{"id":3264,"date":"2024-01-28T17:16:58","date_gmt":"2024-01-28T16:16:58","guid":{"rendered":"https:\/\/vincenzodellavecchia.it\/?page_id=3264"},"modified":"2026-01-03T14:49:41","modified_gmt":"2026-01-03T13:49:41","slug":"altre","status":"publish","type":"page","link":"https:\/\/vincenzodellavecchia.it\/en_us\/altre\/","title":{"rendered":"Others"},"content":{"rendered":"

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The nights of the Geminids<\/h1><\/span>
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Less well-known than the Perseids, but no less spectacular, the Geminids streak across the winter skies on the nights between December 13th and 15th. When the lunar phase is not too advanced, and the geometry is favorable, it is possible to engage in an interesting and relatively recent field of research: monitoring lunar impacts. In fact, the peak meteor frequency on Earth coincides approximately with that of our satellite; the notable difference is that, due to the absence of an atmosphere, meteoroids transfer almost all of their kinetic energy to the lunar surface, causing the dust to rapidly heat up and become emitting (flashes). Impacts are much more likely to be detected on the dark side of the Moon, which is the one monitored for the longest possible time. <\/div>\n

This year, observations were very successful, and I personally managed to record a dozen of pretty much certain impact flashes. Researchers are still analyzing the large amount of data collected.<\/p>\n

The attached GIF shows 15 confirmed or very likely impacts extracted from my own data, at slow motion. Be warned that not all of them are perfectly centered or highly contrasted.<\/p>\n

Technical data<\/h4>\n

RC 10\u2033 f\/5.6 \u2666 Player One Ares M camera<\/p>\n<\/p>\n

13-14 December 2025 <\/b><\/p>\n<\/div>

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Zeta cancri revolution in 20 years<\/h1><\/span>
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Double star enthusiast David Cotterell (\u201cCotts\u201d on the CloudyNights forum) has assembled these four images of Zeta Cancri, one of the most famous multiple stars. The images span twenty years, from the first taken by Damian Peach in 2004 (C14) to my last one in 2024 (a 30-cm Cassegrain). Since the C star orbits the system's center of mass with a much longer period than the AB pair (about 800 years versus 60), David used the AC pair as a basis for evaluating the displacement of the other (the rotation is about 8 degrees, giving rise to no appreciable error). The clockwise displacement of the secondary star (b) around the primary (a) is clearly visible.<\/p>\n

Captions are mine. Image credits go to their respective authors, listed at the bottom along with the acquisition date. <\/p>\n

Technical data<\/h4>\n

Classical Cassegrain 30 cm f\/20 \u2666 Astronomik R filter (colorized)<\/p>\n<\/p>\n

March 2023 (publication November 2025)<\/b><\/p>\n<\/div>

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SATURN SPECTRUM<\/h1><\/span>
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By the operation of spectra division it is possible to \"clean\" the solar component from Saturn's spectrum, which thus shows two of the most pronounced methane absorption bands at 7120 and 6190 \u00c5ngstroms, clearly visible even in the raw spectrum below. HD225239 (spectral type G2V, like the Sun) was used as the reference star for sunlight. <\/div>\n

The strongest absorption band of CH4 is located at about 900 nm and is the one upon which is centered the usual methane filters used by amateurs for scientific imaging of planets. Unfortunately, the sensor's poor sensitivity at those wavelengths prevented it from being recorded. <\/p>\n

Technical data<\/h4>\n

GSO RC 10\u2033 f\/8 \u2666 Star Analyzer 200 + 2\u00b0 prism \u2666 Player One Ares M<\/p>\n<\/p>\n

October 10, 2025<\/b><\/p>\n<\/div>

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Zambuto 10\u2033 f\/5 textbook star test +roddier test
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Star test of my Zambuto 10\u2033 f\/5 mirror, mounted on the Sumerian Alkaid Dobsonian (completely manual). The star chosen for the test was Polaris. The two intra- and extrafocal figures are pretty much identical, justifying the worldwide reputation of Carl Zambuto. <\/p>\n

The three primary-holding clips and the intrusion of the focuser into the cone of light are visible on the edge (11-17 o'clock). <\/p>\n

The Roddier test gives a Strehl ratio of 0.98 on the focal plane and a correction of 1\/50 wave RMS. The coma was removed to account for slight miscollimations, quite difficult to get rid of on this telescope. <\/p>\n

