Kim - Although you are probably returning from the Capitol Reef star party and your question is dated, here are some follow-up notes. Kim wrote:
So, if I've done this right, the anti-solar point should be about midway and north of a line between Neptune and Uranus. Correct?
For the sighting opportunties from Sept 6 to Sept 20, it is closer to north of Neptune, near beta Aqr (Sadalsud), at around 11:00 MDT. There are a couple of other parameters involved in identifying likely gegenschien sighting opportunities in addition to the basic constraint of identifying the anti-solar point. These additional constraints are related to the counter-glow's faintness relative to other objects. Those constraints are: 1) The Moon should be below the horizon - preferably less than 6 degs alt. 2) The Milky Way's disk should be more than 20 degrees away from the gegenschien region. 3) The gegenschien region should be at maximum altitude to minimize atmospheric extinction. These constraints generally combine to make the most likely sighting opportunities to occur when the anti-solar point transits the south meridian, the Moon is down, and the galactic disk is near the horizon. The link table that I posted time that meet those constraints with alt-az coordinates. The times are good for all Utah observing points regardless of latitude. I did not give right ascension and declination coordinates only alt and az. Most of the points are within 10 degrees alt and 10 degrees az of where the ecliptic crosses the meridian at the standard time listed in the table. http://members.csolutions.net/fisherka/astronote/astromath/2007GegenschienEp... As to photographing the gegenschien, Covington's _Astrophotography_ recommends: 1) 2 to 5 minute exposures at 400 ISO. 2) Take two images 1 hour apart to confirm that you have captured the gegenchien. Wide-field lenses can cause a brightening effect in the central field. The two photos should show the heightened brightness move with respect to the stellar background. In surveying web photos, I do not see anyone using specialty filters or polarizers to enhance the image. The poorest web image used a DSLR with a IR cut-off filter, but this is to be expected since the gegenschien is brighter in the near-IR. Polarizers were used in Spacelab experiments to image the zodical light in the 1970s. Because of the faintness of the gegenschien, I'd recommend first trying without any filters that would reduce the amount of captured light. Once you can capture an image, then try with Chuck's recommended polarizing filter. - Kurt _______________________________________________ Sent via CSolutions - http://www.csolutions.net