WASHINGTON - NASA's Cassini spacecraft, now exploring Saturn, will take a picture of our home planet from a distance of hundreds of millions of miles on July 19. NASA is inviting the public to help acknowledge the historic interplanetary portrait as it is being taken.
Earth will appear as a small, pale blue dot between the rings of Saturn in the image, which will be part of a mosaic, or multi-image portrait, of the Saturn system Cassini is composing.
"While Earth will be only about a pixel in size from Cassini's vantage point 898 million (1.44 billion kilometers) away, the team is looking forward to giving the world a chance to see what their home looks like from Saturn," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "We hope you'll join us in waving at Saturn from Earth, so we can commemorate this special opportunity."
Cassini will start obtaining the Earth part of the mosaic at 5:27 p.m. EDT (2:27 p.m. PDT or 21:27 UTC) and end about 15 minutes later, all while Saturn is eclipsing the sun from Cassini's point of view. The spacecraft's unique vantage point in Saturn's shadow will provide a special scientific opportunity to look at the planet's rings. At the time of the photo, North America and part of the Atlantic Ocean will be in sunlight.
Unlike two previous Cassini eclipse mosaics of the Saturn system in 2006, which captured Earth, and another in 2012, the July 19 image will be the first to capture the Saturn system with Earth in natural color, as human eyes would see it. It also will be the first to capture Earth and its moon with Cassini's highest-resolution camera. The probe's position will allow it to turn its cameras in the direction of the sun, where Earth will be, without damaging the spacecraft's sensitive detectors.
"Ever since we caught sight of the Earth among the rings of Saturn in September 2006 in a mosaic that has become one of Cassini's most beloved images, I have wanted to do it all over again, only better," said Carolyn Porco, Cassini imaging team lead at the Space Science Institute in Boulder, Colo. "This time, I wanted to turn the entire event into an opportunity for everyone around the globe to savor the uniqueness of our planet and the preciousness of the life on it."
Porco and her imaging team associates examined Cassini's planned flight path for the remainder of its Saturn mission in search of a time when Earth would not be obstructed by Saturn or its rings. Working with other Cassini team members, they found the July 19 opportunity would permit the spacecraft to spend time in Saturn's shadow to duplicate the views from earlier in the mission to collect both visible and infrared imagery of the planet and its ring system.
"Looking back towards the sun through the rings highlights the tiniest of ring particles, whose width is comparable to the thickness of hair and which are difficult to see from ground-based telescopes," said Matt Hedman, a Cassini science team member based at Cornell University in Ithaca, N.Y., and a member of the rings working group. "We're particularly interested in seeing the structures within Saturn's dusty E ring, which is sculpted by the activity of the geysers on the moon Enceladus, Saturn's magnetic field and even solar radiation pressure."
This latest image will continue a NASA legacy of space-based images of our fragile home, including the 1968 "Earthrise" image taken by the Apollo 8 moon mission from about 240,000 miles (380,000 kilometers) away and the 1990 "Pale Blue Dot" image taken by Voyager 1 from about 4 billion miles (6 billion kilometers) away.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages the Cassini-Huygens mission for NASA's Science Mission Directorate in Washington, and designed, developed and assembled the Cassini orbiter and its two onboard cameras. The imaging team consists of scientists from the United States, the United Kingdom, France and Germany. The imaging operations center is based at the Space Science Institute in Boulder, Colo.
To learn more about the public outreach activities associated with the taking of the image, visit:
After about one year of maintenance (I have rebuilt all the circuit) the lightning radar, an invention of Frank Kooiman, is back on-line.
Now will follow a period of verification of the generated output, after which will be it put on the pages of KWOS.
At the moment you can display the screens of the software on this blog, or on the site Lightningradar.net
This system was developed as a hobby alternative to the existing
commercial Boltek lightning detector. The advantages of the
lightning radar are the low cost (€40 and up) compared to the
Boltek (€350 to €600 depending on theversion),
the extreme sensitivity of the system, and the possibility of
joining the group system via the internet. Where Boltek
detectors can detect lightning up to a range of 500km, the LR
(lightning radar) has a range of 2000 to 3000km over land and
several thousand km over water (e.g. lightning in Florida, south
One disadvantage of the LR is that it is not a plug-and-play
system and therefore requires some knowledge
of electronics and
familiarity with a soldering iron. In practice, this is not
really a disadvantage since it means that
you learn a lot more about the science of detecting lightning.
The software functions as a single station showing the direction
and estimated distance, or connects with other LR stations via
the internet to perform a localisation function, displaying the
result (specific direction and distance) on a map. In addition
these maps can be uploaded to your website. The electronics consists of
an amplifier which boosts and filters the signal from an antenna
and passes it to the soundcard of a computer (Line-in).
The lightning strikes are received using a frame antenna set at
10 kHz. At this frequency range the lightning sends impulses
over a range of several thousand kilometres. The antenna
consists of a frame, around which wire is wound in multiple
windings. The antenna measures the magnetic part of a wave and
has the advantage that it is less sensitive to interfering
electrical fields. With a single antenna, the lightning strike
can be detected but the direction cannot be measured. For this
reason a second identical antenna is mounted at 90 degrees to
the first antenna. The direction can be calculated from the two
signals measured. It is still not possible to say for certain
the lightning strike occurred at one direction, exactly
opposite direction could also have been possible (+180 degrees).
This is also due to the fact that we do not know if the
lightning strike had a positive or negative charge. If you are
working with a single station, a third antenna is therefore
necessary to detect the charge and therefore the correct
direction of the strike. A single station cannot be used to
determine the exact position / distance of the strike. This can
only be estimated from the strength of the signal, since not all
lightning strikes have the same energy. Lightning Radar works in
a group of a number of stations and can therefore calculate the
correct direction and the position / distance using only 2
I have in test two ferrite antennas just like the ones used for
the TOA system. It's not simple to adapt them to the RDF hardware
but some good result is coming :-) You can find information about
Lightning Radar on: http://www.lightningradar.net
Use the following image to check the result from the first image.
The development of ADS-B software in Java continues. Another programmer has joined our group: i0kte, Stefano Ricciardetto. He is an expert on radar console, has worked for many years as a software programmer for the ATC.
Now the software in addition to the display of the aircraft on the maps of Nasa World Winds, allows to upload outlines which are usually employed with Basestation or Planeplotter.
The planes seen at close range, are represented in 3D.
At the moment you can add various sources ADS-B but only in SBS format (port 30003).
The icon that identifies the aircraft, the track and the direction it will be soon changed according to the ATC standards.
Currently we are investigating to solve a java heap space error that occurs about 2 days after the software is started.
Set to peak on Sunday, June 23, the 2013 supermoon is noteworthy not only for the remarkable sight it will present to skywatchers but also because it will be the largest supermoon this year. Also known as a perigee moon, the event occurs when a full moon lines up with the Earth and the sun at a specific point in its orbit, called the lunar perigee. That's the point at which the moon is nearest to Earth as it traces its elliptical path around our planet. Since it's closer to us, the moon appears up to 14 percent bigger and 30 percent brighter than usual. Coined by astrologer Richard Nolle, the term "supermoon"essentially means a bigger and brighter full moon. But what makes Sunday's supermoon so special? While skywatchers will be able to spot another supermoon in July, the moon will not be this close again until August 2014.
This shower is active during June 10 to 21, producing predominantly blue and white meteors at a maximum hourly rate of 8 per hour on June 15 (λ=84.5°). At maximum the radiant is located at α=278°, δ=+35°. The average observed magnitude of this shower is near 3, while about 32% of the meteors leave trains.
