When estimating the distance between given points on the Koronus Map, how should I gage that distance in light years?

Or to put a slightly finer point to it, how far would one inch equate to light years for warp jump calculations?

The map at the front and back of the core book have a grid over them, but the one from download section does not. Would this equal anything?

Layton Draxby said:

Do it however you want. Considering the location in the galactic halo, the scale of the map could be anything from a few dozen to a few thousand light years across.

Consdering the unsettled nature of the warp in the area, you are probably better off just defining times of transit instead of distances.

IMHO

I'm very roughly using the following rules:

Every square on the map = 2 warp days.

Reality Traveltime = (2d10-DoS / +DoF on Stage 4 of the Navigation test)*warp time for travel outside of known warplanes, or that value divided by 2 for known travel. Maybe divide by 3 or 4 for commercial routes (I like this a lot better then the static factor mentioned in the book, making the Warp more unpredictable and adding general value to an expert navigator).

It's pretty much a case of "what you think looks and feels right".

My personal take is that as a navigational aid, they make great posters. One reason being is that the Koronus Expanse is a volume, not an area. Any 2-dimensional map is going to suffer in terms of utility without some notation detailing the "vertical" component off some arbitrary plane.

Another, equally important reason is that warp travel in 40k is more than pointing your ship in the right direction and pressing the "go" button. Even in an area where the warp is relatively calm and stable, there will be currents and eddies that can drastically alter the routes taken and/or the travel times. A case in point: there is a large (meta)stable current leading from the Realm of Ultramar spinwards towards Hydraphur, which drastically reduces travel times for ships travelling in that direction (it's worth noting that such a current passes through or close to most key worlds in the Imperium) but means that a ship travelling to Ultramar has to claw its way far corewards before taking a rimwards-by trailing tack out. Obviously this takes far longer.
However, without a chart showing this, even a relatively short hop becomes much harder on a Navigator (arguably equivalent to flying an uncharted route). None of the maps produced by FFG (or Black Industries before them) include notations showing prevailing warp conditions, somewhat understandably, as that would necessarily increase the complexity of the map, probably to the degree that no-one could make heads or tails of it.

However, if you decide that you can use them, even for at-a-glance rough idea work, well; a rough idea of scale could be worked out starting from the assumption that the Koronus Expanse is roughly the same size as the average Imperial sector. Battlefleet Gothic tells us that the average sector is (or can be thought of) as a cube 60 light years on a side. If the Expanse is intended to be roughly that size, then you could take the dimensions of the map, and divide them by sixty to find scale. Or something like that.

Old Rules/Fluff from the Games Workshop game "space fleet" (1991). Heres some information from White Dwarf 139 &140 written by pace by Jervis Johnson, Andy Jones, Simon Forrest & Rick Priestley

Bear in mind that much of the fluff is old and may have changed substantiallly from those early years:

Sectors
Each Segmentum is divided into sectors. The size of a Sector varies according to local demands and stellar density. A typical sector might encompass 7 million cubic light years, equivalent to a cube with sides almost 200 light years long.

Sub-Sectors
Sectors are divided into sub-sectors, usually comprising between 2 and 8 star systems within a 10 light year radius (some may encompass more systems - others only 1). This size is governed by the practical patrol ranges of spaceships. Because sub-sectors are divisions of worlds (rather than volumes of space) there are vast numbers of star systems within each sector which do not fall with in a sub-sector. These are referred to as inter sectors - and are commonly known as wilderness zones, forbidden zones, empty space and frontier space. Inter-sectors may contain gas or dust nebulae, inaccessible areas, alien systems, unexplored systems, uninhabited systems and uninhabitable worlds.

And later

A typical command comprises about 50 interstellar ships, although the number would obviously vary depending upon the needs of the sector. Fifty ships is very few when you consider that a typical sector has between 30 and 40 thousand stars forming a cube with sides approximately 200 light years long!

There is also information on a chart which wont copy and paste on the forum giving a detailed realtime/warptime vs lightyear distance averages with the following information

So, for example, a 100 light year jump will seem to take from 2.5 to 9.5 hours to a spaceship's crew, but between 3 days and 3 weeks will have passed in real space. These times do not include journey times out to and from jump points on the edge of the star systems. It takes from days to weeks of travel at sub-light speeds to reach a drop from the spaceship's starting planet, and a similar time to re-enter the destination system.

