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Spectroscopic follow-up of a subset of the Gaia/IPHAS catalogue of Hα-excess sources

Fratta, M; Scaringi, S; Monguió, M; Pala, AF; Drew, JE; Knigge, C; Iłkiewicz, KA; Gandhi, P

Spectroscopic follow-up of a subset of the Gaia/IPHAS catalogue of Hα-excess sources Thumbnail


M Monguió

AF Pala

JE Drew

C Knigge

KA Iłkiewicz

P Gandhi


State-of-the-art techniques to identify Hα emission-line sources in narrow-band photometric surveys consist of searching for  Hα excess with reference to nearby objects in the sky (position-based selection). However, while this approach usually yields very few spurious detections, it may fail to select intrinsically faint and/or rare Hα-excess sources. In order to obtain a more complete representation of the heterogeneous emission-line populations, we recently developed a technique to find outliers relative to nearby objects in the colour–magnitude diagram (CMD-based selection). By combining position-based and CMD-based selections, we built an updated catalogue of Hα-excess candidates in the Northern Galactic Plane. Here, we present spectroscopic follow-up observations and classification of 114 objects from this catalogue that enables us to test our novel selection method. Out of the 70 spectroscopically confirmed Hα-emitters in our sample, 15 were identified only by the CMD-based selection, and would have been thus missed by the classic position-based technique. In addition, we explore the distribution of our spectroscopically confirmed emitters in the Gaia CMD. This information can support the classification of emission-line sources in large surveys such as the upcoming WEAVE and 4-m Multi-Object Spectroscopic Telescope, especially if augmented with the introduction of other colours.


Fratta, M., Scaringi, S., Monguió, M., Pala, A., Drew, J., Knigge, C., …Gandhi, P. (2022). Spectroscopic follow-up of a subset of the Gaia/IPHAS catalogue of Hα-excess sources. Monthly Notices of the Royal Astronomical Society, 518(3), 3301-3311.

Journal Article Type Article
Acceptance Date Nov 2, 2022
Online Publication Date Nov 30, 2022
Publication Date 2022
Deposit Date Jan 6, 2023
Publicly Available Date Jan 6, 2023
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 518
Issue 3
Pages 3301-3311


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Copyright Statement
This is an Open Access article distributed under the terms of the Creative<br /> Commons Attribution License (, which permits unrestricted reuse, distribution, and reproduction in any medium,<br /> provided the original work is properly cited.

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