The station known as the Dehesa San Francisco forms a part of the network of meteorite and shooting star detection in association with the Málaga Association of Astronomy. They are a tripartite activity including the Foundation Monte Mediterráneo, and the Andalusian Ministry for Environment and Land Management.
This includes an illumination scale meter and a “fish eye lens” camera allowing us to capture the night sky from every angle.
COMPLETE ANGLE CAMERA
This camera is able to capture an extended image every 5 minutes. During the pauses between images, the camera is still in observation mode, able to detect the entrance of meteors and shooting stars into the earth’s atmosphere. If these falling objects reach the luminic intensity of Venus we call them shooting stars: that of the full moon: fireballs, and those which actually fall through the earths atmosphere to reach the planet are denominated meteorites.
Above each image displayed, you will find the following data in the upper left hand corner:
1) Date and hour at the beginning of each image (International time). To obtain the local time one will have to add another hour in winter and 2 in summer.
2) Percentage of lunar illumination. 100% would indicate a full moon.
3) Zenithal distance in degrees. 0 would mean that the moon is just at its zenith, or vertical. At 90 degrees the moon is found o the horizon. Anything above 90 degrees indicates that the moon is no longer visible.
4) Number of visible stars. This data provides a concept of the state of the sky at the time of the photo. On a clear night with few or no clouds, this should come close to 100% visibility.
5) Percentage of weaker stars still visible. This data suggests the existence of high clouds or ground and atmospheric humidity which impedes the visibility of dimmer stars while still being able to detect the brighter ones.
In the photo images we find North at the top and West to the right, looking towards a lightening rod located on a nearby farm.
On clear and moonless nights, we get spectacular images from the camera. On these nights especially, one appreciates one can enjoy the Milky Way from lower left to the upper right of the pictures. Thus, we can enjoy the following constellations: Canis Minor, Gemini, Auriga, Perseus, Cassiopeia, Lacerta, and Cygnus. In the lower left quadrant we can see Orion, who’s three central stars draw a straight line to Sirius, the brightest str in the sky very close to the end of the horizon.
On cloudy nights or those with a full moon, the resulting images are of far poorer quality. That’s what there is. In Astronomy we must always be aware of the meteorological conditions. It is also possible that a heavy rain or very thick dew will block the images.
BRIGHTNESS METER IN DEEP SPACE.
Our lab or station is also equipped with a Sky Quality Meter which measures the brightness at the depth of the sky, behind the stars. These measurements are taken through the night and measured in arcs per second squared. The higher the measurement indicates a darker sky which enables a far better quality image and also facilitates more stable conditions for flora and fauna and even our human health.
Here we have an example of the graphs used by the SQM:
In this image, at 7 PM we see that the dusk hours turn quickly into night and the light factor is greatly reduced. The shaded part of the image on the right side indicates that at this time the moon was directly above the horizon. In the middle of the night we measure 22, suggesting that the Dehesa San Francisco is one of the best places in Spain for viewing and measuring the stars. Its rare that any measurements in other locations reach even 21.5. In most major cities or larger towns its rare to even reach 18 due to light contamination from streetlights and individual illumination. The slight bumps in the graphics represent clouds passing.
With the data received through the SQM from the camera images it is feasible to study the evolution of the sky quality on a long term basis.
INTERESTING PHENOMENA REGISTERED BY THE STATION
On the nights of 27-28 of September 2015 we had a complete lunar eclipse. At that time there was another camera installed in our astrological station. In the video found below, we can appreciate the complete evolution of the lunar eclipse. At the beginning of the video and due to the brightness of the moon, we can see very few stars and a saturated column. As the evening progresses, we begin to see more and more stars and the reduction of the light in the column. During this period, it appears that there is no full moon and the stars are at their maximum. As the moon comes out from behind earth’s shadow the sky again returns to the Full Moon’s maximum illumination, obscuring again the night’s stars.
El SQM registers the evolution of the brightness of the depth of the sky in the below graphic.
Look for the sky and how it is slowly getting darker and darker, from 2:00 am onwards, until it gets to its totality reaching the usual magnitude of 21,6 of a moonless night. Here it stays until the penumbral phase.
METEORS and SHOOTING STARS
The complete angle camera is controlled by a Raspberry Pi 3 whose programs detect the entrance of meteors, shooting stars and fire balls like in the below image from November, 6th, 2015.
The most interesting or spectacular phenomena caught by the network are usually object of articles and publications on the web.
LAST IMAGE TAKEN FROM OUR ASTRONOMICAL STATION
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