15June: Rare event captured by SHG

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15June: Rare event captured by SHG

Post by p_zetner »

Hi Everyone.

Testing out the new SHG I described earlier in the forum, I noticed a disruption in one of the videos I was recording and thought clouds had drifted through the field of view. Looking up, I noticed jet contrails. Lo and behold, I had captured a jet transit. Here is a portion of the recorded video showing the spectrum near the ultraviolet CN band and the effect of the transit ... the sudden shadow of the jet passing and then the slow drift of the contrails afterwards. The dispersion direction in this video is vertical so the spectral lines stretch horizontally. The CN molecular bandhead lies near the centre of the frame.
2021-06-15-111026_jet-transit.gif
2021-06-15-111026_jet-transit.gif (3.69 MiB) Viewed 1197 times
This is the spectroheliogram that results from taking approximately a 0.5 angstrom slice at the CN bandhead:
Montage_2021-06-15-111026-0000_fftH_usm_lvls_proc_crop.png
Montage_2021-06-15-111026-0000_fftH_usm_lvls_proc_crop.png (1.61 MiB) Viewed 1197 times
Generally, the solar image in the spectroheliogram has to be corrected for a distorted aspect ratio (due to the mismatch between the camera frame rate and the scan rate of the solar image). This is what the correction gives:
Montage_2021-06-15-111026-0000_siz2_fftH_usm_lvls_proc_crop.png
Montage_2021-06-15-111026-0000_siz2_fftH_usm_lvls_proc_crop.png (84.99 KiB) Viewed 1196 times
Here, the Sun's limb regains its round contour but the figure of the jet itself is squashed into unrecognizability. The different speeds with which the jet and the solar image scan across the SHG slit gives a "differential" distortion. The fast moving jet is distorted (compressed in the horizontal scan direction) much more severely than the slowly moving Sun.

It's too bad that this particular video was recorded in the CN band rather than something more familiar like Ca K or H alpha but such is the nature of a random event! For interest's sake, here are some details of the spectral region I was studying (dispersion direction horizontal in this picture).
CN spectrum labeled.png
CN spectrum labeled.png (73.83 KiB) Viewed 1197 times
Cheers.
Peter


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Re: 15June: Rare event captured by SHG

Post by Carbon60 »

Very interesting, Peter. A lucky capture. I’m fascinated by how you know exactly the wavelength you’re looking at.

Stu.


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Re: 15June: Rare event captured by SHG

Post by solarchat »

that’s awesome!


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Re: 15June: Rare event captured by SHG

Post by minhlead »

interesting, Peter.


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Re: 15June: Rare event captured by SHG

Post by thesmiths »

Was the scanning just at drift rate (so a stationary telescope)?


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Re: 15June: Rare event captured by SHG

Post by p_zetner »

Thanks Stuart, Stephen, Minh and Douglas!

Stu: My 1st SHG (undergoing modifications at the moment) had provision for using a bandpass filter which helped me quickly locate regions of interest. With very little experience, the major Fraunhofer lines become easy to find, chromospheric lines especially because they become emitting at the limb. With more experience, even without the bandpass filter, even more obscure lines become easier to find. I use the Liege and BASS2000 online solar spectra for help in identification. It’s somewhat like learning the locations of deep sky objects within the constellations! The 2nd SHG, used here, has a mechanical wavelength readout attached to the grating drive which I calibrate on discharge tube line sources (He, H). Easy peasy to find any line I’m interested in.

Douglas: This was recorded with a stationary telescope - solar drift rate.

Cheers.
Peter


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Re: 15June: Rare event captured by SHG

Post by minhlead »

p_zetner wrote: Sat Jun 19, 2021 4:53 pm Thanks Stuart, Stephen, Minh and Douglas!

Stu: My 1st SHG (undergoing modifications at the moment) had provision for using a bandpass filter which helped me quickly locate regions of interest. With very little experience, the major Fraunhofer lines become easy to find, chromospheric lines especially because they become emitting at the limb. With more experience, even without the bandpass filter, even more obscure lines become easier to find. I use the Liege and BASS2000 online solar spectra for help in identification. It’s somewhat like learning the locations of deep sky objects within the constellations! The 2nd SHG, used here, has a mechanical wavelength readout attached to the grating drive which I calibrate on discharge tube line sources (He, H). Easy peasy to find any line I’m interested in.

Douglas: This was recorded with a stationary telescope - solar drift rate.

Cheers.
Peter
Hello Peter, i'd like to know more about your DIY SHG. How much for each scope?


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Re: 15June: Rare event captured by SHG

Post by p_zetner »

Hi Minh.

Here are a couple of pix of my first SHG which has undergone a few changes (since 2013) but the basic assembly is the same.
2013_SHG.jpg
2013_SHG.jpg (196.56 KiB) Viewed 1128 times
2013_SHG_schematic.jpg
2013_SHG_schematic.jpg (239.23 KiB) Viewed 1128 times
It's constructed from M42 telephoto camera lenses and an old, modified Czerny-Turner spectrograph. The telescope is now a Celestron NexStar 4SE in place of the original Astro-Rubinar 1000mmfl, f/10 catadioptric lens. I accumulated the various components over time largely from eBay when sellers hadn't yet started the routine practice of gouging buyers. I am quite happy with the performance of this SHG and have used it for image making as well as some scientific studies (described in the English version of Astronomie Solaire by Christian Vladrich et al.). Here are some recent images from this SHG: viewtopic.php?f=8&t=29168

My newest SHG, which I am still testing and modifying, is described here:
viewtopic.php?f=8&t=30793
I'm still determining how best to use it to complement my first instrument.

Cheers.
Peter


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Re: 15June: Rare event captured by SHG

Post by christian viladrich »

This is excellent Peter !!
Just wondering whether what is seen on the spectrum is the "turbulent wave" generated by the plane or the contrail ? I saw this wave several times in visible light, doing imaging on planets or the Moon.
Maybe turbulence effects won't appear at all in the spectrum ?
Cheers
Christian


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Re: 15June: Rare event captured by SHG

Post by christian viladrich »

BTW, do you have any image comparing CN et Ca II ?


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Re: 15June: Rare event captured by SHG

Post by Montana »

That's absolutely incredible :bow :bow :bow

Alexandra


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