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Photometric Observations

U, B, V, R, and I CCD observations were obtained at the 1.52-m telescope at Palomar Observatory on the nights of 7-9 January 1997. In addition, U, B, V, and I CCD observations were made at Kitt Peak National Observatory on 4 April 1997. The Palomar 1.52-m observations were made with a 2048 tex2html_wrap_inline1372 2048 CCD with a pixel scale of 0.37'' per pixel, resulting in a 1263 field of view. Though photometric, the seeing was poor (2-5'' on 7 January, 1.5 - 2.5'' on 8,9 January) during the Palomar run, so higher resolution (1.2 - 1.4'' seeing) images were obtained with the KPNO 4-m telescope in April. The KPNO observations were made with the prime focus T2KB CCD with a pixel scale of 0.47'' per pixel, resulting in a 16' field of view. Because the KPNO data were not taken in photometric conditions, the Palomar data remained useful for calibration. Data from both observing runs were reduced using the standard IRAF CCDRED reduction tasks.

After the initial reduction, aperture photometry was performed on the host galaxy of NVSS 2146+82 using the IRAF package APPHOT. Unfortunately, due to the poor seeing on the first night of the Palomar run and the proximity of the foreground star (see 3.3) to the AGN host, it was impossible to photometer NVSS 2146+82 without significant flux contamination from the foreground star. Therefore, we used the DAOPHOT II package ([Stetson 1987]) to PSF fit and subtract stars from the Palomar NVSS 2146+82 images.

After the foreground star was subtracted, photometry of the galaxy was performed identically to the photometry of several [Landolt (1992)] standard stars. Approximately 20 stars were selected from each frame containing the AGN host galaxy. A circular aperture 2.5 times the average FWHM of these stars was used to measure the flux of the host galaxy. This aperture was chosen to be consistent with the standard star photometry and because it completely enclosed the host without including contaminating flux from other nearby objects.

Once instrumental magnitudes for the galaxy were determined, they were transformed to the standard system using transformation equations incorporating an airmass and color term that were determined for the Landolt standard stars. The results of our U,B,V,R,& I photometry of the host galaxy are listed in Table 3.


Table 3: Mean Aperture Magnitudes
for NVSS 2146+82 Host Galaxy

Night

Filter Magnitude Error

2

U 19.57 0.45
1 B 18.83 0.09
1 V 17.53 0.04
2 R 17.19 0.07
2 I 16.47 0.07

 


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Fri Feb 4 16:02:06 EST 2000