Meteor Activity Outlook for July 16-22, 2011

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During this period the moon wanes from a full phase down to nearly half illuminated. This weekend the nearly full moon will be in the sky all night long. This is the worst time of the month to try and view meteor activity. As the week progresses, the moon will rise later in the evening but will still interfere with observing during the prime morning hours. The estimated total hourly rates for evening observers this week is near one no matter your location. For morning observers the estimated total hourly rates should be near five from the northern hemisphere and six as seen from south of the equator. The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity. Rates are reduced this week due to moonlight.

The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning July 16/17. These positions do not change greatly day to day so the listed coordinates may be used during this entire period. Most star atlases (available at science stores and planetariums) will provide maps with grid lines of the celestial coordinates so that you may find out exactly where these positions are located in the sky. A planisphere or computer planetarium program is also useful in showing the sky at any time of night on any date of the year. Activity from each radiant is best seen when it is positioned highest in the sky, either due north or south along the meridian, depending on your latitude. It must be remembered that meteor activity is rarely seen at the radiant position. Rather they shoot outwards from the radiant so it is best to center your field of view so that the radiant lies at the edge and not the center. Viewing there will allow you to easily trace the path of each meteor back to the radiant (if it is a shower member) or in another direction if it is a sporadic. Meteor activity is not seen from radiants that are located below the horizon. The positions below are listed in a west to east manner in order of right ascension (celestial longitude). The positions listed first are located further west therefore are accessible earlier in the night while those listed further down the list rise later in the night.

The following showers are expected to be active this week. Details concerning each shower will continue next week when the moon will not be so troublesome.

SHOWER DATE OF MAXIMUM ACTIVITY CELESTIAL POSITION ENTRY VELOCITY CULMINATION HOURLY RATE CLASS
RA (RA in Deg.) DEC Km/Sec Local Daylight Time North-South
Mu Lyrids (MUL) July 18 18:04 (271) +40 23 00:00 <1 – <1 IV
Alpha Capricornids (CAP) July 30 19:52 (298) -14 25 01:00 <1 – 1 II
Antihelion (ANT) 20:28 (307) -18 30 02:00 <1 – 1 II
July Pegasids (JPE) July 11 23:32 (353) +13 71 05:00 <1 – <1 IV
Perseids (PER) Aug 13 00:36 (009) +51 61 06:00 1 – <1 I

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2 comments

  • David 5 years ago

    On the night of July 22, 2011 I was on the beach in Dennisport, MA (southern side of Cape Cod) and was looking south around 10pm, when I saw a “star” (for lack of a better word) glowing VERY brightly, more brightly than any other object in the sky. I thought at first it might be Venus but my rudimentary knowledge of astronomy told me that it was perhaps too late in the evening. As I looked at the object it got brighter still – so bright I almost couldn’t look at it, then suddenly it dimmed and then disappeared completely, like a filament of an incandescent bulb that had burned out. I saw no trail or tail, like a meteor, making me wonder (a) was this a meteor heading directly towards my location or (b) was this a star going nova? (Again, my knowledge of astronomy is basic)

    Can anyone tell me what it is I saw?

    Thanks. Please feel free to email me here: hotelvendome@comcast.net

    David

    Reply to David
    • amsadmin 5 years ago

      David and All,

      What you most likely witnessed was an Iridium flare. These are bright glints of sunlight reflected off Iridium satellites. If the geometry is just right they can become very bright, far exceeding the light of any star or planet for a few seconds. You can obtain information on Iridium flares on Wikipedia at: http://en.wikipedia.org/wiki/Iridium_flares There are predictions for iridium flares available at heavensabove.com You need to sign up and give your geographical coordinates and then you can obtain a list of iridium flares, satellite passes, and a number of other phenomena visible from your location.

      I hope this helps!

      Robert Lunsford

      Reply to amsadmin

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