Image of the day

Captured by
Craig Bobchin

Coathanger CR 399

About Astromart

My Account

New to Astromart?

Register an account...

Need Help?

Posts Made By: Alex McConahay

August 15, 2005 07:08 PM Forum: Politics

Re: Justice for all

Posted By Alex McConahay
Jim,

You have two statements in this thread that seem to run counter to each other:

You started with a "Nobody covers the Administration side":

It is also interesting how the coverage on TV seems to be mostly about her and her friends, and ignores the counter protesters that support the President.

And then, after hearing that the counter protests were very well covered, you came bach with a rather sheepish:

I did not see the coverage, maybe someone else has a source.

Maybe you should cosider what is really out there before starting your diatribe.

It seems that both sides are getting coverage pretty well....

--Did you hear about the neighbor who is practicing for Dove hunting season by shooting in the air near the protest? Wonder what kind of dove he is shooting for? Does this mean that the liberal press will soon come up with a story about somebody else going out hunting for HAWKS?

Alex

August 20, 2005 09:44 PM Forum: Beginning Astronomy?

Re: equatorial mount

Posted By Alex McConahay
That would be a big mount if you are planning to use a 10 inch Newt on it. Even the old Starfinder Equatorials were hard pressed to hold their 10 inch F4.5. I imagine they would be your best bet if you insist on this changeover--but they were very limited.

And, before you decide to change--make sure your mirror cell can handle being turned weird ways.

Alex

August 31, 2005 04:34 AM Forum: Equipment Talk

G-11 Tracking Problem

Posted By Alex McConahay
I'm having a tracking error on my Losmandy G-11. Anybody have any ideas?

Attached is a graph of a four or so minute run on as tracked by DSLR Focus. I have my G-11, a C9.25 at F6.3 (1345 mm effective FL). The units are pixels on my Canon D20. As you can see, Delta X (lower graph)is relatively stable, with just a little drift (probably polar alignment off). But Y has a periodic error on a 78 second cycle. A very pretty Sine Wave. (By the way--this confirms the visual. At F10, with a 12 mm eyepiece, the star moves at more than the double-crosshair box in the center. First up, then down, then back up, then down, etc.

I have unbalanced the mount. I have swapped the dec motor for the RA motor. I have changed cables. I have changed electronic control box. I have changed power supplies. I have removed my Digital encoder. I have even changed from the upgraded worm gear that was in there to the earlier worm gear--and the abberation is still there.

This is obviously a periodic error--but certainly not the kind we may expect( roughly four minute cycle). This is not only very large but on a much shorter cycle than one would expect.

Any ideas?

Alex

September 2, 2005 03:36 PM Forum: Equipment Talk

Field of View

Posted By Alex McConahay
I have a problem with my mount, with a strange periodic error. I am trying to figure how large the error is. With a 12 mm double crosshair reticle in a Celestron 9.25 (2135 focal length), a star moves a bit more than the distance between the crosshairs.

What formula does one use to calculate how many arc seconds this is? Or what does one do to determine how large this error is?

The mount is supposed to have no more than +/-5 arc seconds error. What does 5 arc seconds look like in an eyepiece?

Alex

September 6, 2005 04:09 AM Forum: Equipment Talk

Newsletter

Posted By Alex McConahay
This month our club, the Riverside Astronomical Society (of Riverside, California), is making its monthly newsletter available to the general public. It is at

http://www.rivastro.org/ras_aug05_pf_download.html

Every month we distribute a link just to club members so that they may download and read the newsletter. This month, though, we thought others might like to see what we put out, so we have a public link from our home page (rivastro.org).

I hope you enjoy the newsletter.

If any of you have an electronic newsletter you would like to share, please post a link to it.

And, for the purists, sorry for posting in the "Equipment" section, but I could see no place more appropriate, and this gets the high traffic (well, except for politics and religion).

Alex

September 20, 2005 01:42 PM Forum: Religion

Re: Another tolerance scenario for the Musketeers

Posted By Alex McConahay
Just a thought about your Dad's ability to think things out.

Why did he not move so that the dangerous object (the glass door) was not behind him?

Alex

September 21, 2005 02:40 AM Forum: Equipment Talk

Vandenberg Sunset Launch Thursday

Posted By Alex McConahay
Okay--I couldn't figure where this should be posted, and Equipment gets the most traffic......

If you are in Southern California Thursday evening, be prepared for one of the great SOuthern California experiences--A Sunset Launch from Vandenberg at 7:24 p.m.

You can generally see the plume from a huge section of the southwest--and when it gets lit in the upper atmosphere it is glorious.

Launch window is something like 16 minutes--so find a western horizon and check it out.

ALex

October 19, 2005 12:35 AM Forum: CCD Imaging and Processing/Deep Sky

What makes a good astrophoto

Posted By Alex McConahay
I've been doing some research to get ready to present a program on astrophotography. And I have a fundamental question for which I have not found a comprehensive answer. I've looked at books and websites, and can find lots of comments about how to take and process astrophotos......But I find nothing to tell me what the goal is.

Now, I could say "pretty." But what does that mean?

When you get an exposure out of your camera and start to process it, what are you trying to get out of it? Where are you headed?

Alex

November 6, 2005 02:07 PM Forum: Landscape Photography

Re: Digital Photography Advice

Posted By Alex McConahay
Sandy,

<<(Don't you just hate utility poles and wires!! ) >>

What utility poles? What wires?

Alex

November 11, 2005 05:04 AM Forum: Digital SLR AstroPhotography

My m31

Posted By Alex McConahay
So, here's my M31

Canon 20D, TV 85 on Losmandy G-11 w/ ST-4.
9x330 seconda @ISO 1600, Images Plus for stacking and dark frame subtraction/ Photoshop for rest of the processing.
GMARS/Landers,California, October 28,

Alex


Funding Member

Sponsors


View all sponsors

Search