#Iridium flare full

Mission Antenna (MMA) on each of the satellites. The mechanism providing the flare/glint are the Main Provided by Boeing's Delta II, the dispenser failed to achieve a lowerĮccentric orbit and went into a higher eccentric orbit. With its jobĭone, the satellite dispenser at the 500 km altitude is placed in a lowerĮccentric orbit to accelerate decay and re-entry. Individually raised to a circular orbit of approximately 780 km. Normally, over a two week period the satellites are Initially, the Iridium satellite is placed in a circular orbit at anĪltitude of approximately 500 km. Knowing where to look to observe theseįlares during the daylight hours is essential. Someįlares have been observed during the daylight hours which is very unusual for The flares/glints can last anywhere from 5 to 20 secondsīefore the satellite once again becomes almost invisible to the naked eye. For comparison, Venus canīe as bright as magnitude (-)4.9, thus reflections can be up to 30 timesīrighter than Venus. Provide reflective flares/glints of magnitude (-)8. (binoculars are useful to spot it), occasionally some of the Iridium satellites With only a normal brightness of +6 magnitude Visible reflective flares/glints to observers on the ground (*refer to respectfully submitted definition for Here's the reason why the flare is produced.Ī relatively small communications satellite has been providing spectacular (this image (c): Chris Dorreman) Additional photos can be found in Part Furtherĭetails can be found in a SeeSat-L messageīy his father Bram Dorreman. Stars are on the CYG-LAC-PEG border (northwest is up). Flare was bright enough to cause a reflection on the right side of Zenith is UP with sat moving left to right. Details: 1 minute exposure on Fuji chromeĤ00ASA. Programs were published) magnitude -8 (estimated) flare produced by Iridium 12

It is believed to be one of theĮarliest pictures taken of a unpredicted (before any Iridium flare prediction Provided information and programs that made this page 'award winning'Ĭatch a *Flaring/Glinting Iridium Updated February 7, 2007ĭorreman on Sat 19:10:23 UT. Thanks Allan for an interesting question.Iridium Flares Thanks to all on SeeSat-L who Hence we can regard an Iridium flare as the brighter!

#Iridium flare full

Thus we can say that the average surface brightness of the full Moon per square arc minute is -5.6 which is much fainter than the maximum -9.5 brightness of an Iridium flare. Taking m1 as the magnitude given for the full Moon by Allan as -12.74 and the intensity ratio as 707 we find that the smallest resolvable spot on the Moon has a magnitude of -5.6. M1 – m2 = -2.5 log (I1/I2) where m is magnitude and I is intensity.

Now our unaided eyes can resolve an angle of about one minute of arc, so we can take the brightness of the flash as spread over a box in the sky with sides of width one arc minute.įor comparison, into how many such boxes could we divide the full Moon? Taking the width of the full Moon from Earth as 30 minutes of arc and noting that area is given by the formula πr² where r is the radius, we find the area of the full Moon as 707 square arc minutes or 707 resolvable spots.Īs magnitude is a logarithmic scale we need to find the magnitude of one resolvable spot on the Moon using the formula If everything is lined up perfectly so that the satellite reflects the sunlight straight towards us the brightness is equivalent to a magnitude of -9.5, which is much brighter than the maximum brightness of the planet Venus.Īs Allan says, an Iridium flare appears like a point source to us. If we look at a small segment of the Moon there would be less light coming from it and its magnitude would be less.Īn Iridium flare is a reflection of sunlight from an Iridium satellite towards us on the ground. Yes, the listed apparent brightness of the Moon refers to the total light that comes from its disc. However, as the flare is point source while the Moon’s light is from a diffuse area, is the flare actually brighter to the eye? Most sources have the Moon as apparent magnitude -12.74 (or -12.92) and iridium flares are listed as max -9.5. A question from my Sydney Observatory colleague Allan: