Meteor observation with webcams ?

Mee_n_Mac · Aug 7, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>If you want to try and capture meteors, longer exposures would be better, depending on how long the skyglow takes to overcome things. I'd suggest trying a few longer exposures up to 10 or 15 minutes and seeing what looks best. On one hand, the stars will be slightly smeared, but you will capture star colors better, and have much better odds of caoturing a meteor. Even on the peak Perseid night, a few minutes of exposure would vastly increase your odds.If you wish, I can suggest a field to aim for on that night. Posted by MeteorWayne</DIV> By all means suggest.  I'm torn between the 2 approaches. One is as you mention.  Leave the shutter open for a long time and make some star trails. Any meteor trail will make a nice contrast across them. But the sky glow may wash out the picture if you use a high enough ISO speed to capture a faint meteor.Alternately you take a series of short (30 secs or less) exposures. With a wide angle lens there won't be any star trails but your'e stuck hitting the shutter release over and over (unless you have an intervalometer built in or connected to your remote release). I've generally tried this approach.  Still with either the picture isn't as good as seeing it with the naked eye because (IMO) your eye will track and zoom. To get a "good" image I still think you need a version of a wide angle detector and narrow FOV imager along the lines of the AMIT system.  I don't think a typical webcam will make if for the wide angle detector but some have used relatively cheap imagers and/or security cameras to that end. SBIG makes (?made?) a dedicated wide angle system but it's a bit pricey (2k$). They seem to be in the process of making a newer version, details unknown to me.  <div class="Discussion_UserSignature"> -----------------------------------------------------Ask not what your Forum Software can do do on you,Ask it to, please for the love of all that's Holy, STOP ! </div>

Mee_n_Mac · Aug 7, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Mee_n_mac, send me an e-mail with your e-mail address. I'll send you the info on our system.Mine is  [deleted].  Posted by MeteorWayne</DIV> Done.  Hopefully you have mail.  I tried the back door via NJAA but I guess that didn't work.You may want to take down your e-mail addy to prevent an onslaught of SPAM.THX <div class="Discussion_UserSignature"> -----------------------------------------------------Ask not what your Forum Software can do do on you,Ask it to, please for the love of all that's Holy, STOP ! </div>

MeteorWayne · Aug 7, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Done.  You may want to take down your e-mail addy to prevent an onslaught of SPAM.THX Posted by mee_n_mac</DIV> Done, thanx for reading my mind. Though I doubt even SPAMBOTS would waste their time wading through the fog of Pluck. You should have a reply by now.Catcha a bit later, I have to run out for a few minutes. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

Mee_n_Mac · Aug 13, 2008

Thx to MW for forwarding the info on what NJAA has done.  Seems they reached the same conclusion I did; that webcams, even with some of the mods QCUIAG has done, probably aren't sensitive enough to be a cheapo meteor imager.  (Aside from that I also had concerns that the MPEG compression might obscure the trail.)  That said it appears that one not need spend the big $$s on something like SBIG's meteor cam (fine as I'm sure it is).  There exist other imagers that are used for security cams (in the $100 range) that apparently have enough sensitivity to do a yeomans job of the task.  I do have a few questions for MW though.1) Did NJAA modify, or exert external control over, their imager's exposure time ?  I wonder if a bit more sensitivity might be gained via increasing it given I don't care if some of the brightest objects get overexposed.2) I assume the frame rate is 60 Hz as it seems the cam uses NTSC/EIA standard for it's video transmission. Did anyone consider modifying the frame rate ?  (side note: As much as I dislike taking the digital info and translating into analog, it at least allows the signal to go a greater ditance than would the USB link used in a webcam).I can pose these questions directly to the NJAA if you like.  I thought some here might be interested in this topic.  <div class="Discussion_UserSignature"> -----------------------------------------------------Ask not what your Forum Software can do do on you,Ask it to, please for the love of all that's Holy, STOP ! </div>

