Happy New Year 0409!

Question

The date 0409·01·MO is New Year’s Day in the Ceres Calendar. Wish everyone and everything in the Asteroid Belt, Jupiter, Saturn and beyond a belated Happy New Year by writing a program to convert Julian Dates (JD) to Ceres Dates using these helpful landmarks:

 JD CMJD Ceres Date (& Time*) ISO 8601 (approx.)
Start of Ceres calendar 2309103.500 0.000 0000·01·MO 00:00 1610
Start of JD calendar 0.000 -2309103.500 -6344·17·MO 4713 BCE
Earliest recorded eclipse 501822.000 -1807281.500 -4966·49·SU 3339 BCE
Battle of Megiddo 1189360.000 -1119743.500 -3077·41·FR 1456 BCE
Battle of Halys 1507900.000 -801203.500 -2202·47·WE 584 BCE
Alexander the Great (b) 1591596.000 -717507.500 -1972·43·SU 355 BCE
Crab Nebula supernova 2106216.000 -202887.500 -0558·33·MO 1054
Discovery of Galilean moons 2309107.000 3.500 0000·01·TH 1610
Discovery of Titan by Huygens 2325616.000 16512.500 0045·19·SU 1655
Discovery of Uranus by Herschel 2371629.000 62525.500 0171·41·TU 1781
Discovery of Ceres by Piazzi 2378862.000 69758.500 0191·34·TH 1801
Discovery of Pallas by Olbers 2379313.000 70209.500 0192·46·SU 1802
Discovery of Juno by Harding 2380201.000 71097.500 0195·17·SA 1804
Discovery of Vesta by Olbers 2381140.000 72036.500 0197·47·SU 1807
Discovery of Astraea by Hencke 2395274.000 86170.500 0236·39·MO 1845
Discovery of Neptune by Galle & Le Verrier 2395563.000 86459.500 0237·28·WE 1846
First Nobel Prizes awarded 2415729.000 106625.500 0292·49·TU 1901年12月10日
Archduke Franz Ferdinand (d) 2420312.000 111208.500 0305·27·SU 1914年06月28日
Discovery of Pluto by Tombaugh 2426054.000 116950.500 0321·16·TU 1930年03月18日
Hiroshima bombing 2431673.469 122569.969 0336·38·SU 23:15 1945年08月05日
Dawn probe started exploration of Ceres 2457088.028 147984.528 0406·29·FR 12:40 2015年03月06日
Gravitational waves first detected by LIGO 2457279.910 148176.410 0407·05·MO 09:50 2015年09月14日
New Year’s Day 0409 2457980.000 148876.500 0409·01·MO 12:00 2017年08月14日

CMJD stands for Ceres Modified JD, a convenient offset. CMJD is related to JD by the formula:

CMJD = JD - 2309103.5

The Ceres Calendar has 52 weeks (01 - 52) of seven days, with Monday (MO) as the first day of the week, the rest are TU, WE, TH, FR, SA, & SU and the time synchronized to UTC formatted as HH:MM or HH:MM:SS. There are no leap days in the Ceres Calendar.

* The Ceres Dates lacking times are only known to the day, so as a convention the middle of the day 12:00 is chosen as the time. Displaying 12:00 for these cases is perfectly acceptable.

Note that the Calendar starts on the Monday before Galileo discovered his satellites, that’s to have the start of the calendar on a Monday to correspond to the ISO 8601 start of the week. The discovery of the Galilean Satellites is more important to them than the Discovery of Ceres but not so important as to mess up the start of the week or the start of the year! That’s just how they roll!

Your program must convert JD ≥ 0.000 to Ceres Date in the format above, using - (U+2212 MINUS SIGN) and · (U+00B7 MIDDLE DOT) as required. Especially for those using ASCII-only languages, you can substitute ~ (U+007E TILDE) and * (U+002A ASTERISK) for the minus sign and middle dot, respectively. The format for dates beyond 9999·52·SU is undefined.

Here’s a handy page to convert to Julian Dates and lots of other useful information.

This is code-golf, so shortest answer in bytes wins.

• hyperneutrino: Bonus points for doing it in Ceres: TIO
• Jonathan Allan: "with seven days" lists only six EDIT: I see SU in the landmarks list, so must be that that is missing.
• Jonathan Allan: The requirement for a subtraction sign is rather strange for a negative number, hyphen-minus (U+002D) would be more appropriate.
• user15259: @JonathanAllan - thanks for catching missed SU, and apparently the dedicated MINUS SIGN is "more correct" for subtraction operations and negative numbers!
• user15259: @Notatree - Have added provisions to allow substitutions of ~ (U+007E TILDE) and * (U+002A ASTERISK) for the minus sign and middle dot, respectively.

Answer 1

Jelly, 92 bytes

^{Definitely beatable by languages with built-in time-formatting or even just better string-formatting.}

×ばつ(¢Ẓd60
_"#ḟf’_.μd364Ad0¦7Ẏ;ÇḞ‘2¦ị3¦"TUWETHFRSASUMO"s2¤Ṛ€o0ẋ(¡Ḳḃ4¤¤U(œọ;"ṢṢ :‘¤Ọ¤żFḊ8Ṡ>-¤¡

A full program accepting a single argument (decimal number representation) and printing the result.

Try it online!

How?

