How to Hear Meteors on Your FM Radio???
Introduction to hearing meteors on your FM radio
There are always meteors burning up in the Earth's atmosphere, and during certain times of the year there are major meteor showers. You want to watch the meteors but it's cloudy or the moon is too bright or you live in the city with too much light pollution. Even if you can't see the meteors, you can still have fun listening to the meteors.
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Friday, November 26, 2010
Thursday, November 25, 2010
Fireballs in the Sky -
Geminids Meteor Shower on Dec 14th
Geminids Meteor Shower on Dec 14th
Avid star gazers can soon witness another sky theatre spectacle in the mesmerizing night skies - the Geminids Meteor Shower, peaking on 13th/14th Dec. This is one of the best meteor showers of the year and never disappoints observers. The peak of the shower this year falls just after the first quarter Moon. Moonset is within half an hour of local midnight across the globe for the maximum, while the Geminid radiant will be overhead around 02h local time.
The source of the Geminids shower is asteroid 3200 Phaethon. There's a cloud of dust trailing the asteroid and the Earth plows through it every year in mid-December. Bits of dust traveling at 80,000 mph hit our atmosphere and turn into glowing meteors.The Geminids got its name because its radiant position, from which it appears to originate, lies in the constellation Gemini.
Observe and Photograph the Geminids:
SPACE has the following handouts and suggestions to ensure that each one of you can go out and observe this wonderful spectacle.
SPACE suggests that students, amateur astronomers and the public go out on Dec 14th morning to a dark site away from lights and observe this nightsky spectacle. Details about timing and observing suggestions can be found listed below.
Meteor Showers provide a wonderful photographic opportunity. Another post in this blog provides details on techniques and suggestions by SPACE to employ for meteor photography.
SPACE will webcast a workshop on 'Meteor Showers and the Geminids' on 14th Dec. Find details on this website.
Record and Report:
This year we would like all observers to become Citizen Scientists and record their results and report it to IMO (International Meteor Organization). Details can be found in the attachment, as well as on the IMO website, listed below. Each citizen scientist who reports their observations will have the privilege to have their names and results listed on the IMO website.
Interested in Joining an Observation?
If you or a group from your school would be interested in joining a tour to beautiful Rishikesh or to nearby Sakra to observe and photograph these spectacular fireballs, then contact STEPL Astrotourism at rishabhj@stepl.org for further details.
SPACE Plans:
SPACE plans to send a scientific team to witness and record the Geminid Meteor Showers to a dark site away from Delhi. In 2009, SPACE observed and created a very successful report for the IMO. This can be found on the blog listed below.
Geminids Details:
Maxima - Dec 14th at 11h UT or 16:30 h IST
ZHR (Zenith Hourly Rate) - around 120.
The best time to watch the activity near the peak in India is on 13th December night/early morning on 14th after moonset.
SPACE astrophotography of Geminids:
http://picasaweb.google.com/
IMO website reporting location:
http://www.imo.net/visual/
Photographing the Geminds
Shoot the Geminids
Photographing meteors such as the Geminids is possible using a Single Lens Reflex (SLR) camera. The camera must have a "T" (time) or "B" (bulb) setting for taking time exposures. You will also need a cable release, a tripod or a very stable surface to place the camera on, for best results. The camera will need a lens that is between "fisheye" and 50mm. Lenses larger than 50mm may capture too small a field of view. This article is written for the film camera but can be used as it is for digital SLRs.
Here is what you will need to do.
Set up your photography equipment in an area that is shaded from any stray lights that may interfere. This is absolutely necessary!
Set the camera on a tripod or some other surface that is very stable. Make sure the focal ratio is set to the lowest possible setting. This means that the aperture of the camera is "wide open". Make sure the camera is set to "B" or "T" for time exposure. Set the focus to infinity.
Aim the camera at the area of the sky that you intend to photograph. Once positioned properly, make sure the tripod is locked down to prevent its "head" from moving under the weight of the camera. If you do not have a tripod, use things to prop the camera up in a way so that it is stable and so that you can still look thru the view finder.
Depress the cable release button and lock it in place. Allow the camera to take a picture for anywhere from 15 to 30 seconds, maybe more. Once the desired time has elapsed, release the cable release lock which will end the exposure. While taking the picture, do not move the camera at all.
The length of time that you should expose the film can be a tricky thing. Light pollution will shorten the amount of time that an exposure can be made before the file reaches it's "Sky Fog Limit" or is effectively overexposed. Experimenting with the length of time an exposure is well worth the effort!
