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J/A+AS/71/297      CCD UBV photometry of stars in Sex A     (Aparicio+, 1987)

CCD photometry of resolved dwarf irregular galaxies. I. Sextans A. Aparicio A., Garcia-Pelayo J.M., Moles M., Melnick J. <Astron. Astrophys. Suppl. Ser. 71, 297 (1987)> =1987A&AS...71..297A
ADC_Keywords: Galaxies, photometry ; Photometry, UBV ; Photometry, CCD Keywords: galaxies: irregular - stellar content - luminosity function, mass function Abstract: CCD UBV photometry of 2279 stars in Sextans A is presented. Differences with the photometric scales of Sandage and Carlson (1985AJ.....90.1019S) and Hoessel et al. (1983ApJ...274..577H) are discussed; recalibration of the Sandage and Carlson data for Cepheids in Sextans A results in a smaller value for the distance modulus, µ=25.6. A similar value for the distance modulus is obtained from the colour-colour diagram. Colour-colour and colour-magnitude diagrams for the whole galaxy and for different parts are presented indicating a general star formation activity all over Sextans A. The contribution of stars brighter than Mpg=-3 to the total blue light of the galaxy amounts to 25%, a much higher value than what is found for other dwarf irregular galaxies in the Local Group. The integrated birthrate per unit mass of massive stars for the galaxy is found to be much higher than in the Magellanic Clouds, suggesting that the rate in Sextans A was probably smaller in the past. Different slopes for high mass and low mass IMF parts are needed to account for its low surface brightness. The formation of massive stars seems to be favoured for systems of decreasing mass or, given the relation between total mass and metal content, for galaxies of decreasing metallicity. Objects: ---------------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------------- 10 11 05.7 -04 42 28 Sextans A = UGCA 205 = PGC 29653 ---------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 51 2279 CCD UBV photometry results
See also: J/AJ/116/2341 : UBVRI photometry in Sextans A (Van Dyk+ 1998) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 4 I4 --- AGM [1/2279]+ Sequential number (<AGM Sextans A NNNN> in Simbad) 6- 11 F6.2 pix Xpos X position (1) 13- 18 F6.2 pix Ypos Y position (1) 20- 24 F5.2 mag U-B ? U-B colour index 26- 29 F4.2 mag e_U-B ? rms uncertainty on U-B 31- 35 F5.2 mag B-V B-V colour index 37- 40 F4.2 mag e_B-V rms uncertainty on B-V 42- 46 F5.2 mag Vmag V magnitude 48- 51 F4.2 mag e_Vmag rms uncertainty on Vmag
Note (1): x increases to the East, y increases to the Norh. Origin is in the left down corner.
History: Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer [CDS] 29-Jul-2000
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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