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J/PASP/115/413    BVI photometry in the open cluster NGC 6791  (Stetson+, 2003)

Homogeneous photometry. III. A star catalog for the open cluster NGC 6791. Stetson P.B., Bruntt H., Grundahl F. <Publ. Astron. Soc. Pac., 115, 413-447 (2003)> =2003PASP..115..413S
ADC_Keywords: Clusters, open ; Photometry, UBVRI ; Photometry, CCD Abstract: We present broadband BVI photometry for the open cluster NGC 6791, based upon analysis of 1764 individual CCD images. Data tables listing measured magnitudes and standard errors, image-quality indices, a variability index, and equinox J2000.0 equatorial coordinates for 14,342 stars to V∼24 have been made available to the public through the services of the Canadian Astronomy Data Centre. Equatorial coordinates only have been provided for a further 1916 stars, the photometry for which we were unable to calibrate because of lack of color information. Description: During an eight-night observing run on the 2.5m Nordic Optical Telescope that took place 2001 July 9-17, we obtained 957 CCD images of NGC 6791 in the BVI filters (57, 333, and 565 individual exposures, respectively). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file catalog.dat 144 16258 Main data table crossid.dat 57 10389 Transit table containing star cross-identifications
See also: J/PASP/110/533 : BR photometry of Fornax bright stars (Stetson+ 1998) J/AJ/108/585 : UBVI photometry of NGC 6791 (Montgomery+, 1994) J/A+AS/114/1 : CCD UBVI photometry of NGC 6791 (Kaluzny+, 1995) J/AJ/123/3460 : Low-amplitude variables in NGC 6791 (Mochejska+, 2002) J/AJ/129/656 : Infrared photometry of NGC 6791 (Carney+, 2005) Byte-by-byte Description of file: catalog.dat
Bytes Format Units Label Explanations
1- 5 I5 --- SBG Sequential identification number (1) 7- 12 F6.1 pix Xpos X in accompanying image (2) 14- 19 F6.1 pix Ypos Y in accompanying image (2) 21- 26 F6.3 mag Bmag ?=99.999 B-band magnitude 28- 33 F6.4 mag e_Bmag ?=9.9999 σ(B), standard error of the mean 35- 38 I4 --- o_Bmag Number of valid photometric measurements in B 40- 45 F6.3 mag Vmag ?=99.999 V-band magnitude 47- 52 F6.4 mag e_Vmag ?=9.9999 σ(V), standard error of the mean 54- 57 I4 --- o_Vmag Number of valid photometric measurements in V 59- 64 F6.3 mag Imag ?=99.999 I-band magnitude 66- 71 F6.4 mag e_Imag ?=9.9999 σ(I), standard error of the mean 73- 76 I4 --- o_Imag Number of valid photometric measurements in I 79- 84 F6.3 --- chi Mean value of the χ image-quality index (3) 86- 92 F7.3 --- sharp Mean value of the sharp image-quality index (4) 95- 99 F5.2 --- sep ?=99.99 Value of the sep image-isolation index (5) 101-107 F7.3 --- VI Value of the variability index 109-113 F5.1 --- w_VI Weight of the variability index 115-117 I3 h RAh Hour of Right Ascension (J2000.0) 119-120 I2 min RAm Minute of Right Ascension (J2000.0) 122-126 F5.2 s RAs Second of Right Ascension (J2000.0) 128 A1 --- DE- Sign of the Declination (J2000.0) 129-130 I2 deg DEd Degree of Declination (J2000.0) 132-133 I2 arcmin DEm Arcminute of Declination (J2000.0) 135-138 F4.1 arcsec DEs Arcsecond of Declination (J2000.0) 141-144 I4 --- Num Number of images used for the astrometry
