Published June 16, 2026 | Version v1

J-PLUS PSF-photometry for IC 1613

  • 1. ROR icon Centro de Estudios de Física del Cosmos de Aragón

Description

OBA stars members
Selection of OBA star members of IC1613 is based on the CMD rSDSS vs. (rSDSS-gSDSS).

To guarantee the reliability of our selection, we first apply some cuts:
rSDSS_MAG0_PSF < 21
gSDSS_MAG0_PSF < 26
SNR_rSDSS > 3
SNR_gSDSS > 3
rSDSS_chi2dof > 2
gSDSS_chi2dof > 2

Note that magnitudes denoted as XXXX_MAG0_PSF correspond to PSF magnitudes corrected by
extinction according to Planck et al. 2016 (https://ui.adsabs.harvard.edu/abs/
2016A%26A...596A.109P/abstract).

The catalog containing all the sources (3165) that satisfy the cuts above is named as
IC1613_OBA_PSF.fits.

As the separation is clear in the (rSDSS - gSDSS) color between stars in the IC1613 field and in
the parallel fields, we determine the probability of being a member according to only the (rSDSS -
gSDSS) color. We take into account uncertainties in color.

We find a color cut at (rSDSS - gSDSS) < 0.065 for a purity of OBA members of 95%. The
probability of being an OBA star member is denoted as P_blue in the corresponding catalog. A cut
in P_blue > 0.5 ensures the 95% purity of OBA star members (612 candidates).

Red giant star members
Selection of red giant star members of IC1613 is based on the CCD (J0515 - gSDSS) vs.
(gSDSS-iSDSS).

To guarantee the reliability of our selection, we first apply some cuts:
14 < J0510_MAG0_PSF < 21.5
14 < gSDSS_MAG0_PSF < 21.5
14 < iSDSS_MAG0_PSF < 21.5
J0510_MAG_PSF_ERROR > 0
iSDSS_MAG_PSF_ERROR > 0
gSDSS_MAG_PSF_ERROR > 0
SNR_J0515 > 3
SNR_gSDSS > 3
SNR_iSDSS > 3
J0515_chi2dof > 1.8
J0515_chi2dof > 1.8
J0515_chi2dof > 1.8
(gSDSS_MAG0_PSF - iSDSS_MAG0_PSF) > 0.5

The catalog containing all the sources (275) that satisfy the cuts above is named as
IC1613_Predgiant.fits.

We determine the probability of being a red giant star member according to a 2D density criteria
based on (J0515 - gSDSS) vs. (gSDSS-iSDSS) and the position of the stars in the IC1613 field
and in the parallel fields. We take into account uncertainties in both colors.

We obtain a probability for each source for a purity of red giant star members of 95%. The
probability of being a red giant star member is denoted as P_RG in the corresponding catalog.
The cut in P_RG > 0.74 ensures the 95% purity of red giant star members (103 candidates).

Catalogs
Both catalogs, OBA and red giant star members, include the same number of columns (219).

Column 1 (ID): arbitrary ID.
Column 2 (catalog): JPLUS, only JPLUS photometry available; GNU, detected by gnuastro and
PSF photometry available; BOTH, both photometries available.
Column 3 (RA): right ascension from detection in the rSDSS band with gnuastro.
Column 4 (DEC): declination from detection in the rSDSS band with gnuastro.
Columns 5-56: JPLUS catalog entries
Columns 57-98: BANNJOS catalog entries
Columns 99-106: Flux and magnitude aperture corrected for 3 and 6 arcsec. Uncertainties
included.
Column 107 (match_sep_arcsec): separation un arcsec between JPLUS and gnuastro detected
sources.
Columns 108-131: PSF magnitudes and their uncertainties obtained with astrophot.
Columns 132-15: PSF uxes and their uncertainties in log obtained with astrophot.
Columns 156-167: Zero Points for each band.
Columns 168-179: Zero Point corrections according to the position in the image of each source
for each band.
Columns 180-191: chi2dof of the point-source t to each source in each band obtained with
astrophot.
Column 192 (conv): yes, convergence achieved; no, no-convergence achieved; in, convergence
achieved by immobility. These are the results of the astrophotographers t to each source
assuming a point-source model.
Column 193 (chi2dof): Total chi2dof in all bands obtained with astrophot.
Column 194 (E_BV): Dust extinction according to the position in the sky of each source using
https://dustmaps.readthedocs.io/en/latest/maps.html and considering Planck et al. 2016 (https://
ui.adsabs.harvard.edu/abs/2016A%26A...596A.109P/abstract).
Columns 195-218: Correction of dust extinction in each band (A_XXXX) and magnitude corrected
by dust extinction in each band (XXX_MAG0_PSF).
Column 219: probability of being an OBA star member (P_blue) or red giant member (P_RG)

 

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