[AstroPy] Meteor Methods--Atmospheric Trajectories, PC Book on Astronomy
Wayne Watson
sierra_mtnview at sbcglobal.net
Fri Dec 18 10:15:21 EST 2009
It's the latter. If I understand your question correctly, the parallax
is the angle the two planes make with one another, the angle of
intersection. Ceplecha, I think I mentioned him, calls it Q. As the
measure shrinks, the intersection fit loses its significance. I'm
attaching his paper and a related one. (Omitted on post to mail list.)
Paul Barrett wrote:
> Yes, I understand. My question was do you intend to get the parallax
> of the meteor trail using a simultaneous set of equations for each
> plate or process each plate separately and then estimate the parallax.
> Your response below indicates the latter: process each plate
> separately and then determine the parallax. We will have to solve a
> similar problem in the future. We may want to start looking into it
> now. I'll let you know if I have any updates.
>
> -- Paul
>
> On Thu, Dec 17, 2009 at 10:30 PM, Wayne Watson
> <sierra_mtnview at sbcglobal.net> wrote:
>
>> Hi.
>> Together. That is data from two stations widely separated, maybe 40-170
>> miles, possibly more. A meteor at 60 miles can be seen by an observer over
>> an elevation of 15-20 degrees some 3-400 miles away. The rough idea is to ID
>> stars in the image, and do a plate reduction to bring out dim stars, and
>> identify them and produce their ra/dec. One then uses the reduction to get
>> ra/dec on the track for each station. A plane is passed through each station
>> and it's tracks. The two planes produce an intersection, and that is the
>> track. It gets pretty deep, but those are necessary steps to get anything.
>>
>> One image might work in some usual case like a meteor flying directly
>> overhead.
>>
>> Paul Barrett wrote:
>>
>>> Hi Wayne,
>>>
>>> Are you trying to calculate the meteor trajectory using both images
>>> simultaneously or processing each image separately and then calculate
>>> the trajectory?
>>>
>>> On Thu, Dec 17, 2009 at 4:59 PM, Wayne Watson
>>> <sierra_mtnview at sbcglobal.net> wrote:
>>>
>>>
>>>> Hi, the problem is very complex. I only cited the book as a reference to
>>>> give some idea of how what the plate reduction phase is done for an
>>>> ordinary
>>>> camera.
>>>>
>>>> I think the first solution to the more general method was provided by
>>>> Ceplecha in his 1989 paper. He goes into multiple station observations,
>>>> ground track, atmospheric track, orbit calculation and more.Our
>>>> observations
>>>> are from two video cameras spaced about 35 miles away.
>>>>
>>>> I was hoping to turn up someone who might be familiar with these ideas.
>>>> I've
>>>> begun working with a pro astronomer who has a fairly decent handle on
>>>> these
>>>> matters, and, I'm at the early stages of trying some methods he proposed.
>>>> If
>>>> nothing else, I think some rough estimates of the two trajectories can be
>>>> made without months of coding.
>>>>
>>>> What I find odd about this type of meteor work is that I have yet to see
>>>> it
>>>> mentioned in any book on celestial mechanics. There are a number of
>>>> papers
>>>> on the web, but it takes a bit to understand them. Further, no one seems
>>>> to
>>>> have recently written any code to do the calculations. Ceplecha wrote a
>>>> 4000
>>>> line FORTRAN program for it all, but it is no longer available.
>>>>
>>>> Paul Barrett wrote:
>>>>
>>>>
>>>>> Hi Wayne,
>>>>>
>>>>> Sorry to take so long to respond. I have not been able to look at the
>>>>> book that you referred to on Amazon - I will check it out of the
>>>>> library tomorrow, but am quite familiar with the algorithms. What
>>>>> exactly are are you trying to do? Do you have CCD images that you
>>>>> would like to get accurate star positions from, or are you trying to
>>>>> use known star positions to accurately measure the position of an
>>>>> asteroid or similar object? These are variations on the same problem,
>>>>> but the algorithms differ, i.e., can be simplified, depending on the
>>>>> question that you are trying to ask. The latter problem just requires
>>>>> accurately estimating the plate parameters in order to measure the
>>>>> object's position. The size of the matrix depends on the number of
>>>>> stars that have been measured and the number of plate or image
>>>>> parameters. Of course there is freely available software that can do
>>>>> much of this for you. Let me know your exact problem and I'll try to
>>>>> provide a more explicit response.
>>>>>
>>>>> -- Paul
>>>>>
>>>>> On Mon, Nov 30, 2009 at 1:26 PM, Wayne Watson
>>>>> <sierra_mtnview at sbcglobal.net> wrote:
>>>>>
>>>>>
>>>>>
>>>>>> I sent a follow up msg that would make this easier; however, the
>>>>>> moderator is holding on to it. It had attachments.
>>>>>>
>>>>>> Wayne Watson wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>> Perhaps the best way is to refer you to the 2009 edition of the book.
>>>>>>> You'll be using the Amazon Search Book facility. They've made it a bit
>>>>>>> harder to use, perhaps, but the paragraph below will let you piece
>>>>>>> together the critical pages in the astrometry section. I have some
>>>>>>> these
>>>>>>> pages copied from a much earlier book, and this section has definitely
>>>>>>> been expanded. The ppmcat portion I finally direct you looks like a
>>>>>>> big
>>>>>>> improvement on the tiny catalog they used in an earlier edition.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> <http://www.amazon.com/Astronomy-Personal-Computer-Oliver-Montenbruck/dp/3540672214/ref=sr_1_1?ie=UTF8&s=books&qid=1259111820&sr=1-1>
>>>>>>> See the Look Inside icon on the upper left and enter the word
>>>>>>> astrometry
>>>>>>> when the small dialog window opens up. You will then see the first
>>>>>>> page
>>>>>>> that shows that word. Use the right button to go to the next result.
