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02-23-2013, 02:14 PM   #541
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QuoteOriginally posted by Dr_who Quote
I use a 8" reflector, but I agree it's amazing what details you can pull out of even "wide angle" telescopes. Some objects are quite big but obviously very dim, hence the long amount of stubs. This image is with same camera and scope.

http://stevenkovickart.com/astro/sizecomparison.jpg
Astonishing detail in that M42 shot.

02-27-2013, 04:58 PM   #542
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QuoteOriginally posted by Sagitta Quote
Hooked my adapter up to my scope, stuck my camera in... and had the whole scope jut sag southwards.

The mount can't support the weight of the K-30.

I may see if I can get creative - I bought the scope as much for terrestial viewing as stars, and with the O-GPS1 unit I *should* be able to cheat and just set the camera to having an 800mm and see how things fare (the scope is a 910mm).
I made my own counterweight for my setup. I actually just taped a bunch of my military challenge coins to the end of my scope until it was balanced. Worked great and is FREE!
02-27-2013, 05:33 PM   #543
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QuoteOriginally posted by GWARmachine Quote
I made my own counterweight for my setup. I actually just taped a bunch of my military challenge coins to the end of my scope until it was balanced. Worked great and is FREE!
I didn't even think of counterbalancing the setup. I'm going to be housebound for a few days (BIIIIG storm rolling in) so I have time to play a bit.
03-03-2013, 01:28 PM   #544
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Astrotracer - Calibration Hazzels?

QuoteOriginally posted by Sagitta Quote
Still feeling out my locations/settings/etc. I'm finding the O-GPS1 to be annoyingly finicky to get set just right so you don't wind up with trails, even with the UWA. That said, when it DOES get things right...
I know well of calibration hazzels on certain nights, when everything seems to conspire against you - but not that frequently. And I am mostly using lenses in the 200-350mm range.

But I got a silly idea the other day: What if one excersises care to keep the long axis of the camera patrallel to the horizon, also when the capera is pointing up in the sky? The manual speaks nothing about this, but it would appear to take one of the unknowns out of the calibration procedure.

I have had almost nothing but cloudy nights since October, but this Friday skies cleared enough that I could give it a first try with my 200mm f/3.5 lens. It may have been sheer luck but I was able to maintain pin-point stellar images up to 45 seconds, where clouds made further test rather hopeless for that night. Due to the clouds, I couldn't use the longest exposures for much, but I was able to produce this from a series of exposures between 10 and 25 seconds:


Stack of 25 exposures between 10 and 25 seconds with 200mm lens at f/3.5 at ISO 1600. Click to see larger version (about 35% of original)

For me this is actually somewhat of an achievement. I have oiften been chasing the faint smudge of light from M51 in my light polluted urban sky, but this time I actally got something look-alike:


100% non-resized crop of the above.

As said, I may have been just lucky this time, but I would be interesting to hear, if others have had similar or dissimilar experiences by parallelizing the camera long axis with the horizonthal plane? At least I shall try to pursue this idea further.

03-03-2013, 01:35 PM   #545
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QuoteOriginally posted by Stone G. Quote
As said, I may have been just lucky this time, but I would be interesting to hear, if others have had similar or dissimilar experiences by parallelizing the camera long axis with the horizonthal plane? At least I shall try to pursue this idea further.
The weather's been conspiring against me as well. The one night it was clear (last Monday) I needed to go to bed due to work in the AM.

I think part of it could be the urge to turn the GPS on, then immediately try calibrating it. If I turn my tablet on, it takes a good bit before he thing actually sees all the satellites for what it does, so I can't imagine the O-GPS being any different.
I'll have to try the make-sure-you're-level bit when I can to see ho it plays out.

Your 200mm shots inspire me to see what I can do with a similar set-up. Come better weather, I can even take the 30 minute drive out to our property in the Boonies and see what I can do with really, REALLY dark skies.
03-03-2013, 03:52 PM   #546
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Everyone watch for comet PANSTARRS this coming weekend. I'll be posting pictures as long as the weather holds up. I'm glad (and sad) that I'm not the only one experiencing this horrible run with the weather. Somebody please make it all go AWAY!!!
03-03-2013, 05:38 PM   #547
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The weather has been overcast here for weeks as well. One day it was clear but was also the height of the full moon.
03-03-2013, 07:12 PM   #548
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Here's more information on Comet Panstarrs: Earth Sky
Just after sunset on the 12th, the comet will be 5-6 degrees away from the crescent moon, creating an awesome photo opportunity. Hopefully the weather is clear, this will be the first naked eye comet I've ever seen.

03-04-2013, 02:27 AM   #549
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QuoteOriginally posted by Stone G. Quote
But I got a silly idea the other day: What if one excersises care to keep the long axis of the camera patrallel to the horizon, also when the capera is pointing up in the sky? The manual speaks nothing about this, but it would appear to take one of the unknowns out of the calibration procedure.

As said, I may have been just lucky this time, but I would be interesting to hear, if others have had similar or dissimilar experiences by parallelizing the camera long axis with the horizonthal plane? At least I shall try to pursue this idea further.
I have tried this and different variations on the idea such as trying to align the stars movement with the "horizon" in the camera so that most of the movements will be in one direction. But the result has always been, well, random. Sometimes I think I'm on to something but ten minutes later it kind of stops working and then for some reason a completely different approach works better.

