Starship Asterisk*

http://antwrp.gsfc.nasa.gov/apod/ap060829.html
the view of this nova with the SMC almost overshadows the fact that Hubble is studying the remnants of Ed102.

With all the knowledge we gain from Hubble like this view of the super nova in the SMC; I think it is important to keep Hubble upgraded. For all the cost of building this wonderful space telescope; it is worth keeping it going because it has opened the windows to valuable information. At least until a bigger better one is put into service.
Orin

I second that notion.

This might be a faq, but I could not easily find the answer. I apologize if this has already been discussed many times before.

I noticed that on the APOD of august 28, 2006 ( http://antwrp.gsfc.nasa.gov/apod/ap060829.html ) the bigger stars show 'twinkles' in the exact vertical and horizontal directions. Does anyone know what causes these lines of light? Are they an undesired artefact that cannot be removed easily?


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Matthijs Sypkens Smit

Hi matthijs

The effect is called bleeding, its when charge in the CCD bleeds up and down columns and across rows when the target saturates the detector. In other words the brightest pixel in the centre of the star image cannot hold any more electrons (which are released by the light impinging on the chip) so the charge tends to fall down the rows and columns. They can generally be removed by taking more shorter exposures so that the central pixel does not saturate. However if pretty pictures are not the main driver (and generally they arent) then they dont tend to cause too many problems so its easier not to break up the exposures.

Also some telecsopes have these diffraction spikes due to diffraction with some of the mirror and equipment supports

cosmo_uk wrote:Also some telecsopes have these diffraction spikes due to diffraction with some of the mirror and equipment supports

In regards to Hubble, you are correct. It is diffract ions caused by the secondary mirror supports, many time this effect is digitally removed.

http://www.ocastronomers.org/gallery/artifact.asp
A good explination is found here

http://www.astronomy-images.com/Equipme ... -vanes.htm

Thank you all for your contributions. I had not heard of diffraction spikes before.

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Matthijs Sypkens Smit

Here's more information found because of Hubble!

http://hubblesite.org/newscenter/newsde ... s/2006/42/

Let shuttle service to Hubble be restored.
Orin

Hubble has my vote, and I wish most of my tax dollars too.

Norval

Giving my tax dollars to the Hubble Program gets my vote too.