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Comet

Tilbrook

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C/1999 A1 (Tilbrook)

Tilbrook is a comet in the Comet orbit class. Its orbit takes it from 0.73 AU to 355.28 AU from the Sun; one orbit takes 2,375 years. Orbit from the JPL solution of 15 April 2021.

Where is it now

Distance from Sun
49.274 AU
True anomaly
167.01°
Distance from Earth
49.791 AU
As of
24 October 2026

Two-body Kepler propagation — accurate to ~0.1% for major planets over decades, less so for highly-perturbed bodies. Use JPL Horizons for high precision.

Sun Earth — 0.994 AU from the Sun Earth Tilbrook — 49.274 AU from the Sun Tilbrook
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Tilbrook is 49.791 AU from Earth today (6.9 light-hours).

In the sky

Right ascension
17h 22m 52s
Declination
+16° 06′ 27″
Constellation
Hercules
Distance from Earth
49.8 AU
Elongation from the Sun
57.57° — near the Sun — look low at dusk or dawn

Favours the northern hemisphere; low or below the horizon from far south.

From your location

See how high it is right now, whether it is up after civil twilight, and when it rises and sets where you are.

How do I find my coordinates?

Google Maps on a computer

  1. Right-click the spot where you'll be observing.
  2. The first line of the menu is the coordinates, e.g. 51.50722, -0.12758 — click it and they're copied.
  3. Paste them above.

Google Maps on a phone

  1. Press and hold the spot to drop a pin.
  2. The coordinates appear in the search bar (or on the pin's card) — tap to copy, then paste above.

A full Google Maps link works too, but the short maps.app.goo.gl share links don't carry coordinates — copy the numbers instead. We round to about a kilometre; that's all the sky calculation needs.

Know your what3words address? Paste it, e.g. ///filled.count.soap. This is optional — the three words are sent to what3words to convert them, and we don't store the address or the result.

Your location stays in your browser and is sent only for this calculation. Using a what3words address is optional; if you do, the three words go to what3words to be converted and we don't record them. Set a location first, then you can save an email alert for this object. See our privacy policy.

Two-body approximation, good to about a degree for the planets — enough to find the constellation and know whether it is up.

Orbital elements

Semi-major axis
178.008 AU
Eccentricity
0.9959
Inclination
89.48°
Orbital period
2,375 years
Perihelion
0.731 AU
Aphelion
355.285 AU
Longitude of ascending node
259.12°
Argument of periapsis
232.67°
Epoch · J2000
2451198.5
Orbit class · COM
Comet
Earth MOID · 26.5 LD
0.0682 AU
Tisserand (Jupiter)
0.039

Orbit quality

Observations used
68
Data arc
43 days
First observed
13 January 1999
Last observed
25 February 1999
Residual RMS
0.76 ″
Solution · Otto Matic
15 April 2021

Visual & observation

Absolute magnitude (H)
14.3
Total magnitude M₁ · K₁ 10
14.3

Discovery & classification

Also known as 1999 A1

Named

Sources