But what I have discovered by experimenting in the comfort of my home is that the compass calibration is pretty hard to get right. If I calibrate say five times in a row (very carefully, rotating in a steady pace), only one of them will be "perfect" all 360 degrees around. Most of them will be good at for instance 0 and 180 degrees but wrong at 90 and 270, or the other way around.
03-04-2013, 04:51 AM   #550
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Thanks Gimbal,

You are unquestionably right that the compass accuracy is by far the largest, single source of error.

Well.....if at first you don't succeed then try, try and try again. (Not much different for me than when I try to align my portable equatorial mounts, anyway).
03-04-2013, 11:34 AM   #551
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What kind of object has this type of orbit?

Last night (Sunday 03 March) wasn't particularly well suited for astrophotography but after months of overcast night, I am desperate to try anything as long as the skies clear for an hour or so. So, I decided to train my Astrotracer and my smc Pentax.FA 50mm f/1.4 at Leo, the Lion.

As expected, results were a bleak so-so:


Single, unprocessed exposure: 50mm f/1.4 at ISO 250 for 20 seconds. Click to se larger version.

That is, until I scrutinized the region around star Chort (Theta Leonis) and found a short streak of light that "shouldn't" be there. I am well familiar with the tracks of satellites in low orbit, but this was shorter and thus, slower. Aligning my 11 exposures of 20 seconds each produced this (with excuses for the field rotation inaccuracies):


11 exposures as above merged and cropped.

Now I have the accurate timing from the Pentax O-GPS1, I know my focal length of 50mm, my sensor size of 23,5mm, pixel size of 0,0047mm and I can measure the lenght of the trail. Further, the line-up of specific hot pixels tells me the inclination of my camera relative to the Equator:




And thus, I find that I have an object that travels 34 degrees per hour in an orbit with an inclination of 57 degrees to the Equator.

I know very little about satellites, but the angular speed would indicate a satellite at a distance roughly 10,000 miles away if it was a satellite in a circular orbit. But could I really capture such a relatively small object at such distance?

On the other hand, if it were a natural, solar system object, the angular movement seems unusually high - and what abou the inclination of the orbit?

So, are there some knowlegable folks out there who can tell me, what this really was?!?
03-04-2013, 03:36 PM   #552
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Far...

QuoteOriginally posted by Stone G. Quote
. . . And thus, I find that I have an object that travels 34 degrees per hour in an orbit with an inclination of 57 degrees to the Equator.

I know very little about satellites, but the angular speed would indicate a satellite at a distance roughly 10,000 miles away if it was a satellite in a circular orbit. But could I really capture such a relatively small object at such distance?

On the other hand, if it were a natural, solar system object, the angular movement seems unusually high - and what abou the inclination of the orbit?

So, are there some knowlegable folks out there who can tell me, what this really was?!?
The geosynchronous satellites are beyond 20K miles so I don't think 10K is that far in comparison. I've also watched how a satellite can go from bright to dark and back again all the way across the sky. There is a website, Spaceweather.com's Simple Satellite Tracker: International Space Station, spy satellites, Hubble Space Telescope that will tell you whats flying around up there.

I've also gotta say Stone, your math skills and knowledge about how to figure all those specifics out are STELLAR!
03-05-2013, 01:39 AM   #553
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QuoteOriginally posted by GWARmachine Quote
I've also gotta say Stone,....
Why, thank you Josh! You know, I found geometry with all its proofs pretty boring, and my high school physics teacher had the idea that the proper introduction to astronomy would be about spherical geometry, right ascension, declination, great and parallel circles. And there I was, yearning to know what was inside the stars, how galaxies formed and what was the end of the universe like......

It was only 15 years later that I discovered the beauty of geometry and celestial mechanics. That was when when I took my first steps into astrophotography and wanted to understand how the celestial sphere pictured on my flat film.
03-06-2013, 02:59 PM   #554
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QuoteOriginally posted by Stone G. Quote
Why, thank you Josh! You know, I found geometry with all its proofs pretty boring, and my high school physics teacher had the idea that the proper introduction to astronomy would be about spherical geometry, right ascension, declination, great and parallel circles. And there I was, yearning to know what was inside the stars, how galaxies formed and what was the end of the universe like......

It was only 15 years later that I discovered the beauty of geometry and celestial mechanics. That was when when I took my first steps into astrophotography and wanted to understand how the celestial sphere pictured on my flat film.
Amazing. I often wonder many of the same things. Unfortunately something usually interrupts me like the urge to play drums or ride my motorcycle. I just have too many hobbies I think sometimes.
03-11-2013, 11:18 PM   #555
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New photos

Finally made some new photos!!! These were both taken on somewhat windy nights so I can't wait until I have steady air and seeing to try again. This is my first attempt at each one. Oh yeah, and I also picked up a brand new K-5IIs here in Japan on sale for $800! So far it's great!

Pentax K-5IIs, Orion ED80CFT, tracked with AstroTrac, (8) 60 second and (2) 120 second subs @800ISO and one 3minute exposure at 1600ISO (no darks, flats, bias), stacked with DSS, processed with CS5.


K-5IIs, EDOrion80CF, five 1min subs 800ISO (no darks, flats, bias), stacked with DSS, processed with CS5, tracked with AstroTrac.
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