Technical data<\/h4>\n

ASI174MM \u2666 Baader 685 nm filter <\/p>\n<\/p>\n

December 17, 2024
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NEA 2007 YZ and 2016 UN54 of 20th and 21st magnitudine<\/h1><\/span>
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Using the \u201cTrack & Stack\u201d technique with about half an hour of data, I managed to image this Near-Earth asteroid (provisional name 2007 YZ) of magnitude 20.2 from my suburban observatory. The night was particularly clear and moonless, and the asteroid was quite high above my horizon (45\u00b0).
Update. <\/u> Exactly one year later, I took advantage of a long session dedicated to obtain an asteroid light curve (about 4 hours) to check what magnitude I had reached in that field of view. Asteroid 2016 UN54 was the faintest, with a V-band magnitude of about 21.<\/p>\n

Technical data<\/h4>\n

RC GSO 10\u2033 f\/5,6 \u2666 Ares-M cooled camera<\/p>\n<\/p>\n

November 11, 2024\/November 11, 2025<\/b><\/p>\n<\/div>

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Wolf-Rayet 136 spectrum
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At the center of the famous Crescent Nebula in Cygnus, the Wolf-Rayet 136 looms large, whose spectrum I recorded with the C8, the ASI462MM and the Star Analyzer 100. <\/p>\n

After an accurate and not quite easy stacking of 100 frames I achieved a good S\/N ratio, as can be seen from the cleanliness of the monochromatic spectrum above, which clearly shows the bright emission lines. In particular, the two yellow lines of C IV and He I are close but very distinct. <\/p>\n

I used the latter couple of lines to estimate the resolution of the spectrum, equal to 45 \u00c5. <\/p>\n

Technical data<\/h4>\n

C8EdgeHD \u2666 Star Analyzer 100 \u2666 Apollo-M camera<\/p>\n

Dispersion=6.2 \u00c5\/pixel<\/p>\n

July 23, 2024<\/b><\/p>\n<\/div>

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PROCYON B ORBIT (HST DATA)
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Collecting some 1 GB of Hubble Space Telescope data, spanning more than 15 years, I was able to draw the orbit of Procyon B around the main star.<\/p>\n

Due to huge magnitude difference, the double is one of the toughest to observe from the ground, so researchers were forced to request HST time to study the astrometry of the system (see Bond et al.<\/a>). They say it was impossible to avoid saturating the CCD with the new WFC3 detector, so you can see the blooming in all the FITS.<\/p>\n

The ellipse I obtained fits quite well with the white dwarf apparent orbit presented in the paper. Procyon B completes one revolution in around 40 years.<\/p>\n<\/div>

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HD 56515 split at Rayleigh limit<\/h1><\/span>
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The double HD 56515 in Canis Minor, clearly resolved at just under 0.7\u2033 of separation, compared with a theorical image of the Rayleigh limit (equal to approximately 0.69\u2033 for C8 at green wavelengths). In addition to the usual checks on the position angle, I also carried out a plate solving on the star field to make sure I imaged the right star. <\/p>\n

Technical data<\/h4>\n

C8EdgeHD \u2666 ZWO ASI462MM \u2666 Astronomik G<\/p>\n

March 19, 2024 <\/b><\/p><\/p>\n<\/div>

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Ceres resolution
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An attempt to resolve Ceres (the largest of the asteroids), in opposition those days. The third and fourth images were obtained with the camera rotated 90\u00b0; you can clearly see how the axis of the asteroid (which is cigar-shaped) rotates in accordance. For comparison, the last image shows the PSF of a nearby star. The image obtained (rescaled and blurred) matches almost perfectly with the Hubble image.<\/p>\n

This image is one of the very few (among amateur ones) to clearly resolve this asteroid.<\/p>\n<\/div>

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Sirius A\/B
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The white dwarf Sirius B (aka \"The Pup\") is in recent years at the maximum distance from the main star (more than 11\u2033), so it is not difficult to spot in the glare of the primary, both visually and digitally. The optics must be very clean and the seeing conditions fair, at least. The diagonal reflection in the image is given by the ADC prisms, with the 4 secondary diffraction spikes superimposed. The processing is light, to give an idea of \u200b\u200bhow the double looks like at the eyepiece.<\/p>\n

Technical data<\/h4>\n

14″ Newton (Zen optics) \u2666 Player One Saturn-C camera<\/p>\n

October 17, 2022 <\/b><\/p>\n<\/div>

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Venus clouds animation
imaged by akatsuki probe
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This animation had been assembled with images taken by the Japanese Akatsuki probe (Planet-C) in orbit around Venus. The instrument used was UVI<\/b> (UltraViolet Imager), while the sequence spans approximately 6 1\/2 days.<\/p>\n

The size of the planet changes according to the distance of the probe. The famous Venusian Y is recognizable at the beginning and towards the end of the sequence. <\/p>\n

South at top.<\/p>\n

2016 June 22-28<\/b><\/p>\n<\/div>

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