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ASASSN-19wu: new transient (14.3 mag) in Scorpius

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SPK
SPK's picture
ASASSN-19wu: new transient (14.3 mag) in Scorpius

ASASSN-19wu (N:/UG:)
https://www.aavso.org/vsx/index.php?view=detail.top&oid=945689

Nova or CV near the galactic plane, rapid rise, matches to PS1 g=17.8,
g>16.8 on 2019-09-15.85, g=17.2 on 2019-09-16.11, g=15.7 on 2019-09-17.10, g=14.3 on 2019-09-17.79.
http://www.astronomy.ohio-state.edu/~assassin/transients.html

ASASSN-19wu 20190915.85 <168g ASN
ASASSN-19wu 20190916.11 172g ASN
ASASSN-19wu 20190917.10 157g ASN
ASASSN-19wu 20190917.79 143g ASN

For a dwarf nova with a short orbital period this would be a relatively slow rise, so this transient may be a nova eruption or an SS Cyg-type dwarf nova outburst.

No previous eruptions or outbursts were recorded since 2016 March 10 in ASAS-SN Sky Patrol data (Shappee et al. 2014ApJ...788...48S and Kochanek et al. 2017 PASP..129j4502K):
https://asas-sn.osu.edu/light_curves/f962a5ee-7413-4425-9a59-0b54b67c3d7b

Precise astrometry, spectroscopy, and multiband (also time-resolved) photometry are urgently required.

Clear skies,
Patrick

Filipp Romanov
Filipp Romanov's picture
ASASSN-19wu

Hello all!

2019 Sep. 18.43852 <10.3 TG

Canon EOS 60D, 135 mm, f/5.6, 30 sec., ISO-2000.
Yuzhno-Morskoy (near Nakhodka, Russia).

File upload: 
SPK
SPK's picture
Rapidly fading – snapshot urgently required!

Faded to gmag. 15.8 on 2019 Sept. 19.10 UT:
https://asas-sn.osu.edu/light_curves/09e3a60d-648b-4e26-bc99-6668c2ef1139

Normal UGSU/UGWZ/... outburst? Very fast (reddened) nova??
Astrometry (or at least a snapshot) is urgently required – two snapshots (V and B) would be even better.

Clear skies,
Patrick

VAastro
ASASSN-19wu Snapshot

Hi Patrick,

I have 10-60 second exposures in V taken 2019-09-20 UT00:29:41.6 but the VSP comp stars are near saturation .

Let me know if you want the .fit files.

Erik

SPK
SPK's picture
Re: ASASSN-19wu Snapshot

Hi Erik,

Thanks a lot for your response.
Yes, these FITS files would be very helpful. What is the magnitude limit?
CCD images are mainly needed for precise astrometry of the transient.

Patrick (Schmeer)

VAastro
ASASSN-19wu Snapshot

Hi Patrick,

It looks like limiting magnitude of each 60 second exposure is around magnitude 17 (S/N 6).

CCD FOV 22.5'X16.9'      0.7"/pixel

altitude approx 20 degrees

Erik

SPK
SPK's picture
Link needed

Thanks, Erik. Can you provide a link for your files?

Patrick

VAastro
ASASSN-19wu Snapshot

I can load the raw .ftp files to Dropbox.

Do you have a Dropbox account?

ejs758 at lumos.net

Erik

SPK
SPK's picture
Rapid fading continued

ASAS-SN Sky Patrol light curve: https://asas-sn.osu.edu/light_curves/83500888-1156-4677-8b0a-c57ed5e8411d

Regards,
Patrick

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