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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 (35 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: 5 hours ago

TLE from 5 hours ago

0 USA 77
1 21809U 91076E   26150.16421823  .00003376  00000-0  27285-3 0  9990
2 21809  63.2953 205.9314 0899137  74.3099 295.5188 13.56334566101825

Epoch: 2026-05-30T03:56Z

TLE epoch observation values (Epoch: 2026-05-30T03:56:28.455Z)

Latitude

-0.00003°

Longitude

-100.87136°

Altitude

814.738 km

Speed

7.564 km/s

True Right ascension

13h 43m 43s

True Declination

0° 00' 00"

Sunlit

Object was in full shadow 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

18:52:55

Azimuth

Unknown

Elevation

Unknown

Doppler factor

Unknown

Orbital elements

Apogee altitude

1,715.564 km

Perigee altitude

380.166 km

Semi-major axis

7,426.002 km

Eccentricity

0.08991

Inclination

63.2953°

RAAN

205.9314°

Arg. of periapsis

74.3099°

True anomaly

285.79565°

Mean anomaly

295.5188°

Eccentric anomaly

290.69969°

Mean motion

3.39165 °/min

Orbital period

106.14 mins

BSTAR

0.00027285

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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.
6 mins	2026-05-30 13:16:46.463Z	1.265° NNE	2026-05-30 13:19:46.463Z	56.784° ENE	20.803°	2026-05-30 13:22:46.463Z	98.268° ESE
7 mins	2026-05-30 15:06:46.463Z	289.031° WNW	2026-05-30 15:08:46.463Z	239.707° WSW	32.035°	2026-05-30 15:13:46.463Z	173.672° S
4 mins	2026-05-31 04:51:46.463Z	163.794° S	2026-05-31 04:53:46.463Z	116.311° SE	23.892°	2026-05-31 04:55:46.463Z	68.756° E

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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: 5 hours ago

TLE from 5 hours ago

TLE epoch observation values (Epoch: 2026-05-30T03:56:28.455Z)

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: 5 hours ago