Bibliography

3

Frogel, J. A. 1998, PASP, 110, 200.

3

Nikolaev, S. 1998, in preparation.

3

Weinberg, M. D., Nikolaev, S. 1998, Global Photometric Scheme posted on the WEB at http://scruffy.phast.umass.edu/PROPHOT/node2.html

  

Figure 1: 2MASS temporal drift. Each point on the plot represents the average value of the difference (eqn. 1) for all fiducial standards observed on a given night as the function of time. The amplitude and the period of the best-fit sinusoid are given in Table 2 (Model a).

  

Figure: 2MASS spatial drift. Each point represent the average residual for a given fiducial standard over all observations of that standard, as a function of the coordinate. The error bars show the standard deviation about the mean for each field. For clarity of presentation, the horizontal axis spans two periods in $\alpha$.

  

Figure: K-band sensitivity (photometric zero points a_n) as the function of time. The linear drift has the slope of $(-2.10\pm 0.71)\times 10^{-4}$ and is probably caused by the lower sensitivity during the first few months of the survey (survey days 100 - 200).

  

Figure 4: Sky coverage as the function of time. Plotted are the R.A. coordinates of the calibration fields as they are being observed during the year. As in Figure 2, for clarity, the right ascension axis spans two periods.

  

Figure: The same as in Figure 1, but for two separate solutions: low-airmass and high-airmass data. Squares - high airmass solution, triangles - low airmass solution. The absolute offset in $\Delta$ is arbitrary for these internally calibrated solutions.