Showing posts with label Observatory. Show all posts
Showing posts with label Observatory. Show all posts

Wednesday, January 28, 2009

Sidewalk astronomy

If you are an amateur astronomer, I do recommend that you try sidewalk astronomy. I have found it to be a truly rewarding experience. People are very appreciative of the effort and always have a great time. It is nice to take along a friend or another amateur astronomer for moral support. In fact, several telescopes really make it an event that will attract a crowd. The best time to go out is between First Quarter and Full Moon when deep sky observing is not possible. People love to see the moon through a telescope and are usually awestruck! When I started sidewalk astronomy, I never observed the Moon or planets for more than a minute or two during a session as I felt is was a waste of my time since I was only interested in deep sky objects. Now I enjoy lunar and planetary observing and have learned a great deal about these objects through my research which I conducted in order to better answer questions I was asked by the public. Anyways the best places to set up are areas of high foot traffic such as Barnes and Noble, and Starbucks. Attracting a crowd is easy when you have a telescope set up.Here is a picture of a small group around my scope in a Albertson's Supermarket parking lot. I had over 30 people come over to my scope and everyone enjoyed viewing the moon that night.




March, and the Messier Marathon grows near! AGAIN!

In the latter part of the eighteenth century, astronomers gained fame and wealth by discovering comets, still thought to foretell the future. One of these skywatchers was Charles Messier, who observed from Paris. Occasionally, M. Messier would chance upon a whitish blob, such as comets look when they are first seen. On August 28, 1758, he spotted such an object. Unfortunately, after watching it for a few evenings, he found that the blob maintained the same position among the stars, unlike a comet. Determined not to be fooled if he encountered the same object in the future, Messier determined and saved its coordinates. Over the next several decades, with the help of his colleague Pierre Méchain, many other entries were made in a list of deceivers. The list now contains 110 objects (though historians quarrel about the exact number), and are referred to as M1 through M110. A few objects had incorrect coordinates or may have been duplicates. It is generally agreed now that M101 and M102 are the same.This list has become the beginning observer's guide book, for it contains most of the interesting celestial objects to be found with a small (4" diameter) telescope. These objects include reflection nebulae, emission nebulae, planetary nebulae, open clusters, globular clusters, spiral galaxies and elliptical galaxies. Objects of all these types can look like a blob. (Modern telescope usually see open clusters as individual stars, but with the crude telescope Messier used many clusters looked like small clouds.) Interestingly enough, the first false comet Messier discovered was different from the rest. M1 is the Crab Nebula, the detritus from a supernova explosion.I mention all this because around the spring equinox it is possible to see all the Messier objects in a single night (sunset to sunrise). Only at this time are all of them far enough from the Sun to be seen sometime during the night (although M30 is quite difficult from latitude 40° north). Amateur astronomers call such an attempt a Messier Marathon. You'll need a dark sky, a medium-sized scope (4 to 8 inches in aperture, depending on experience), coffee, snacks and warm clothing. Of course you can see all of Messier's menagerie in bite-size chunks -- twelve monthly expeditions, four seasonal trips and so forth. But where's the fun in that? ?

Renting the 60" Mt. Wilson reflector telescope!

My club the High Desert Astronomical Society is confirmed for a night of observing at the 60" reflector up on top of Mt. Wilson. The outing is scheduled for April. This is going to be an awesome experience and I can hardly wait to go. Here is a little bit of the history of the telescope.The 60-inch reflector at Mount Wilson was constructed in 1908. Hale used the 60-inch glass blank that his father purchased for him in 1896. George Ritchey finished the glass blank into a mirror of the proper size in the Mount Wilson optical shops in Pasadena, California. Ritchey also designed the tube and mounting for the telescope, which were built by the Union Iron Works in San Francisco. The design drew heavily on experience gained with the use of the 36-inch Crossley reflector at the Lick Observatory.The telescope is supported by a 15-foot tube, which contains eight separate steel tubes and cross-braces designed to provide a stiffer truss and support system than was originally found in the Crossley reflector. The mirror is supported by a system of levers in a steel housing attached to the bottom of the tube and is fork-mounted on the polar axis. Just below the fork is a 10-foot diameter mercury float-bearing system designed to carry the weight of the telescope. The telescope is moved with electric motors. The 58-foot dome of the telescope is built from steel, on a concrete foundation, with double walls for the free circulation of air. This design is necessary to minimize temperature variations which could alter the shape of the mirror.Hale designed the optical system of the 60-inch reflector so that the instrument could be used for a variety of purposes. As a Newtonian telescope it was an f/5 instrument for photography and low-dispersion spectroscopy. In a modified Cassegrain configuration, using a convex hyperboloidal mirror before the prime focus and a plane mirror at the lower end of the tube to reflect light to the side of the tube, it could be used at f/16 for spectrography and an f/20 for photography. Finally, as an f/30 Coude, light was reflected by an appropriately geared mirror through the hollow polar axis into a constant-temperature room housing a large spectrograph. This flexible optical system, which allowed the telescope to be used for photographic and spectrographic purposes, was a model for future large reflectors. After the trip I will write a blog and post photos of the trip. Now maybe we will do the same thing at the Mt. Palomar Observatory next year!

