Icosahedron

H-gamma prominence at full resolution:

Hydrogen-gamma and neutral iron at 438.36 nm:

Are you still around Kitsunegari? Ba II, 455.4 nm:

This doublet is situated between the H and K lines:

What I meant to say in my previous post is that the Sun crossed the optical axis of the telescope in a line from the 2 o'clock to 8 o'clock position. Anyway, here's one more, H-beta reprocessed:

I've added a processing routine to constrain the shape to a disc in a lossless manner, only geometry is affected. The sharply defined limb at 2 and 8 o'clock is due to it passing through the centre of the telescope objective during the capture sequence. The limb at 5 o'clock confirms a spectroscope/camera alignment problem that I've noted before while using a test setup.

Thanks all for the kind comments.

@Merlin66:
The wavelengths are 410.17 nm (H-delta), 434.05 nm (H-gamma) and 486.13 nm (H-beta).

@vineyard:
The images were captured with a spectroheliograph using the drift method. It takes about two minutes to perform a capture and as it was windy, movement of the instrument affected the shape. The limb of the Sun was also affected but the software routine that I use to address the effect of atmospheric seeing on the limb restored it. Still need to do a routine to constrain the shape to a disc.

A sunny morning at last...

Here is a comparison with the Meudon spectroheliograph at Paris Observatory. I assume that the plage areas are not the result of overexposure and that a narrower bandwidth makes a difference there. Filaments are definitely very wispy now so no further attempts at reducing the bandwidth.

I recently finished the construction of my latest camera and jumped at the opportunity that presented itself yesterday to try it out. The new camera with smaller pixels reduces the bandwidth to 0.01 (H-alpha) to 0.02 (Ca II K) Angstrom/pixel. Narrowing the bandwidth unfortunately results in fainter filaments and prominences. For the first time I made an attempt to process the prominences to see what I'm left with. Next time I'll overexpose the disc of the sun to see if I can improve the result. For now the camera is a keeper.

Not present in solar spectrum. Check Rowland's Preliminary Table of Solar Spectrum Wavelengths pages 79 and 234.

Hi Apollo,

I'm about to construct a camera with smaller pixels and will attempt Ba again after that and solving the interference problem. No Hg lines present in the solar spectrum according to the reference I use.

Thanks Rusted. Yes, left-clicking three times on the image will take you to full resolution.

H-eta: 383.54 nm
Ca II: 393.37 nm
Fe I: 404.58 nm
Ca I: 422.67 nm
Fe I: 438.36 nm
H-beta: 486.13 nm
Mg I: 518.36 nm
Fe I: 558.68 nm
Na I: 589.0 nm
Ca I: 612.22 nm
H-alpha: 656.28 nm

These images are the first to be processed by a mainly automated process which is still a work in progress. The narrow lines of Fe I (558.68 nm) and Ca I (612.22 nm) expose electrical interference that needs to be addressed:

H-zeta and epsilon compared to H-delta on 4 April:

This set of images from 17 July shows the alikeness between H-delta, gamma and beta:

I've been observing the lines of hydrogen and noted that H-alpha detail is unique. Except for slight differences in contrast, beta, gamma and delta are identical. Then follows the rest represented here by H-eta at 383.54 nm:

Hi Ken,

Very nice detail you have there, what telescope objective do you use with your setup? I eventually upgraded to a 2400 lpmm grating and already being borderline in the UV had to opt for a 90 mm objective (AliExpress) to compensate for light loss due to the wider dispersion.

Ca II K, Fe I (432.56 nm), H-beta, Mg I (518.36 nm), Na I (589 nm) and H-alpha:

True colour:

False colour:

I tried the two Ba wavelengths and found them to appear the same as the continuum with a little less brightness. Any detail was probably lost in the seeing.

Here are a few captures from 17 July; H-alpha, beta, gamma and delta:

Fe I at 438.36 and Ca I at 422.67 nm as well:

I've been reading up on impact events and although there are countless mentions of an asteroid or comet hitting the earth I can't find anything on confirmed comet impacts. However, what I found very interesting is the velocities of the objects relative to earth. One source states a typical 17 km/s for an asteroid (NEA) compared to 51 km/s for a comet, which in my mind puts a comet impact in a different class of event.

As far as the Tunguska event is concerned I think the possibility exists that a suitably sized comet was entirely vapourised in a collision with earth's atmospheric with only an energetic ball of gas making it to the surface.

The light reaching us from galaxies moving away from us is red-shifted. The "edge" of the observable universe is where light is red-shifted into the infrared range. Due to infrared interference from the sun and earth current telescopes can't be made sensitive enough to detect what lies further out. This is where the James Webb Space Telescope comes into play, an infrared telescope that will be positioned away from earth and shielded from the sun. It will allow us to observe what lies beyond the current "edge".

I've also read that the impactor could have been a small comet. I'm sure there is more to the constitution of comets than just icy material but is it reasonable to expect to find fragments now if it was the case?

This is definitely H12 (375.02 nm), note the bright spot in the southern hemisphere.

Blurriness is the result of poor sensitivity of the image sensor in the UV. A longer exposure time is required during which seeing takes its toll. Here is a comparison of the sources which were acquired minutes apart. The horizontal lines show how seeing affects the shorter but not the longer wavelength. The well-defined squiggles in a few places show that focusing is not the problem.