Sorry for adding more 'junk', but this colour picture shows a little more clearly the model of Pelorus in the Luke Field Inventory, and just how simple the thing is. Also how easy it is to move from one base to another and the simple directional thingummies.
https://timeandnavigation.si.edu/multimedia-asset/mark-iib-pelorus-drift-sightWhile I can't find a reference to using one at night, it would be possible to get a rough 'direction' of a star not too high above the horizon by aiming the thing like a shotgun.
I'm not suggesting Fred would have been clever enough to do that, but I'm damned sure I would have been using that, in combination with a sextant or octant.
It is so many years since I was properly active on the forum, that I can't remember if Fred carried an Octant aboard. I do recall something about the sextant box and an unusual eyepiece.
Anyway, I found the download links for my early WWII Navigation manual and it talks about how to use a 'Bubbie Octant'.
The other 275 odd pages are great homework for anyone still interested in the LOP and the Celestial Navigation stuff (How to completely miss an island on a simple over water hop).
It is probably on the Forum under Celestial Choir - but here 'tis for Drift Fans..
The Pelorusy stuff is around Page 30ish.
https://archive.org/download/aircraftnavigati00unit/aircraftnavigati00unit_bw.pdfEDIT
For any Newer Members of the forum who missed Choir Practice (see the Celestial Choir pages) there are lots of references on the forum to 'the LOP. The manual linked above has information about advancing a Line Of Position around page 170, and how to use a 'Bubble Octant' about page 176ish.
Noonan carried both an octant and a sextant.
Navigators aboard ships use a sextant, among other devices to find their position.
Airborne Navigators can also use a sextant, but it requires the horizon to be visible to be accurate.
A bubble sextant or bubble octant uses a bubble, like that in a spirit level but round and of a variable size, as I understand it, to give a reference point that simulates a horizon if none is visible.
The info above is 'simplified' - NOT 'technically correct'.