Return to the Cloudy Nights Telescope Reviews home page


Observing >> Double Star Observing

Pages: 1 | 2 | 3 | (show all)
Rutilus
Carpal Tunnel


Reged: 12/17/10

Re: Do you measure double stars?? new [Re: Rutilus]
      #5341787 - 07/29/12 02:51 PM Attachment (70 downloads)

Final one.

Post Extras: Print Post   Remind Me!   Notify Moderator  
rookie
Good Night Nurse
*****

Reged: 01/14/06

Loc: St. Petersburg, FL
Re: Do you measure double stars?? new [Re: Rutilus]
      #5342137 - 07/29/12 06:16 PM

Rutilus,
Very nicely done! It looks like fun too. Thanks for posting your pictures.

Fyi, I calibrated my ep with Psi Picium sep 30" for even numbers. If you ever decide to observe it you can double check your current reference measures to extrapolate your ep scale values.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Rutilus
Carpal Tunnel


Reged: 12/17/10

Re: Do you measure double stars?? new [Re: rookie]
      #5342258 - 07/29/12 07:34 PM

Many thanks Rookie, I will have to check out Psi Picium.
Just had a very short session this evening, thanks to the clouds that have rolled in again.

Only managed 5 readings for Alpha Her, got a P.A. of 107 degress, would have liked to obtain quite a few more
readings. Also think I need to increase the magnification,to help with making readings. Still this cheap to make
system appears to have potential.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Rich (RLTYS)Moderator
Post Laureate
*****

Reged: 12/18/04

Loc: New York (Long Island)
Re: Do you measure double stars?? new [Re: Rutilus]
      #5342869 - 07/30/12 06:21 AM

Looks good. Have fun.

Rich (RLTYS)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ed Whitney
sage


Reged: 07/08/10

Loc: Palm Coast, Florida
Re: Do you measure double stars?? new [Re: Rich (RLTYS)]
      #5366989 - 08/13/12 05:46 PM

Rutilus,

Any chance you could post info on how to make that neat device?

Does it measure PA and also separation? Or is sep measuring a separate operation?

Or, can you just post some info on its use?

I've been trying to get into DS observing and perhaps measuring but after reading some of the methodology have turned instead to simpler things.

Thing is, I would like to "just" be able to do this!

You're right about the clouds! Palm Coast has had rain and clouds now for weeks! When I get to see anything, it's usually thru a "mushy" sky. BUT! double stars are still doable! (sometimes)

Your pictures are great! Thanks!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Rutilus
Carpal Tunnel


Reged: 12/17/10

Re: Do you measure double stars?? new [Re: Ed Whitney]
      #5368831 - 08/14/12 06:22 PM Attachment (41 downloads)

Ed - I'm new to this measuring business so I'm very much at an experimenting phase at the moment. At the moment I'm
using the eyepiece to measure P.A. only. The eyepiece and protractor are fixed together with the 0 and 180 degree marker
fixed in line with one of the eyepiece grid lines. The outer board with the pointer on, is on a rotating collar that is locked
in place when required.
In use I get he primary star to travel along the 0 and 180 degree grid line with as little deviation as possible.
The outer ring with the pointer is rotated and locked in place at the 0 degree marker. This outer ring now
stays locked in place for the rest of the session.

With the primary star in the middle of the eyepiece, I rotate the whole eyepiece until the North/south
grid line bi-sects the primary and companion. Then it is just a matter of reading off the angle measurment
from the pointer on the outer board.
I always start the session by measuring a calibration star, at the moment I'm using Beta Cygni.

Not had much time to try it out recently due to weather and work, also been making a device to try and have a
go at measuring separation.
This was my first attempt, but I'm now working a MK2 version which is more compact and less weight.
Hope to have the new version near complition this weekend, so I can try it out. However here are a couple of
pictures of the prototype.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Rutilus
Carpal Tunnel


Reged: 12/17/10

Re: Do you measure double stars?? new [Re: Rutilus]
      #5368833 - 08/14/12 06:23 PM Attachment (41 downloads)

another.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Rutilus
Carpal Tunnel


Reged: 12/17/10

Re: Do you measure double stars?? new [Re: Rutilus]
      #5368835 - 08/14/12 06:24 PM Attachment (37 downloads)

last one.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Rich (RLTYS)Moderator
Post Laureate
*****

Reged: 12/18/04

Loc: New York (Long Island)
Re: Do you measure double stars?? new [Re: Rutilus]
      #5369555 - 08/15/12 05:57 AM

Cool looking, good luck with your measurements.

