Tootfinder

The uncertain brightness and tail(s) development of #Kreutz #comet C/2026 A1 (MAPS) is one thing - see the curves in https://astro.vanbuitenen.nl/comet/2026A1 and https://aerith.net/comet/catalog/2026A1/2026A1.html for guesses and https://cobs.si/obs_list?id=2688 for the current value which is ~8.5 mag. - but the viewing geometry is the other: here it is for 51.5° North (my place Bochum) and 22.5° South (Windhoek) as the view is much better from the southern hemisphere.
The table first gives the elongation (angle between comet and Sun in the sky) and the phase angle (the angle Sun - comet - Earth) which nearing 180° can lead to significant boost of brightness by forward scattering on dust.
And this is followed by the altitude of the comet at the solar depressions given in the top line, for Bochum and Windhoek: sunset and end of civilian twilight and for the latter also the end of nautical and astronomical twilight, i.e. the onset of night. Also of importance is the angle of a hypothetical dust tail (simulated in https://hdr-astrophotography.com) after perihelion, also much better in the South: https://britastro.org/section_news_item/c-2026-a1-maps-a-kreutz-group-sungrazer - but first MAPS has to survive the latter *and* release a lot of dust at the right time ...

What #comet C/2025 R3 (PANSTARRS) - more pictures from the 28th in https://www.danilopivato.com/solar_system/comets/c2025_r3_panstarrs/2026.03.28.html and https://www.facebook.com/photo/?fbid=34496897756622967 and https://x.com/hositosorekara/status/2037645491253780614 and https://www.facebook.com/groups/227002358661288/posts/1726756352019207 - may be up to brightness-wise and what the viewing geometry will be in central Europe: explanations in https://skyweek.wordpress.com/2026/03/26/allgemeines-live-blog-ab-dem-26-marz-2026/#Mar29

Lots of fascinating detail in the plasma tail of #comet C/2025 R3 (PANSTARRS) this morning in an image by Christoph Gerhard with a 30-cm telescope: https://www.klostersternwarte.de/aktuelles/ein-überraschender-komet-c-2025-r3-panstarrs - this one will stay with us (Northerners) for another three week low before/at dawn before getting lost in the Sun's glare (when dust forward scattering could brighten it even more).

Reversal of Spin - #Comets 41P/Tuttle–Giacobini–Kresak: https://iopscience.iop.org/article/10.3847/1538-3881/ae4355 -> Hubble Detects First-Ever Spin Reversal of Tiny Comet: https://science.nasa.gov/missions/hubble/nasas-hubble-detects-first-ever-spin-reversal-of-tiny-comet/

Byebye, #comet C/2025 R3 (PANSTARRS), now also exiting the LASCO C3 FOV: time lapses at https://www.facebook.com/watch/?v=1006143605637463 and https://www.facebook.com/watch/?v=1991576091447497, a 9:30 UTC still with the funny new tail feature better visible at https://bsky.app/profile/huubeggen.bsky.social/post/3mkfkihl36c2g, CCOR time lapses at https://x.com/frapepppemaria/status/2048282309007167965 and https://x.com/swnews/status/2048180407045390411 and https://bsky.app/profile/aretsch.bsky.social/post/3mke2h5qxfk2d and a HI2 time lapse - with the plasma tail wagging - at https://x.com/swnews/status/2048007525757604173.

The #comet C/2025 R3 (PANSTARRS) will soon leave the FOV of CCOR-1: cropped pictures from 18:15 and 21:30 UTC on 25 April - and the also the bottom of https://skyweek.wordpress.com/2026/04/15/das-zodiakallicht-hinter-dem-mond-und-die-venus/ for many more images!

The #comet C/2025 R3 (PANSTARRS) is now also in the field of view of the coronagraph CCOR-1: https://ccor.nrl.navy.mil/ccor_realtime/last_image_MinBckgnd.png = the latest image (the one here is from 14:00 UTC), https://ccor.nrl.navy.mil/realtime-movie = an animation up to now (and see https://soho.nascom.nasa.gov/data/realtime/c3/1024/latest.html for the LASCO C3 view).

The #comet C/2025 R3 (PANSTARRS) is joined by a nice CME in the CCOR-1 image from 22:00 UTC.

Sequential Fragmentation of C/2025 K1 (ATLAS) After Its Near-Sun Passage: #comet breaking up: https://esahubble.org/news/heic2606/ and https://science.nasa.gov/missions/hubble/nasas-hubble-unexpectedly-catches-comet-breaking-up/ (the paper as submitted had been discussed by me last November in https://skyweek.wordpress.com/2025/11/26/heute-beginnt-die-tagung-des-esa-ministerrats/ - "So sah Hubble den Kometen C/2025 K1 (ATLAS) zerbrechen").

