.3) and soon will start checking archives dating back to 1984.

Clear skies to everyone! William Liller

Astrometry and identification with CI Aql

(vsnet-alert 4703)

Dear all,

On every DSS scans (DSS1 Bj*2, R*1, DSS2 Bj*2, R*4), no possible precurser of the probable nova reported by K. Takamizawa is shown. The nearest stars in USNO-A1.0 are listed below, and no other star can be seen on DSS scans in the several arcsec neighbour of the reported position, except a hint of the object on DSS2 R scan at 18h52m02s.0, -01o28'20" (2000.0), which is about 6" south of the reported position.

At the cataloged position of CI Aql (18h52m03s.5, -01o28'40" (2000.0) from GCVS online), there is another star also cataloged in USNO-A1.0. The identification of CI Aql, the eclipting binary reported in IBVS 4338, 4332), and this probable nova is going on.

Prob. Nova              18h52m02s.0  -01o28'14"   (2000.0)
                          (reported by Takamizawa)
USNO-A1.0 0825.13313509 18h52m02s.88 -01o28'15".7 (2000.0) r=16.9 b=20.1
USNO-A1.0 0825.13311349 18h52m01s.15 -01o28'20".1 (2000.0) r=17.2 b=19.8

CI Aql  11.-15.5p       18h52m03s.5  -01o28'40"   (2000.0) GCVS online
USNO-A1.0 0825.13314226 18h52m03s.48 -01o28'39".7 (2000.0) r=15.5 b=17.4

Sincerely Yours,
Hitoshi Yamaoka, Kyushu Univ., Japan
yamaoka@rc.kyushu-u.ac.jp

(vsnet-alert 4712)

Dear all,

S. Kiyota has kindly provided the image of Probable nova in Aquila. A quick look shows that the position derived by K. Takamizawa was somewhat erronous, and the bright object seems quite near to the GCVS position of CI Aql = the eclipsing binary with strange spectrum (IBVS 4232, 4338). The astrometry is in progress.

Sincerely Yours,
Hitoshi Yamaoka, Kyushu Univ., Japan
yamaoka@rc.kyushu-u.ac.jp

(vsnet-alert 4714)

In response to [vsnet-alert 4712], it has become increasingly established that Nova Aql 2000 (present nova) is a recurrence of CI Aql in 1917. The quiescent identification with a 0.6-day eclipsing binary with He II and C III/N III emission lines would then be interpreted as a system closely related to supersoft X-ray source (SSXS) which repeatedly undergo nova explosions. The eclipse light curve and the orbital period strongly resembles those of known SSXS and V Sge stars. The presence of high excitation emission lines are common among them, and CV-type recurrent novae like U Sco. The present opportunity in observing the eclipsing recurrent nova in outburst should not be overweighted. Time-resolved photometry and spectroscopy, observations at other wavelengths (esp. soft X-rays) are uegently encouaraged. The VSNET collaboration team will continue focusing on this object, and we heartily appreciated efforts from world-wide observers to cover the full orbital period.

Regards,
Taichi Kato
Makoto Uemura
and the VSNET collaboration team

(vsnet-alert 4715)

Dear all,

K. Ayani and K. Shirakami has kindly provided the image of probable nova in Aquila taken with 1.01-m Bisei telescope, which clearly shows that the position of the erupting star is indeed the location of the eclipsing binary with strange spectrum (IBVS 4232, 4338). It is quite acceptable that CI Aql is undergoing the recurrent eruption of nova outburst.

The astrometry is still in progress.

Sincerely Yours,
Hitoshi Yamaoka, Kyushu Univ., Japan
yamaoka@rc.kyushu-u.ac.jp

(vsnet-alert 4717)

Dear all,

With Kiyota-san's image, I have derived the revised position of the erupting star as: 18h52m03s.57, -01o28'41".6 (equinox 2000.0, uncertainty is around 1"). It is strongly suggested that the erupting star is identical with the eclipsing binary with strange spectrum (IBVS 4232, 4338), which is thought to be a quiescent counterpart of Nova Aql 1917 = CI Aql.

Sincerely Yours,
Hitoshi Yamaoka, Kyushu Univ., Japan
yamaoka@rc.kyushu-u.ac.jp

(vsnet-alert 4718)

Now the identity of the nova by Takamizawa and Yamamoto (issued as IAUC 7409) with CI Aql (nova 1917) is firmly established, please use the designation AQLCI (in the VSNET format) in reporting to vsnet-obs (use CI Aql in other situations). The rising trend seen in the Apr. 28 data in Japan may already reflect the orbital modulation. Please make frequent observations, and report your finding timely to VSNET.

Regards,
Taichi Kato
Makoto Uemura
and the VSNET collaboration team

(vsnet-alert 4725)

Dear all,

With Bisei image, I could get more accurate position of probable nova in Aquila = the recurrence of CI Aql (Nova Aql 1917). I reported to CBAT as below.

----
PROBABLE NOVA IN AQUILA = the recurrence of CI Aql

H. Yamaoka, Kyushu University, reports the accurate position of the probable nova in Aquila (IAUC 7409), measured with the unfiltered CCD image taken with Bisei 1.01-m telescope by K. Ayani, Bisei Astronomical Observatory, and K. Shirakami, Okayama, Japan, as R.A. = 18h52m03s.55, Decl. = -01o28'38".9 (equinox 2000.0, uncertainty around 0".2). This position is nearly identical to that of the eclipsing binary, which was proposed to be the quiescent counterpart of the suspected nova 1917 (IBVS 4338 and Duerbeck 1987, SSR, 45, 1). It is strongly suggested that the suspected Nova Aql 1917 = CI Aql was real and the ongoing eruption is the recurrence of it.

Sincerely Yours,
Hitoshi Yamaoka, Kyushu Univ., Japan
yamaoka@rc.kyushu-u.ac.jp

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