Subject: I would Like to get into Double Star work with the Club

I would like to get in to Double star work with the Club dose any one in the club do it and would be willing to have a Person work with them on this type of work

I dont know to much about it but I will read and work Hard to learn and would like to Use the Big Scope at Colman to do this work
Thanks Keith

Re:I would Like to get into Double Star work with the Club

Hi, Keith.

I'm glad to hear you want to get into double stars. There are currently no members who do any type of double star observations, but that doesn't mean you can't start with a little help.

Double star work is tedious, and you should be aware of this. More than 60% of all stars are multiples, meaning that they are double, triple, quadruple, even sextuple (6) stars sharing a common center of gravity. With such a huge percentage of stars, there are tons of stars that need to be measured. Double stars are measured by determining the pair's orientation to one-another, based on the true north direction. This means that you must be able to accurately determine the position angle (PA) of the secondary star in regards to it's companion, the primary. Once that is determined, the separation must be measured, and again, this needs to be done with as much accuracy as possible. Then you must re-measure the star every-so-often to determine the orbital motion of the secondary around the primary, and keep doing this until a complete orbit can be established. Some stars (relatively few) will complete an orbit around their companion star within a dozen years or so, and others may take a decade or two. Some take well over 100 years to complete an orbit.

Obviously, there's a LOT of work involved with double-star work. To do it properly, a good quality measuring device is needed, and these are not cheap. They run from a few hundred dollars to well over $3000. I want to add a high-quality Bi-Filar Micrometer from Van Slyke Engineering to our grant proposal to allow Coleman Observatory to someday do quality double-star work which will be on par with the professional astronomer's work. Measuring the orbital period of two stars is still the most accurate way to "weigh" the mass of a pair of stars, and amateur astronomers or amateur observatories are often the most active in providing measurements for professional needs. Do a search for VSE to see some of the many astronomical accessories that they build and offer for sale.

This is more than you wanted to know, I realize, but it's an undertaking that will require more than simply finding and observing a pretty pair of stars such as Albireo.

Are you still interested? I hope so, so send me an email at caretaker@aoas.org and I can give you some target stars to practice with to get a feel for what double-star work really involves. If you don't have a scope, we can do a little of this next time you come to Coleman Observatory.

Later
Bob

Re:I would Like to get into Double Star work with the Club

OK Bob i would like to get with you on this at the Best Time for you and me both i have been doing a Little Reading on this and would Like to Talk to about How to go about setting this up I will Use My Scope at home to play with and be looking for Some doubleStars will Make notes on what I find the Best way i can I Have some Feild Notes and stuff I also Have a Small Laptop with some Star chats on it. I will get with you on the way I will do this with you at a Later Date. I was Just thinking do you or do you know someone that has the
Proper Eyepiecese to do this Kinda work I would Like to Bye or Use if I could
Thanks Keith PS I Have 1.25 Eyepiecese

Re:I would Like to get into Double Star work with the Club

Hi, Keith.

I'm sorry, but I don't have one of the eyepieces that can be used as a "beginner's tool" for binary star measurements. The proper name for gravitationally bound pairs of stars is BINARY Stars. The eyepiece I refer to is the MicroGuide eyepiece, but I can't remember whether it's a Celestron or a Meade item. I do know that these eyepieces are about $160 which is pretty steep.

I have the new issues of Night Sky magazine now, and it has a good starter's list for your first few double stars. Simply using the charts in this magazine and finding these particular stars for yourself would be a great way to start. I'll give you a copy as soon as you come up again. Please contact me a day in advance before you come up. School is about to start and I'm likely to be too busy to do much to help other than lend a helpful hint or two.

Let me know and I'll be glad to meet with you and talk over your plans.

Later
Bob

Re:I would Like to get into Double Star work with the Club

OK I will try to get my notes and stuff worked out and get with you on a Time to meet I will Show you what I have and How I intend to use it and you tell me if I am ok or not. I was going to Just Try to Keep a List of Ones that I find and List as much Information on the Stars that I can and At a Later time when I can get the Money to Bye Proper Equipment to Messure the stars I will add that to my Notes on each Double or Veriable Star I Have Listed information on and then work from there.

Re:I would Like to get into Double Star work with the Club

I'll be glad to help, Keith. And yes, you may use the 13" here at the observatory to do this work. We'll make a stop-down mask to help you see close pairs more easily and I'll help in any other way that I can. Maybe we'll get that big grant we want and be able to buy a proper Bi-Filar Micrometer someday.

Keep your fingers crossed with me on that.

I'll be here all weekend so if you want to come up and talk things over, feel free.

Bob

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