This meteor shower was discovered on the evening of June 15, 1966, by S. Dvorak (California, USA) while camping out in the San Bernardino mountains. His attention had been drawn to the region of Lyra by a very bright meteor that moved swiftly to the northeast through that constellation. Another meteor was noted a short time later and Dvorak began plotting additional meteors. After 1 1/2 hours he had managed to plot 16 meteors, of which 13 appeared to originate from a hitherto unknown radiant located at RA=278°, DECL=+30°. Just a few hours later, F. W. Talbot (Cheshire, England) independently discovered the radiant at RA=275.5°, DECL=+30°, and noted an hourly rate near 9.
Moonlight from a waning moon interfered with observations in 1967, but, in June 1968, confirmation of this shower's existence came from Richard Nolthenius (Hacienda Heights, California). During one hour on the 15th, he detected 8 June Lyrids, while a similar hour on the 17th revealed 7. Observations of this shower have continued annually ever since, however, to date, the most elaborate study of this shower was made from observations obtained during 1969.
Observations from 46 observers, totalling 172 man-hours, were gathered and analyzed by Keith B. Hindley of the British Astronomical Association. The observations covered the period of June 11.5 to 21.0 (Solar Longitude=80.2 deg to 89.2 deg) and the total number of June Lyrids observed was 363. Against a fairly constant sporadic meteor rate of 8.7 per hour, the June Lyrids displayed a broad maximum of about 6 per hour during June 13 to 17, with a sharp peak of 9 per hour on June 16.0 (Solar Longitude=84.5 deg). The average magnitude was found to be 2.0 and 32% of the shower's meteors showed persistent trains. Colors displayed a prominence of white, as did sporadic meteors, however, there was also a large number of blue meteors. The exact percentages of colors seen among the June Lyrids were as follows: 33%, blue, 52%, white, 9%, yellow, and 6%, orange-red.
The average radiant, as determined by Hindley, was found to be RA=278 deg+/-2 deg, DECL=+35 deg+/-3 deg. From this position, a parabolic orbit was calculated, which revealed a close, but "not convincing" similarity to comet Mellish (1915 II). This comet possesses a slightly hyperbolic orbit with an eccentricity of 1.0002. A radar orbit obtained by Zdenek Sekanina from observations made at Havana, Illinois, in 1969, actually seemed to strengthen the similarity between the June Lyrids and 1915 II, except for the fact that the radar orbit revealed a period of 2.94 years. These orbits are compared later.
Although observations continued after 1969, there seemed an indication that the meteor rates of 8 or 9 per hour had vanished. In 1971, about 215 hours of observations were acquired by 26 observers from Canada and the United States. The shower's ZHR irregularly varied during the period of June 10 to 24, with
maximum peaks of 1.3 to 3.5. The radiant of the stream was determined from 37 meteors plotted by an Ottawa observing group from observations made during June 14 to 17, with the result being RA=278.3 deg, DECL=+41 deg.
In 1972, the shower again showed a poor return. Meteor News combined the observations of 20 observers, made during June 9 to 22, and found the maximum ZHR to be only 2.3---a value that came on June 15/16. What the observations also revealed were activity levels between 1.2 and 1.3 during June 12 to 15, which suddenly jumped to 2.3, then rapidly fell to only 0.3 by the night of June 18/19. Thus, the shower's date of maximum and variation of activity levels closely reflected those noted in 1969, but the ZHRs were typically down by about 6 or 7 meteors per hour!
Observations in 1974 indicated a resurgence of activity. The shower's discoverer, Dvorak, observed on four nights during mid-June, with the following average hourly rates (not ZHRs) being noted: June 14/15, 2.9, June 15/16, 6.5, June 16/17, 6.2, June 17/18, 2.3. Dvorak added that the meteors moved swiftly, with the majority being bluish-green. Also, in 1974, Nolthenius, Alan Devault and Bob Fischer (all of California) observed during 7 nights between June 9 and 22. Overall, they observed 32 June Lyrids, with the average magnitude being determined as 3.09. Slightly less than half of their total number of June Lyrids were seen on the shower's night of maximum (June 15/16). The average number of meteors seen from this radiant was 4 per hour.