MeteorWayne · Aug 14, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Thx to MW for forwarding the info on what NJAA has done.  Seems they reached the same conclusion I did; that webcams, even with some of the mods QCUIAG has done, probably aren't sensitive enough to be a cheapo meteor imager.  (Aside from that I also had concerns that the MPEG compression might obscure the trail.)  That said it appears that one not need spend the big $$s on something like SBIG's meteor cam (fine as I'm sure it is).  There exist other imagers that are used for security cams (in the $100 range) that apparently have enough sensitivity to do a yeomans job of the task.  I do have a few questions for MW though.1) Did NJAA modify, or exert external control over, their imager's exposure time ?  I wonder if a bit more sensitivity might be gained via increasing it given I don't care if some of the brightest objects get overexposed.2) I assume the frame rate is 60 Hz as it seems the cam uses NTSC/EIA standard for it's video transmission. Did anyone consider modifying the frame rate ?  (side note: As much as I dislike taking the digital info and translating into analog, it at least allows the signal to go a greater ditance than would the USB link used in a webcam).I can pose these questions directly to the NJAA if you like.  I thought some here might be interested in this topic.  Posted by mee_n_mac</DIV> Exposure time is kind of moot, since as you said it is continuously imaging. at a 60 Hz frame rate.Modifying that rate would be quite complicated, since the video card is set up for that rate; you'd have to design your own video capture card, so small undertaking.What the MetRec software (open source, available for free from the IMO) does is capture all the frames that contain a meteor, since all last more than 1/60 second; in fact they must, or they would not be detected. The software looks for motion over a series of frames, then saves the ones that contain the meteor.Hope that helps.I'm still processing my Perseid data from Aug 12/13, so have to run now. Just wanted to check in for relevant questions.MW <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

aphh · Aug 18, 2008

Just when I started thinking about the webcam star tracker, it just so happend that we're covering the spherical trig and the needed formulas for translating from local horizontal to universal equatorial coordinates and vice versa in school.I'm pretty sure it gets easily more complex, if the star tracker is traveling at orbital velocity and especially in the vicinity of the moon or mars. Maybe the local coordinates would then be those of the moon or mars, but how are the declination and right ascension defined for a interplanetary star tracker? It looks like I'm going to have to get to the bottom of this, should I want to make my way through this course (Astronavigation 101).

adrenalynn · Aug 21, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Thx to MW for forwarding the info on what NJAA has done.  Seems they reached the same conclusion I did; that webcams, even with some of the mods QCUIAG has done, probably aren't sensitive enough to be a cheapo meteor imager.  (Aside from that I also had concerns that the MPEG compression might obscure the trail.)  That said it appears that one not need spend the big $$s on something like SBIG's meteor cam (fine as I'm sure it is).  There exist other imagers that are used for security cams (in the $100 range) that apparently have enough sensitivity to do a yeomans job of the task.  I do have a few questions for MW though.1) Did NJAA modify, or exert external control over, their imager's exposure time ?  I wonder if a bit more sensitivity might be gained via increasing it given I don't care if some of the brightest objects get overexposed.2) I assume the frame rate is 60 Hz as it seems the cam uses NTSC/EIA standard for it's video transmission. Did anyone consider modifying the frame rate ?  (side note: As much as I dislike taking the digital info and translating into analog, it at least allows the signal to go a greater ditance than would the USB link used in a webcam).I can pose these questions directly to the NJAA if you like.  I thought some here might be interested in this topic.  Posted by Mee_n_Mac</DIV>Just a note - NTSC frame rate is 29.974, not 60.  It's about 60 interlaced fields/sec (When NTSC color was introduced, the rate was reduced 1000/1001 to avoid interference betwixt the chroma subcarrier and sound.)Webcams tend to be progressive scan (double the vertical resolution, non-interlaced) at 30frames/sec.  NTSC cameras are actually a pretty poor choice for anything moving quickly. <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

