Thermal imaging Arietid and other meteor showers? - Page 1
Forum section: electronics / general

author: Ultrapurple
author_rank: Super Contributor
timestamp: June 08, 2021, 10:06:31 am
content: Has anyone here tried looking for daytime meteors using a thermal camera? The month-long Arietids daylight shower (presently nearing its peak of ~1 per minute) would seem to be an ideal candidate to investigate.I know it has been done before - Ireported hereon an article from 2008 where some military-grade cameras had been temporarily repurposed for the experiment.As I write this I am listening tometeor scatter 'pings'from theGRAVES radar transmitter(143.050MHz) several hundred miles away in France - not exactly thermal imaging, but a good indicator throughout most of Europe whenever meteors are around. You don't require fancy equipment, just a simple <=US$10 'RTLSDR dongle' (USB digital TV tuner), 50cm aerial and a laptop (or tablet or phone) running free SDR software. Tune to 143.050MHz SSB and listen for occasional 'whoop' noises.It's worth knowing that you're very unlikely to hear a 'ping' at the same time as physically observing a meteor trail.

author: Lambda
author_rank: Regular Contributor
timestamp: June 08, 2021, 12:13:23 pm
content: Thank you Ultrapurple for having introduced to us this interesting thema.I am active in an astro forum and a member, "Pejive", from there, is quite active in this domain:http://astronomie-va.com/forum/viewtopic.php?f=36&t=1097&sid=a9ab9ef91b063c797e5889dba739f6fdHe is using a SDR Key roughly similar to the one you mentioned. I use also a SDR key (and up converter) for shortwave listening with a DIY loop antenna (a passive version and then an active one)https://www.rtl-sdr.com/forum/viewtopic.php?f=3&t=5901Here is the set up with the active loop (a crude Q mulitplier antenna (FET based)[see below]Sorry for the disgression, Just for mentioning that indeed a cheap SDR key is a wonderful tool for experimenting on a very large range of radio frequencies. 20 years ago, it would have been only possible to do that in some uni lab, for instance....For the using of a thermal camera, observing a meteor shower would be indeed a very interesting experience to do. I am just curious with which kind of camera it would be the most effective. And would the MWIR domain not be more suitable than the LWIR domain, according the transitory high temperatures reached by meteors falling through atmosphere?Regards.Lambda

author: Ultrapurple
author_rank: Super Contributor
timestamp: June 08, 2021, 01:00:53 pm
content: Thanks for the feedback!Quote from: Lambda on June 08, 2021, 12:13:23 pmAccording to the 2008 article they had top-quality LWIR and MWIR cameras in use simultaneously and there was no clear winner between them. I hadn't actually considered it from the point of view of emission spectrum but I suspect that an incoming meteor emits from (high) radio frequencies upwards - we know they go as high as visible light (!) - and whatever wavelength you try exploring, it's likely to offer averyhigh contrast against the cold blackness of space.I wish this topic had occurred to me a few days ago: I am up against a deadline at work and will have a hard time taking the few minutes necessary to set up a LWIR camera and video recorder to see if I can see anything.

author: Vipitis
author_rank: Frequent Contributor
timestamp: June 08, 2021, 10:23:51 pm
content: I have tried to do some observations but without any success. A year ago I spent some hours outside on a clear night and observed some meteors with my eyes. None showed up on the thermal images I took when I reviewed my results later. But I wasn't using a wide angle lens.As doing astrophotography was my original one try to this forum and is still my big dream goal, I have put time, effort and money into it without much success yet.But I do have a Watec 902h ultimate CCD camera with a 9mm lens that is used by lots of amateur satellite spotters and even the recommended camera for meteor observation. There is a large network running all sky cameras every night to collect data. I should be able to do some of these observations myself, but I have yet to gets portable power source (I am thinking NP-F) and a better capture solution.I want to use the CCD and my thermal camera (using the 32mm lens as that is working right now) to do some observations, but I am not sure I will find the time. And I am also limited by location, since from my backyard it's rather occluded and I can't see much of the sky.

author: DaJMasta
author_rank: Super Contributor
timestamp: June 09, 2021, 02:16:35 am
content: I don't know if this counts, but have you tried with NIR or SWIR cameras? They should be burning plenty hot enough to emit lots in the nearer IR bands, and while there is a lot of IR coming in from the sun, the scattering from the atmosphere may be less (so not as much brightness looking with the sun out of frame), and may be sufficient for you to get images where the visible light doesn't show.

