I'll admit it has bitten me.The source of much cartographic confusion in Traveller.![]()
I'll admit it has bitten me.The source of much cartographic confusion in Traveller.![]()
It's interesting to note that the MT CD Rom from FFE has a hand-drawn annotated map of charted space that shows Deneb beyond Zhodani space in what would be Viajlefliez Sector. It also shows Antares in Ley Sector. It shows the location of a pretty fair number of stars in the region of the Solomani Sphere. I'm not sure how close it is to being accurate, but it's worth looking at as part of this discussion.I have one of the original MT-CDROMs (from about ~2005); I am wondering whether or not the current edition on FFE is an updated 2nd Edition of the Disc (and whether or not I should repurchase the disc)?
Hand-drawn, annotated map of charted space is in the Images directory.
At least on *my* version of the CD ROM. It looks like it is from 2012.
Looks like I need to get an updated CDROM . . .
And "Kursa" (Beta Eridani) is located in Subsector P of Magyar Sector (is this the homeworld of the Kursae?).
Beta Eridani would be a terrible idea for any species' homeworld anyway -- or any life-bearing planet at all, really -- since it can't be any older than 1.7 billion years, and it's already well into its post main sequence phase (in other words, about where the Sun will be in about 5-6 billion years).Weird to place Beta Eridani there; I'd have to find my protractor to see if that's actually 5h 7m RA.
For what it's worth, I put the star in Kursa subsector (H) of Aldebaran. The T5 rulebook notes the Kursae are "From an unidentified homeworld somewhere in now-Charted Space," so Beta Eridani -- wherever it is -- probably wasn't the true homeworld, but the first Kursae-settled world discovered by Terrans very well might have been in or around the Kursa system.
I also placed an unidentified minor race on nearby world in subsector H, just in case.
This list gives distance from Terra and position in galactic longitude. Assuming 0 degrees galactic longitude corresponds to coreward, and 90 degrees corresponds to spinward, using a little trigonometry we can then calculate the approximate position within Charted Space of these stars. I was hoping to get some eyes on my Google Sheets to make sure my methodology works:
The Google Sheets workbook contains a Notes sheet that goes into more detail, but basically I translated the galactic longitude and distance into polar coordinates with Terra (Solomani Rim 1827) at position (0,0). I then converted those coordinates into hex offsets, and then determined where the resulting position fell within Charted Space to get a sector and hex number.
There are several places where I could have screwed up, so I would welcome any questions, thoughts, or corrections.
First, thanks for taking a look at this -- better late than never!Only RA,DEC and parallax are needed for a three dimensional solution, so doing the spherical to cartesian mapping you get {3.153575,1.53956,-1.002277} parsec - this in the equatorial plane. Rotate that into the ecliptic plane and you get {3.15358,1.01384,-1.53197} and then rotate that into the galactic plane and you get {-0.317353,-0.0371296,-3.63562} - 3.64 parsec away, which is catalogue distance, just that most of the distance is in the z component. In this case, Tau Ceti is almost directly under us relative to the galactic plane. It looks to me like you might have taken the z distance component for y?
My general philosophy is that if one is assigning the position of a Real-Universe star to a Traveller Map hex, it should be acceptable if:NOTE CONCERNING STAR POSITIONS:
When comparing real-astronomical star positions to the Traveller Map of Charted Space, it needs to be observed that the axes of the Charted Space Map appear to be tilted almost exactly 45o counter-clockwise from the correct position (i.e. "true" Coreward would seem to lie parallel to the Lesser Rift). If one makes that adjustment, about 70% of the named stars will fall roughly along their correct bearing. However, there are some exceptions in which the star in question lies in roughly the correct position relative to the Charted Space Map without the need to rotate the coordinate axes.
Do the canonical traveller maps use the galactic plane as a basis for the mapping?
According to SIMBAD, Tau Ceti (i.e. "Iilike") is located at:
Radial Distance: 3.65pc
Galactic Longitude: 173.1007o
Galactic Latitude: -73.4397o
This would put it at a highly Galactic South latitude, and at a bearing slightly spinward of rimward.
However, when looking at the Traveller Map coordinates, keep the following in mind:
My general philosophy is that if one is assigning the position of a Real-Universe star to a Traveller Map hex, it should be acceptable if:
1) The star's longitude angle (θ) is within a 45o bearing-arc between the "true" coordinate axes and the ''Traveller'' Charted Space Map coordinate axes, and
2) The star's assigned distance from Terra on the hexmap falls somewhere between its true distance R in parsecs, and its 2D-projection onto the flat map as seen from above, found by Dproj = {R * cos(ɸ)}, where (ɸ) is the latitude angle. If desired, the distance above/below the plane can be determined by Z = {R * sin(ɸ)}.
According to SIMBAD, Tau Ceti (i.e. "Iilike") is located at:
Radial Distance: 3.65pc
Galactic Longitude: 173.1007o
Galactic Latitude: -73.4397o
This would put it at a highly Galactic South latitude, and at a bearing slightly spinward of rimward.