Testing · Aug 21, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Just a note - NTSC frame rate is 29.974, not 60.  It's about 60 interlaced fields/sec (When NTSC color was introduced, the rate was reduced 1000/1001 to avoid interference betwixt the chroma subcarrier and sound.)Webcams tend to be progressive scan (double the vertical resolution, non-interlaced) at 30frames/sec.  NTSC cameras are actually a pretty poor choice for anything moving quickly. Posted by adrenalynn</DIV> Welcome back! Hope your time has been productive to the goal. <div class="Discussion_UserSignature"> </div>

adrenalynn · Aug 21, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Welcome back! Hope your time has been productive to the goal. Posted by Testing</DIV>Thanks!  But early for a WB.  I'm more waiting to see what Super MeteorWayne can do with my fireball description. I've been thinking of hanging one of these cameras I have laying around out back.  By comparison, the best webcam I've seen is 3-5lux, and this is a .01lux Sony ExView with Fujinon glass lens.  From what I'm seeing with it I doubt it can see -2 Mag.  <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

MeteorWayne · Aug 21, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Thanks!  But early for a WB.  I'm more waiting to see what Super MeteorWayne can do with my fireball description. I've been thinking of hanging one of these cameras I have laying around out back.  By comparison, the best webcam I've seen is 3-5lux, and this is a .01lux Sony ExView with Fujinon glass lens.  From what I'm seeing with it I doubt it can see -2 Mag.  Posted by adrenalynn</DIV> I was in the city yesterday, so didn't have time to work on yer' flying eye burner, but will today. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

Mee_n_Mac · Aug 21, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Thanks!  But early for a WB.  I'm more waiting to see what Super MeteorWayne can do with my fireball description. I've been thinking of hanging one of these cameras I have laying around out back.  By comparison, the best webcam I've seen is 3-5lux, and this is a .01lux Sony ExView with Fujinon glass lens.  From what I'm seeing with it I doubt it can see -2 Mag.  Posted by adrenalynn</DIV> Webcams aren't going to cut it, as you've noted they just don't have the sensitivity. The various security cams are more promising, those built around Sony's SuperHAD chips claim 0.0003 lux rating and people using them have claimed visibility to around 2 to 4 Mag. My guess is they all output RS-170 video given their intended use.  Not what you'd choose but it is what it is.  If you wanted to throw $$s at the problem there are all sorts of systems you could assemble ... or buy complete.  I started on this track more from the photographer's angle vs the astronomer's.  I wondered what would it take to capture a "pretty picture" of a meteor other than sitting outside with the dSLR aimed up and hoping to capture one. ATM my tentative conclusion is you really need a wide angle detector of reasonable sensitivity and also an aimable narrow FOV "capture system".  For cheap $$s you can make the first part (as people have done) using the aforementioned video cams. I'm now trying to figure out what to use for the 2'nd part. <div class="Discussion_UserSignature"> -----------------------------------------------------Ask not what your Forum Software can do do on you,Ask it to, please for the love of all that's Holy, STOP ! </div>

adrenalynn · Aug 22, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Webcams aren't going to cut it, as you've noted they just don't have the sensitivity. The various security cams are more promising, those built around Sony's SuperHAD chips claim 0.0003 lux rating and people using them have claimed visibility to around 2 to 4 Mag. My guess is they all output RS-170 video given their intended use.  Not what you'd choose but it is what it is.  If you wanted to throw $$s at the problem there are all sorts of systems you could assemble ... or buy complete.  I started on this track more from the photographer's angle vs the astronomer's.  I wondered what would it take to capture a "pretty picture" of a meteor other than sitting outside with the dSLR aimed up and hoping to capture one. ATM my temtative conclusion is you really need a wide angle detector of reasonable sensitivity and an aimable narrow FOV "capture system".  For cheap $$s you can make the first part (as people have done) using the aforementioned video cams. I'm now trying to figure out what to use for the 2'nd part. Posted by mee_n_mac</DIV> Psh.  I don't stand around outside babysitting my camera (ok, I did for the Aurigids - too important) - I plug my DSLR into my laptop and shoot it tethered on a MaxDSL script.  15sec exposures, rinse, lather, repeat until I remember how much each shutter-fall costs in maintanence.

<div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

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