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View Full Version : Not Geocaching .... But Cool Anyway.



astrodav
04-22-2010, 01:07 AM
As many have figured out, I'm a very active amateur astronomer. (AstroDav ... gee, whodda ever thunk it? :lol: ) Around a year ago, I was able to image a VERY rare phenomenon. This image was featured on several different astro-sites over the following month or so after I snapped it. It's a dual Iridium flare.

For those who don't know what Iridium's are, they are a "constellation" of around 50 or so commo-satellites. They provide the workage of the expensive "Iridium satellite phones", which are still used, but have experienced several periods of less-than-profitable times ever since they were first brought into service years ago.

These satellites are unique in that they have large ultra-reflective solar-cell arrays which often catch the sun's light at times, producing a "flare" which can last about 1 minute. During these flares, the satellite commonly brightens from around magnitude 6 (just visible to the eye), up to a whopping magnitude -9. That makes them the brightest normal thing in the sky, by far, other than the Moon & Sun.

That latter value is so bright that it will easily cast shadows & will definitely ruin your night vision if you are looking right at it. The real neat thing about these flares is that they are 100% predictable & are listed on several sites for weeks out at a time. All you need is your exact time, down to about 10 seconds accuracy, & your exact location. The difference between so-so bright & super-bright can be only 10 miles or so down here on Earth, so many Iridium-chasers will actually take short trips to get right under the spot of maximum intensity .... sorta like chasing a solar eclipse.

These things AREN'T rare .... they happen several times per night all over the Earth. At any one location (your back-yard), a medium-brightness flare will occur about once a week. A super-bright one about twice per month.

Due to orbital specifics, they tend to happen in waves however. Your location might go 2 weeks without any nice ones, but then have 2 every evening & 2 every morning for 3 days at a time. They will be all brightness's & you can usually expect a REALLY good one at least once during that "outbreak".

But what IS rare is for 2 of them to happen side-by-side, at the same time. And what is REALLY rare is for both of those to be super-bright flares. That's why this image is pretty much a once-a-year thing for any one location, most likely even further apart than a year.

I'd have to dig into my notes to list the exacts, but the dimmest one here is about a mag. -3, while the bright one is around a -7. This exposure is about 1 minute long, so that gives you an idea of what speed they move & the time it takes to flare up & then dim back down.

Very little equipment is needed to do this. This was through a Canon D400 digital camera, with a 35mm lens. The only thing is, since the flares last about a minute, the stars will trail if you don't have the camera mounted on a tracking mount. 30-40 seconds is as long as you can expose a stationary camera without that happening. This was piggy-backed on my 12" telescope, which you can see part of at bottom. It was tracking at the time, allowing me to take a long exposure & still have pin-point stars.

But not having something to track wth doesn't mean at all the image can't be spectacular. Star trails are the most basic type of astrophotography possible, other than perhaps moon-shots. And they are also among the most favorite, even amongst those of us who might typically be stacking dozens of 20 minute CCD exposures of deep-sky objects, taken through huge computer-controlled scopes.

The reason being is that star-trails are simply simple & simply beautiful, the very most basic way of showing the heavens are actually always in motion, never staying the same. Because of this, trailed stars can actually INCREASE the beauty of an image like this. Not only will it draw attention to the non-trailled flare, but provides a startling contrast between the "natural" heavens, and the artificial stuff that we've put up there. All's you's needs is a camera & a tripod. 8)

Since these things only happen within about 90 minutes of sunrise & sunset, you can see the last bit of purple twilight at bottom of the image. Actually, it was dark to the unaided eye when I imaged this. But with the long exposure & my camera modified for extra sensitivity, the picture picked up some remaining twilight that the eye couldn't see. I think it just adds to the image myself, sorta framing it along with the front of my telescope.

I have exposed literally hundreds of celestial images, probably thousands, in scopes as large as 24" & with CCD's costing 10,000 $$$'s. But this very simple image, taken with nothing more than a $500 digital camera, is my very favorite of all.

Sometimes the simplest things are the most beautiful:

http://img541.imageshack.us/img541/5522/dualiriduse.png

arkfiremedic
04-22-2010, 06:11 AM
Astrodav this is a beautiful picture. This would definitely worthy of framing. Any word on the First Annual Astrodav Astronomy Event?

wilddav
04-22-2010, 06:25 AM
8O 8O 8O w0w this is AWSOME so this is where you get ur name→astrodav//dont ask me where i g0t my name ??

chimps8mybaby
04-22-2010, 07:15 AM
I was thinking about bringing my scope to Petit Jean but I didn't know the conditions of the area...ie; light pollution, proximity to lakes, and an open sky

arkfiremedic
04-22-2010, 08:40 AM
That would be fun to look at some starts at Petit Jean!

arkfiremedic
04-22-2010, 08:41 AM
ask me where i g0t my name
O.K. Where did you get your name?

jclaudii
04-22-2010, 10:56 AM
That is truly spectacular! I've tried to catch the space station in it's orbit around us but never got it....but that shot is truly unique!

wilddav
04-22-2010, 12:56 PM
ask me where i g0t my name
O.K. Where did you get your name?
my past will come back to hault me,and i didnt ask you to ask me i had wrote dont ask me how i got my user name i was the first to do all of the above on a dare list and i picked up the name wilddav or crazydav//it was crazydav,and my(dates) females always called me wilddav//but that was some 10yrs or s0 ago i want to leave those days behind of being the crazy one :lol:

chimps8mybaby
04-22-2010, 03:43 PM
That is truly spectacular! I've tried to catch the space station in it's orbit around us but never got it....but that shot is truly unique!

http://www.heavens-above.com/

This will give you pass times for your location.

astrodav
04-22-2010, 05:31 PM
That is one of the location's which you can use to check the flares for your location also. You'll have to tell it your location, preferably by starting a free acct & putting in exact coords. 1 mile & 1 minute can make a LOT of difference on these flares.

