29 March 2007 W. Romanishin (wjr@nhn.ou.edu) The 18 March 2007 occultation of a star by Pluto was observed at the University of Oklahoma Observatory, Norman. IAU Code: H30 (see below for coordinates) Observer: W. Romanishin (wjr@nhn.ou.edu) Telescope: 0.4 meter Meade Schmidt-Cassegrain CCD: Apogee AP7p 512x512 SITEe back-illuminated chip Filter: Optec 23A (blocks light blueward of about 580 nm- red side of observed passband defined by CCD- so passband is approximately "R+I") Exposures: 4 seconds Dead time between exposures: ~2.2 seconds Timing: Times given are midpoints of exposures. Times from computer, which was set to WWV to within about 1 second. Observatory info (IAU Code= H30) CON W. Romanishin, Physics and Astronomy Dept., U. of Oklahoma, Norman OK 73019 CON [wjr@nhn.ou.edu] COM observatory name= University of Oklahoma Observatory, Norman COM Long. 262 33 21 E, Lat. 35 12 09 N, Alt. 372m Pluto subtraction: Due to travel and bad weather, I was unable to re-observe the occulted star until 28 March. On 28 March, the observed magnitude difference between the occulted star and reference star ~45 arcsec west was 2.762 (+- 0.006) magnitudes. Using this star magnitude, I derived the flux of Pluto at the time of occultation and subtracted Pluto's flux from that of Pluto+occulted star during the occultation event. Contact me if you want to use these data in a publication. Data table: column 1: time in minutes from 10 UT 18 March 2007 for midpoints of 4 second exposures. column 2: time in seconds from 0 UT 18 March for midpoints of 4 second exposures column 3: observed magnitude difference between Pluto+occulted star and reference star 45 arcsec west. Difference measured in an aperture of 4 pixels (4.98 arcsec) diameter. This gave optimum signal to noise for Pluto+occulted star. column 4: flux ratio between the occulted star (Pluto light subtracted) and reference star 45 arcsec west. column 5: same as column 4, but star flux normalized to 1.00 outside occultation 52.03 39121.9 1.759 0.0776 0.9874 52.13 39128.0 1.727 0.0835 1.0627 52.24 39134.2 1.780 0.0738 0.9391 52.34 39140.4 1.742 0.0807 1.0271 52.44 39146.6 1.771 0.0754 0.9597 52.55 39152.8 1.738 0.0814 1.0366 52.65 39159.0 1.770 0.0756 0.9620 52.75 39165.2 1.755 0.0783 0.9967 52.86 39171.4 1.732 0.0825 1.0508 52.96 39177.6 1.743 0.0805 1.0248 53.06 39183.8 1.773 0.0750 0.9551 53.17 39190.0 1.769 0.0757 0.9643 53.27 39196.3 1.750 0.0792 1.0084 53.38 39202.5 1.749 0.0794 1.0107 53.48 39208.8 1.760 0.0774 0.9851 53.58 39215.0 1.773 0.0750 0.9551 53.69 39221.2 1.731 0.0827 1.0532 53.79 39227.4 1.742 0.0807 1.0271 53.89 39233.7 1.738 0.0814 1.0366 54.00 39239.9 1.762 0.0770 0.9804 54.10 39246.1 1.766 0.0763 0.9712 54.21 39252.3 1.746 0.0799 1.0177 54.31 39258.5 1.731 0.0827 1.0532 54.41 39264.7 1.779 0.0739 0.9414 54.52 39270.9 1.719 0.0850 1.0819 54.62 39277.1 1.758 0.0777 0.9897 54.72 39283.4 1.745 0.0801 1.0201 54.83 39289.6 1.790 0.0720 0.9165 54.93 39295.8 1.790 0.0720 0.9165 55.03 39302.0 1.764 0.0766 0.9758 55.14 39308.2 1.827 0.0655 0.8344 55.24 39314.5 1.832 0.0647 0.8236 55.34 39320.7 1.838 0.0637 0.8106 55.45 39326.9 1.882 0.0564 0.7176 55.55 39333.1 1.845 0.0625 0.7955 55.66 39339.3 1.932 0.0484 0.6163 55.76 39345.5 1.869 0.0585 0.7447 55.86 39351.7 1.914 0.0512 0.6522 55.97 39357.9 1.975 0.0419 0.5329 56.07 39364.2 1.946 0.0463 0.5888 56.17 39370.4 1.961 0.0440 0.5597 56.28 39376.6 1.995 0.0389 0.4952 56.38 39382.8 1.951 0.0455 0.5791 56.48 39389.0 1.996 0.0388 0.4934 56.59 39395.3 2.020 0.0353 0.4491 56.69 39401.5 1.969 0.0428 0.5444 56.80 39407.7 1.965 0.0434 0.5520 56.90 39414.0 1.976 0.0417 0.5310 57.00 39420.2 1.999 0.0383 0.4878 57.11 39426.4 1.927 0.0492 0.6262 57.21 39432.6 2.012 0.0364 0.4637 57.31 39438.8 2.002 0.0379 0.4822 57.42 39445.0 1.945 0.0464 0.5908 57.52 39451.3 1.961 0.0440 0.5597 57.62 39457.5 1.939 0.0473 0.6025 57.73 39463.7 1.924 0.0497 0.6322 57.83 39469.8 1.932 0.0484 0.6163 57.93 39476.0 1.888 0.0554 0.7052 58.04 39482.3 1.942 0.0469 0.5966 58.14 39488.4 1.884 0.0560 0.7134 58.24 39494.6 1.842 0.0630 0.8020 58.35 39500.8 1.912 0.0515 0.6563 58.45 39507.0 1.842 0.0630 0.8020 58.55 39513.2 1.886 0.0557 0.7093 58.66 39519.4 1.813 0.0680 0.8652 58.76 39525.7 1.781 0.0736 0.9369 58.86 39531.9 1.781 0.0736 0.9369 58.97 39538.1 1.785 0.0729 0.9278 59.07 39544.3 1.773 0.0750 0.9551 59.17 39550.5 1.783 0.0732 0.9323 59.28 39556.7 1.732 0.0825 1.0508 59.38 39562.9 1.742 0.0807 1.0271 59.48 39569.1 1.732 0.0825 1.0508 59.59 39575.3 1.777 0.0743 0.9460 59.69 39581.5 1.748 0.0796 1.0130 59.80 39587.7 1.778 0.0741 0.9437 59.90 39593.9 1.751 0.0790 1.0060 60.00 39600.2 1.759 0.0776 0.9874 60.11 39606.4 1.731 0.0827 1.0532 60.21 39612.7 1.766 0.0763 0.9712 60.31 39618.9 1.776 0.0745 0.9482 60.42 39625.1 1.732 0.0825 1.0508 60.52 39631.3 1.746 0.0799 1.0177 60.62 39637.5 1.740 0.0811 1.0319 60.73 39643.7 1.736 0.0818 1.0413 60.83 39649.9 1.774 0.0748 0.9528 60.93 39656.1 1.762 0.0770 0.9804 61.04 39662.3 1.770 0.0756 0.9620 61.14 39668.4 1.735 0.0820 1.0437 61.24 39674.6 1.745 0.0801 1.0201 61.35 39680.8 1.776 0.0745 0.9482 61.45 39687.1 1.757 0.0779 0.9920 61.55 39693.3 1.724 0.0840 1.0699 61.66 39699.4 1.772 0.0752 0.9574 61.76 39705.6 1.745 0.0801 1.0201 61.86 39711.9 1.773 0.0750 0.9551 61.97 39718.1 1.759 0.0776 0.9874