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That is very odd. I haven’t been able to find why they think it is an asteroid. At mag 13 it is either huge (in which case it would have been discovered already) or very close (in which case it would have a large apparent motion unless it is heading straight for us). There is nothing matching it on the NEOCP (the brightest object there is 18.2. It is possibly AI gone mad but there is a long list of real people on the discovery report.
It will be interesting to see what this turns out to be. Possibly a subject for my next Christmas Sky Notes.
The comet is showing a fairly bright ion tail to the north but its length depends very much on sky conditions since it has a low surface brightness. The current total magnitude is around 6.6 so it should be approaching naked eye visibility at really dark sites. In a 9 arcsec radius the magnitude is around 10.4 and this is a bit above the trend for that aperture. It looks as if there have been a couple of small outbursts in the last week.
Attachments:
It is very close to the Horizons prediction and around mag 12 at the moment (Feb 15.95). It’s been almost total overcast here tonight but I managed to get a few images in small gaps.
Attachments:
This is usually a good source of re-entry predictions too: https://aerospace.org/reentries.
James – The discussion was streamed as part of the SGM. The video is online here:
https://www.youtube.com/live/-ARFP-FBl98?si=4dGJXXjJV23UHccI&t=173
According to this thread from six years ago:
https://www.aavso.org/reducing-fits-size-use-vphot
Vphot has an upload file size limit of 50 MB. That is probably why your attempt to upload the FP images fails since the filesize is 65 MB. I would have thought that it would tell you this rather than failing silently.
I doubt very much that a few singing astronomers will rank very highly on that bar’s rowdy meter. It’s a student bar for farmers…
And we now have a confirmed meteorite find from this impact:
David – Are you sure that is the best idea? It is a well-known fact that people are a lot less inhibited in bars which is why you don’t often see decent karaoke anywhere else. Perhaps you could do both. A formal concert version and a bootleg B-side bar version.
I would hope they use a standard library (e.g. cfitsio) to read and write FITS files rather than something homebrew. I use cfitsio for all of my code and it is very robust.
It looks as if it is something to do with the data format. A lot of programs can read FP files now (even Astrometrica) but they assume that the data is scaled in the same way as an integer format file, i.e. a range of 0..65535 and they just truncate to the nearest integer. FP format FITS files can have some wacky scalings. I’ve seen some where the entire image dynamic range is in the range of 0.0 to 1.0 and that clearly doesn’t work very well if you just truncate. From looking at the header of your calibrated file that does not look to be the case here.
The headers look OK with nothing obvious. Do you get any hint in the error message from VPHOT or does it just silently die? As a workaround can you get ASTAP to save your calibrated files in integer format? I would have thought that there would be some option to do this.
The file extension shouldn’t make any difference.
Are the files roughly the same size? The raw files you get from the camera are probably 16-bit integer (BITPIX=16). After calibration they may be floating point (BITPIX=-32) and it may be that Vphot can’t cope with that. The FP files will be twice the size of the integer ones. If Vphot can’t cope with FP that is a bit poor but there may be an option in ASTAP to save as ints.
Failing that, have a look at the FITS header and see if you can spot any significant differences. That might give a clue as to what is going wrong.
Sadly, I’ll miss Winchester again this year so you’ll be denied the experience of my G&S baritone but please record this if it goes ahead. It should be a hoot. Something to feature in the next Christmas Sky Notes.
Using astrometry from me (970), Peter Birtwhistle (J95) and Patrick Wiggins (718) obtained since the propellant leak stopped I get a nice fit (3-day arc, 0″.2 residuals) to a gravitational only orbit for the lander using Findorb. This gives a predicted Earth impact time of 23:44 UTC on 2024-01-18 over northern Australia in daylight. The lander is potentially imageable from the UK a few hours before re-entry on the night of the 18th as it moves through Cancer, low down in the east after sunset, although it will be moving very rapidly across the sky.
Just imaged the lander and the Centaur and they are both close to the position predicted by Bill Gray’s site (https://projectpluto.com/sat_eph.htm). The Centaur (2024-006B) is around 17.0 now and the lander (2024-006A) is around 17.6. Astrobotic have said that the mission will end when the lander burns up at the next perigee on January 18.
The lander trajectory is being significantly affected by the propellant leak. My astrometry of it tonight (Jan 10) is around 2 arcmins from where it should be assuming a ballistic trajectory. The spacecraft is around mag 18 tonight. The Centaur is much better behaved and quite bright (mag 14). We should be able to follow that for quite some time as it goes off in a heliocentric orbit. I’ve attached an ephemeris for the Centaur in case you want to have a go.
Gennady Borisov has found the Centaur too and this was briefly listed as gb00471 on the NEOCP. I’ve just imaged it and it is around 12 deg SW of the spacecraft and quite a bit brighter at 14th mag.
This is a good summary of the angular momentum misalignment and some of the theories put forward to explain it:
https://iopscience.iop.org/article/10.3847/0004-6256/152/5/126
Short answer, as Dominic says this is a coincidence. Longer answer as follows…
I assume that the tilt you mention is the apparent position angle of the sun’s rotation axis in equatorial coordinates. This is a function of the sun’s axial tilt with respect to the ecliptic (around 7.3 degrees), the Earth’s axial tilt (around 23.5 degrees) the orientation of the two spin axes in space and where we are in our annual orbit around the Sun. In the short term the rotation axes of the Sun and Earth and the plane of the Earth’s orbit have a fixed orientation so as we travel around the Sun the relative geometry changes on an annual cycle.
Our view of this tilt depends on the coordinate system we use.
In ecliptic coordinates (i.e. not including the Earth’s axial tilt) you would see the rotation axis nodding from side to side in a simple sinewave over 12 months going through a minimum in March when we see the south pole tilted towards us and in September when we see the north pole. In between it reaches its maximum tilt of 7.3 degrees tilted left or right. When you look in the equatorial coordinate system you have to add in the effects due to the Earth’s axial tilt as well. This makes the geometry more complex since you have two sinewaves adding together but, as you have noted, the tilt is around 0 in early January and reaches around 26 degrees in early April.
The orientation of the Earth’s perihelion in its orbit is completely unrelated to the orientation of the rotation axes and, as Dominic noted, precession affects the Earth’s axis orientation and the perihelion orientation over the long term so this “coincidence” will not last forever.
The thing that is surprising, following up on Dominic’s comment, is why there is a such a large angle between the Sun’s rotation axis and the normal to the Solar System’s invariable plane (essentially the perpendicular to Jupiter’s orbit plane). Since the Sun and its planetary system formed out of the same rotating cloud of material you would expect them to have the same angular momentum orientation. The fact that the planets now move in a plane tilted at around 6 degrees to the Sun’s equator is a bit surprising. There are some quite inventive theories out there to explain this.
It was cloudy in Chelmsford but here it is from my SW pointing camera.
https://nickdjames.com/meteor/2023/202312/UK004F_20231230_020727_ndj.mp4
