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USA 77, 21809

Orbit data source: Space-Track

USA 77, 21809 is an American payload satellite in LEO that was launched on Fri, 08 Nov 1991 UTC via a TITAN 403A launch vehicle from the Air Force Western Test Range (AFWTR). Payload-class satellites include a variety of spacecraft equipped with specific instruments for various scientific and technological missions. These include communications satellites like Starlink; space stations such as the ISS; scientific satellites like the Hubble; Earth observation satellites from companies like Planet Labs, Umbra, and HawkEye 360; GPS; miniature CubeSats for education and research; and military/defense satellites.

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<iframe src="https://www.satcat.com/sats-embedded/21809?theme=dark&initialShowStats=false" width="600" height="400" frameborder="0" title="Kayhan Space Satcat Satellite Viewer"></iframe>

Iframe URL

https://www.satcat.com/sats-embedded/21809?theme=dark&initialShowStats=false

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ISO8601 Format

Identifier

21809, 1991-076E

Orbit

LEO

Country

Related business

National Reconnaissance Office (US)

Manufacturer

NRL

Mission

Defense Sigint

Bus & Motor

NOSS B SSU, Unknown motor

Mass

~400 kg wet, ~400 kg dry

Launch date (UTC)

1991-11-08 (34 years ago)

Launch vehicle

TITAN 403A

Launch site

Air Force Western Test Range (AFWTR)

Object type

Payload

Rocket body

Debris

Shape & HBR

Cyl, 0.5 m

Radar Cross Section

1.178 m², Large (>1 m²)

Expand to show TLE details & history
Last TLE update: 12 hours ago

TLE from 12 hours ago

0 USA 77
1 21809U 91076E   26060.04658538  .00003613  00000-0  29739-3 0  9992
2 21809  63.2960  86.3871 0900100  72.5852 297.1482 13.55564833 89609

Epoch: 2026-03-01T01:07Z

TLE epoch observation values (Epoch: 2026-03-01T01:07:04.976Z)

Latitude

-0.00007°

Longitude

-89.24364°

Altitude

798.967 km

Speed

7.581 km/s

True Right ascension

05h 45m 32s

True Declination

0° 00' 00"

Sunlit

Object was in daylight at epoch

Visualization orbit readout

Latitude

Unknown

Longitude

Unknown

Altitude

Unknown

Speed

Unknown

Apparent Right ascension

Unknown

Apparent Declination

Unknown

Sunlit

N/A

Visualization observer readout

Local Sidereal Time

16:24:20

Azimuth

Unknown

Elevation

Unknown

Doppler factor

Unknown

Orbital elements

Apogee altitude

1,719.344 km

Perigee altitude

382.009 km

Semi-major axis

7,428.814 km

Eccentricity

0.09001

Inclination

63.296°

RAAN

86.3871°

Arg. of periapsis

72.5852°

True anomaly

287.5204°

Mean anomaly

297.1482°

Eccentric anomaly

292.37943°

Mean motion

3.38972 °/min

Orbital period

106.2 mins

BSTAR

0.00029739

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Other satellites on launch #76 in the year 1991 (1991-11-08 UTC)

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USA 77 Visibility forecast

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Span	Click to sort rows by Start time (UTC) header in descending order	Start Az.	Max El. time (UTC)	Max El. Az.	Max El.	End time (UTC)	End Az.
5 mins	2026-03-02 03:50:27.017Z	232.937° WSW	2026-03-02 03:53:27.017Z	337.901° N	35.411°	2026-03-02 03:55:27.017Z	20.291° NNE
6 mins	2026-03-02 11:16:27.017Z	12.902° NNE	2026-03-02 11:18:27.017Z	62.994° ENE	27.13°	2026-03-02 11:22:27.017Z	113.743° SE

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Co-orbital & Co-planar RSOs

Thresholds — Semi-major Axis: ±100 km, RAAN: ±3°, Inclination: ±5°
TCA is derived from TLE conjunctions

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CAUTION: Conjunctions in this section are generated from low-fidelity TLE screenings

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Check out USA 77, 21809 on other resources

View USA 77, 21809 on NASA - NSSDCA Website

View USA 77, 21809 on Heavens-Above

View USA 77, 21809 on Keep Track

View USA 77, 21809 on Celestrak

View USA 77, 21809 on Gunter's Space Page

Satcat and Kayhan Space are not affiliated with NASA, Celestrak, Heavens-Above, Keep Track, or Gunter's Space Page.

USA 77, 21809

Orbit data source: Space-Track

Expand to show TLE details & historyLast TLE update: 12 hours ago

TLE from 12 hours ago

TLE epoch observation values (Epoch: 2026-03-01T01:07:04.976Z)

Visualization orbit readout

Visualization observer readout

Orbital elements

Other satellites on launch #76 in the year 1991 (1991-11-08 UTC)

USA 77 Visibility forecast

Co-orbital & Co-planar RSOs

Check out USA 77, 21809 on other resources

Documentation

Expand to show TLE details & history
Last TLE update: 12 hours ago