{"id":41105658,"url":"https://github.com/morphism/sgp4go","last_synced_at":"2026-01-22T15:18:39.142Z","repository":{"id":57557918,"uuid":"321371001","full_name":"morphism/sgp4go","owner":"morphism","description":"SGP4 transpiled to Go","archived":false,"fork":false,"pushed_at":"2022-12-29T18:23:34.000Z","size":164,"stargazers_count":2,"open_issues_count":0,"forks_count":0,"subscribers_count":2,"default_branch":"main","last_synced_at":"2023-07-27T22:23:03.776Z","etag":null,"topics":["satellites","sgp4","tle"],"latest_commit_sha":null,"homepage":"","language":"Go","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":"mit","status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/morphism.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":"LICENSE","code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null}},"created_at":"2020-12-14T14:20:41.000Z","updated_at":"2023-05-17T13:21:15.000Z","dependencies_parsed_at":"2023-01-31T09:31:38.409Z","dependency_job_id":null,"html_url":"https://github.com/morphism/sgp4go","commit_stats":null,"previous_names":[],"tags_count":3,"template":null,"template_full_name":null,"purl":"pkg:github/morphism/sgp4go","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/morphism%2Fsgp4go","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/morphism%2Fsgp4go/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/morphism%2Fsgp4go/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/morphism%2Fsgp4go/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/morphism","download_url":"https://codeload.github.com/morphism/sgp4go/tar.gz/refs/heads/main","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/morphism%2Fsgp4go/sbom","scorecard":null,"host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":286080680,"owners_count":28665036,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2026-01-22T14:01:31.714Z","status":"ssl_error","status_checked_at":"2026-01-22T13:59:23.143Z","response_time":144,"last_error":"SSL_connect returned=1 errno=0 peeraddr=140.82.121.6:443 state=error: unexpected eof while reading","robots_txt_status":"success","robots_txt_updated_at":"2025-07-24T06:49:26.215Z","robots_txt_url":"https://github.com/robots.txt","online":false,"can_crawl_api":true,"host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["satellites","sgp4","tle"],"created_at":"2026-01-22T15:18:39.039Z","updated_at":"2026-01-22T15:18:39.126Z","avatar_url":"https://github.com/morphism.png","language":"Go","funding_links":[],"categories":[],"sub_categories":[],"readme":"# SGP4 C transpiled to Go\n\n_Warning: This code is experimental; please see the\n[LICENSE](LICENSE)._\n\nAn\n[SGP4](http://celestrak.com/publications/AIAA/2006-6753/AIAA-2006-6753-Rev2.pdf)\nimplementation based on\n[`github.com/aholinch/sgp4/tree/master/src/c`](https://github.com/aholinch/sgp4/tree/master/src/c),\nwhich ultimately originated with [David\nVallado](https://celestrak.com/software/vallado-sw.php).\n\n```\n    This file contains the sgp4 procedures for analytical propagation\n    of a satellite. the code was originally released in the 1980 and\n    1986 spacetrack papers. a detailed discussion of the theory and\n    history may be found in the 2006 aiaa paper by vallado, crawford,\n    hujsak, and kelso.\n\n                           companion code for\n              fundamentals of astrodynamics and applications\n                                   2013\n                             by david vallado\n     (w) 719-573-2600, email dvallado@agi.com, davallado@gmail.com\n```\n\nThis implementation is a hand-edited transpilation of [C\nsources](https://github.com/aholinch/sgp4/tree/master/src/c) to\n[Go](https://golang.org/) by\n[`c2go`](https://github.com/elliotchance/c2go) (version v0.25.9\nDubnium 2018-12-30), and the emitted code was edited by hand.  The\noriginal C implementation test suite was included in this process.\n\nThe substantive edits (of Go sources emitted by the transpiler) were\nthe use of 64-bit integers to address at least one 32-bit overflow and\nusing floating point constants instead of naked integer constants when\nthe entire expression consisted of the latter with some division.\nExample: `var x2o3 float64 = 2 / 3` was edited to be `var x2o3 float64\n= 2.0 / 3.0`.\n\nWith those changes, the original (transpiled and hand-edited) tests\nalmost all pass.  The one exception is for NORAD ID\n[20413](https://www.n2yo.com/satellite/?s=20413) at `mins=1844335`,\nwhere 1e-07 \u003c _rdist_ \u003c 1e-06.  The tests have been edited to tolerate\n_rdist_ \u003c 1e-06 rather than demand _rdist_ \u003c 1e-07.\n\n## Usage\n\nThe main constructor is `NewTLE()`, and the primary method is\n`Prop()`.  See `ExampleProp()` in\n[`surface_test.go`](surface_test.go).\n\nSee [the documentation](https://godoc.org/github.com/morphism/sgp4go)\nfor details.\n\nThe example command-line program [`sgp4go`](cmd/sgp4go) reads TLEs\nfrom `stdin` and writes propagation data to `stdout`. See\n[`test.sh`](test.sh) for an example invocation.\n\nSome `sgp4go` executables are available\n[here](https://github.com/morphism/sgp4go/releases).\n\n## References\n\n1. [SGP4 in\n   AIAA-2006-6753-Rev2](http://celestrak.com/publications/AIAA/2006-6753/AIAA-2006-6753-Rev2.pdf).\n\n1. [Fundamentals of Astrodynamics and\n   Applications](https://celestrak.com/software/vallado-sw.php) (also\n   [at\n   Amazon](https://www.amazon.com/Fundamentals-Astrodynamics-Applications-Technology-Library/dp/1881883183/ref=pd_lpo_14_t_0/140-1650425-3257455)).\n   \n1. [`space-trace.org`](https://www.space-track.org/)'s [SGP4 binaries\n   and example code](https://www.space-track.org/documentation#/sgp4).\n\n1. [C source code for this implementation](https://github.com/aholinch/sgp4/tree/master/src/c).\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fmorphism%2Fsgp4go","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fmorphism%2Fsgp4go","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fmorphism%2Fsgp4go/lists"}