PARTS of Petit Jean would be ideal for astronomy. Dr. Clay, one of Ark's more well known astronomers, has his observatory up there. We talked a couple years back about building another back-up observatory for him at my place, but he decided not to.

astrodav
04-22-2010, 09:03 PM
Here's a couple more of my favorites.

Another example of simple astrophotography .... the moon through fog, making a halo. Although ALL haloes are actually raindow-colored, we usually don't see this with our eye. The colors are just too subtle to activate our color recepters. A 1-second exposure with a digital camera works just fine however. (My scope is set up now with a front-mounted piggyback, to keep the dew-shield from hogging the bottom of the image. The camera is so heavy that I had to use it on back until I was able to rig up a proper counterweight system, to keep from straining the drive motors):

http://img338.imageshack.us/img338/4066/greyhalo.jpg


The next one is the only shot here which actually required a telescope. It's an SBIG CCD camera, at Prime Focus through the 12" scope. I thought it was neat because it shows the landing site of Surveyor7, right at the base of the crater Tycho. That's the one you can see with the unaided eye, which has ejecta rays stretching all the way across te Moon.

A close-up like this will pracically eliminate the rays, although you can see a trace of them on the right side of the image. But these type shots reveal the inner structures of the craters.

One curiousity here .... if you look right above the 1st "r" in "Surveyor", you can see what appears to be a scratch, or a canyon. That's actually just a mistake I made. This CCD magnifies so much that the FOV wasn't big enough for what I wanted here. So I took 1 exposure, then slewed the scope a bit to the North & immediately took another identical exposure. I then stitched the 2 together.

This is almost impossible to do with 100% accuracy for 2 reasons, one of them preventable. The 1st is that there is so much fine detail on the Moon, as compared with most other celestial objects, that any amount of turbulence in the atmosphere will show up on the image also. Thus, no 2 images will ever be identical. That's NOT preventable.

The preventable one is that a telescope has several different drive speeds to it, depending upon what you are tracking. "Sidereal" is the default speed, which is one revolution every 24 hours. That is to track non-moving stars, which are only moving because of the rotaton of the Earth.

However, the Sun, Moon, & transient objects such as asteroids move at different speeds. Being as this was only about a 1/100th second exposure, I thought I could get away with NOT switching the scope over to "Lunar". But at this high magnification, it still caught the difference. The Moon is so fast (27 days to cover 1.5 million miles), even that slight 1/4 degree change in my scope's altitude produces an image a bit more tilted one way or another. So it's VERY hard to line 2 images up perfectly.

Looking below the word "Surveyor", you can see where the image is blurred a little from lower-right to upper-left. I was able to process this blur out of most of the rest of the image by warping it. But here, near where the 2 images are stitched, I just couldn't manage to do it:

http://img338.imageshack.us/img338/3992/largemark7.png

astrodav
04-22-2010, 10:51 PM
Astrodav this is a beautiful picture. This would definitely worthy of framing. Any word on the First Annual Astrodav Astronomy Event?


I assume you are talking about the AstroCache Event I mentioned a month or two back, possibly on Magazine.

Not forgotten at all, just not the right time yet. But it IS time for me to start pre-planning, basically meaning consulting with the Magazine Park Staff about it. Being as we've had star-parties there before, I don't see a problem.

But I think the prime time will be late September or any time October. Even early November would work, if we don't have a quick cool Winter. This would let the creepie-crawlie-flyee's thin out a bit & also keep it from being so hot & humid on us.

And as far as the sky-event, the very best area for that is the summer Milky Way. Because of an ineresting little thing called precession, the "summer" Milky Way is now well visible even into December. Being as this will be geared as a day-time caching event, with the night part being a secondary add-on, then that part will be right at the beginning of night. So we'll till have plenty of time for that part of the sky, up until about midnight. A side-benefit is that the days will be getting shorter then, giving us even earlier time for that part to start up.

Will let you know more as it gets closer. I'm sure we could make a really neat event out of this. And too, I've always wanted an event that has a major section allocated for night-caching .... say at least 3 of them set up. This type of event would provide a perfect excuse to do that.

Ashallond
04-22-2010, 10:53 PM
Man, I so forgot about your hobby here. So should have talked shop with you. I have a degree in Physics with a specialization in astronomy.

I'm looking forward to late July/Early August. there's going to be a triple conjunction of Mars, Jupiter, and Venus, and slightly farther away, Mercury to the Southeast.

Then in mid August, literally as Mercury is going below the horizon, the triple conjunction will tighten up and be right next to a cresent moon.

This site has a animation of it.

http://www.shadowandsubstance.com/

arkfiremedic
04-22-2010, 11:16 PM
Man, I so forgot about your hobby here. So should have talked shop with you. I have a degree in Physics with a specialization in astronomy.

I'm looking forward to late July/Early August. there's going to be a triple conjunction of Mars, Jupiter, and Venus, and slightly farther away, Mercury to the Southeast.

Then in mid August, literally as Mercury is going below the horizon, the triple conjunction will tighten up and be right next to a cresent moon.

This site has a animation of it.

http://www.shadowandsubstance.com/

This is EXACTLY what I was going to say 8O O.K. not really, but whatever you said it sounded cool. 2ter and I would love to come see some conjunctions with ya'll :?:

Ashallond
04-23-2010, 07:49 PM
A conjunction is simply where planets and/or other objects appear to be very close to each other in the sky.

It's been a while since this nice of a conjunction set has happened.