×ばつ(¢Ẓd60 - Link 1, get hours and minutes portion of days: number (of days)
%1 - modulo by one - get the fractional part
 (¢Ẓ - base 250 number = 1440 (that's 60*24)
 ×ばつ - multiply
 d60 - divmod 60 (integer divide by sixty and yield result and remainder)
_"#ḟf’_.μd364Ad0¦7Ẏ;ÇḞ‘2¦ị3¦"TUWETHFRSASUMO"s2¤Ṛ€o0ẋ(¡Ḳḃ4¤¤U(œọ;"ṢṢ :‘¤Ọ¤żFḊ8Ṡ>-¤¡
 - Main link: number, JulianDate -- breaking this down into parts...
_"#ḟf’_.μ - Main link part 1 (get the CMJD): number, JulianDate
 "#ḟf’ - base 250 number = 2309103
_ - subtract from JulianDate
 _. - subtract a half
 μ - monadic chan separation, call that CMJD
d364Ad0¦7Ẏ;ÇḞ‘2¦ - Main link part 2 (get the numeric parts): number, CMJD
d364 - divmod 364 (integer divide by 364 and yield result and remainder)
 A - absolute value (removes the sign from the year part)
 ¦ - sparse application:
 0 - ...to index: zero (rightmost - the remainder)
 d 7 - ...action: divmod 7 (integer divide by 7 and yield result and remainder)
 Ẏ - tighten (to a list of three items)
 Ç - call the last link (1) as a monad with argument CMJD
 ; - concatenate (now we have floats [abs(Y.0), W.0, D.0, H.0, M.x])
 Ḟ - floor (vectorises) (yielding ints [abs(Y), W, D, H, M]
 ¦ - sparse application:
 2 - ...to index: 2 (W)
 ‘ - ...action: increment (CD weeks are 1-indexed, W is 0 indexed)
ị3¦"TUWETHFRSASUMO"s2¤ - Main link part 3 (make the day-string): result of part 2
 ¦ - sparse application:
 3 - ...to index: 3 (D)
ị - ...action: index into:
 ¤ - nilad followed by link(s) as a nilad:
 "TUWETHFRSASUMO" - list of characters = "TUWETHFRSASUMO"
 s2 - split into chunks of length two
 - (note: D=0 yields "MO" due to 1-based & modular indexing)
Ṛ€o0ẋ(¡Ḳḃ4¤¤U - Main link part 4 (pad parts with zeros): result of part 3
Ṛ€ - reverse each (implicit decimal-list, so reverse of 289 is [9,8,2])
 ¤ - nilad followed by link(s) as a nilad:
 0 - zero
 ¤ - nilad followed by link(s) as a nilad:
 (¡Ḳ - base 250 number = 1178
 ḃ4 - convert to bijective-base 4 = [4,2,1,2,2]
 ẋ - repeat = [[0,0,0,0],[0,0],[0],[0,0],[0,0]]
 o - logical or (vectorises) (yielding the reversed zero padded entries)
 U - upend (reverse each - everything is already a list so not Ṛ€)
 - now we have something like: [[Ya,Yb,Yc,Yd],[Wa,Wb],['Da','Db'],[ha,hb],[ma,mb]]
(œọ;"ṢṢ :‘¤Ọ¤ż - Main link part 5 (include the separators): result of part 4
 ¤ - nilad followed by link(s) as a nilad:
 ¤ - nilad followed by link(s) as a nilad:
(œọ - base 250 literal = 8722
 "ṢṢ :‘ - code-page indices = [183,183,32,58]
 ; - concatenate = [8722,183,183,32,58]
 Ọ - covert ordinals to characters = "−·· :"
 ż - zip with the result from part 4, i.e. [['−',[Ya,Yb,Yc,Yd]],['·',[Wa,Wb]],['·',['Da','Db']],[' ',[ha,hb]],[':',[ma,mb]]]
FḊ8Ṡ>-¤¡ - Main link part 6 (remove the sign if need be): result from part 5
F - flatten the result from part 5 into a single list: ['−',Ya,Yb,Yc,Yd,'·',Wa,Wb,'·','Da','Db',' ',ha,hb,':',ma,mb]
 ¡ - repeat:
 Ḋ - ...action: dequeue (remove first element)
 ¤ - ...number of times: nilad followed by link(s) as a nilad:
 8 - chain's left argument = CMJD
 Ṡ - sign (-1 if less than 0, 0 if equal to 0, 1 if greater than 0)
 >- - greater than -1?
 - implicit print

• Stephen: 92 bytes 0.o this isn't the Jelly I'm used to
• Jonathan Allan: Me neither, many things lacking really: not just the (mentioned) time formatting and string formatting, but also mixed-radix conversion which is the reason for repeatedly using sparse application of divmod here.
• Magic Octopus Urn: TUWETHFRSASUMO - TUESDAY! WEDNESDAY! THURSDAY! FRIDAY! SATURDAY! SUMO! SUMO! SUMO!
• Jonathan Allan: Funnily enough I tried using dictionary compressions, and the word sumo, but can't actually get fewer bytes (need to uppercase it usually for 2 bytes). Mmmm Satsumos.

Answer 2

Ruby, 120 bytes

^{Despite being a language with built-in time formatting and string formatting, I still can't beat the Jelly answer...}

->n{n-=2309103.5;Time.at((n%7+4)*86400).strftime('%04d·%02d·%%^a %%H:%%M'%[n/364,n%364/7+1]).sub(/. /,' ').tr ?-,?−}

Try it online!