GALANTE

Description

GALANTE is an optical photometric survey currently being undertaken with the T-80 telescope at the Observatorio Astrofísico de Javalambre (OAJ) in Teruel, Spain. Its main characteristics are:

• Coverage of the northern Galactic Plane defined by δ > 0^o and |b| < 3^o which requires 1005 fields, with seven intermediate+narrow band filters. The survey also includes some 63 interesting fields outside the main footprint, such as the Orion Nebula, the Pleiades, M31, and M33 for a total of 1068 fields. Each field is 1.4^ox1.4^o.
• Measurement of the magnitudes of all stars in that region of the sky with AB magnitudes < 17 and a minimum S/N of 70.
• Since we want to include all bright stars and our magnitude limit is not too deep, we need to do several short exposures per field for each filter but not very long exposures. Hence, the survey length is heavily influenced by the overheads (pointing, readouts, and filter changes).
• The observation strategy for each filter is:
  • Four exposures of 50 s or 100 s each (long exposures) at two different air masses.
  • Two exposures of 10 s each (intermediate exposures).
  • Two exposures of 1 s each (short exposures).
  • Two exposures of 0.1 s each (very short exposures).
• The brightest stars (starting around magnitude 4-5) saturate even in the 0.1 s exposures. In those cases we have checked that PSF fitting of the profile wings is enough to obtain accurate photometry.
• For the long exposures, the fields are observed twice during the night at different air masses to provide a more accurate photometric calibration and eliminate possible color effects introduced by the atmosphere.

The seven filters used are listed below in order of decreasing central wavelength. Four of them belong to the J-PLUS dataset and the other three are specific filters designed for this project.

• F861M (J-PLUS). This is an intermediate filter in the Calcium triplet window. It will be used to detect the largest possible number of stars (as the population in our neighborhood is dominated by cool, red objects), to tie the astrometry and photometry with 2MASS, and to produce (together with F665N) colors for many stars.
• F660N (J-PLUS) and F665N (GALANTE specific). These are two narrow-band filters to measure Hα, the first one including the line and the second one just the continuum. Their purpose is to: [a] measure the red continuum, [b] estimate gravity by means of the equivalent width of Hα, and [c] flag objects with Hα emission.
• F515N (J-PLUS). This is a Strömgren y-like filter in a wavelength region relatively free of lines and a width of 145 Å. It will be used as the V-equivalent filter for the survey.
• F450N (GALANTE specific) and F420N (GALANTE specific). They are probably the most original filters in the survey. They have been chosen to fill the gaps between Hγ and Hδ and between Hβ and Hγ, respectively. For most hot stars these are the bluemost regions of the spectrum to the right of the Balmer jump broad enough to fit a 100-200 Å wide filter without interference from strong absorption lines. Therefore, they provide a measurement of the blue continuum. In combination with other filters they will be used to simultaneously measure the T_eff and the amount of extinction for hot stars. They will also be used to estimate metallicity in cool stars.
• F348M (J-PLUS). This is a Strömgren u-like filter that measures the continuum to the left of the Balmer jump. In combination with F420N and F450N it is needed to measure the Balmer jump and, from there, the T_eff of hot stars.

Scientific objectives

The three main scientific objectives of GALANTE are:

• The identification of the population of OB stars within a few kpc of the Sun.
• The measurement of the optical dust extinction properties within that region.
• Cataloguing the F and G stars in the solar neighborhood.

In addition, we will also generate a sub-arcsecond map of Hα in the Northern Galactic Plane, produce a catalog of objects with Hα emission, study the SED distribution of peculiar objects such as AGB stars, and complement the Gaia information at wavelengths shorter than the Balmer jump and in crowded and nebular regions.

Publications

• The GALANTE photometric system. Lorenzo Gutiérrez et al. (2019). MNRAS 486, 966.
• Deriving stellar parameters from GALANTE photometry: bias and precision. Lorenzo Gutiérrez et al. (2020). MNRAS 494, 3342.
• The GALANTE photometric survey of the northern Galactic plane: project description and pipeline. Maíz Apellániz et al. (2021). MNRAS 506, 3138. This is the primary reference for citing GALANTE.

Data Release 1 (April 2021)

The Data Release 1 (DR1) includes 20 different fields from four regions in the sky:

• The H II region Berkeley 59 (1 field).
• The H II region NGC 2244 (2 fields).
• The OB association Cygnus OB2 (3 fields).
• A large section of the Galactic plane in Cassiopeia-Perseus (14 fields).

The Berkeley 59 field was already included in DR0 but the data in DR1 has a new calibration. The other 19 fields are new. DR1 includes three different types of files:

• Input information compiled from Gaia DR2, 2MASS, and other sources and processed with CHORIZOS to derive the input photometry.
• 5-pixel radius aperture photometry in the seven GALANTE bands. All magnitudes are in the AB system and calibrated with respect to Gaia DR2 and 2MASS.
• Explanatory supplement.
• Images with the GALANTE filter combination: F665N+F450N+F420N.
• Images with the JPLUS first filter combination: F861M+F660N+F515N.
• Images with the JPLUS second filter combination: F861M+F515N+F348M.

Data Release 0 (July 2020)

The Data Release 0 (DR0) includes the Berkeley 59 field, centered on right ascension of 0.70° and declination of +67.15° (J2000) took place on 30 June 2020. The field was selected as a representative of a nearby (d ~ 1.1 kpc) H II region that fits within a single GALANTE field. DR0 includes information for 62 262 stars with AB magnitudes between 5 and 20. In addition, there are three GALANTE images of Berkeley 59 with the astrometric information embedded in their headers that can be used with Aladin.

• Input information compiled from Gaia DR2, 2MASS, and other sources and processed with CHORIZOS to derive the input photometry.
• 3-pixel radius aperture photometry in the seven GALANTE bands. All magnitudes are in the AB system and calibrated with respect to Gaia DR2 and 2MASS.
• 5-pixel radius aperture photometry in the seven GALANTE bands. All magnitudes are in the AB system and calibrated with respect to Gaia DR2 and 2MASS.
• Explanatory supplement.
• Berkeley 59 with the GALANTE filter combination: F665N+F450N+F420N, 1/4 resolution.
• Berkeley 59 with the JPLUS first filter combination: F861M+F660N+F515N, 1/4 resolution.
• Berkeley 59 with the JPLUS second filter combination: F861M+F515N+F348M, 1/4 resolution.

Who are we?

The GALANTE team includes researchers that arre currently working on the project from different institutions:

• Centro de Astrobiología, Villanueva de la Cañada, Madrid, Spain:
  • Jesús Maíz Apellániz (PI)
  • Míriam García
• Instituto de Astrofísica de Andalucía, Granada, Spain:
  • Emilio J. Alfaro Navarro
• Centro de Estudios de Física del Cosmos de Aragón, Teruel, Spain:
  • Héctor Vázquez Ramió
  • Jesús Varela
• Universidad de La Serena, La Serena, Chile:
  • Rodolfo H. Barbá
• European Space Astronomy Centre, Villanueva de la Cañada, Madrid, Spain:
  • Pedro García Lario
• Instituto de Astrofísica de Canarias, San Cristobal de La Laguna, Tenerife, Spain:
  • Gonzalo Holgado Alijo
• Universidade de São Paulo, São Paulo, Brazil:
  • Alessandro Ederoclite
  • Paula Rodrigues Teixeira Coelho
• Previously active members:
  • Antonio Marín Franch
  • A. Javier Cenarro
  • Carlos López San Juan
  • Daniel J. Lennon
  • Antonio Lorenzo Gutiérrez
  • Helena García Escudero
  • Rosa Arenales Lope