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Archival Data Spectral Energy Distribution and Variability of the ASASSN-17mt Transient

ATel #10774; Peter Pessev (GRANTECAN, IAC, ULL)
on 24 Sep 2017; 23:33 UT
Credential Certification: Peter Pessev (peter.pessev@gtc.iac.es)

Subjects: Far-Infra-Red, Infra-Red, Optical, Request for Observations, Transient

The ASASSN-17mt transient was recently reported by the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN), as a possible classical nova or a bright CV. The historic light curve, based on the ASAS-SN observations, could be seen in ATel #10772. On both 2017-09-23.40UT and 2017-09-24.39UT, the source was reported with V~11.3 mag.

A comprehensive search of the available surveys data on the reported location was carried out. The data is given below, organized by increasing wavelength. The bulk of the optical information is based on the PPMXL catalogue, the V band data is from the NOMAD1 catalogue.


Survey SourceID Distance Band Magnitude MagErr

PPMXL 6174775978413473599 0.00015 B2 17.39

NOMAD1 0422-0196640 0.00019 V 16.66

Gaia 5328722974475504256 0.00013 G 16.367

PPMXL 6174775978413473599 0.00015 R1 15.09

PPMXL 6174775978413473599 0.00015 R2 15.38

PPMXL 6174775978413473599 0.00015 I 14.97

2MASS 08502962-4745283 0.00015 J 13.807 0.038

2MASS 08502962-4745283 0.00015 H 13.310 0.047

2MASS 08502962-4745283 0.00015 Ks 13.043 0.041

WISE J085029.63-474528.0 0.00021 W1 12.673 0.024

WISE J085029.63-474528.0 0.00021 W2 12.595 0.025

WISE J085029.63-474528.0 0.00021 W3 10.373 0.143

WISE J085029.63-474528.0 0.00021 W4 7.935 0.296

The reported SED spans from ~0.4 to 22 microns and in the photometric systems of the surveys. According to the Schlafly & Finkbeiner 2011 (ApJ 737, 103) reddening map, we have Av = 3.03, Aj = 0.82 and Ak = 0.35, which transfers to (V-Ks)0 ~ 0.94 and (J-Ks)0 ~ 0.3. Both values refer to a F type star (Ducati et al. 2001, ApJ 558, 309).

There is photometry from two epochs, available in the USNO-B1.0 catalogue:


Survey SourceID Distance Epoch Band Magnitude

USNO-B1.0 0422-0194885 0.00027 1984.7 B2 17.39

USNO-B1.0 0422-0194883 0.00019 1980.5 R1 16.08

USNO-B1.0 0422-0194885 0.00027 1984.7 R1 15.09

USNO-B1.0 0422-0194885 0.00027 1984.7 R2 15.38

USNO-B1.0 0422-0194883 0.00019 1980.5 I 17.87

USNO-B1.0 0422-0194885 0.00027 1984.7 I 14.97

There is a dR1 ~ 1 mag and dI ~ 2.9 mag between the 1980.5 and 1984.7 observations. (Unfortunately no information about the measurement uncertainties).

Based on the progenitor colours/rough spectral type, historic photometry and the duration of the seasonal gap in the ASAS-SN observations, ASASSN-17mt could be a recurrent nova that went off after the last observations of the field and is now on the decline. As noted in ATel #10772, further observations (especially spectroscopy) are needed to constrain the nature of the transient.

This research has made use of the VizieR catalogue access tool, CDS, Strasbourg, France. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. This research has made use of the NASA/ IPAC Infrared Science Archive, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.