The Imperium is approximately 75 thousand light years from edge to edge. A journey of this length would take between 75 and 300 days in warp time, and between 6 years and 40 years real time.

On the chart its says that:

100 light years equals minimum warptime 2.5 hrs maximum 9.5 hours which translate as minimum 3 days and maximum 3 weeks respectively.

so 200 you could traverse apparently between 5 and 18 hours and 6 days or 6 weeks, which seems dodgy already.

But agin this is OOOOOOLD fluff..Battlefleet gothic already contradicts the average sector size, and there is no way to discerne if the Koronus expanse really is the size of a average imperial sector.

I've been using in my games. I find it works quite well.

I'd assume the Expanse would be larger than a standard sector - a sector is a mostly political unit, likely big enough to be self-sufficient and small enough to be both readily administrable on a high level and not in danger of being able to secede. The Expanse is defined as "Here be dragons". It's the blank part of the map beyond Calixis. I don't think there would be a specific end to it beyond what Rogue Traders are able to travel to and return from.

Some of the fluff seems to indicate that "west" (I can never remember the proper 40k terms) of the given Koronus Expanse map is "Halo Star Territory", aka space that is so far from Earth that Navigators cannot locate the Astronomican with any accuracy. That would make only the most brave/foolhardy willing to enter there.

SanderJK said:

Generally this can occur at "any" time in the Halo Stars. Because there's an actual modifier involved in whether the Astronomican is visible or not I usually use these general rules:

The Cauldron: Visible

Foundling Worlds: Visible

Winterscale's Realm: Visible

Heathen Stars: Visible

Accursed Demesne: Sometimes Visible

Cineris Maleficum Sometimes Visible

Unbeholden Reaches: Never

Rifts of Hecaton: Never

Too add another fun layer of uncertainty to all this, can we really assume that any map of the mostly uncharted Koronus Expanse is actually to scale?

Psychopomp said:

For safety, you should never assume that any map, chart or road directions scrambled on a piece of paper is anything but bullcrap. Always have a back up plan.

But, no, seriously, I am of the mind that the further out you get, the less accurate the scale of any chart is, as well as likely missing bits here and there. Also, adding the warp to this, it's quite possible that worlds that once was, suddenly dissapear to re-apear a few houndred years later, somewhere else.

I prefer the time aspect of warp travel to be much more simple then what I have seen written, so I am for a system wich simply states amount of time taken for:
Travel within a sub-sector
Travel to a nearby sub-sector

Travel through a sub-sector ( as in, going to a distant one)

and for the traveling types, Travel through a sector

With all that can go wrong during warptravel, such as our navigator dropping our frigate on a collision course with Footfall, and the amount of rolls needed, I find that adding a bunch of charts, and tables, and explanations, and rolls, and what have you, simply to determine the time taken, is way to annoying.

I as the GM and the player behind the Navigator in my campaign find all the rolls needed to make a Warp excursion tedious. In the end, we've boiled the whole process down to one Navigation (Warp) roll. All I do is determine if the voyage will take days, weeks, or months. If the roll is a success the digit in the 1s place determines how many time increments pass within the ship, while the digit in the 10s place determines how many of the increments pass in the physical universe. The Navigator can spend degrees of success to shorten these times. If the roll is a failure both travel times are increased by one increment per degree of failure.

Psychopomp said:

Honestly? No. Not even the maps of the Calixis sector have been to scale (just look at the Lathes- a trinary star system where the components orbit their mutual barycentre so closely it does funky things to gravity, and the maps show them to be further apart than some other star systems). That's another reason I treat the BI/FFG maps as showcase pieces a character might keep around to show off to the groundsiders.

Attila-IV said:

Going through the Maw for the first time must have been terribly boring for your group.

The campaign began with their ship exiting the Maw. We skipped all that to get right into the action.

Thanks all. That's a lot of really handy suggestions.

I think I will take a use the grid as a basic guide of counting and include an additional role to determineif more or less time needs to be added to factor in the lack of 3D aspect.

I'll probbaly go with one square 3 days.

With more well used routes factoring less time.