>>>>>>> That is the page that's the start of chapter 12. Now use the right
>>>>>>> arrow
>>>>>>> to move through the pages. I can only get through the first three
>>>>>>> pages,
>>>>>>> but you'll begin to see what they are doing. To go further, do this.
>>>>>>> Go
>>>>>>> back to the search dialog and enter "plate reduction" (no quotes).
>>>>>>> Skip
>>>>>>> to the second result and you should be on page 254. Now use the arrow
>>>>>>> to
>>>>>>> go to successive pages. You'll get some more info about what they are
>>>>>>> doing. If you care to go on, go back to find again and enter squares
>>>>>>> adjustment. Move via next button to 256, then move ahead one page at a
>>>>>>> time. By then you should have a good idea of what this is about.
>>>>>>>
>>>>>>> To get a summary of that section use ppmcat for find. Some of the
>>>>>>> summary pages are blocked, but at least you'll get some idea what all
>>>>>>> this produces.
>>>>>>>
>>>>>>> Paul Barrett wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> Wayne,
>>>>>>>>
>>>>>>>> I am not familiar with the book, but your comment about astrometry
>>>>>>>> caught my eye. We are currently implementing the plate reduction
>>>>>>>> methods as part of our work, actually on a much larger scale, of
>>>>>>>> order
>>>>>>>> one million images. These calculations should be easy to do in
>>>>>>>> Python
>>>>>>>> for just a few images. The important point is to properly set up the
>>>>>>>> arrays. You can then use the routines in scipy to do the least
>>>>>>>> squares
>>>>>>>> adjustment.
>>>>>>>>
>>>>>>>> I might be able to help if you can describe you problem in more
>>>>>>>> detail.
>>>>>>>>
>>>>>>>> -- Paul
>>>>>>>>
>>>>>>>> On Tue, Nov 24, 2009 at 4:21 PM, Wayne Watson
>>>>>>>> <sierra_mtnview at sbcglobal.net> wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>> Is anyone familiar with some of the mathematical methods for
>>>>>>>>> calculating
>>>>>>>>> atmospheric trajectories for two stations. Have they been
>>>>>>>>> implemented
>>>>>>>>> in
>>>>>>>>> Python?
>>>>>>>>>
>>>>>>>>> There's a computer book with the title something like PC
>>>>>>>>> Computations
>>>>>>>>> for Astronomy. (Ah, Astronomy for the Personal Computer) I believe
>>>>>>>>> the
>>>>>>>>> latest version provides methods for C++, and earlier editions for
>>>>>>>>> older
>>>>>>>>> languages. In one of the later chapters the authors delve into what
>>>>>>>>> I
>>>>>>>>> think is called plate reduction. (Ah, the chapter is titled
>>>>>>>>> Astrometry.)
>>>>>>>>> The idea is that an image of the night sky is provided and a catalog
>>>>>>>>> is
>>>>>>>>> examined to identify stars on the image. Has anyone implemented the
>>>>>>>>> various algorithms used for this in Python?
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> Wayne Watson (Watson Adventures, Prop., Nevada City, CA)
>>>>>>>>>
>>>>>>>>> (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
>>>>>>>>> Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet
>>>>>>>>>
>>>>>>>>> 350 350 350 350 350 350 350 350 350 350
>>>>>>>>> Make the number famous. See 350.org
>>>>>>>>> The major event has passed, but keep the number alive.
>>>>>>>>>
>>>>>>>>> Web Page: <www.speckledwithstars.net/>
>>>>>>>>>
>>>>>>>>> _______________________________________________
>>>>>>>>> AstroPy mailing list
>>>>>>>>> AstroPy at scipy.org
>>>>>>>>> http://mail.scipy.org/mailman/listinfo/astropy
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>> --
>>>>>> Wayne Watson (Watson Adventures, Prop., Nevada City, CA)
>>>>>>
>>>>>> (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
>>>>>> Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet
>>>>>>
>>>>>> The popular press and many authorities believe the number
>>>>>> of pedifiles that prowl the web is 50,00. There are no
>>>>>> figures that support this. The number of children below
>>>>>> 18 years of age kidnapped by strangers is 1 in 600,00,
>>>>>> or 115 per year. -- The Science of Fear by D. Gardner
>>>>>>
>>>>>> Web Page: <www.speckledwithstars.net/>
>>>>>>
>>>>>> _______________________________________________
>>>>>> AstroPy mailing list
>>>>>> AstroPy at scipy.org
>>>>>> http://mail.scipy.org/mailman/listinfo/astropy
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>> --
>>>> Wayne Watson (Watson Adventures, Prop., Nevada City, CA)
>>>>
>>>> (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
>>>> Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet
>>>> "... humans'innate skills with numbers isn't much
>>>> better than that of rats and dolphins."
>>>> --
>>>> Stanislas Dehaene, neurosurgeon
>>>> Web Page: <www.speckledwithstars.net/>
>>>>
>>>>
>>>>
>>>>
>>>
>> --
>> Wayne Watson (Watson Adventures, Prop., Nevada City, CA)
>>
>> (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
>> Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet
>> "... humans'innate skills with numbers isn't much
>> better than that of rats and dolphins." --
>> Stanislas Dehaene, neurosurgeon
>> Web Page: <www.speckledwithstars.net/>
>>
>>
>>
>
>
--
Wayne Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet
"... humans'innate skills with numbers isn't much
better than that of rats and dolphins."
-- Stanislas Dehaene, neurosurgeon
Web Page: <www.speckledwithstars.net/>
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