Attempting to pick #comet C/2025 R3 (PANSTARRS) ouf of dawn today in MŸn at 55°N, at 4:13, :33 and :39 CEDT: solar depressions 14.5°, 12 1/3° and 11 3/4°, comet elevations 7 1/3°, 10° and 10 3/4° - so darker sky is more important that higher elevation. Visually the comet was underwhelming in 11x70 binoculars: that's certainly one for (bigger) cameras, not the eye. And the viewing window is closing fast anyway.

Whatever eagerly awaited #Kreutz #comet C/2026 A1 (MAPS) is up to - see also https://groups.io/g/comets-ml/topic/118409957 and https://nitter.net/JAtanackov/status/2035718257060036738 and https://scicomm.xyz/@qicheng@cometary.org/116262858373488354 - less than two weeks from perihelion, it has developed a long plasma tail now: https://www.facebook.com/photo/?fbid=25816609931372735 (Rhemann & Jäger yesterday with a 12 inch telescope; full and detail).

A clear detection of #comet C/2025 R3 (PANSTARRS) on the morning of March 2 "despite the 99% illuminated Moon, morning twilight and the comet at an altitude of 4.2 degrees": https://groups.io/g/comets-ml/message/34974 -> "The fact that the comet is showing this much detail under such bad conditions with such bad equipment and software bodes well for what we expect will be a very nice comet in the next few months."

So the new #Kreutz #comet #MAPS is *still* following the constant rapid rise in brightness it has shown since discovery: a dumb extrapolation - https://cobs.si/analysis/?comet=2688&from_date=2026-01-15 00:00&to_date=2026-04-30 00:00&observation_type=V&observation_type=C&plot_x_value=1&plot_y_value=1&fit_option=1&exclude_faint=on&exclude_issue=on&observer=&association=&country=&compare_values=compare - has it get 10,000-times brighter than the Sun at its extremely close perihelion which makes so sense at all, of course, physically.
"It must therefore be assumed that this increase in activity will level off significantly in the near future," writes https://fg-kometen.vdsastro.de/koj_2026/c2026a1/26a1eaus.htm: "More likely are parameters m m0=12.0 mag / n=4 (or even lower), which would still result in a (very short-term) maximum brightness of about –9 mag (but this would probably still be significantly too bright) – always assuming that the comet survives its perihelion passage unscathed."
For other views see http://www.cbat.eps.harvard.edu/iau/cbet/005600/CBET005663.txt and https://arxiv.org/abs/2602.17626 and https://www.facebook.com/photo?fbid=10236580364221799 and https://cometografia.es/cometa-kreutz-2026-a1-maps-analisis/ - and the actual brightness is tracked at https://cobs.si/obs_list?id=2688 where it has reached ~11.5 mag. now.

Today it took Michael Jäger and Gerald Rhemann a 12-inch telescope and 27 minutes of total exposure time to show #comet C/2025 R3 (PANSTARRS) this nicely: https://www.facebook.com/photo/?fbid=2382646772252141 - but if it stays the course (brightness-wise speaking) it could be quite impressive for much smaller gear as well as the human eye just a month from now.

The most interesting #comet right now, C/2025 R3 (PANSTARRS), imaged by Michael Jäger and Gerald Rhemann on the morning of 9 April in Martinsberg, Lower Austria with a 12"/4 Lacerta-Newton QHY 600 - the brightness at that time was around 5.5 mag. so the hoped-for forward scattering surge is much subdued ... too little dust in the coma? If it stays that way the coma brightness would only rise by another magnitude or so before the comet is lost in the twilight mid-month - but enjoy its great plasma tail (even accessible to low-end smart telescopes, by the way) while you can.

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Giovanni de Macque & Comet Musicke:
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#GiovannideMacque #CometMusicke
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40 years ago tonight the #Giotto spacecraft passed the nucleus of #comet #Halley at great speed: the documentary https://www.youtube.com/watch?v=eI-W8ss4x5I from back then - also at https://www.esa.int/ESA_Multimedia/Videos/Undated/Giotto_-_English with bonus material - tells the story well. A big special issue of the ESA Bulletin about the mission is at https://esamultimedia.esa.int/multimedia/publications/ESA-Bulletin-046/offline/download.pdf and other historical material like some photos is linked from https://historicalarchives.esa.int/giotto-cometary-encounters-and-archival-sources while a recording of the BBC's live coverage is at https://www.youtube.com/watch?v=QxDMdH4uzxI

The #Kreutz #comet #MAPS "has become more than 1 mag brighter between March 6 and 9" and stands at 10.5 mag. right now: https://groups.io/g/comets-ml/message/35019 and https://www.facebook.com/photo/?fbid=2374472359736249 with the latest picture by Jäger & Rhemann here - less than 4 weeks til perihelion, and the brightness continues to rise with a strong n~8 ...

What #comet C/2025 R3 (PANSTARRS) looks like now - for a 12-inch telescope in Namibia last evening, by Gerald Rhemann & Michael Jäger: the dust tail, lacking the forward scatter enhancement around solar conjunction, is invisible again, the plasma tail is just as gorgeous as in April.