TCP J21040470+4631129: new transient (9.2 mag) in Cygnus

Announcement: New Forums

We are excited to announce the launch of our new forums! You can access it forums.aavso.org. For questions, please see our blog post. The forums at aavso.org/forum have become read-only.

Affiliation
Association Française des Observateurs d'Étoiles Variables (AFOEV)
Fri, 07/12/2019 - 16:16

TCP J21040470+4631129 (UG:)
https://www.aavso.org/vsx/index.php?view=detail.top&oid=838181

Spectroscopy, precise astrometry, and multiband as well as time-resolved photometry are urgently required (I renamed the transient, as it is probably a dwarf nova outburst and not a "possible supernova").

Discovery details:
R.A. 21h04m04.70s, Decl. +46°31'12.9" (J2000.0)
2019 July 12.490 UT, 9.2 mag (CCD, unfiltered)
Discoverer: Hideo Nishimura (Shizuoka-ken, Japan)

2019 07 12.490 UT
Discovered by Hideo Nishimura, Shizuoka-ken, Japan, on three frames using Canon EOS 6D Digital camera + 200-mm f/3.2 lens under the limiting mag = 14.5, who writes nothing is visible at this location on a frame taken on 2019 July 10.502 UT with the limit mag.= 15s and there is a candidate star (mag = 17) on DSS. An image will be provided later.

2019 07 12.490 UT
A discovery image at http://www.oaa.gr.jp/~oaacs/image/PSNinCyg2019.jpg

2019 07 12.61 UT
This transient does not look like a "possible supernova", but is likely a nearby dwarf nova outburst. I strongly recommend to use the designation TCP J21040470+4631129 instead of PSN J21040470+4631129. --- Patrick Schmeer (Saarbrücken-Bischmisheim, Germany)

2019 07 12.61 UT
The likely (blue) progenitor (supposedly Nishimura-san's mag. 17 candidate star) is USNO-A2.0 1350-13375367 (Bmag. 17.7, Rmag. 17.2) with Gaia DR2 position end figures 04.688s, 13.75" (equinox J2000.0, epoch 2015.5, Gmag. 17.77, parallax 9.1337 ± 0.1156 mas (distance 109.2 ± 1.4 pc)). Other designations are USNO-B1.0 1365-0394214, GSC2.3 N31X108363 (Fmag. 15.71, Bjmag. 17.76, Vmag. 18.34), PSO J210404.693+463113.906 (gmag. 18.20, rmag. 18.01), IPHAS J210404.68+463114.0. No outbursts were recorded by the ASAS-SN Sky Patrol (Shappee et al. 2014ApJ...788...48S and Kochanek et al. 2017PASP..129j4502K) between 2015 March 20 and 2019 July 9; complete light curve at https://asas-sn.osu.edu/light_curves/56580af1-4b5a-4270-b96b-b77ef1ea87…. The transient is probably a dwarf nova outburst with an amplitude of at least 9 magnitudes (WZ Sge type?). Spectroscopy as well as multiband and time-resolved photometry are strongly recommended. --- Patrick Schmeer (Saarbrücken-Bischmisheim, Germany)

http://www.cbat.eps.harvard.edu/unconf/followups/J21040470+4631129.html

Clear skies,
Patrick

Affiliation
American Association of Variable Star Observers (AAVSO)
Spectra of transient

Hi,

I took a time-series of low-res (R=2000 or so) 100 sec spectra of that object. It is a pretty bright one by now..

Just a raw 1-D extraction is shown on graph. At very left there is Hbeta, right: Halpha and HeI 6678. When looking at the spectrum, it is quite evident that it's not a nova or supernova ;-)

Maybe some of you will find that data useful, I have it with all the calibs etc.

Best wishes,
Tõnis

Affiliation
American Association of Variable Star Observers (AAVSO)
TCP J21040470+4631129 sequence

TCP J21040470+4631129 now has a sequence....

Beware that brighter comps have close companions and color options are probably not ideal, especially for brighter comps.

Tim Crawford, Sequence Team

 

Visual observation

I think this star is much brighter than the original CCD 9.2, my estimate is 8.2 21h57 UTC color blue but from the Tycho II catalog.

Michel

Affiliation
None
ATel

***Instant Email Notice***: Transients

------------------------------------------------------------------------------

------------------------------------------------------------------------------

The Astronomer's Telegram http://www.astronomerstelegram.org

==============================================================================
ATEL #12936 ATEL #12936

Title: Echelle spectroscopy of TCP J21040470+4631129
Author: Francois Teyssier (ARAS Group, Rouen, France)
Queries: shore@df.unipi.it
Posted: 13 Jul 2019; 02:43 UT
Subjects:Cataclysmic Variable, Transient

We report optical echelle spectroscopy (R ~ 11000, 4100-7300A) the newly
reported transient TCP J21040470+4631129 (discovered on 2019 Jul.12.190
UT by Hideo Nishimura). The spectrum is consistent, obtains on 2019 Jul
12.9 UT (exposure time of 2589 sec, S/N ~ 40 hat 6100 A). The spectrum
is consistent with a large amplitude outburst of a cataclysmic variable.
The He I lines (e.g. 4471, 5013, 5876, 6678, 7065) all show symmetric
double peaks with separation 210 km/s (HWZI ~ 540 km/s). He II 4686 shows
peak separation of 310 km/s (but with there are also weak peaks coincident
with the He I lines) and broader wings, HWZI ~ 700 km/s; the redshifted
peak (+130 km/s) is slightly stronger and narrower. The profiles are centered
at 12 km/s but the wings show asymmetric extensions. The H-alpha and H-beta
profiles are asymmetric (R/V peak ~ 1.14±0.05) with separation of 160
km/s (HWZI = 600 km/s). There may be an absorption component at -30 km/s
(a similar minimum is seen on the He I lines) and H-beta and H-gamma show
an underlying broad absorption line that is redshifted relative to the
emission component by about 150±50 km/s, based on the profile asymmetry.
Additional emission includes the C III lines as a broad, featureless profile.
The precursor candidate noted in the CBAT report coincides with Gaia (DR2)
2163612727665972096 with parallax 9.134+/-0.116 (g=17.77 mag)

ARAS Spectral Database: http://www.astrosurf.com/aras/Aras_DataBase/DataBase.htm
------------------------------------------------------------------------------
Password Certification: S. N. Shore (shore@df.unipi.it)
http://www.astronomerstelegram.org/?read=12936
==============================================================================