author: Ultrapurple
author_rank: Super Contributor
timestamp: June 09, 2021, 09:22:43 am
content: I'm not sure that it would make much of a difference. The cloudless sky is essentially black at all wavelengths below about visible yellow. The longer the wavelength, the blacker the sky gets.Here's a sample taken in the near-IR band (1.1-0.85µm).And the same subject, at about the same time, in LWIR (14-7µm):

author: Bill W
author_rank: Super Contributor
timestamp: June 09, 2021, 11:53:34 am
content: Quote from: DaJMasta on June 09, 2021, 02:16:35 amThe problem is that the energy is a very small angular source being spread out over a relatively large TIC pixel 'IFOV' angle, especially as you'd probably be quite wide field to stand a good chance of catching one.Meteor trails are said to be a meter or so wide at 150km rangehttp://adsabs.harvard.edu/full/1958AJ.....63..283HEven with a VGA sensor, a 32 degree lens is 1/20th degree per pixel. At 150km that is 130m wide.So the trail is attenuated by a factor of about 100, and could even go in between the pixels if you were unlucky.Bill

author: Ultrapurple
author_rank: Super Contributor
timestamp: June 09, 2021, 02:34:14 pm
content: Thanks Bill - a good point and an interesting paper.I love it when I find words like 'residuum' in the first paragraph of a report. But I do make my living from the English language so I'm probably biased.

author: DaJMasta
author_rank: Super Contributor
timestamp: June 09, 2021, 03:04:05 pm
content: Quote from: Bill W on June 09, 2021, 11:53:34 amI guess part of my point being that especially with a silicon based NIR camera, you can get much higher resolution than VGA for a much lower price, so if you can get less background brightness from sky scattering, the smaller pixels, cheaper optics, and better contrast on a sun lit sky, you may be able to capture them much more easily/cheaply during the day in the NIR band.

author: bap2703
author_rank: Regular Contributor
timestamp: June 09, 2021, 06:30:17 pm
content: Maybe it's even better to just use an astro-ready DSLR (with it's IR blocking filter removed) but with an IR pass filter.A polarizing filter can also be added to remove some scattered light at 90° from the Sun.

author: Ultrapurple
author_rank: Super Contributor
timestamp: June 09, 2021, 07:17:02 pm
content: I hadn't considered using a NIR-pass filter and astro-type camera for meteors. I have done some moderately successful lucky-photography of random meteors with a wide angle lens and several-second exposures, however as thelight pollution in my area is terrible(and getting worse thanks to all the white LED lighting that you can't filter out like you could with yellow sodium), I am severely limited in terms of the exposure duration.All of this is of course way off-topic for thermal imaging, but what the heck: you can only be banned once...There's apartial eclipse of the sun tomorrow (10 June 2021)and I'm planning to try to photograph that in the visible spectrum with a 400mm prime lens and x2 teleconverter on a Nikon D850. We'll see what happens.The last decent eclipse I was able to experience was 97%, during an insanely busy time in 2015. I drove 500 milesafter workto be as far towards totality as I could manage; at home it would only have been a much less-dramatic 85%. Thepath of totality was mostly over seaand I don't have the financial clout to charter a boat (and not only is my aeroplane not really suitable for flying over open water, its last Permit to Fly expired in 2008).This is one of the best images I managed, taken about 15 minutes before maximum on a Nikon D700 with the same 400mm lens (but no teleconerter).Why? Well, in the few minutes before the critical moment the clouds rolled in. This was my view at the time of eclipse maximum:A thousand miles for nothingIf I get time I will try photographing tomorrow's partial eclipse with a full-spectrum camera and near-IR filter, just to see what happens.

author: Fraser
author_rank: Super Contributor
timestamp: June 09, 2021, 07:40:21 pm
content: Ultrapurple,It is only off topic if not connected with the current threads discussion. The move to IR or Visible light imaging from an idea to use thermal wavelengths is just ‘working the problem’ and helping others to learn about when thermal imaging is appropriate and when other wavelengths may offer a better result. All good stuff in my opinionFraser

author: Bill W
author_rank: Super Contributor
timestamp: June 09, 2021, 09:14:31 pm
content: As we stray off topic.... two photos of the 2003 annular eclipse from northern Scotland. Pictures taken at the same time in monochrome did not show the sun at all.Much as the one tomorrow, the path for a sunrise eclipse is quite wide as it glances across the earth.Bill

author: bap2703
author_rank: Regular Contributor
timestamp: June 10, 2021, 07:50:42 pm
content: Lol Ultrapurple.The best I have is this one.In late 2019 for the Mercury transit, I carried camera gear and a telescope up to 2000m in the snow "to get a clearer view"...Clouds came with meGot back home: clear sky, could have taken it from my parking lot but it was too late

author: Ultrapurple
author_rank: Super Contributor
timestamp: June 11, 2021, 12:29:01 pm
content: I was fortunate with the weather and got some decent visible light views. The lens wasn't great though, and I wasn't overly pleased with the result. (The funny colour is down to the optical attenuator I used).Time was, as usual, against me but I did manage to take a few snapshots with a UV-sensitive camera, though only with a 105mm lens so the image was rather small. And the prints are not back from the e-chemist yet but if anything is worth seeing I will post it.

author: Ultrapurple
author_rank: Super Contributor
timestamp: June 11, 2021, 03:29:11 pm
content: And here is one taken predominantly in UV (380-320nm band pass filter) and a 105mm UV-capable lens on a full spectrum converted Nikon D600.