[vsnet-alert 24504] Re: ASASSN-20jl - strange 12.8m object in Hercules

Sat Aug 1 06:14:13 JST 2020

Dear Dennis,

Photometry obtained at CBA Extremadura Observatory using a 0.40-m f/5.1 telescope and SX-46 CCD camera under clear skies:

2020 Jul 31.871 UT: V = 12.97
2020 Jul 31.872 UT: B = 13.19
2020 Jul 31.873 UT: R = 12.96
2020 Jul 31.874 UT: I = 12.89

I can start a V-filtered (or multi-filter) time series photometry session of this target if you want ...

Best regards
Tonny

-----Original Message-----
From: vsnet-alert [mailto:vsnet-alert-bounces at ooruri.kusastro.kyoto-u.ac.jp] On Behalf Of Denis Denisenko d.v.denisenko at gmail.com via vsnet-alert
Sent: vrijdag 31 juli 2020 21:25
To: vsnet-alert at ooruri.kusastro.kyoto-u.ac.jp
Subject: [vsnet-alert 24501] ASASSN-20jl - strange 12.8m object in Hercules

ASAS-SN (Shappee et al., 2014; Kochanek et al., 2017) has reported a bright, low-amplitude transient in Hercules on July 31:

ASASSN-20jl
  20200729.2489  15.010g  ASAS-SN
  20200729.2502  15.050g  ASAS-SN
  20200729.2515  15.075g  ASAS-SN
  20200731.2993  12.844g  ASAS-SN
  20200731.3006  12.827g  ASAS-SN
  20200731.3019  12.849g  ASAS-SN

ASAS-SN light curve for the last 100 days:
https://asas-sn.osu.edu/light_curves/b149e6ec-6b17-4d74-9f57-cb5d070d9ffb

Gaia DR2 position: 16 46 14.67 +17 00 17.5
Plx=1.16(3) mas, pmRA=9.47(3) mas/yr, pmDE=-11.09(3) mas/yr.

Color-combined DSS finder chart:
http://scan.sai.msu.ru/~denis/ASASSN-20lj-BRIR.jpg

IDs from other catalogs:
2MASS J16461467+1700175
GSC 01524-01167
NSVS 10719460
SDSS J164614.67+170017.4
USNO-A2.0 1050-08124731
USNO-B1.0 1070-0305017
WISE J164614.68+170017.4

The star of a kind that shouldn't go into outburst. Neither blue, nor particularly red object. No UV excess (V=14.7, NUV=20.8). Gaia absolute magnitude M=+4.9, effective temperature 5592+/-54 K (Bai et al., 2019) - pretty Sun-like. No sign of the past variability in CRTS, NSVS, ASAS, DASCH, ZTF data or on the NEAT images. APASS magnitudes are V=14.716+/-0.016, B=15.431+/-0.083. No asteroids or minor planets at this position in MPChecker.

Confirmation from Europe or South Africa is required.

Denis Denisenko