The speed and grain size of the film is an important consideration. Generally speaking, ASA 400 film is "fast" enough for these purposes. Fine grained film such as ASA 100 will give you sharper images than ASA 400 but the pictures would be much darker. With low light levels, "fast" film is highly desired. ASA 800 will expose quicker than ASA 400 but will be grainier. Kodak Gold and Fuji Film's of ASA 400 or ASA 800 should suffice.
The "F" stop or "focal ratio" setting is very important. As mentioned above, you want the camera to be "wide open" or set to lowest focal ratio setting. The reason is that the film will be able to gather more light if the aperture is wider. Your pictures will capture more fainter meteors at a lower focal ratio than at a higher focal ratio. If your camera produces fuzzy results and it is indeed correctly focused, close the aperture down one stop.
Go out on a clear night and test your setup! On a clear night prior to the Geminid meteor shower, set your camera up and take a few pictures. This will help you determine what works best for your camera and how the film reacts to the night sky in your area. Try a few exposures of 15 seconds, 30 seconds, 1 minute, 2 minutes, 3 minutes and 4 minutes using the lowest focal ratio, and record the frame number and exposure time on a scratch pad. Repeat the process with the focal ratio backed off one stop. When you get the film developed, you'll be able to compare the results with your notes and determine what works best for your camera and sky conditions. What you will see are called "star trails". Every star in the photo will appear to be "trailed" for all photos over 20-30 seconds in duration. This is OK though as many meteor photographers do use this method. You would need an "equatorial" mount with a tracking motor to eliminate this effect. Knowing how your camera records light before the main event is essential!
Warn the film developer that your pictures may be very dim! When getting your photographs developed, it is a good idea to make sure they know your photographs are dim and to the untrained eye, may appear to be of nothing at all. If the developer uses normal processing, you should at least get some kind of results. The important thing is that they print them! It is a better idea to have them developed locally, where you can discuss what's on the film prior to processing it.
Some Geminids are exceedingly bright and may possibly overexpose or ruin a time exposure. If a very bright fireball crosses the camera's field of view, end the exposure shortly thereafter. Know where your camera is pointing! Sometimes, a bright meteor will leave a "train" or trail. These make very interesting photographs as the trails become twisted and contorted by winds high in the upper atmosphere.
Framing your picture with natural landscapes will help to make it more interesting and will provide the viewer with a better perspective of the event. Trees, cactus, rock formations and distant mountains are all good objects to try this on. A wide field photograph of meteors while looking across a very still lake or pond may make for astounding poster quality shots, especially if the water surface is very still and reflects the meteor well. If you have a lake or pond nearby, give this a try. It may actually be possible if the meteor counts are high and if they are bright. Although the moon will significantly interfere with meteor observing and photography this year, it may provide a bit of foreground illumination to the setting.
Enjoy the show and Good Luck!
Tuesday, November 16, 2010
Shoot the Leonids
Shoot the Leonids
Photographing meteors such as the Leonids is possible using a Single Lens Reflex (SLR) camera. The camera must have a "T" (time) or "B" (bulb) setting for taking time exposures. You will also need a cable release, a tripod or a very stable surface to place the camera on, for best results. The camera will need a lens that is between "fisheye" and 50mm. Lenses larger than 50mm may capture too small a field of view. This article is written for the film camera but can be used as it is for digital SLRs.
Here is what you will need to do.
Set up your photography equipment in an area that is shaded from any stray lights that may interfere. This is absolutely necessary!
Set the camera on a tripod or some other surface that is very stable. Make sure the focal ratio is set to the lowest possible setting. This means that the aperture of the camera is "wide open". Make sure the camera is set to "B" or "T" for time exposure. Set the focus to infinity.
Aim the camera at the area of the sky that you intend to photograph. Once positioned properly, make sure the tripod is locked down to prevent its "head" from moving under the weight of the camera. If you do not have a tripod, use things to prop the camera up in a way so that it is stable and so that you can still look thru the view finder.
Depress the cable release button and lock it in place. Allow the camera to take a picture for anywhere from 15 to 30 seconds, maybe more. Once the desired time has elapsed, release the cable release lock which will end the exposure. While taking the picture, do not move the camera at all.
The length of time that you should expose the film can be a tricky thing. Light pollution will shorten the amount of time that an exposure can be made before the file reaches it's "Sky Fog Limit" or is effectively overexposed. Experimenting with the length of time an exposure is well worth the effort!
The speed and grain size of the film is an important consideration. Generally speaking, ASA 400 film is "fast" enough for these purposes. Fine grained film such as ASA 100 will give you sharper images than ASA 400 but the pictures would be much darker. With low light levels, "fast" film is highly desired. ASA 800 will expose quicker than ASA 400 but will be grainier. Kodak Gold and Fuji Film's of ASA 400 or ASA 800 should suffice.