Small Astrograph setup

Here is a pic of my new setup I've been working on the past month. Orion 4.25" (114mm) F3.5 newtonian with rings and dovetal mounted on the Celestron CG-5 equitorial mount. I added the Celestron dual axis drive system, some old knobs from http://www.msplinks.com/MDFodHRwOi8vd3d3LmZvY3Vza25vYnMuY29t , my LXD55 polar scope and also did more mods to the DeWalt construction tripod to make it very rigid. I used Birch to make the eyepiece tray- leg speader and I am in the process of making a wheely bar system to roll it out and level the scope. I disassembled the mount completely then soaked and cleaned the original grease from all the interior parts, deburred the wormgear, and relubed all of the bearing components with white lithium grease which the manufacturer should use. After that I made critical adjustments to the wormgears and now the mount motions are smooth as butter with no backlash at all and the tracking is dead on. This is turning out to be a really fun project!
Now my next project on this system is to solder in an ST-4 usb autoguider port which I will obtain from http://www.msplinks.com/MDFodHRwOi8vd3d3LnNob2VzdHJpbmdhc3Ryb25vbXkuY29t . My 102mm Maksutov will be mounted piggyback as a guide scope as soon as I get a set of mounting rings. The Maksutov alone is quite a nice scope giving nice images of planets, the moon, and brighter nebula. It is also excellent for splitting double stars. This whole project came about by a myspace friend ( Dave )sending me the EQ head at no charge or this project would have never started. Since I had open heart surgery I have ALOT of idle time and lack of funds, so this project was just what the doctor ordered! I can't thank you enough Dave.The info for the CG-5 mount at http://www.msplinks.com/MDFodHRwOi8vd3d3LmFzdHJvbm9teWJveS5jb20= is priceless. There is step by step instructions there for doing the mount tune up for the CG5 and LXD55/75 mounts. If you have one of these mounts I would recommend this project.

Dual Speed Crayford Focuser w/ 10:1 Ratio



I have just installed a new GSO (Guan Sheng Optical) dual speed low profile crayford focuser with a 10:1 ratio on my 12.5" Dicovery PDHQ Dob. The focuser really has a nice feel and finish, better than I had expected. The focuser and the 1.25" adapter both utilize compression rings which will save my eyepieces from set screw marks on the barrels. I ordered it through Agena Astro and it arrived in 2 days. They always treat their customers right. Installation was a snap, I only had to drill 2 mounting holes in the telescope tube and that's it. I bolted it on and re-collimated my scope. My heaviest eyepiece setup is 4 lbs. and this focuser lifts it with no problems at all which seems to be the concern of some folks but that sure seems unfounded by me. With the micro focus I have been able to squeeze out the finest details from Jupiter and other objects.

Cleaning your telescope's primary mirror.

Okay here is the technique I use for cleaning my primary mirror. In the 4 years I have owned my scope, I have cleaned the primary and secondary mirror twice. Since I live in the desert my scope picks up alot of dust and I do hold off as long as possible before I do this. My mirror costs $850.00 to replace or $250.00 to recoat so I don't take cleaning it lightly. I have cleaned over 20 primary mirrors and have not had any problems with this technique. Here is the formula for the cleaning solution.....
2 cups distilled water
1/8th cup of 90% Isopropyl Alcohol
3 small drops of clear dishwashing liquid
I gallon of distilled water for rinsing.
1 bag of sterile cotton balls
You can get distilled water at the grocery store for around a buck a gallon.
Add the 2 cups of distilled water into a bowl, then add the alcohol, then the dishwashing soap (in that order) then mix with a spoon. you don't want the soap to foam up your mixture.
Remove the primary mirror from the mirror cell and blow off the dust with your breath. I don't use canned air because the propellant can damage your mirror coatings instantly. Fill your kitchen sink half full with lukewarm tap water and place the mirror in water face up and let it soak for around 10 to 20 minutes. Pour your cleaning solution in a bowl and add about 20 cotton balls into the solution. Take the mirror out and place it on a towell and keep it wet with the distilled water. Now take a soaked cotton ball from the solution and place it in the center of the mirror. Now drag the cotton ball using only its own weight (don't push down on it) to the edge of the mirror and throw the cotton ball away. Take another soaked cotton ball and do the same thing. Work your way in a circle around the mirror only pulling the cotton balls from the center to the edge. NEVER use a cotton ball twice. Always throw them away after 1 pass. After going around the entire mirror tilt the mirror up (in the sink) and rinse with the distilled water. The distilled water will mostly run off in a solid sheet . For any remaining spots of water use a paper towell folded to a small point and just barely touch it to the water droplet and it will soak it off of the mirror. That is pretty much it. Don't resort to cleaning the mirror unless it is REALLY dirty. If you end up 1 or 2 water spots don't worry about them for they will not affect your viewing at all.