The Cadence of Mass-Shadow Route Closures on Charted Hyperlanes: A Records Study of 2,414 Advisory Bulletins from the Duro Astrogation Institute and the Republic Hyperspace Survey Office, 32–22 BBY

1. Introduction

A charted hyperlane is a sequence of jump plots, each avoiding the catalogued mass concentrations known at the time of the last survey pass. The catalogue is not static. Stars drift, brown dwarfs and small dense bodies are reclassified by improved measurement, and transient events put mass on the record where none was reckoned before. The astrogation record is kept current by two overlapping systems: the periodic revision of the published charts and the issuance of an advisory bulletin that closes a named segment to civil traffic for a stated interval. The cadence and composition of those bulletins describe the operational state of the record and, in a mild sense, the galaxy underneath it. The question of their rate, duration and attributed cause has been treated piecemeal in the trade press and has not had a records study in the current period.

We ask four questions. How often, in bulletins per standard year, is civil traffic closed on a named segment? How long does a closure last, and what distribution of duration best fits the record? What causes do the issuing offices attribute to closures, and does the attributed cause predict the time to reopen? Finally, are closures spatially clustered within the galactic volume, and if so, is the clustering a feature of the galaxy or of the survey schedule? The vantage is 25 BBY. We stay strictly within the record of the Duro Astrogation Institute and the Republic Hyperspace Survey Office, the two issuing offices whose bulletins are deposited at our academies.

The results bear on the planning of civil routing and on the engineering of a safety margin for charts in use. They do not bear on the physics of hyperspace propagation, on which the astrogation theory is settled (see cited work, below), nor on the design of the drive itself. Where the paper slides between the two, it is at the interface between a theorist's catalogue and an operator's bulletin.

2. Methods

The file is every advisory bulletin issued by the Duro Astrogation Institute and the Republic Hyperspace Survey Office in the ten standard years from 32 to 22 BBY, exclusive of the last standard day of 22 BBY. The two offices use substantially the same bulletin format, carrying a serial number, a date, a named segment, an attributed source, a projected closure interval and, when applicable, a revision pointer to the amended chart. We extracted every bulletin from the deposited copies at our academies; the Institute's series is complete, and the Survey Office's series is missing nine bulletins across two short gaps that we leave as missing data.

Attribution of cause was taken from the bulletin itself. The two offices use a shared taxonomy with five categories: drift of a catalogued mass concentration; identification of an uncatalogued source; revised estimate of a catalogued source whose gravitational signature was previously undercalled; stellar or nebular event, including novae and flare-driven stellar reconfiguration; and debris field of recent origin, including the breakup of small bodies and the deposit of large derelict wreckage. The categories are mutually exclusive at issue; where a later bulletin reclassifies the same closure, we take the attribution of the first bulletin.

Closure duration is the interval from the time of issue of the bulletin to the time of issue of the reopening notice, in standard hours. Closures still open at the end of the record period are right-censored at the end of their observation window. The duration distribution was fit as a Weibull and as a log-logistic; the log-logistic gave a slightly better fit on the Akaike criterion and is used for the point estimates below. We fit a Cox model for the hazard of reopening with the five cause categories as the principal exposure, a binary indicator for the segment having had a survey pass in the preceding standard year, the segment's class rating relative to the default of six, and the issuing office as a stratum.

Spatial clustering was examined by sector. The galaxy is divided into sectors in the shared Institute and Survey Office scheme, and we tabulated bulletins per sector per year. We tested for spatial clustering by comparing the observed sector-level variance of the annual bulletin count with the variance expected under a Poisson model with the empirical mean. We treat the result as descriptive; a formal test of spatial point-process clustering would require sector-level exposure data we do not have, and we do not report one.

3. Results

Table 1 gives the annual count and the cause mix. Bulletins ran at a mean of 241 a year with a standard deviation of 38, with no linear trend across the ten years (slope 1.1 bulletins per year, 95% CI from -3.7 to 5.9). The cause mix was dominated by drift of a catalogued source at 1,942 bulletins (80.4%), followed by revised estimates at 231 (9.6%), uncatalogued sources at 139 (5.8%), stellar or nebular events at 71 (2.9%) and debris fields at 31 (1.3%). The share of catalogued-drift bulletins rose from 76.1% in the first two years of the record to 83.4% in the last two, mostly at the expense of the revised-estimate category.

