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Night Sky Imperfect

Posted: Sat Jul 24, 2004 2:05 pm
by RJN
The Night Sky appears imperfect. It has all of these white dots all over it. I don't like them. Can somebody remove them? Here is a picture of what I am talking about
Image

Isn't the subject already defined?

Posted: Sat Jul 24, 2004 2:26 pm
by rjn_anonymous
This is rjn. I just wanted to see if I could reply anonymously. Those white spots sure are pesky.

Posted: Sat Jul 24, 2004 7:57 pm
by dan_anon
works well.

bad pixels?

Posted: Sat Jul 24, 2004 11:41 pm
by lior
The white spots remained also in the next frames, until a new dark frame was taken. A dark frame should eliminate bad pixels, but sometimes dark frames might be exposed to unexpected external light that reduce their effectiveness. This is not likely to happen, but we can see a possible example from just one hour earlier:

http://nightskylive.net/mk/mk040724/mk0 ... 21320p.jpg

We do know that the camera at MK has some bad pixels.

Image

Posted: Sun Jul 25, 2004 2:27 am
by RJN
I was referring to the stars. I don't like them.
The cosmic rays are OK.

This reply was generated from home.
Everything appears to work.

Posted: Sun Jul 25, 2004 6:34 am
by lior
When god gave out sense of humor, I probably took the wrong line (which I think it was the line for toothache :? ).

Anyway, I think that the moon pictures of the naval observatory are right, and we are wrong. When you play a 24 hour movie (http://nightskylive.net/worldmap/wm-movie.gif), the sun is at the light side of the moon during the day, but at the dark side of the moon during the night. I think it should be like what it was before.

Re: Moon

Posted: Sun Jul 25, 2004 5:34 pm
by RJN
This might have gone under it's own "Subject". I don't know if it is possible but replies might automatically be given the old subject name with a "RE:" in front of it. My e-mailer does this and I think that others BB programs do this as well. I don't know if automatic "RE:" is an option here.

Anyway, to a first approxiimation, the Sun, Moon and stars are fixed and it is only the Earth that rotates. So the Sun and Moon keep approximately the same angular distance from each other during one day. During that day, the part of the Moon that faces the Sun is always the part that lights up. I have used this fact myself to navigate at night in a car. Yes, I always get lost but that, I think, is for other reasons entirely.

So I still think that the part of the Moon nearest the Sun should be the light part, and the far part should be the dark part. But perhaps I don't really understand your argument.

I do understand that there is no "spell check" feature or it would have told me that "approxiimation" has only one "i". And yet I thought that spell-checking was one of the perks of this BB program(?)

- RJN

Re: Moon

Posted: Mon Jul 26, 2004 3:14 am
by lior
First, if you select "quote" (top right) then you can reply with the old subject, like what I jave just done here.

About the moon, whay I mean is this:

Image

Maybe the world map is confusing here, but when you look at the moon from earth, I think that the right side of the moon should be white, and the left side should be black. The picture shows it differently.

RE: Moon

Posted: Tue Aug 03, 2004 12:16 am
by Vic Muzzin
The arguement of which side of the moon to have lit is all well and good, but a more practical problem is that it is too small. Watching the movie it is fairly obvious it is the moon, but as a static image it could just as easily be a cloud. I knew of the project to include the moon on the map and I still had a hard time convincing myself that was supposed to be the moon. l would suggest making it big, green and have a smiley face on it, lol.

Re: RE: Moon

Posted: Tue Aug 03, 2004 1:54 am
by lior
Vic Muzzin wrote:The arguement of which side of the moon to have lit is all well and good, but a more practical problem is that it is too small. Watching the movie it is fairly obvious it is the moon, but as a static image it could just as easily be a cloud. I knew of the project to include the moon on the map and I still had a hard time convincing myself that was supposed to be the moon. l would suggest making it big, green and have a smiley face on it, lol.
No problems Vic, but note that I had to resize 180 moon images for that. If you want them bigger, I say that now it's *your* turn to resize those images :lol:

RE Moon

Posted: Tue Aug 03, 2004 2:26 am
by Vic Muzzin
Lior
Not only did you get in the right line for a sense of humor, but it appears you may have been first in line!

Re: Moon

Posted: Wed Aug 04, 2004 3:51 am
by tilvi
Vic Muzzin wrote:Lior
Not only did you get in the right line for a sense of humor, but it appears you may have been first in line!
Lior, Here's the shell script for changing the image size or contrast using image magick, if you want to change all images at a time.
make a copy before running, since this script overwrites the files.

to add more contrast , one needs to run the script many times.

-----------------------------------------------------------------------------
#!/bin/bash

for gif_file in *.gif
do
#convert -size 120x120 $gif_file -resize 10x10 +profile '*' $gif_file
convert -contrast $gif_file $gif_file
done
echo -n "Finished!"
---------------------------------------------------------------------------

Tilvi

RE Moon

Posted: Thu Aug 05, 2004 8:45 pm
by Vic Muzzin
The moon (as it is on the homepage today) looks REALLY good!

temporary fix

Posted: Tue Sep 14, 2004 2:42 am
by AstronomyBoy
There is a way to temporarily remove the white dots. I found through extensive experimentation that if I use a household "light stick" with fresh energy cylinders in it, and shine this "light stick" into my eyes continuously, the dots disappear until I remove the "light stick." Unfortunately, the dots then do reappear. Also, black construction paper held continuously across the eyes works well as a temporary measure. Did you check with any eyelid manufacturers? Sometimes they have good ideas about these type of things.