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RELAY 2, 737

Orbit data source: Space-Track

RELAY 2, 737 is a payload satellite owned by GSFC (US) that was launched on Tue, 21 Jan 1964 UTC via a THOR DELTA B launch vehicle from the Air Force Eastern Test Range (AFETR). 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/737?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/737?theme=dark&initialShowStats=false

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Identifier

737, 1964-003A

Orbit

Active

Country

Related business

National Aeronautics and Space Administration (NASA) (US)

Manufacturer

RCA/East Windsor

Mission

Spacecraft

Bus & Motor

RELAY, Unknown motor

Mass

83 kg wet, 83 kg dry

Launch date (UTC)

1964-01-21 (62 years ago)

Launch vehicle

THOR DELTA B

Launch site

Air Force Eastern Test Range (AFETR)

Object type

Payload

Rocket body

Debris

Shape & HBR

Unknown

Radar Cross Section

Medium (>0.1 m² and <1 m²)

Expand to show TLE details & history
Last TLE update: 13 hours ago

TLE from 13 hours ago

0 RELAY 2
1 00737U 64003A   26044.62109352 -.00000011  00000-0  00000-0 0  9997
2 00737  46.4623 124.7537 2599793 242.7414  88.5469  7.39536880676953

Epoch: 2026-02-13T14:54Z

TLE epoch observation values (Epoch: 2026-02-13T14:54:22.480Z)

Latitude

-0.00004°

Longitude

117.50412°

Altitude

5,403.631 km

Speed

5.644 km/s

True Right ascension

08h 19m 00s

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

06:29:14

Azimuth

Unknown

Elevation

Unknown

Doppler factor

Unknown

Orbital elements

Apogee altitude

7,644.465 km

Perigee altitude

1,857.725 km

Semi-major axis

11,129.232 km

Eccentricity

0.25998

Inclination

46.4623°

RAAN

124.7537°

Arg. of periapsis

242.7414°

True anomaly

117.3194°

Mean anomaly

88.5469°

Eccentric anomaly

103.05747°

Mean motion

1.84861 °/min

Orbital period

194.74 mins

BSTAR

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Other satellites on launch #3 in the year 1964 (1964-01-21 UTC)

DELTA 1 R/B, 738

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You can import UDL-sourced sensor .json files into the Sandbox to generate a visibility chart that accounts for multi-vendor sensor geometry.

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RELAY 2 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.
53 mins	2026-02-14 03:52:57.813Z	141.491° SSE	2026-02-14 04:15:57.813Z	100.896° ESE	21.052°	2026-02-14 04:45:57.813Z	62.774° ENE
86 mins	2026-02-14 07:06:57.813Z	212.564° SW	2026-02-14 07:44:57.813Z	135.819° SSE	43.868°	2026-02-14 08:32:57.813Z	61.056° ENE
87 mins	2026-02-14 10:42:57.813Z	264.807° W	2026-02-14 11:33:57.813Z	354.908° N	44.326°	2026-02-14 12:09:57.813Z	89.543° E
66 mins	2026-02-14 14:32:57.813Z	298.427° NW	2026-02-14 15:17:57.813Z	219.556° SW	43.892°	2026-02-14 15:38:57.813Z	142.218° SSE
26 mins	2026-02-14 18:25:57.813Z	291.211° WNW	2026-02-14 18:40:57.813Z	261.328° W	16.485°	2026-02-14 18:51:57.813Z	227.817° WSW

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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 RELAY 2, 737 on other resources

View RELAY 2, 737 on NASA - NSSDCA Website

View RELAY 2, 737 on Heavens-Above

View RELAY 2, 737 on Keep Track

View RELAY 2, 737 on Celestrak

View RELAY 2, 737 on Gunter's Space Page

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

RELAY 2, 737

Orbit data source: Space-Track

Expand to show TLE details & historyLast TLE update: 13 hours ago

TLE from 13 hours ago

TLE epoch observation values (Epoch: 2026-02-13T14:54:22.480Z)

Visualization orbit readout

Visualization observer readout

Orbital elements

Other satellites on launch #3 in the year 1964 (1964-01-21 UTC)

RELAY 2 Visibility forecast

Co-orbital & Co-planar RSOs

Check out RELAY 2, 737 on other resources

Documentation

Expand to show TLE details & history
Last TLE update: 13 hours ago