J/PASP/97/753 BVR CCD photometry on NGC 1777 (Mateo+, 1985)
CCD photometry of Large Magellanic Cloud clusters.
I. The remote cluster NGC 1777.
Mateo M., Hodge P.
<Publ. Astron. Soc. Pac. 97, 753 (1985)>
=1985PASP...97..753M 1985PASP...97..753M
ADC_Keywords: Magellanic Clouds ; Associations, stellar ; Photometry, CCD
Keywords: clusters: individual: Large Magellanic Cloud - Photometry
Abstract:
We present photographic (B and V) and CCD (B, V, and R) photometry of
stars in the remote LMC cluster NGC 1777, and integrated UBV
photometry of the inner part of the cluster. A comparison of the
results from the two techniques reveals large (∼0.20m) systematic
differences which we attribute to the difficulty of faint photometry.
The photographic calibration depended on images produced by a Racine
wedge, while the CCD calibration was accomplished in a manner
analogous to photoelectric photometry. The stellar photometry provides
a C-M diagram to V=21.5 which includes an evolved main sequence and a
well-populated giant branch. A variety of methods, including
comparisons of the observations to two sets of isochrones, allows us
to estimate the cluster age as 0.9±0.2x109 years. However we are
only able to estimate the metallicity ([Fe/H]) crudely as -0.7±0.5.
The C-M diagrams of the field in three regions near NGC 1777 indicate
the presence of stars in the age range 1x109 to ≥3x109 years,
although we are unable to discern whether a mixture of two or more
distinct populations or a continuous distribution of field-star ages
is responsible for this spread.
Objects:
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RA (2000) DE Designation(s)
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04 55 42 -74 16.0 NGC 1777
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table6.dat 44 1531 CCD photometry
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- MH [1/2068]+ Sequential number
(Cl* NGC 1777 MH NNNN in Simbad)
6- 10 F5.1 pix xpos X position (1)
12- 16 F5.1 pix ypos Y position (1)
18- 23 F6.3 mag Vmag V magnitude
25- 30 F6.3 mag B-V ? B-V colour index
33- 38 F6.3 mag V-R ? V-R colour magnitude
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Note (1): x increases to North and y increases to East.
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History: Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer [CDS] 22-Mar-1999