During 1975, observations were quite scarce. Between June 6 and 15, Norman W. McLeod III (Florida) saw only 2 June Lyrids, while, during the period June 9 to 14, Mark Adams (Pennsylvania) noted 5 members, with 4 coming in less than 3.5 hours on the final date of observation. Finally, Paul Jones (St. Augustine, Florida) observed for 3 hours on the night of maximum and detected 20 June Lyrids.
Interest in the June Lyrids seems to have waned in the latter half of the 1970s and into the 1980s, with only a few individuals continuing to monitor the shower annually---many of them rarely observing around the time of the shower's established date of maximum. As is evident from the previously listed observations, activity from this radiant can be virtually nonexistent on dates other than June 15 and 16, due to the June Lyrids' very pronounced peak of activity.
In 1979, observers in Texas observed on June 15/16 and 17/18, with meteors being seen to reach nearly 2 per hour on the latter date. In Quebec, F. Roy observed during June 16/17, 18/19 and 20/21 and noted 12 meteors in about 3.5 hours---certainly marking the most activity seen from this radiant since 1974. During 1980, the enhanced rates still seemed present, with John West (Texas) noting 18 meteors in only 5 hours on June 13/14 and 14/15. Since 1980, the shower's activity has again dropped to maximum rates of about 1
A search for pre-1966 observations of this shower has not revealed many clues to the shower's history. From observations by G. Zeziolli, G. V. Schiaparelli isolated 11 meteors observed on June 14, 1869, from a radiant of RA=280 deg, DECL=+35 deg. No convincing June Lyrid radiants were observed by members of the American Meteor Society prior to 1966, nor were any observations present among the extensive visual radiants obtained by A. S. Herschel, A. King, C. Hoffmeister or E. Opik.
Aside from the 1969 study by Hindley, studies of the June Lyrids have been rare, with the only other information gathered on the individual meteors involving the average magnitude. John West observed 59 June Lyrids during 1967 to 1982, and found the average magnitude to be 3.02. During 1967 to 1981, R. Hill (North Carolina, USA) observed 65 June Lyrids and found the average magnitude to be 2.71.
While I'm continuing my studies on navigational aids, I've just bought two new books (Navigazione Aerea e Electronic Installation Instructions for ILS facilities), I begun the reception of another Aeronautical communication system: HFDL.
Aircraft utilize HF communications when VHF (Line of Sight) communications is not sufficient. The primary usage of HF is for Trans-oceanic flights. Trans-oceanic flights communicate with ground stations via HF for position reports and other purposes. Another utilization of HF communications is for HFDL or High Frequency DataLink. Finally Military Aircraft (MILCRAFT) utilize HF for operational and training. HFDL is a HF data link protocol, defined in ARINC spec 635-3. It may be described as some sort of HF ACARS. Transmissions on HF are in USB on a sub carrier of 1440 Hz with a symbol speed of 1800 baud. Modulation is 2-PSK, 4-PSK or 8-PSK with effective bit rates of 300, 600, 1200 or 1800 bits/sec. The HFDL service is operated by ARINC as GLOBALink service through a worldwide network of HF stations.
On board the aircraft, a pilot simply sets one of the HF radios to "DATA" after takeoff, and the HFDL seamlessly integrated into the flight management system.
The ACARS will use HF or VHF depending on what is available. The HF part of the system is usually taken out of "DATA" mode before landing to prevent inadvertent RF exposure to ground personnel, since the system will start to tune around and seek a connection to the network as HF conditions change.
HFDL signals are present whenever the HF bands are open, and are actually more robust than voice transmissions. The author has often gotten solid copy of HFDL transmissions while finding voice from the same geographic area to be a struggle. Even when conditions are marginal, a scan of the current HFDL frequencies will often yield readable data. With a suitable computer controlled radio, the HFDL nets can be followed up and down the spectrum with the diurnal cycle of the ionosphere.