Tuesday, 26 June 2007

Moon 2007-06-24

On Sunday (2007-06-24 22:30 GMT) and from Majadahonda, I imaged the Moon in UV, RGB and NIR with a C8 and a DSI Meade Camera. I tried to check if the response of different surface materials could be characterized from the Earth surface. For this purpose, the images should be as zenithal as possible. However, due to the date, the images were taken close to the terminator. The false color combination was (Red:NIR; Green:G; Blue:UV). This color was saturated in order to better appreciate the different responses.

The first image shows the Copernicus and Erathostenes craters and it is centered in the large ejecta complex surrounding Copernicus.

The second image is centered in the Montes Apeninnus that separate the Mare Imbrium and the Mare Vaporum. The large crater of the image is Archimedes and the smaller ones are Aristillus and Antolycus.

Using this false color combination, the different surface responses can be discriminated. However, the fact that the images are very closed to the terminator difficults the direct mapping of the surface elements. This could be solved removing the illumination effects using an elevation model or taking the images as close as possible to the full Moon. This last option seems more feasible for testing...

Monday, 25 June 2007

Deep Sky Tour at ESAC 2007-06-22

Last Friday, Leo, Michel, Fernando and me met here to try to image Venus with the UV filter and The Leo's telescope. After some trials and errors, the results were unsuccessful... it seems that we have lost some training using the Dobsonian with a Barlow... Later than the Moonset, we tried to image some deep sky objects from ESAC. Despite the light pollution, the bad seeing and a non-accurate tracking, some good deep sky images were taken. We used a C8 telescope with a 0.33 focal reducer and the DSI Meade CCD camera. The exposures ranged from 45 sec. to 1.5 minutes. Of course, we tried with some of the easiest Messier objects.

M51 Whirlpool Galaxy M82- Cigar Galaxy M27 - Dumbbell Planetary Nebula
M20 - Trifid Nebula

Thursday, 21 June 2007

Celestial Line 2007-06-20

Last night in Majadahonda, the sky cleared and I photographed an infrequent alignment of the Moon, Regulus, Saturn and Venus (from left to right). This alignment marks approximately the ecliptic. Technically it is the place where lunar and solar eclipses take place. However, during the last two days, the Moon has been eclipsing all the elements that has been encountering along the line... it seems that at least in this case the ecliptic definition could be extended a little...

Wednesday, 20 June 2007

Small Astrophoto Tour 2007-06-18/19

Yet I am testing my Baader U Filter. So, I tried to take again a picture of the Venus atmospheric features with my C8 Celestron from Majadahonda. In the previous post referred to Venus imaging, I showed a firsts UV picture. But there is something strange... it seems that a ghost image appears superposed to the main image. After some research in the technical specifications I discovered that the Baader U-filter has some small transmission in the NIR. If the observed object doesn't has a large emission in the UV, the NIR contribution can achieve the same magnitude. It should explain the detection of superposed double images slightly separated by the atmospheric refraction. In consequence, to use adequately the Baader U-filter it is necessary to combine it with a NIR blocking filter or a blue wide band filter to remove the NIR contribution.

The following image is the first result after combining the U-filter with a NIR blocking filter (the Astronomik NIR blocking filter, the Baader one blocks also the UV). In order to increase the exposure, instead the Toucam Webcam Pro, I used a CCD (Meade DSI) with a filter wheel. However, due to a large seeing and the low height of Venus at the imaging, large atmospheric distortions affected the image. After the stack of 10 images with 0.7 secs exposure, this is the best I achieved. Yes... I know any atmospheric feature is visible. Next time I will image early and with a better seeing.

After the Venus set, all the equipment was mounted. So I decided to perform a small astrophoto tour. The next image is the result to combine 40 images of Jupiter of 0.003 secs each.

The image shows the M22 Globular Cluster. For the generation of this image, 80 images of 15 secs were combined.

Thursday, 14 June 2007

Apophis: the End of the World is Nigh?

Talk from Mark Kidger on June 14th, 2007 at ESAC
Download pdf

A world with oceans...

This could be the look of the red planet 2.000 millions of years ago!

Perron et al, NATURE| Vol 447| 14 June 2007

Wednesday, 13 June 2007

2007-06-11: Venus in UV - First Test

Last month I adquired a Baader U filter to observe Venus. Two days ago I did my first test with the filter using my C8 and a Toucam Pro webcam. The sensibility of the camera is very low in UV. Therefore, I used the camera at the limit of gain and exposure. The following images show the result with the webcam CCD in the focal plane after a postprocessing with Registax.

There some estructure was clearly visible in UV in the Venus atmosphere. But when I tried to use a Barlow lens to magnificate the image, I reduced the luminosity of the image out to the detection range of the camera. What to do?. To increase the diameter of the telescope ( I think in Leo's telescope...) or use a CCD with a wider detection range. However, a larger exposure can difficult seriously the seeing compensation in posprocessing...

Monday, 4 June 2007

Sun in H-Alpha 20070601

Despite of some problems with the electrical current in the Satan site, last Friday we imaged the Sun in H-alpha using the Leo's CORONADO telescope again. The following images show the full disk and the prominences.

I post also some images of the observers and the equipment. Only Michel, Leo and Me are in the pictures but Ricardo and Luis were also here.