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According to NASA, a 1.1-kilometer asteroid called 7482 (1994 PC1) will be visible tonight at 5:50PM.

How do I know if this asteroid will be visible at my location with the naked eye? When NASA says 5:50PM today, what location and/or timezone are they referring to?

Is there an intuitive iphone app that will help mere mortals like myself identify the stuff I see when I look up at the sky?

This is what I see in the NASA website https://eyes.nasa.gov/apps/asteroids/#/asteroids/watch/7482_1994_pc1:

enter image description here

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2 Answers 2

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When NASA says 5:50PM today, what location and/or timezone are they referring to?

This particular website (eyes.nasa.gov) is using your system's local time to tell you the closest approach in your timezone. So when it says 5:50 PM today, it is when your clock reads 5:50 PM. Just be warned, if you have your system set to something else or possibly if you're using a VPN, NASA's website may be working of the wrong information and tell you a time which is not correct for your current location.

How do I know if this asteroid will be visible at my location with the naked eye?

NASA's asteroid tracking website does not appear to provide any information relating to visibility or brightness. I'd suggest other websites such as in-the-sky.org. On the linked page it shows asteroids which may be visible from your location (which you can change or set properly), including the magnitude of the asteroid, the constellation to look at, and the time range to view.

The page for Asteroid 7482 tells you specific information about visible in your area. You might also use free software like Stellarium for figuring out where objects may be and their observability.

Although I would caution that for this specific asteroid, you may have trouble viewing it. You will need to be fairly far south and have a good telescope in a dark area as the apparent brightness doesn't seem to get above 10 or 11 magnitude

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    $\begingroup$ FWIW I just observed it from a site which was neither particularly dark nor far south. Stellarium computed an accurate position though! $\endgroup$
    – Mike G
    Jan 19 at 0:14
  • $\begingroup$ I don't think a VPN would cause a problem, unless the site is using IP geolocation to determine the timezone. Usually converting to the user's timezone is done using JavaScript in the browser. $\endgroup$
    – Barmar
    Jan 19 at 16:36
  • $\begingroup$ That's why I said possibly if you're using a VPN. I assume it's grabbing your system time, but you never know and I wanted to call out the possibility, seeing as OP was explicitly trying to figure out what the time was referencing. No stone unturned... $\endgroup$
    – zephyr
    Jan 19 at 16:41
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The JPL Small Body Database shows this asteroid having a close approach to Earth at Jan 18 21:51 TDB or 21:50 UTC. NASA Eyes shows me that time in my local time zone. JPL HORIZONS estimates it peaking at magnitude 10.2 a few hours earlier on the 18th, and magnitude 12 or brighter from January 15 to 20.

The naked eye is limited to magnitude 6 at best, so this pass of (7482) 1994 PC1 is definitely not visible that way. However, if you have access to a 10 cm or larger telescope, Sky and Telescope has a chart which may help you find it. If you did, it would look like a faint star moving past the other stars at a rate comparable to the minute hand on a clock.

If you want to look in its general direction anyway, try matching the S&T finder chart to your favorite planetarium app or the current month's evening sky map at skymaps.com.

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