Candidate NGC 4649 globular clusters (Table 1)

Full description

Images were taken of NGC 4649 using the GMOS in imaging mode on the Gemini North telescope on 2002 April 10, 11 and 14. The internal Gemini program ID is 20020410-GN-2002A-Q-21/Q-13. The instrument consists of three 2048 x 4608 pixel CCDs, with a scale of 0.072 arcsec pixel−1, yielding a 5.5 x 5.5 arcmin2 field-of-view in a single pointing. We obtained three pointings close to the galaxy centre: the north-east (field No. 1), south-east (field No. 2), and east (field No. 3). The images were taken using modified Sloan g and i filters (centred at wavelengths of 475 and 780 nm, respectively). Both g and i images had exposure times of 4 x 120 s, and the subexposures were dithered to remove the gaps between the CCD chips. The seeing for the three fields were similar in the g and i filters, with 0.6, 0.7 and 1.0 arcsec for field Nos 1, 2 and 3, respectively. Table 1 gives the photometry for the candidate GCs. Table columns include x and y position in pixels, defined in a rectangular system with its origin at the galaxy centre with x positive towards west and y positive towards the north (columns Xpos and Ypos); galactocentric radius in arcsec (column RadGC); Modified Sloan i magnitude (column imag); Modified Sloan g−i colour index (g-i) and their errors (columns e_imag and e_g-i). Finally, column _RA contains position computed from Xpos and Ypos, assuming the position of M60 centre at 12:43:40.20+11:33:09.0 (right ascension part) (pos.eq.ra;meta.main); and column _DE contains position computed from (Xpos, Ypos), assuming the position of M60 centre at 12:43:40.20+11:33:09.0 (declination part) (pos.eq.dec;meta.main).