Rich (RLTYS)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ed Whitney
sage


Reged: 07/08/10

Loc: Palm Coast, Florida
Re: Do you measure double stars?? new [Re: Rich (RLTYS)]
      #5370083 - 08/15/12 12:51 PM

Rutilus, Wow! Thanks for the instructions and photos. Looks like you are trying to make one device to measure both sep and PA in one session. That's a goal worth achieving.

From your info, now see how the PA part works. It's elegantly simple!

The only stumbling block I see is the eyepiece itself. The Celestron Micro Guide eyepiece is very similar and has a grid I believe or reticle, but it is pricey at $180. But, it may not have the "correct" or similar grid lines your ep has.

Can the ep you use still be had somewhere's?

Also understand that the separation can be determined by the drift method, but think that means you need an eyepiece with a calibrated grid that will work with only the scope it was calibrated to. Someone correct me on this please, or add some other info about drift methods, etc.

FWIW, Years ago (1966) I took an eyepiece apart and inserted a homemade grid made from Lucite. I scratched thin lines in the Lucite at about 1/8in spacing in a cross-hatch pattern. Then I drilled a 1/8in hole in the side of the ep at its focal plane opposite to where the grid would be. I cemented a grain-of-wheat 1.5v bulb in the hole of the eyepiece and powered it with a battery and rheostat to vary brightness. It worked real well and the grid lines showed up nicely in focus too! But, the light was "white" that hurt night vision and the grid lines were not calibrated to anything definite. But it did work.

Good Luck with your measurement experiments and do look forward to reading how you are making out.

BEST to all!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Rutilus
Carpal Tunnel


Reged: 12/17/10

Re: Do you measure double stars?? new [Re: Ed Whitney]
      #5371983 - 08/16/12 06:23 PM

Quote:

Can the ep you use still be had somewhere's?






Ed - My eyepiece was bought around 7 years ago, and over the last couple of years I've been trying to to purchase
another one, but for the life of me I cannot find one that is the same. I guess I could buy a Celestron Micro guide,or the Baader version (which costs yet more) but I like building things and seeing what results I obtain from the homemade kit.
Last night I tried out my MK2 version for star separation, it gave some promising results. I need to do a bit of tweaking at the weeekend. It uses two moving field stops and does not require any field illumination, so should work for fainter stars. The Mk1 version had a fixed field stop which was placed over the primary, then by turning the micrometer handle the illuminated eyepiece moved until it covered the companion star. Then a reading was taken.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ed Whitney
sage


Reged: 07/08/10

Loc: Palm Coast, Florida
Re: Do you measure double stars?? new [Re: Rutilus]
      #5372849 - 08/17/12 10:04 AM

Rutilus, that is NEAT! I can almost visualize how it works too. Was wondering what the digital micrometer was there for. Can see you are trying to invent a system that can really get accurate results! Just GO FOR IT!

About your eyepiece; do you use a reticle insert? I almost get the impression there might not be one.

You know, it's the same old story about buying things. I buy something today and next week can't find it again!

BTW, here is a link that explains measuring doubles with a video camera I came across:

http://www.poyntsource.com/Richard/double_stars_video.htm

But for the un-initiated (like me), this is a bit of a heavy lift of a read.

All this kind of makes you wonder what kind of equipment the old timers used to measure doubles. Knowing how they did things in the past adds important perspective to where we are now.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ed Wiley
scholastic sledgehammer


Reged: 05/18/05

Loc: Kansas, USA
Re: Do you measure double stars?? new [Re: Ed Whitney]
      #5375123 - 08/18/12 07:38 PM

Actually, videos are easier, and can be as or more accurate that astrometric eyepieces or even micrometers. The "easier" is provided by Florent Losse's REDUC. To see how easy it can be, see:

http://www.astrosurf.com/hfosaf/uk/doeva1.htm

I use and recommend the DMK21 video camera. I hear Flea3s are great. You can even start with a used TouCam, VistaPro, etc.

The "drift method" with webcams and CCDs does have advantages in situations where there is a large difference in magnitude and is just as accurate when used correctly.

Ed


Post Extras: Print Post   Remind Me!   Notify Moderator  
Rutilus
Carpal Tunnel


Reged: 12/17/10

Re: Do you measure double stars?? new [Re: Ed Wiley]
      #5375575 - 08/19/12 08:21 AM Attachment (31 downloads)

Ed - Here is photo of my MK2 device. It is a working model at the moment, still needs wheels attaching to the turning bolt/screws and larger protractor wheel for attaching to the underside. I have removed the micrometer on this model, so that it can be more compact and weigh less. Last night I made 50 observations of Beta Cygni and measured the two up-right post with a micrometer. For getting into the ball park and quicker use, I think I can glue a standard measuring ruler to one edge and take a reading from that.

