This page shows Comet C/2021 T4 (Lemmon) location and other relevant astronomical data in real time. The celestial coordinates, magnitude, distances and speed are updated in real time and are computed using high quality data sets provided by the JPL Horizons ephemeris service (see acknowledgements for details). The sky map shown in the background represents a rectangular portion of the sky 60x40 arcminutes wide. By comparison the diameter of the full Moon is about 30 arcmins, so the full horizontal extent of the map is approximately 2 full Moons wide. Depending on the device you are using, the map can be dragged horizondally or vertically using the mouse or touchscreen. The deep sky image in the background is provided by the Digitized Sky Survey (acknowledgements).

Current close conjunctions

List of bright objects (stars brighter than magnitude 9.0 and galaxies brighter than magmitude 14.0) close to Comet C/2021 T4 (Lemmon) (less than 1.5 degrees):

Additional resources

• 15 Days Ephemerides
• Interactive Sky Map (Planetarium)
• Rise & Set Times
• Distance from Earth
• Light Curve
• Orbital Elements

Astronomy databases

This online sky chart is created using the following astronomy databases and services:

1. The Digitized Sky Survey, a photographic survey of the whole sky created using images from different telescopes, including the Oschin Schmidt Telescope on Palomar Mountain
2. The Hipparcos Star Catalogue, containing more than 100.000 bright stars
3. The PGC 2003 Catalogue, containing information about 1 million galaxies
4. The GSC 2.3 Catalogue, containing information about more than 2 billion stars and galaxies