[vsnet-alert 20354] ASASSN-16ne

[Taichi Kato]

ASASSN-16ne

   It's a dwarf nova showing a previous outburst.
Time-resolved photometry is encouraged.

ASASSN-16ne 	AT 2016iad 	CLOSED 	11:43:39.42 	-10:16:11.1 	2016-11-11.63 	14.94 	SDSS 	DSS 	VIZIER 	------- 	SN or CV candidate, gradual rise, no Vizier or DSS match, V>17 on 2016-11-05.64, V=16.5 on 2016-11-07.64, V=15.7 on 2016-11-10.64, V=15.1 on 2016-11-11.63, V=15.3 on 2016-11-12.64

ASASSN-16ne 20161105.64 <170V ASN
ASASSN-16ne 20161107.64 165V ASN
ASASSN-16ne 20161110.64 157V ASN
ASASSN-16ne 20161111.63 151V ASN
ASASSN-16ne 20161112.64 153V ASN

===
ATEL #9759                                                           ATEL #9759

Title:  ASASSN-16ne follow-up and archival outburst detection
Author: D. Denisenko (Sternberg Astronomical Institute, Lomonosov
                Moscow State University), S. Korotkiy (Ka-Dar observatory; Noosfera
                foundation)
Queries:        d.v.denisenko at gmail.com
Posted: 14 Nov 2016; 13:01 UT
Subjects:Optical, Cataclysmic Variable, Transient

Rapidly rising optical transient ASASSN-16ne was announced by ASAS-SN project
(Shappee et al., 2014) on 2016 Nov. 11 via Transient Name Server as <a
href="https://wis-tns.weizmann.ac.il/object/2016iad">AT 2016iad</a>. The
following photometry was reported by ASAS-SN: 2016 Nov. 05.64 UT, <17m
(last non-detection); 07.64, 16.5; 10.64, 15.7; 11.63, 15.1. The object
is located in Crater constellation at R.A. = 11 43 39.42, Decl. = -10 16
11.2 (galactic latitude is +49). This area of sky is not covered by SDSS.
There is nothing at this position on the DSS plates and on their sum to
the limiting magnitude ~21. Color-combined DSS finder chart centered at
ASASSN-16ne coordinates is posted at http://scan.sai.msu.ru/~denis/ASASSN-16ne-JRIR.jpg
(10'x10' FOV). 

We have obtained the follow up observations of ASASSN-16ne remotely using
iTelescope.Net's T21 instrument (0.43-m f/6.8 reflector equipped with 6-Mpix
FLI CCD and f/4.5 focal reducer) located in Mayhill (New Mexico, USA).
Five unfiltered images with 60-sec exposures were taken from 12:14 to 12:25
UT on 2016 Nov. 14. USNO-B1.0 0797-0223782 (11 43 41.0 -10 15 50) located
32" NE of ASASSN-16ne was used as a reference star with Vmag=15.59 from
APASS DR9 (Henden et al., 2016). The magnitude measured at 2016-11-14.513
UT (JD=2457707.013) is 15.26+/-0.04. 

We have also checked the archival images of this field by NEAT project
(S. Pravdo et al.) available at SkyMorph website. The object was detected
on three 20-sec exposures taken on 2002 Mar. 23 at 07:54:51, 08:10:26 and
08:26:37 UT. Coordinates measured from the combined image (11 43 39.37
-10 16 11.4) are in excellent agreement with ASASSN-16ne. No minor planets
were found at this position at 2002 03 23.34 UT, and the object did not
move in 32 minutes. The magnitude measured from the sum of three NEAT images
on 2002-03-23.34 UT (JD=2452356.840) is 18.9m. The object was not present
on 3x60-sec exposures obtained 9 days before, on 2002-03-14.46 UT (JD=2452347.966,
limiting magnitude ~20), as well as on 3x20-sec exposures taken 13 days
later (JD=2452369.728, m_lim~20.5). Comparison of NEAT images from 2002
Mar. 14, Mar. 23 and Apr. 05 is uploaded to http://scan.sai.msu.ru/~denis/ASASSN-16ne-NEAT-2
002-anim.gif

We consider 2002 March 23 detection to be a previous outburst of ASASSN-16ne.
Taking into account the absence of host galaxy at the position of this
transient and previous outburst lasting less than 20 days, ASASSN-16ne
is likely not a supernova, but a cataclysmic variable (dwarf nova with
outburst amplitude more than 6m). The rising rate of the current outburst
(1.4m over 4 days) appears to be too slow for typical UGSU and USWZ dwarf
novae, being more consistent with that of AM CVn type variable (IBWD).

Follow up observations of this optical transient are encouraged, despite
the unfavorable object position in the sky. The current elongation from
the Sun is only 53 degree, but it improves every morning while the Sun
moves towards the southern declinations. 

Authors thank Education Support Foundation "Noosfera" for providing the
access to iTelescope network.