It has 3 grid lines made from monofilament fishing line.
One line is fixed (east/west) while the other two are moveable. The mono line is fantastic stuff, for when the target star is placed in the centre of the mono line you can still see the star. You get a tiny bit of light scattering, but the centre of the star is still visible.

Also attached is a drawing showing how the eyepiece view looks. One interesting thing happened, if I sit with a small white light on my lap, some of the light is refracted into the eyepiece view via the plexi-glass and this illuminated the outer two edges of the mono.
Please take a look at my other posting (Monofilament -neat stuff) this as now given me an idea of making an easy and cheap eyepiece for measuring star separation.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Rutilus
Carpal Tunnel


Reged: 12/17/10

Re: Do you measure double stars?? new [Re: Rutilus]
      #5375576 - 08/19/12 08:22 AM Attachment (26 downloads)

Eyepiece view.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Ed Whitney
sage


Reged: 07/08/10

Loc: Palm Coast, Florida
Re: Do you measure double stars?? new [Re: Rutilus]
      #5375795 - 08/19/12 11:19 AM

Rutilus,
Wow! Thanks for the continued info on your cool project! You are some inventer too! I can see you are trying to make a simple tool to measure both PA and separation almost at the same time. Can also see that astrometric eyepieces per se, can be somewhat limited and take many tries or "samples" to get a good reading.

Ed Wiley,
Thank you for the webcam link and info! Was thinking of getting/trying a webcam to photograph doubles, but this project is a bit stalled right now.

However, for the amateur, I think using an opto-mechanical device to measure doubles helps establish a connection with,... what has gone before.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ed Wiley
scholastic sledgehammer


Reged: 05/18/05

Loc: Kansas, USA
Re: Do you measure double stars?? new [Re: Ed Whitney]
      #5376821 - 08/20/12 12:08 AM

Beautiful piece of equipment, Rutilus, I would be interested to know your experience when it is operational. (Or is it now?)

Ed -- Thanks for the nod, Florent is a great guy and very accomplished double star observer who gives a lot back to the community in terms of both advice and very neat software. I admit to being lazy -- I just want to collect as much data with the minimum of effort in the least amount of time. Thus video....

Ed


Post Extras: Print Post   Remind Me!   Notify Moderator  
Rich (RLTYS)Moderator
Post Laureate
*****

Reged: 12/18/04

Loc: New York (Long Island)
Re: Do you measure double stars?? new [Re: Rutilus]
      #5377461 - 08/20/12 12:30 PM

That is so cool looking.

Rich(RLTYS)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Rutilus
Carpal Tunnel


Reged: 12/17/10

Re: Do you measure double stars?? new [Re: Rich (RLTYS)]
      #5388510 - 08/26/12 06:59 PM Attachment (31 downloads)

Ed - The device is fully working, since my last post I've
obtained some 0.06mm mono line and fitted the moving arms with 25 strands. The results I've been getting have been very good. For quite close pairs I use the visible grid lines of the 25 strands for measuring the separation.

For much wider pairs I use the two moving arms and take a reading from the micrometer. For my own use I would have been happy getting the separation to within one arc second, but over the last three nights I've been getting results which are better than this so I'm very pleased indeed.

If I convert the cost of the project into U.S. Dollar, then it comes out at $36 and that includes the cost of the micrometer. BTW, I got hold of digital caliper which works just as well for me and cost half the price of what the micrometer did.

Here is a photo of the 25 strands mounted onto the moving arm. Mounting them actually turned out to be an easy job.
So I'm going to go ahead and make an eyepiece version of a micro guide eyepiece.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ed Wiley
scholastic sledgehammer


Reged: 05/18/05

Loc: Kansas, USA
Re: Do you measure double stars?? new [Re: Rutilus]
      #5392239 - 08/28/12 09:11 PM

Sounds like you had a bunch of fun and produced a very useful and innovative micrometer.

Good Measures!

Ed


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | 3 | (show all)


Extra information
0 registered and 5 anonymous users are browsing this forum.

Moderator:  PJ Anway, Rich (RLTYS), rflinn68 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 6148

Jump to

CN Forums Home




Cloudy Nights Sponsor: Astronomics