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Photometry

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Photometric Standard Stars

Standard star observations are required for NIR photometry. These observations allow the calibration of data acquired into a magnitude or flux scale. Below are links to catalogues of photometric standard stars that can be used with Gemini near-IR imaging instruments. If possible use the UKIRT1 MKO JHKL′M catalogue (Leggett et al. 2003, 2006), as these data are on the same photometric system as the Gemini cameras. The Persson et al. (1998) 2 and Hunt et al. (1998)3 JHK catalogues can also be used, but there will be small (up to 3%, or 10% for the Persson red stars) color terms introduced by the use of a different photometric system. Hunt et al. should be used primarily as a source of brighter standards. See the camera web pages for guides to appropriate calibrator magnitudes.


Quick Links:


Detailed Descriptions of Catalogs:

Faint Standards for ZYJHK from the UKIDSS and VISTA Surveys (paper)

Based on multi-epoch observations taken as part of the UKIRT Infrared Deep Sky Survey (UKIDSS) and the Visible and Infrared Survey Telescope for Astronomy (VISTA) surveys to identify non-variable stars with JHK magnitudes in the range 16-19 mag. The stars were selected from the UKIDSS Deep Extragalactic Survey (DXS) and Ultra Deep Survey (UDS), the WFCAM calibration data (WFCAMCAL08B), the VISTA Deep Extragalactic Observations (VIDEO) and UltraVISTA. Sources selected from the near-infrared databases were paired with the Pan-STARRS Data Release 2 of optical to near-infrared photometry and the Gaia astrometric Data Release 2. Colour indices and other measurements were used to exclude sources that did not appear to be simple single stars. From an initial selection of 169 sources, this is a final sample of 81 standard stars with ZYJHK magnitudes, or a subset, each with 20 to 600 observations in each filter. The new standards have a median Ks = 17.5 mag. The relative photometric uncertainty for the sample is <0.006 mag and the absolute uncertainty is estimated to be <~0.02 mag. The sources are distributed equatorially and are accessible from both hemispheres.

1 to 5 microns (J, H, K, L′ , M) UKIRT Mauna Kea Observatory Photometric Standards, with additional ZY data

Leggett et al. (2006, MNRAS in press; 2003, MNRAS 345, 144) present J, H, K, L′ and M magnitudes on the Mauna Kea Observatory infrared photometric system. JHK data are presented for 114 stars, including 79 UKIRT faint standards, and 42 Persson standards. Average uncertainty is 0.011 magnitudes, and the stars range in brightness from 10th to 15th magnitude. L′ and M data are given for 46 and 31 stars respectively. The average uncertainty is 0.015 mag for the bright L′ standards and 0.025 mag for the fainter L′ standards, and 0.026 mag for the M standards. The full electronic version of the Leggett et al. L′ M (2003) paper give more information.

Unpublished MKO ZY data are also available. Y magnitudes are also available for some of the UKIRT standards via the UKIRT Infrared Deep Sky Survey and the WFCAM Science Archive.

The complete dataset, including the unpublished Z and Y data, can be viewed at the following link:
UKIRT MKO ZYJHKL′M Catalogue.

1 to 2.5 microns (J, H, K) Hunt et al. (1998) Photometric Standards

Hunt et al. (1998, AJ 115, 2594) reported J, H and K observations of 86 stars in 40 northern hemisphere fields containing UKIRT Faint Standards. K magnitudes range from 8.5 to 14 and J-K colours from -0.2 to 1.2. Typical errors on the photometric results are 0.012 magnitudes. The full electronic version of the Hunt et al. (1998) paper contains finding charts for all sources observed. The full catalogue of sources, coordinates and photometry may be viewed here:
Hunt et al. (1998) Catalogue

1 to 2.5 microns (J, H, K, Ks) Persson et al. (1998) Photometric Standards

Persson et al. (1998, AJ 116, 2475) reported J, H, K and Ks observations 65 faint stars forming a grid of faint near-IR photometric standards. The stars have K magnitudes between 10 and 12 and are measured to a precision of 0.001 magnitudes. A secondary list of 27 red stars suitable for the determination of colour transformations is also presented. Note these red stars will require a large (up to 10%) color correction to get them onto the Gemini MKO photometric system (see discussion in the Leggett et al. JHK (2006) paper). Avoid S705-D which may be variable (Leggett et al. 2006). The full electronic electronic version of the Persson et al. (1998) paper contains finding charts for all sources observed.


1We acknowledge the Joint Astronomy Centre, Hawaii (JAC) and the United Kingdom InfraRed Telescope (UKIRT) for the reproduction of their photometric standard star catalogues.

2We acknowledge E. Persson, Astronomical Journal and the Observatories of the Carnegie Institution of Washington for the reproduction of the Persson et al. (1998) catalogues.

3We acknowledge L. Hunt, Astronomical Journal and Osservatorio Astrofisico di Arcetri for the reproduction of the Hunt et al. (1998) catalogue.

Last update October 5th 2006, Sandy Leggett; previously February 8th 2005 by T. Geballe & Andrew Stephens

Photometry and Colors