Closure durations were right-skewed. The median closure was 11 standard hours (interquartile range 4 to 38 hours), the 90th percentile was 112 hours and the longest observed closure in the record ran to 414 hours before the segment was reopened on a revised chart. 7.2% of closures were still open at the end of their observation window and were right-censored. The log-logistic fit gave a scale parameter of 12.6 hours (95% CI 11.9–13.3) and a shape parameter of 0.68 (95% CI 0.65–0.71), consistent with a heavy-tailed distribution in which the typical closure is short but a non-trivial minority runs long.

Adjusted hazard ratios for reopening are given in Table 2. The reference category is uncatalogued sources, which were among the slowest to reopen; the ratio for catalogued-drift closures was 1.42 (95% CI 1.27–1.59), for revised-estimate closures 1.19 (1.03–1.37), for stellar or nebular events 0.74 (0.57–0.95) and for debris-field closures 0.81 (0.56–1.18). The absence of a prior-year survey pass gave an adjusted ratio of 0.67 (0.60–0.75), meaning segments with no recent survey pass took correspondingly longer to reopen. Each class-rating step above the default of six gave an adjusted ratio of 1.12 (1.05–1.19) for the hazard of reopening; the busier segments are reopened faster.

Spatial clustering was marked. The sector-level variance of the annual bulletin count was 3.2 times the Poisson expectation. Of 118 sectors with any bulletin activity, the top ten held 41.6% of all bulletins in the file, and nine of the top ten lay in the Mid Rim; the tenth was the Corellian Trade Spine sector in the Core. The pattern inverts a naive reading of a mass-shadow process: the Mid Rim is not denser in matter than the Core margins. Instead, the Mid Rim sectors in the top ten have median survey intervals of 2.4 standard years against 0.9 in the Core margins, and the lagged survey, not the galaxy, is the parsimonious account.

4. Discussion

The practical reading of the result is a one-line decision rule for a civil routing planner. A segment with a catalogued-drift bulletin at or below its class default and a survey pass in the preceding year will be reopened at a median of about seven standard hours and almost always within two standard days; a segment with an uncatalogued-source bulletin, or no recent survey, will be reopened at a median of about twenty hours and non-trivially often takes several days. A routing policy that writes a hard delay into its own schedule only after the first eight standard hours of closure will do very little work on the first class of bulletin and useful work on the second.

The attribution mix is of a different kind of interest. The dominant category by a wide margin is drift of a catalogued source, and the fastest to reopen as well. In practice a catalogued-drift closure is a bookkeeping event: the source is known, the correction is standard, and the chart revision is pre-staged. An uncatalogued-source closure is a knowledge event, and the long tail of multi-day closures is heavily uncatalogued. A margin of survey capacity directed at frequently closed segments would compress the uncatalogued category into the catalogued, and the model gives a point estimate for the compression that a planner can act on.

The spatial pattern is the point we take most care over. The Mid Rim is not denser in mass than the Core margins; it is less densely surveyed. The nine Mid Rim sectors in the top ten of our tabulation have median survey intervals of nearly three times those of the Core margin sectors, and if the hazard model is used to project a world with the Mid Rim surveyed at the Core cadence, the Mid Rim bulletin count falls by roughly a third and the spatial clustering is halved. The projection is a model-based extrapolation and is useful for the planning of survey capacity, not for a claim about the galaxy. The transit-time variation on these segments is quantitatively compatible with the broader class-rating result reported for charted lanes by the matched transit-time literature (see cited work, below), and reinforces the reading of the pattern as a feature of the record.

5. Limitations

The file is a record of what the two offices issued, not of what the galaxy did. A mass shadow that moved onto a segment and was not noticed by either office is absent from the file. The nine missing Survey Office bulletins are not reconstructible, and we have not imputed them; a comparison with the Institute's parallel issuance in the same date ranges does not suggest a systematic gap. The attribution taxonomy is the offices' own, and the uncatalogued and revised-estimate categories are the two most vulnerable to a change in office practice; the rising share of the catalogued-drift category over the ten years is best read as a tightening of attribution and not as a change in the galaxy.

The hazard model uses the issuing office as a stratum, which absorbs any systematic difference in reopening practice between the two but foregoes a direct estimate of it. The class-rating covariate is the segment's rating at the start of the closure, not the rating in force at the moment of reopening; a rating change during a long closure, which has happened in nine of the 2,414 bulletins, is not modelled. Spatial clustering is reported as a descriptive variance ratio and not as a formal statistical test; the sector-level exposure data a test would need were not available to us. The spatial projection in Section 4 is model-based and should be treated as a decision aid, not as a counterfactual estimate.