APOD and General Astronomy Discussion Forum
https://asterisk.apod.com/
Hmmm, something about him may have tipped them off.BMAONE23 wrote:At least the police didn't kill this crazy person even though it could have been devastating if the device were real. I'm kinda surprised that they didn't shoot to kill
The high-pressure sodium lamp outside my window has been replaced with an LED lamp. Darkness is no longer an option! There is another HPSL still remaining down the street. I used the diffraction grating / rainbow maker and compared the spectra. The LED lamp has no discernible emission or absorption lines that I could see Completely smooth. The HPSL's emission lines and one absorption line are comparatively impressive.Chris Peterson wrote:CDs work even better. That's what I use in the classroom, and we can easily see the solar spectrum as well as the distinct lines that show up from sodium and mercury lights, from fluorescent lights, and from monitors and LED projectors.geckzilla wrote:I've got a high pressure sodium lamp outside my window which I curse on a near nightly basis but I have noticed it plays rather well with this toy. Somehow I got the idea that maybe I could see emission lines through the thing and ended up putting my eyeball right up to the thing and sure enough there were definite intensity peaks. This is just a toy, though, and I can't figure out if it's just an imperfection in the thing or if they're actually what I think they are. I managed to take a photo.
Some years back I was at a star party and they were handing out little cards with a 1/4" hole containing a transmission grating (you can make one by peeling the metallic coating off a CD). Printed on the card are images of the appearance of all the major light pollution sources as seen through the grating.
I have to ask, would it be possible for you to take spectra of PN?geckzilla wrote:The high-pressure sodium lamp outside my window has been replaced with an LED lamp. Darkness is no longer an option! There is another HPSL still remaining down the street. I used the diffraction grating / rainbow maker and compared the spectra. The LED lamp has no discernible emission or absorption lines that I could see Completely smooth. The HPSL's emission lines and one absorption line are comparatively impressive.Chris Peterson wrote:CDs work even better. That's what I use in the classroom, and we can easily see the solar spectrum as well as the distinct lines that show up from sodium and mercury lights, from fluorescent lights, and from monitors and LED projectors.geckzilla wrote:I've got a high pressure sodium lamp outside my window which I curse on a near nightly basis but I have noticed it plays rather well with this toy. Somehow I got the idea that maybe I could see emission lines through the thing and ended up putting my eyeball right up to the thing and sure enough there were definite intensity peaks. This is just a toy, though, and I can't figure out if it's just an imperfection in the thing or if they're actually what I think they are. I managed to take a photo.
Some years back I was at a star party and they were handing out little cards with a 1/4" hole containing a transmission grating (you can make one by peeling the metallic coating off a CD). Printed on the card are images of the appearance of all the major light pollution sources as seen through the grating.
Spectra, like narrowband images, are very tolerant of light pollution- especially of continuum pollution as we get with LEDs. Broadband imaging is intolerant of continuum light pollution, but can be conducted reasonably well under light pollution from gas discharge sources like sodium lights because there are blocking filters that can reduce most of that while still letting most light through.starsurfer wrote:I have to ask, would it be possible for you to take spectra of PN?geckzilla wrote:The high-pressure sodium lamp outside my window has been replaced with an LED lamp. Darkness is no longer an option! There is another HPSL still remaining down the street. I used the diffraction grating / rainbow maker and compared the spectra. The LED lamp has no discernible emission or absorption lines that I could see Completely smooth. The HPSL's emission lines and one absorption line are comparatively impressive.Chris Peterson wrote: CDs work even better. That's what I use in the classroom, and we can easily see the solar spectrum as well as the distinct lines that show up from sodium and mercury lights, from fluorescent lights, and from monitors and LED projectors.
Some years back I was at a star party and they were handing out little cards with a 1/4" hole containing a transmission grating (you can make one by peeling the metallic coating off a CD). Printed on the card are images of the appearance of all the major light pollution sources as seen through the grating.