Translation of oracle bone《甲骨文合集》11503
I won't claim expertise, but the following is my interpretation. Corrections welcome!


  Format:
  
  Transcription given in 《甲骨文合集》
  
  How it should be read using more modern characters
  
  English translation




《合集》11503 正


ＡＢ〔卜〕(1)Ｃ貞〔旬亡〕

ＡＢ卜Ｃ貞旬無禍

Divination (卜) on heavenly stem A(2), earthly branch B(3): C(4) asks (貞): [Will we have] ten days (旬) without (亡(5)) calamity ((6))?
癸Ｂ〔卜〕Ｃ〔貞〕……丙……

(same)

Divination on heavenly stem 癸, earthly branch B: C asks: ……(7)丙(8)……(9)
癸丑卜爭〔貞〕……〔㛸〕……

癸丑卜爭貞……艱……

Divination on heavenly stem 癸, earthly branch 丑: 爭(10) asks: ……difficulty/danger/hardship (㛸(11))……




《合集》11503 反


……七日己巳夕……㞢新大晶竝火……

……七日己巳夕Ｄ(12)……有新大星竝火……

……Day (日) seven (七), the evening (夕) of the day of 己巳……appeared(13) (㞢(14)) [a] new (新) great (大) star (晶(15)) next to (竝) Antares(16) (火(17))……
……〔㞢〕求其㞢來嬄……不吉

……有咎其有來艱……不吉

……has calamity (求(18)), also(19) (其) there comes (來) difficulty/danger/hardship……ominous (不吉)



  Notes:
  
  
  I think parentheses〔〕indicate a filled-in character that may not be immediately obvious on the bone fragment.
  「Ａ」is a placeholder for a hypothesised/unknown heavenly stem.
  「Ｂ」is a placeholder for a hypothesised/unknown earthly branch.
  「Ｃ」is a placeholder for a hypothesised/unknown name of the oracle doing the divination.
  
  
  AB refers to the timekeeping system called the Sexagenary cycle.
  The structure AB卜C貞… means Divination on heavenly stem A, earthly branch B, oracle C asks…
  
  「亡」is used to mean without in oracle bone inscriptions, written as「無」now.「亡」(Proto-Sino-Tibetan: /*maŋ/, comprised of /*ma/ + termative suffix /ŋ/) is cognate to「無」(/*ma/).
  「」has several interpretations, among them「憂」,「咎」, and「禍」; I don't know which one is correct, but I think「憂」means worry, and both「咎」and「禍」mean disaster/calamity, so the interpretation shouldn't vary too greatly.
  Unknown inscriptions, if any. Might be faded out from the bone.
  I don't know how to interpret this without more context.
  「」is the name of a hostile tribe neighbouring the Shang Dynasty.
  「爭」, in this context, is the name of an oracle.
  「㛸」is commonly interpreted in oracle bone scripts as「艱」.
  「」here has far too many conflicting interpretations. I'm not even sure of the correctness of this transcription, so I used the placeholder「Ｄ」.
  「有」literally means there exists, so depending on the context it can be seen as there appeared, or has, or just there.
  「㞢」is an oracle bone variant of「有」or「又」. Do not interpret this as「之」, which much later also became the shape of「㞢」.
  「晶」originally meant star, now written as「星」. The current meaning of「晶」is sparkling/crystal/radiant, which is a semantic extension of the original meaning. For reference, the glyph evolution of「星」:
  
  商甲後2.9.1合集11503商甲前7.26.3合集11501西周金麓伯星父簋　秦簡睡・日乙41　今楷　
  
  The second form above changes the number of stars「日」and adds phonetic「生」. The third form shifts all the stars to the top. The fourth form simplifies all the stars down to one star, and forms the basis of the modern shape「星」.
  The nova interpretation hinges on「火」being interpreted as Antares or its other astronomical meaning Mars, rather than its basic meaning fire.  There is no explicit inscription of「心宿二」, which is the full name of Antares. The good news is that there appeared a new great star next to the fire doesn't really make sense, but we're lacking the rest of the text (if any) to confirm anything.
  「火」(oracle bone sample view) is frequently confused with「山」(mountain; oracle bone sample view) in oracle bone texts. YMMV on this interpretation.
  「求」is used as a phonetic loan for「咎」in oracle bone script. It is a picture of a multi-legged insect, and was the original character for「蛷」.
  Many possible interpretations for「其」.