Wednesday, 30 May 2007

Sun in H-alpha 20070529

Finally, the sky cleared and yesterday (2007-05-29), Leo, Michel and me went to the hill to test the new solar telescope of Leo. Thus, around 17:45 GMT we captured some images with a small digital camera (Werlisa SLIM 30 Pro) attached to the telescope. After some processing, the following image was produced:

The image processing was as follow:
  • The original caption was transformed into a grayscale image.
  • The grayscale image was transformed into a RGB image.
  • A color map was applied to each channel of the RGB image to show in the same image the prominences and the surface details simulating as possible the observed colour.

Thursday, 24 May 2007

Sun Dogs

I know that anybody is for the conversion of the astroclub into an astrometeoclub ;)... but I cannot resist the temptation to put here a meteo picture again... Last days the changing weather shows several amazing phenomena. The new meteo event posted here is a Sun Dog (parhelia) taken from Majadahonda during the 2007-05-19 afternoon. It is caused by the ice crystals hosted in the clouds when the light passes throught their side faces. The phenomena is very well described in this link. Here you can find also a SW to simulate the different ice halos that can be produced by the Sun depending on the size of the ice crystals.

Looking for some related info, I found a good place gathering this kind of images in the same way than the Astronomy Picture of the Day (APOD) website. Of course, it is the Earth Science Picture of the day (EPOD) website!.

I promise that the next time I will post something more "astronomical"...

Wednesday, 23 May 2007

Saturn Occultation 20070522

Finally we observed a Saturn occultation. But not by the Moon... At approx. the sime time of the event (19:30 GMT) a big storm passed over this area. The following pictures were taken close the ESAC observation place.

... and more storms are forecasted for today!

Monday, 21 May 2007

A Star Formation Region?

Unfortunatelly no. I don't know if I should be able to take an image of a similar nebula with my equipment and our usual observation place. What I know is that the weather during the last month has been uncredibly bad. And, what to do when the clouds difficult the observation of the sky?... The direct option is to observe clouds!. And this the subject of the picture. If you observe the clouded sky you can observe very amazing events. The posted image is an altered subscene of this image that I captured from Majadahonda during the May, 19th 2007 morning. It shows a fragment of an iridiscent cloud. This is a well know atmospheric optics phenomena. It is caused by water droplet diffraction in thin clouds with similar size droplets. The colours are organized into coronal rings when the droplet size is uniform across the cloud. The iridiscence is more frequently visible when part of the cloud is forming. During the cloud formation the produced droplets have a similar history and consequently a similar size. However, in other cases the clouds can be random patches or bands at the clouds edges.

In my opinion, after several years seen the atmosphere, during the last times iridiscent clouds are surprisingly frequent. I saw one twenty year ago in high mountain conditions. However during the last two years I have been able to observe several ones from different places and conditions. Can be this something related to a variation of the cloud formation patterns?... you know... Could be related to a climate warming scenario?... the debate is open.

Monday, 14 May 2007

Half Full Venus

Shortly after the last sunset, I tried to image Venus from Majadahonda to check if something could be discriminated in the atmosphere using the filters that I have. The camera was the usual Phillips Toucam Pro with the following set of filters: a hand-made NIR filter, RGB filters and an OIII emission filter. The telescope was my Celestron 8" SCT. As Venus is still very far from us, I used a 3x Barlow to increase as possible the size of the disk in the camera detector. The following image is the obtained visible image.

As expected any atmosphere structure could be detected. The histogram can be equalized or streghtened but anything can be discriminated in the atmosphere disk. And the same happens with the other filters. Leo was very interested to check this in the NIR. The following image shows this.

However, it is well known that the Venus atmosphere presents some UV absorvers. They are distributed in atmospheric dark bands that could be constituted by chlorine or/and sulfure compounds. It is known since the Mariner 10 captured the firsts closed images of the planet. At present, Venus Express is the spacecraft observing the atmosphere in UV to better understand the composition of these bands and their paper in the atmospheric circulation. So, I tried to isolate the small UV detection range of the camera combining the IR blocking and pass filters. However, anything was observable. It could be that the IR pass filter is very restrictive in the blue part of the spectra and it extends to the UV or that at the height of the observation place the UV absortion is very high, or that the exposures were under 1 sec and perhaps is necesary to take longer exposures to detect the small UV radiation and to exploit the small detection capacity of the camera... Who knows...

Friday, 11 May 2007

Bolid from Majadahonda 2007-05-10 17:55 GMT

Yesterday, May 1oth 2007 at 17:55 GMT, I saw a bolid over Majadahonda while I was driving to home. From the coordinates (40.4488N, 3.86732W), it appeared approx. to the SSE at a height of approx. 20 deg going to the west with a path inclination of -30 deg. Despite the daylight, it was very bright (magnitude -10?) at least during 3 seconds. During the drag its colour was clearly green and it was disrupting into small pieces. Consequently, after the friction the bolid left an irregular white smoke trail of 5-10 degrees lenght. The trail expanded and diffussed in 10-15 minutes. It was very similar to the bolid that passed over Spain during January, 4th 2004 shown in the following picture taken from the web of the Spanish Photographic Meteor Network.

Today I have been looking for some related info in the press and I didn't found any reference. I'm surprised about nobody witnessed the object. As well I have reviewed the upcoming entrys of debris and anything was expected for yesterday. Therefore, it could be probably a meteoroid.