However, when looking at the Traveller Map coordinates, keep the following in mind:
My general philosophy is that if one is assigning the position of a Real-Universe star to a Traveller Map hex, it should be acceptable if:1) The star's longitude angle (θ) is within a 45o bearing-arc between the "true" coordinate axes and the ''Traveller'' Charted Space Map coordinate axes, and2) The star's assigned distance from Terra on the hexmap falls somewhere between its true distance R in parsecs, and its 2D-projection onto the flat map as seen from above, found by Dproj = {R * cos(ɸ)}, where (ɸ) is the latitude angle. If desired, the distance above/below the plane can be determined by Z = {R * sin(ɸ)}.EDIT:
Not sure, but I believe the original Traveller Map was based on Right Ascension and Declination data, based on the axis labels of the hand-drawn map on the MT CD.
One thing to keep in mind is that while the Earth is tilted to the ecliptic by about 23.5o, the entire ecliptic itself is tilted to the mean Galactic plane by about ~ 58o-62o, if I am remembering my numbers correctly. Tilt Images.
...I tried an alternate approach . In this case, I extract the 2d components and then normalize and scale by the distance from the sun. Thus all of the distances from the sun are correct (but any other star to star distance is not).
I'll add more commentary later, but one thing to notice - if you see the line extending from Barnard's Star, that's the proper motion of the star (output of an nbody integrator) in the 3622 years between now and 1116 imperial. This is enough to displace it by a hex or two vs 2017-earth mapping. I don't know if the original traveller mappings were trying to place stars relative to their positions in the 20th century or their future positions.
One of the most mis-matched stars is Epsilon Indi ("Meshan"), which is on entirely the wrong side of the coreward-rimward axis. Epsilon Indi is also a star that is at a significant Galactic South Latitude, so I am curious if perhaps it was placed where it was due to an attempt to preserve various stellar distances when transforming from a 3D to a 2D environment (i.e. preserving an approximate correct distance from Terra, while also attempting to keep it far enough away from other stars that would otherwise be far to close by a simple projection to 2D).
The only oddity about that theory is that in GDW's 2300AD universe, they used a very accurate catalog (for the time - 1969 Gliese catalog) as the basis for an actual 3D starmap out to 50 lightyears. But Epsilon Indi is in the wrong position on that map as well.
The only oddity about that theory is that in GDW's 2300AD universe, they used a very accurate catalog (for the time - 1969 Gliese catalog) as the basis for an actual 3D starmap out to 50 lightyears. But Epsilon Indi is in the wrong position on that map as well.
There is an interesting thing about real world data in tables...
If the data is all real data, the table's contents cannot be protected by US copyright; it's there for academics to be able to update each others' data with new data, and for the press. Cite.
I suppose that could indeed be the reasoning, but it's a little unfortunate when the players happen to be astronomy buffs.
According to SIMBAD, Tau Ceti (i.e. "Iilike") is located at:
Radial Distance: 3.65pc
Galactic Longitude: 173.1007o
Galactic Latitude: -73.4397o
This would put it at a highly Galactic South latitude, and at a bearing slightly spinward of rimward.
However, when looking at the Traveller Map coordinates, keep the following in mind:
My general philosophy is that if one is assigning the position of a Real-Universe star to a Traveller Map hex, it should be acceptable if:1) The star's longitude angle (θ) is within a 45o bearing-arc between the "true" coordinate axes and the ''Traveller'' Charted Space Map coordinate axes, and2) The star's assigned distance from Terra on the hexmap falls somewhere between its true distance R in parsecs, and its 2D-projection onto the flat map as seen from above, found by Dproj = {R * cos(ɸ)}, where (ɸ) is the latitude angle. If desired, the distance above/below the plane can be determined by Z = {R * sin(ɸ)}.EDIT:
Not sure, but I believe the original Traveller Map was based on Right Ascension and Declination data, based on the axis labels of the hand-drawn map on the MT CD.
One thing to keep in mind is that while the Earth is tilted to the ecliptic by about 23.5o, the entire ecliptic itself is tilted to the mean Galactic plane by about ~ 58o-62o, if I am remembering my numbers correctly. Tilt Images.
What is the most distant traveller star that has a real analogue? Deneb? If so, what's after that, Ishdar (epsilon Cygni)?
Deneb is the farthest, I believe. But it is actually way to close. In reality it lies to spinward of Terra, but allowing for the 45o rotational anomaly on the TravellerMap stars, it falls along a consistent bearing realtive to other TravellerMap stars. However, it is at about half its true distance from Terra. It ought to be somewhere along the coreward border of the Zhodani Consulate.
Interestingly, the early hand-drawn map of Charted Space by GDW on the MT CD does place Deneb in the Delta Quadrant of Viajlefliez Sector corespinward of the Zhodani Consulate border. But for some reason it got moved on the published maps.
In reality it lies to spinward of Terra, but allowing for the 45o rotational anomaly on the TravellerMap stars