68r1 and 2

[MarcoP]

Many thanks to Andrew for sharing his original approach to these two diagrams! Years ago, the two “star maps” were extensively discussed on the site of Stephen Bax. A user wrote You are not allowed to view links. Register or Login to view.:

Hypothesis: The number of tips on a star drawn in 68r1 and 68r2 represent some form of category of stars. What comes to my mind at first would be brightness/magnitude.
Remains to be tested.

I don't think the idea has ever been investigated in any detail.

Seems to have ben common practice for star maps, clm 826 (about the same time) has stars of different sizes and numbers of arms for different degrees of brightness

Has there been any tradition to group stars into distinct classes according to degrees of brightness, and to assign separate significance to those classes?

Stars were already grouped into six different mangnitudes in Ptolemy's catalog (in You are not allowed to view links. Register or Login to view.).

Helmut's observation makes Andrew's proposal even more relevant. I don't know if digital images of the whole Clm 826 (Prague, 1400 ca) are available online, but here is an illustration of You are not allowed to view links. Register or Login to view., compared with the corresponding illustration by You are not allowed to view links. Register or Login to view. (1570). I think these two images make clear the correctness of Helmut's remark.

These are all the Perseus stars of magnitude 2 and 3 listed by Piccolomini (magnitude 2 is “larger” that magnitude 3). The other stars are smaller (magnitude 4):

A 2 Right side [alpha, Algenib / Mirfak]
B 2 In the head of Medusa [beta , Algol]
C 3 Tip of the left foot
D 3 Right shoulder [gamma]
E 3 One of three in the right side
F 3 Left knee [epsilon]
G 3 In the left heel

As you can see, both manuscripts represent lesser stars with small 6-pointed stars. In both illustrations, the two brightest stars (A and B) are 8-pointed and marked with different colors. Magnitude 3 stars are treated differently in the two sources: Piccolomini marks them with 6-pointed stars larger than those used for magnitude 4.
Clm 826 uses 8-pointed stars for two of them (D and F, in Piccolomini's atlas); I highlighted these in blue. C and G (in the left foot) are marked as smaller stars and E seems not to have been included. I have mirrored the manuscript illustration to make it more easily comparable with Piccolomini's: ancient illustrations often represent the sky in "God's perspective", as seen from outside the sphere of the fixed stars.

On Islamic globes, stars of different magnitudes were marked with dots of different sizes. Also the Arabic Al-Sufi manuscripts (from which Clm 826 derives) represented stars with small circles. This notation is also used in modern star maps.