March 2011 Meeting Notes
Discussion of business items this month included presentation of our new club banner, discussion of our spring schedule and plans for public events, discussion of plans for school events, and a brief reminder that the Globe at Night project needs sky brightness measurements from local amateurs.
Introduction to Spring Constellations - Daryl Doughty
Prior to this month's program, Daryl Doughty presented a short talk on Spring Constellations. He pointed out that, compared to the bright stars and distinctive constellations of the winter sky, the spring constellations are generally dimmer and somewhat anticlimactic. Using a star map, Daryl highlighted several Spring constellations, including Leo, Bootes and Virgo. Since the latter constellation contains the Autumnal Equinox, the Sun's location at the start of Autumn, this was a good jumping off point for a discussion of the Earth's motion and its effects on celestial coordinates.
Daryl explained that the angle of the Earth's rotational axis with respect to the plane of the solar system causes the celestial equator (the projection of the Earth's equator onto the celestial sphere) to be inclined at 23.5° to the ecliptic (the path that the Sun and planets follow across the sky). This results in two nodes, or intersection points, between the celestial equator and the ecliptic, on opposite sides of the sky. These are the equinoxes. The Sun, moving along the ecliptic passes through the Autumnal Equinox, in the constellation Virgo, in September, and the Spring Equinox, in the constellation Pisces, in March. Expanding further, Daryl touched on the "precession of the equinoxes", which is the roughly 26,000 year cycle of the "wobble" of the Earth's polar axis, much like that of a spinning top. This long term motion results in the gradual movement of the equinoxes along the celestial equator, from one constellation to the next, and is the underlying phenomenon that has led to such ideas as "The Age of Aquarius".
The Cheapskate Astronomer’s Introduction to Astrophotography
Part II: GREMLINS
Speaker - Rick Bryant
Presenting the second in his multipart astrophotography series, Rick Bryant discussed in detail the sixteen most insidious astrophotography gremlins that bedevil amateur astrophotographers. Among these are such things as weather, vermin, equipment failure, alignment and tracking issues, and even image loss. For each of these gremlins Rick analyzed the contributing factors and provided practical advice and recommendations for minimizing or eliminating the problems. In some cases a few simple steps could overcome the problem, while in other cases, such as equipment failure, adaptation is often the answer. In a few cases, such as bad weather, rescheduling may be the only option.
But in all cases Rick stressed the importance of planning ahead. Most of the gremlins can be significantly reduced, if not entirely eliminated, by careful preplanning. In addition to establishing a list of desirable targets, he emphasized the need to spend up front time preparing for every aspect of an imaging session. This includes location and timing considerations, lighting and sky conditions, image scaling and exposure, equipment preparation and redundancy, and secondary target alternatives. Among the most important preparations is a complete mock set up indoors to verify that all equipment is present and in good working order. This setup is then followed by a careful and organized packing process, with many small items, such as cables, going into sealed and labeled plastic bags. Organization is key to efficient assembly and operation of the entire system in twilight or night time conditions.
Clearly Rick's impressive successes in astrophotography are the result of a lot of time, effort, thought and preparation. Those of us aspiring to similar successes have learned a great deal from Part I and Part II that will increase our own chances of astrophotography success. But there's more to learn. We have Part III to look forward to next fall.
Monday, April 4, Daryl Doughty will present "DSLR Astrophotography" in the Bartlesville Public Library Meeting Room. For more information, see the meeting announcement on our website home page at <http://sites.google.com/site/bartlesvilleastronomyclub/> .
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