In conclusion

To echo Hartmann, the simplest interpretation of these photos is that they, indeed, show a distant object. However, simplicity does not necessarily imply truth. ·Further research will be necessary to resolve this case "once and for all."

NOTE: APPENDIX A provides further data and analysis regarding the brightness of a white vertical surface and also provides data to support the veiling glare analysis presented in the text.

The following images also provide further information:

Blbliography and Footnotes

1. Scientific Study of Unidentified Flying Objects, E.U. Condon, Ed. (Bantam, 1969, pg. 396)
2. P.J. Klass, UFO's Explained, Random House, New York (1974)
3. R. Sheaffer, private communication
4. C. Grover, private communication (Grover was a Navy professional photographer)
5. Note that the range increases with assumed darkness of the bottom of the UO. If the bottom were black, B(r,O) = 0, the range would be about 2.4 km with gamma = 0.6·
6. Handbook of Chemistry and Physics, Forty-first Edition, (Chemical Rubber Publishing Company, Cleveland, Ohio 1960)
7. Measurements have been made of the brightnesses of the bottoms of several model UO's made of uniformly translucent materials. The models were oriented with respect to the sun in the same way as it would have been if the UO in photo 1 were a model lit by the morning sun. The brightness of the bottom of each model was measured as a function of position, with the "front" part being that part closest to the sun (in photo 1 the front part of the elliptical image is at the right hand side). The front part of the bottom was found to be from 20% to 40% brighter than the back part for each model. However, the brightness variation of the image of the bottom of the UO in photo 1 is only (+/-)5% with the back somewhat brighter than the front. These experiments, and the comparison with the image of the UO, suggest that if the UO were a nearby model it was not made of a uniformly translucent material.
8. W. Spaulding, GSW Inc., Phoenix, Arizona, private communication. An electron microscope test of the negatives has shown that the grain structure is consistent with that of known Verichrome film, but not with Plus X.
9. However, experiments (e.g. R. S. Laurcnce and J. W. Strohbehn, "A Survey of Clear Air Propagation Effects Relevant to Optical Communications," Proc. IEEE 58, 1523 (1970))have shown that there is a period of time just after sunrise when the turbulence is quite low. The pictures may have been taken during this period. If this were so, even a very small amount of atmospheric edge distortion would correspond to a rather large distance to the object.
10. I thank Charles Grover, William Hartmann, and Robert Sheaffer for instructive comments on earlier versions of this paper. I also thank NICAP for free access to their files and for assistance in obtaining the negatives.
11. Note added in proof: the fog density of the negatives is consistent with the range of values expected when gamma = 0.5 to 0.6, but is larger than expected when gamma = 0.3. The brightness of the illuminated part of.the distant white wall and the brightness of the shaded part of the same wall have been calculated for gamma = 0.3, 0.4, and O.6. The calculated brightness ratios, (illuminated/shaded), are, respectively, 10(+/-)2, 3(+/-)0.5, and 2(+/-)0.2. A field measurement of the same ratio under conditions similar to those when the pictures were taken yielded 1.5 to 2. Thus both the fog density measurement and this brightness ratio measurement indicate that gamma is greater than 0.3 and perhaps even greater than 0.6.

Postpublication Notes

a) Experiments with a Kodak Vigilant lens of 153 mm focal length yielded the same or lower values of veiling glare than assumed in this paper.
b) Shadows on a surface that faces the east when the sun was in the west have been observed when a cumulous cloud was in the sky to the east of the surface.

NOTE 1 ADDED IN APRIL, 2000: A larger paper in which I discussed the "rest of the story", including cloud shadows and verbal testimony, was presented at the second conference of the Center for UFO Studies which occurred in 1981. That paper was eventually published by the Center in the Spectrum of UFO Research in 1988. See "The McMinnville Photos," the companion paper to this one.