Some good thoughts here.I keep coming back to the size that this thing is supposed to be and that it's categorically not a POI. Oh, and you should be armed. And was in-game pre-horizons and PP.
There's a good chance that people have sailed right past it and not realised what it was. I conclude from that, the visible thing is an in-game asset and that is out-of-place. In my mind, that has to be limited to, odd configurations of star-systems or containing celestial objects - maybe odd descriptions. This would only be identifiable by the most diligent explorers, as for those who have done even a little bit of exploring, there is so much variation and "quirks of stellar forge" things that could be out of place are extremely common.
Then add to the vast search area, even if you limit to yourself to 200ly around the CG, that's still a lot of places to look for the unknown. My expectation (foundless) would be some breadcrumbs that lead into a higher frequency of the issue spread over multiple star systems. This is why I started trying to find "dead ends" around the CG area, where the star was over 20ly away from most neighbours (20ly because that's the max range for the nav panel, and also a sensible long range for a Cobra). But there seem to be a few pockets of these "dark patches" around that don't seem to line up anywhere, and before bookmarks, it would have been impossible to work out any pattern.
I've also been keeping an eye on my nav panel to see if any non-generated names crop up. And periodically searching for non-main-sequence stars in the hope that I stumble across a rogue planet or something - which would be awesome.
But in conclusion, I'm stuck. I need to abandon my brief search to get my data to COR before time is up.
My personal suspicion is that what we are looking for are one or more stars that can be seen in the skybox but not in the Galaxy Map or nav panel (and which we cannot therefore travel to, yet). This would match everything I have heard of that describes the puzzle (e.g. not a POI, reading between the lines, having possibly been seen already and noticeable by a single commander). To present this as 'solved' would require identifying those stars that can be seen but which have been removed from the Galaxy Map, presumably by the superpowers to prevent us being suspicious of permit locks in the region.
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To attempt to identify those stars, I have queried Simbad for all objects within 30 arc minutes (half a degree) of the Heart Nebula and gone through the resulting list of almost 1300 objects for the brighter stars, excluding those in the 2MASS catalogue which are mostly in IC 1805, where it would be most difficult to identify a star as being present in the skybox but not the Galaxy Map. It is my intent to check which of these are findable by searching the Galaxy Map, which allows those to be excluded, and to then focus my efforts on trying to find the others in the skybox, that are not findable in the Galaxy Map but which should be in the Formidine Rift area.
Here is the preliminary list, which I have yet to check through in-game:
HD 15558
HD 15570
HD 15629
HD 15557
HD 15851 (Simbad also lists HD 15851A and HD 15851B separately)
HD 15522
V1166 CAS
KM CAS
MWC 50
BD+60 501
BD+60 505
BD+60 506
BD+60 500
BD+60 499
BD+60 498
BD+60 496
BD+60 508
BD+60 512
BD+60 513
BD+60 509
BD+60 497
BD+60 493
BD+60 518
BD+60 519
BD+60 483
BD+60 482
BD+60 510
BD+60 520
BD+60 503
BD+61 427
BD+61 430
HD 15570
HD 15629
HD 15557
HD 15851 (Simbad also lists HD 15851A and HD 15851B separately)
HD 15522
V1166 CAS
KM CAS
MWC 50
BD+60 501
BD+60 505
BD+60 506
BD+60 500
BD+60 499
BD+60 498
BD+60 496
BD+60 508
BD+60 512
BD+60 513
BD+60 509
BD+60 497
BD+60 493
BD+60 518
BD+60 519
BD+60 483
BD+60 482
BD+60 510
BD+60 520
BD+60 503
BD+61 427
BD+61 430
.
If all these stars are findable in the Galaxy Map search, then there are other stars from other catalogues but it becomes harder to trace, as I mention above. I would probably assume that I am wrong if that turns out to be the case. If I am right, however, then there are one or more stars amongst these that, similarly to the 'test lights' near Sol, can be seen visually but not selected or travelled to. If these can be identified, then the way forward would be to write up a Galnet article detailing the find and asking why Universal Cartographics records have been tampered with.
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It may be a couple of days before I get out to the region to check this myself, as I'm still feeling rather tired after recently visiting Hawking's Gap and doing various other things that have left me in need of a break, both in-game and irl, so I might not even be on again for a day or two. Good luck to everyone searching the Rift and I hope you all get back safely (and in time for the CG).