The "F" stop or "focal ratio" setting is very important. As mentioned above, you want the camera to be "wide open" or set to lowest focal ratio setting. The reason is that the film will be able to gather more light if the aperture is wider. Your pictures will capture more fainter meteors at a lower focal ratio than at a higher focal ratio. If your camera produces fuzzy results and it is indeed correctly focused, close the aperture down one stop.
Go out on a clear night and test your setup! On a clear night prior to the Geminid meteor shower, set your camera up and take a few pictures. This will help you determine what works best for your camera and how the film reacts to the night sky in your area. Try a few exposures of 15 seconds, 30 seconds, 1 minute, 2 minutes, 3 minutes and 4 minutes using the lowest focal ratio, and record the frame number and exposure time on a scratch pad. Repeat the process with the focal ratio backed off one stop. When you get the film developed, you'll be able to compare the results with your notes and determine what works best for your camera and sky conditions. What you will see are called "star trails". Every star in the photo will appear to be "trailed" for all photos over 20-30 seconds in duration. This is OK though as many meteor photographers do use this method. You would need an "equatorial" mount with a tracking motor to eliminate this effect. Knowing how your camera records light before the main event is essential!
Warn the film developer that your pictures may be very dim! When getting your photographs developed, it is a good idea to make sure they know your photographs are dim and to the untrained eye, may appear to be of nothing at all. If the developer uses normal processing, you should at least get some kind of results. The important thing is that they print them! It is a better idea to have them developed locally, where you can discuss what's on the film prior to processing it.
Some Leonids are exceedingly bright and may possibly overexpose or ruin a time exposure. If a very bright fireball crosses the camera's field of view, end the exposure shortly thereafter. Know where your camera is pointing! Sometimes, a bright meteor will leave a "train" or trail. These make very interesting photographs as the trails become twisted and contorted by winds high in the upper atmosphere.
Framing your picture with natural landscapes will help to make it more interesting and will provide the viewer with a better perspective of the event. Trees, cactus, rock formations and distant mountains are all good objects to try this on. A wide field photograph of meteors while looking across a very still lake or pond may make for astounding poster quality shots, especially if the water surface is very still and reflects the meteor well. If you have a lake or pond nearby, give this a try. It may actually be possible if the meteor counts are high and if they are bright. Although the moon will significantly interfere with meteor observing and photography this year, it may provide a bit of foreground illumination to the setting.
Enjoy the show and Good Luck!
Leonids Meteor Shower - Nov 18th, 2010
Leonids Meteor Shower - Nov 18th, 2010
The Leonids meteor shower will send trails of shooting stars in the sky on the dawn of Nov 18th. This shower is created by the Earth moving through the debris of comet Tempel-Tuttle. The shower will peak at 2:45 am IST. However, this year the moon is quite full and moonset will only occur around 3:30 am, therefore the shower will be washed out and not offer a good view.
Come November and all amateur astronomers around the world start looking up to the skies for an event which we call the “Leonids Meteor Shower”. One can see trains of shooting stars coming from a particular area in the sky at an amazing rate. This phenomenon can be seen almost any day of the year but a shower of shooting stars is something that happens only a few times a year. Leonids is one of these and the most prominent one.
Leonids are a prolific meteor shower associated with the comet Tempel-Tuttle. The meteor shower is visible every year around November 17 when the Earth moves through the Leonid meteor stream. The stream comprises solid particles, known as meteoroids, ejected by the comet as it passes by the Sun. As the entire meteor streaks are parallel, because of the effect of perspective they appear to originate from a single point in the sky and as a result Leonids get their name from the location of their radiant in the constellation Leo. The Leonids are famous because their meteor showers, or storms, can be among the most spectacular.
Most visible Leonids are between 1 mm and 1 cm in diameter. For example, a Leonid meteor barely visible with the naked eye in a dark sky, is caused by a meteoroid of 0.5 mm in diameter and weights only 0.00006 gram. Just before they enter the Earth's atmosphere, Leonid meteoroids travel at 71 kilometers per second, or 213 times as fast as speed of sound.
It can be seen from Nov 14 till Nov 21. The peak usually occurs around 17/18th November.
This year the peak is happening on 17th Nov night/18th morning at around 02:45 hrs IST. However this year the moon is quite full and the moonset will only happen around 3:30am, which means this year the meteor shower will be washed out. To try and look for Leonids, go to a dark site and try looking during the dawn of Nov18th, but as mentioned this year the viewing will not be good. Although the meteors appear to originate from Leo, they really streak across the whole sky.
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