NGC6838 (M71) 19:53:46.49 +18:46:45.1 NGC7078 (M15) 21:29:58.33 +12:10:01.2 Both are close to us (so ~10sec of exposure time should reach the lower red giant branch) and moderatly extended on the sky. More importantly, there are many sources listed in the corresponding catalogs of Stetson's photometric standards. Thus, assuming that transparency is not really bad, we could use the test exposures to get a first `real-life' estimate of the zero point of the filters. Both clusters are observable through >~the first half of the night. For very late in the night there is no obvious good choice of globular cluster; Pal 1 is close to us and circumpolar, but it's very sparse, NGC2419 is well populated, but much further away.