Chasing the Solar Eclipse

Our speaker this month is local amateur astronomer and veteran eclipse chaser David Buchla. David and his wife Lorraine have been to eight total eclipses and one annular eclipse and will view his ninth total eclipse in Russia this summer. His talk will focus on the mechanics of eclipses, the saros cycle, eclipse photography, and travel highlights from the 2001 eclipse in Zimbabwe and the 2006 eclipse in Egypt. David can answer questions about what to expect if you are considering traveling to one of the eclipses in the near future (Russia this summer, China in 2009, or Easter Island in 2010). The longest eclipse of the 21st century is coming up in 2009 and is part of Saros cycle 136, responsible for the longest eclipses in history.

Astronomy Boot-Camp 101 - From Scope to Sky

April 26, 2008, 3:30 pm to 6:00 pm (Imaginarium), 7:00 pm to 10:00 pm (Ballfield).

The goal of this event is to get people comfortable with astronomy, the equipment and the sky, so they can enjoy it in their back yards, on camping trips, or wherever they might want to observe.

Overcome your fear of astronomy with an afternoon and evening learning the fundamentals of astronomy. Astronomy Boot Camp will teach you how to use a telescope and observe the night sky so that you may get out under the skies in yor own backyard and beyond! Beginnners and novices from 9 to 99 will enjoy this fun and informative event. If you have a telescope make sure to bring it along!

This hand-on workshop event will consist of three different sessions and an evening sky show. Sessions will include a Sky workshop, Equipment Workshop and a Meet & Greet - Show & Tell; participate in all three or pick and choose. After an afternoon of practical learning, put your skill to work at the evening sky show.

NCA is supporting this program and will need volunteers for both the program at the Imaginarium and the sky show at the Ballpark. We will need volunters to provide both scopes and to assist participants that bring their own scopes (set up, alignment, use, etc.).

Daylight Collimation of a SCT or Maksutov-Cassegrain

by Robin Casady


Checking the optical alignment on Schmidt-Cassegrain or Maksutov-Cassegrain telescope can be easily done in broad daylight. It just requires looking into the front of the scope from a very specific location. Finding this location is not difficult. Set up the telescope so the OTA is level and at a height where you can easily look straight into it. Position your eye in front of the OTA about as far away from the front as the focal length of scope. For a scope with a focal length of 2700mm you would stand almost nine feet away. Look into the scope and find the shadow of the central obstruction (CenOb). Position your eye so the shadow is just slightly larger than the CenOb. Move your head until the CenOb and the shadow are concentric. Your eye is now in the correct location to judge the alignment of the optics. You will notice several light and dark rings. If they are perfectly concentric, the scope is properly collimated. If the rings are not concentric, the scope is out of collimation. If you wish to adjust the collimation, it is advisable to set up a white card with a pinhole located at the correct eye position. This makes it easier to keep your eye in the right place, and lets you go back and forth to the scope to make adjustments. I use a photo light stand and clamp to hold the card in place. The light stand has a vertical adjustment the makes it easier to set it to the right location. I've found that I can collimate a scope with a fair amount of accuracy by using the white card. Only on a very steady night can I improve upon it with a star. The other night, in average seeing, I checked a Maksutov at 300x on a star and it seemed fine. When I checked it with the daylight method, it was obviously out of collimation. I was quite surprised.	Blue is telescope, black and white are reflections

	Align your eye so the shadow is concentric with the central obstruction (CenOb).

			This telescope is out of alignment. The CenOb shadow is concentric with the CenOb, but the other rings are not concentric

		This telescope is properly collimated. All rings are concentric.

Above used by permission of Robin Casady. Robin Casady is the owner of Astro Accessories, offering Tandem Bars, Triad Bars, Dovetail Plates and Counterweights for a wide range of telescope mounts.

Please visit http://RobinCasaday.com for a complete listing of Astro Accessories and other astronomy related products.

May constellations

May skys are in transistion between the galaxy rich skies of early spring and the summer Milky Way.
At midnight during the mid-month period, Ursa Minor, Draco, Bootes and Libra dominate the meridian. Virgo is to the West and Lyra and the summer milky way are in ascendency in the East.
The constellations on the meridian while rich in galaxies and some planetaries are deficient in bright objects for small to medium scope.
You will need a good sky chart in order to find the majority of objects. “Sky Atlas 2000" by Wil Tirion is perhaps the best atlas available for the visual observer.

Ursa Minor (Umi, Urr-sah mi-nor, The Lesser Bear)-

Ursa Minor is the little dipper with the end of the handle anchored by Polaris
Check out Gamma Umi, a short period variable (a 3 hour period).

Draco map

Draco (Dra, DRAY-ko, The Dragon)-

NGC 5907 - mag 13.5 - 12'x 2'
NGC 6543 - mag 9 - 18" - "The Cats Eye Nebula" (planetary nebula - small but bright)
NGC 6503- mag 12 - 7'x 3'

Bootes map

Bootes (Boo, boe-OH-teez, The Herdsman) -

NGC 5248 - mag 11 - 6'x 5' - an SBbc spiral
NGC 5466 - mag 9 - 9.2' - A globular cluster

Hercules map

Hercules (Her, HER-kyou-leez) -

M 13 - mag 5.8 - 23.2' - The Great Cluster.
M 92 - mag 6.4 - 12.2' - A globular cluster.

Libra map

Libra (Lib, LIB-rah, The Scales)-

NGC 5897 - mag 8.5 - 8.7' - A loose globular cluster

An excellent resource is “The Interactive NGC Catalog Online” at http://seds.org/~spider/ngc/ngc.html
This resource gives you access to NED, SIMBAD, Digital Sky Survey and other excellent resources for planning your observing session.

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2008 April 16
Flagstaff sky

A Protected Night Sky Over Flagstaff
Credit and Copyright: Dan & Cindy Duriscoe, FDSC, Lowell Obs., USNO

Explanation: This sky is protected. Yesterday marked the 50 year anniversary of the first lighting ordinance ever enacted, which restricted searchlight advertisements from sweeping the night skies above Flagstaff, Arizona, USA. Flagstaff now enjoys the status of being the first International Dark Sky City, and maintains a lighting code that limits lights from polluting this majestic nighttime view. The current dark skies over Flagstaff not only enable local astronomers to decode the universe but allow local sky enthusiasts to see and enjoy a tapestry contemplated previously by every human generation. The above image, pointing just east of north, was taken two weeks ago at 3 am from Fort Valley, only 10 kilometers from central Flagstaff. Visible in the above spectacular panorama are the San Francisco Peaks caped by a lenticular cloud. Far in the distance, the plane of the Milky Way Galaxy arcs diagonally from the lower left to the upper right, highlighted by the constellations of Cassiopeia, Cepheus, and Cygnus. On the far right, the North America Nebula is visible just under the very bright star Deneb.

Astronomy cartoon - http://astro.wsu.edu/worthey/astro/html/im-sydney-harris/3million.gif

Suggestions, comments, articles/pictures - Contact NCA Newsletter

Meeting May 12, 7 pm to 9 pm
Madelyn Helling Library Community Room

Public Welcome

This issue

NCA Potluck Dinner

Chasing the Solar Eclipse

Astronomy Boot-Camp 101 - From Scope to Sky

Daylight Collimation of a SCT or Maksutov-Cassegrain

May constellations