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NGC 4857


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Публикации по объекту

Arcsecond Positions of UGC Galaxies
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.

Galaxy coordinates. II. Accurate equatorial coordinates for 17298 galaxies
Using images of the Digitized Sky Survey we measured coodinates for17298 galaxies having poorly defined coordinates. As a control, wemeasured with the same method 1522 galaxies having accurate coordinates.The comparison with our own measurements shows that the accuracy of themethod is about 6 arcsec on each axis (RA and DEC).

Preliminary results on the study of the environment of a complete sample of Seyfert galaxies:
Not Available

Spectroscopy of Blue Compact Galaxies
Blue Compact Galaxies (BCGs) are gas--rich systems undergoing verymassive starburst events which involve the entire galaxy. We performed aspectroscopic study of 12 BCG in order to determine metallicities andhelium content. Some objects show presence of broadened emission lines,probably due to internal motion of the interstellar medium, caused byintense stellar winds and supernov explosions.

Scaleheights of 486 southern spiral galaxies and some statistical correlation
Based on Peng's method (1988), we obtain scaleheights of 486 southernspiral galaxies, the images of which are taken from the Digitized SkySurvey at Xinglong Station of Beijing Astronomical Observatory. Thefitted spiral arms of 70 galaxies are compared with their images to gettheir optimum inclinations. The scaleheights of other 416 ones arelisted in Table A1 in Appendix. After compiling and analyzing the data,we find some statistical correlations. The most interesting results arethat a flatter galaxy is bluer and looks brighter, and galaxies becomeflatter along the Hubble sequence Sab -- Scd. Based on photographic dataof the National Geographic Society -- Palomar Observatory Sky Survey(NGS-POSS) obtained using the Oschin Telescope Palomar Mountain. TheNGS-POSS was funded by a grant from the National Geographic Society tothe California Institute of Technology. The plates were processed intothe present compressed digital form with their permission. The DigitizedSky Survey was produced at the Space Telescope Science Institute underUS Government grant NAG W-2166. Table A1 is available in electronic fromonly, via anonymous ftp 130.79.128.5 orhttp://cdsweb.u-strasbg.fr/Abstract.html

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Наблюдательные данные и астрометрия

Созвездие:Дракон
Прямое восхождение:12h57m18.30s
Склонение:+70°12'12.0"
Видимый размер:1.175′ × 0.617′

Каталоги и обозначения:
Собственные имена   (Edit)
NGC 2000.0NGC 4857
HYPERLEDA-IPGC 44284

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