2017A&A...599A..48S


Query : 2017A&A...599A..48S

2017A&A...599A..48S - Astronomy and Astrophysics, volume 599A, 48-48 (2017/3-1)

A novel method for transient detection in high-cadence optical surveys. Its application for a systematic search for novae in M 31.

SORAISAM M.D., GILFANOV M., KUPFER T., MASCI F., SHAFTER A.W., PRINCE T.A., KULKARNI S.R., OFEK E.O. and BELLM E.

Abstract (from CDS):

Context. In the present era of large-scale surveys in the time domain, the processing of data, from procurement up to the detection of sources, is generally automated. One of the main challenges in the astrophysical analysis of their output is contamination by artifacts, especially in the regions of high surface brightness of unresolved emission.
Aims. We present a novel method for identifying candidates for variable and transient sources from the outputs of optical time-domain survey data pipelines. We use the method to conduct a systematic search for novae in the intermediate Palomar Transient Factory (iPTF) observations of the bulge part of M 31 during the second half of 2013.
Methods. We demonstrate that a significant fraction of artifacts produced by the iPTF pipeline form a locally uniform background of false detections approximately obeying Poissonian statistics, whereas genuine variable and transient sources, as well as artifacts associated with bright stars, result in clusters of detections whose spread is determined by the source localization accuracy. This makes the problem analogous to source detection on images produced by grazing incidence X-ray telescopes, enabling one to utilize the arsenal of powerful tools developed in X-ray astronomy. In particular, we use a wavelet-based source detection algorithm from the Chandra data analysis package CIAO.
Results. Starting from ∼2.5x105 raw detections made by the iPTF data pipeline, we obtain approximately 4000 unique source candidates. Cross-matching these candidates with the source-catalog of a deep reference image of the same field, we find counterparts for ∼90% of the candidates. These sources are either artifacts due to imperfect PSF matching or genuine variable sources. The remaining approximately 400 detections are transient sources. We identify novae among these candidates by applying selection cuts to their lightcurves based on the expected properties of novae. Thus, we recovered all 12 known novae (not counting one that erupted toward the end of the survey) registered during the time span of the survey and discovered three nova candidates. Our method is generic and can be applied to mining any target out of the artifacts in optical time-domain data. As it is fully automated, its incompleteness can be accurately computed and corrected for.

Abstract Copyright: © ESO, 2017

Journal keyword(s): methods: data analysis - surveys - novae, cataclysmic variables - galaxies: individual: M 31 - galaxies: individual: M 31

Nomenclature: Table 2: [SGK2017] NNNN N=15 among (Nos 89-3182).

Simbad objects: 17

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Number of rows : 17
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 [SGK2017] 1626 No? 00 41 47.020 +41 44 11.59       19.1   ~ 1 0
2 M31N 2014-01b No? 00 42 23.58 +41 29 12.4           ~ 3 0
3 PNV J00423494+4114563 No* 00 42 34.94 +41 14 56.3           ~ 3 0
4 M31N 2013-10e No* 00 42 42.40 +41 17 18.7           ~ 3 0
5 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 11941 1
6 M31N 2013-10b No* 00 42 46.54 +41 17 00.6           ~ 3 0
7 M31N 2013-12a X 00 42 49.9 +41 14 57           ~ 5 0
8 M31N 2013-12b No? 00 42 51.72 +41 18 14.2           ~ 5 0
9 M31N 2013-09c V* 00 43 00.48 +41 12 36.6           ~ 2 0
10 TCP J00430483+4116306 ev 00 43 04.90 +41 16 30.1           ~ 4 0
11 M31N 2013-10c No* 00 43 09.54 +41 15 39.9           ~ 4 0
12 M31N 2014-01a No* 00 43 13.62 +41 14 46.9           ~ 3 0
13 M31N 2013-09a No* 00 43 14.92 +41 19 13.0           ~ 4 0
14 [SGK2017] 3182 No? 00 43 15.560 +42 13 51.34       19.5   ~ 1 0
15 M31N 1918-02b No* 00 43 23.93 +41 21 18.2     17.50     ~ 6 0
16 M31N 2013-10a No* 00 43 24.26 +41 18 19.3           ~ 4 0
17 [SGK2017] 1687 No? 00 43 50.440 +41 46 12.36       19.3   ~ 1 0

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2022.10.02-01:20:22

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