Note (1): Cl* NGC 6791 SBG NNNNN in Simbad Note (2): Equinox J2000.0, α=19h20min53s, δ=+37°46.5arcmin. Xpos increases E at 0.5"/pixel and Ypos increases N at 0.5"/pixel Note (3): The average goodness-of-fit index χ is a dimensionless measure of the agreement between the perceived brightness profile of any given object and the model PSF for the frame in which it is measured; it is essentially the square root of the standard χ2 goodness-of-fit index, with the fitting residual in each pixel of the profile suitably weighted by that pixel's expected standard error (derived from readout and Poisson noise). The perceived range of χ values will tend to taper inward toward unity at increasingly faint magnitudes. Note (4): The index sharp is based upon the pixel-by-pixel residuals from the fitting of the model PSF to the data for any given star, except in this case it is a measure of the degree to which the negative brightness residuals are more or less centrally concentrated than the positive residuals. In essence, it is a first-order estimate of the intrinsic angular radius of a resolved source; assuming that the PSF has a characteristic radius sPSF and the measured image profile has a characteristic radius sobsi, sharp2~|sobs2-sPSF2|. If sobs>sPSF, then sharp is assigned a positive value and if sobs<sPSF, then sharp is assigned a negative value. Note (5): The surface brightness produced by a star of specified apparent magnitude and centroid position can be determined at any point within the field. We can evaluate the local surface brightness at the position of the centroid of that star. At the same time, we can evaluate and sum up the surface brightnesses produced by all the other stars in the field at the position of the centroid of the star in question. The ratio of these two surface brightnesses - the central surface brightness of the star in question as compared to the summed surface brightnesses of all other stars in the list evaluated at the same position - expressed as a magnitude, constitutes our "separation index" sep. For instance, a computed value sep=5 implies that at its centroid the star is about 100 times brighter than the summed profiles of all other stars in the field, and we conclude that the star is contaminated at a level of ∼1%. Conversely, a value sep<0 implies that the central surface brightness of the star in question is fainter than the summed wings of all the other stars at that position, and the detection is possibly spurious or, at best, a poor measurement of a badly crowded object.
Byte-by-byte Description of file: crossid.dat
Bytes Format Units Label Explanations
1- 5 I5 --- SBG Source name 7- 12 A6 --- K65 Object number in Kinman, T. D., 1965ApJ...142..655K 14- 15 A2 --- HC Object number in Harris & Canterna 1981AJ.....86.1332H (1) 17- 19 I3 --- ATT ? Object number in Anthony-Twarog & Twarog 1985ApJ...291..595A (2) 21- 24 I4 --- K90 ? Object number in Kaluzny, J. 1990MNRAS.243..492K 26- 29 I4 --- KU ? Object number in Kaluzni & Udalski 1992AcA....42...29K (3) 31- 33 A3 --- GVZH Object number in Garnavich et al. 1994AJ....107.1097G (4) 35- 38 I4 --- MJP ? Object number in Montgomery et al. 1994, Cat. J/AJ/108/585 (5) 40- 42 A3 --- KUB Object number in Kaluzny & Rucinski 1995, Cat. J/A+AS/114/1 (6) 44- 47 I4 --- KR1 ? Object number in Kaluzny & Rucinski 1995, Cat. J/A+AS/114/1 (7) 49- 53 I5 --- KR2 ? Object number in Kaluzni & Rucinski 1995, Cat. J/A+AS/114/1 (8) 55- 57 A3 --- KR Object number in Mochejska, B. J. 2002, Cat. J/AJ/123/3460 (9)
Note (1): Cl* NGC 6791 HC SN in Simbad Note (2): Cl* NGC 6791 ATT NNN Note (3): Cl* NGC 6791 KU NNNN in Simbad Note (4): Cl* NGC 6791 GVZH RNN in Simbad Note (5): Cl* NGC 6791 MJP NNNN Note (6): Cl* NGC 6791 KU BNN in Simbad Note (7): Cl* NGC 6791 KR 1-NNNN in Simbad Note (8): Cl* NGC 6791 KR 2-NNNNN in Simbad Note (9): Cl* NGC 6791 KR VNN or Cl* NGC 6791 BU BNN in Simbad
History: Copied from References: Stetson et al., Paper I, 1998PASP..110..533S, Cat. J/PASP/110/533 Stetson, Paper II, 2000PASP..112..925S
(End) Marianne Brouty [CDS] 14-Oct-2005
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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