Gina's Observatory

[JamesF]

A bit off-topic in a way... Could I please have suggestions for software that will take the JPG files saved from my webcam and make a video? Preferably for Linux (Ubuntu) but Mac OS X or Windows XP as alternatives. The Video plug-in for GIMP looks like it's supposed to do this but I can't seem to find any info, and trial and error has not worked.

Thanks.

You probably want "mencoder", part of the mplayer package. Google should help you find examples of how to do it.

James

[Astrokev]

Trying to be too clever do you think?

Not really. A logical idea.

[Astrokev]

You could be right

I've got the bottom plate on the pier and levelled. Here are a couple of pics.

This is a smallholding - rustic is the norm... well... how about a rustic pier?? Nothing the previous owner built was square, not a lot we've built is square so why do I expect my pier to come out square?! Try as I might! Hmmmpff! ... Still as long as it works...

The base plate makes a huge difference!

[Gina]

imovie (mac) and movie maker (xp) spring to mind, Edit: Quicktime Pro as well as any video editing software, what you are looking for is 'time lapse video' making.

JCJC's dad

Thanks Just checked out iMovie and it doesn't import JPG files. I'll check movie maker tomorrow.

[Gina]

I think the pier looks good, leave the flower pots, they can be painted if need be, the upper part can be filled or even given a thin coat of plaster later, but I would not bump it to much at the moment, it needs to cure and maybe even need some damp sacking over it to stop it drying out quickly, Sunday looks sunny so no rush

JCLC' dad

I'll take your advice - thank you As for not bumping it too much, I was going to screw on the pier adapter and try the mount on but I'll give it a bit longer - no great hurry.

[Astrokev]

The base plate makes a huge difference!

Gina

Just re-read my own post here and thought, ooh, that sounds a bit insincere/sarcastic! So, just wanted to point out that no sarcasm was intended here - the base plate / adapter really does make the pier come to life. Once you get the mount on the top it'll look the business. As you say, no urgency for this bit though - better to make sure the 'crete has properly gone off.

Look forward to seeing the next stage.

[Gina]

Gina

Just re-read my own post here and thought, ooh, that sounds a bit insincere/sarcastic! So, just wanted to point out that no sarcasm was intended here - the base plate / adapter really does make the pier come to life. Once you get the mount on the top it'll look the business. As you say, no urgency for this bit though - better to make sure the 'crete has properly gone off.

Look forward to seeing the next stage.

Thanks for that Kevin Posts can often be read the wrong way. I too think the steel plate makes the pier look better But I'll leave the rest for a while as you recommend. As you say - no hurry.

It's funny how the sloping ground here makes level things look skew-whiff. That pier base block top is actually level - both ways. I checked it yesterday with a spirit level. But the pier itself is not quite vertical.

Here is the first photo of the day, taken in the shade of the house to avoid sun in the camera lens. (70mm focal length.)

[Gina]

Been working on the beams this morning. One beam cleaned off - removed loose paint and nails, sanded and then given a coat of creosote all over.

Photos to prove it

1. The three beams ready for working on.

2. One beam done.

[Astrokev]

It's funny how the sloping ground here makes level things look skew-whiff.

Nah, that'll be the cows you can smell

[Gina]

Nah, that'll be the cows you can smell

[Gina]

Now I've got the pier made and the adapter on top I'm ready to find the position for the azimuth post. Problem - no sunshine. Could set up with compass but gather the sun shadow (sundial) method is better. Been trying to find out how to calculate the exact time of noon. I remember it was a few minutes either before of after 1pm BST. But can't remember which.

[RogerTheDodger]

I'd wait 'til night and do a rough align to Polaris.

[Freff]

That's what I have done. Used a witness mark on the house and a post in between the pier and witness mark and aligned all three with Polaris.

[Freff]

.....or go this way. The Sundial Primer - Finding True North/South

[Gina]

Thanks I eventually found the info in my pier thread (from about post 153) :- http://stargazerslounge.com/diy-observatories/139715-concrete-pier-preparation-construction-6.html

A few minutes past 1300 BST then.

[malc-c]

I think its something like 13:04 BST - at least that's what time I used and it's good enough to be withing the azimuth adjustment range of the EQ mount when polar aligning...

[Gina]

I think its something like 13:04 BST - at least that's what time I used and it's good enough to be withing the azimuth adjustment range of the EQ mount when polar aligning...

Thanks Malcolm Yes, should be accurate enough, though maybe I ought to correct it for the difference in longitude. The range of adjustment is something like 10 degrees Now we just need a day when the sun is out at the appropriate time. It wasn't today in spite of a nice sunny day forecast!

EDIT... We're about 3 degrees west here. So with 15 deg per hour that's (60x3)/15=12 minutes. Say quarter past one BST then

[Bizibilder]

If you put eg a sheet of ply flat on the ground and a short stick on the mount to cast a shadow on the ply you have made yourself a "local" sundial. If you record the shadow position from, say, a couple of hours before "noon" to a couple of hours afterwards - you only need three or four readings - you have calibrated the sundial. You can take the readings during gaps in the cloud if need be.

Without moving anything you can now calculate and mark the local "Noon" position, calculate true North and therefore align your mount. If you take the equation of time into account (the error due to the Earth's orbit being eliptical) you should be good to about 1 minute.

The attached graph shows the Eof T in minutes vs the day of the year (1-365).

Sounds complicated but it's just a way of not having to have the Sun available at noon

[Gina]

If you put eg a sheet of ply flat on the ground and a short stick on the mount to cast a shadow on the ply you have made yourself a "local" sundial. If you record the shadow position from, say, a couple of hours before "noon" to a couple of hours afterwards - you only need three or four readings - you have calibrated the sundial. You can take the readings during gaps in the cloud if need be.

Without moving anything you can now calculate and mark the local "Noon" position, calculate true North and therefore align your mount. If you take the equation of time into account (the error due to the Earth's orbit being eliptical) you should be good to about 1 minute.

The attached graph shows the Eof T in minutes vs the day of the year (1-365).

Sounds complicated but it's just a way of not having to have the Sun available at noon

Thank you That's a good idea.

Look like EofT is -5 minutes for today then.

[Gina]

Sooo.... +12 mins for longitude and -5 mins for Eq of T gives +7 mins ie. 13:07 BST.

[George]

An easier way todo a celestial true north is use this solar noon just enter your location etc and it will print a exact solar noon calendar for your location. Use a stick and string at solar noon to find true north.....I did this when building my observatory in the middle of winter and it works a treat

[Gina]

An easier way todo a celestial true north is use this solar noon just enter your location etc and it will print a exact solar noon calendar for your location. Use a stick and string at solar noon to find true north.....I did this when building my observatory in the middle of winter and it works a treat

That's great - thank you very much

[Gina]

I've stuck up a "stick" (long wood screw) vertically in the centre of the pier adapter and piece of cardboard on the adapter top for marking.

[Astrokev]

Simple and effective. I llike it!

[Gina]

Thanks

Plenty of cloud about today so using the sundial method. It was cloudy at the true noon time. Just added another mark at 13:40 BST.