Night Sky Imperfect

The cosmos at our fingertips.
Post Reply
User avatar
RJN
Baffled Boffin
Posts: 1673
Joined: Sat Jul 24, 2004 1:58 pm
Location: Michigan Tech

Night Sky Imperfect

Post by RJN » Sat Jul 24, 2004 2:05 pm

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

rjn_anonymous

Isn't the subject already defined?

Post by rjn_anonymous » Sat Jul 24, 2004 2:26 pm

This is rjn. I just wanted to see if I could reply anonymously. Those white spots sure are pesky.

dan_anon

Post by dan_anon » Sat Jul 24, 2004 7:57 pm

works well.

lior
Science Officer
Posts: 111
Joined: Fri Jul 23, 2004 8:58 pm
Location: Michigan Tech

bad pixels?

Post by lior » Sat Jul 24, 2004 11:41 pm

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

User avatar
RJN
Baffled Boffin
Posts: 1673
Joined: Sat Jul 24, 2004 1:58 pm
Location: Michigan Tech

Post by RJN » Sun Jul 25, 2004 2:27 am

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.

lior
Science Officer
Posts: 111
Joined: Fri Jul 23, 2004 8:58 pm
Location: Michigan Tech

Post by lior » Sun Jul 25, 2004 6:34 am

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.

User avatar
RJN
Baffled Boffin
Posts: 1673
Joined: Sat Jul 24, 2004 1:58 pm
Location: Michigan Tech

Re: Moon

Post by RJN » Sun Jul 25, 2004 5:34 pm

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

lior
Science Officer
Posts: 111
Joined: Fri Jul 23, 2004 8:58 pm
Location: Michigan Tech

Re: Moon

Post by lior » Mon Jul 26, 2004 3:14 am

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.

Vic Muzzin
Ensign
Posts: 95
Joined: Fri Jul 30, 2004 8:30 pm

RE: Moon

Post by Vic Muzzin » Tue Aug 03, 2004 12:16 am

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.

lior
Science Officer
Posts: 111
Joined: Fri Jul 23, 2004 8:58 pm
Location: Michigan Tech

Re: RE: Moon

Post by lior » Tue Aug 03, 2004 1:54 am

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:

Vic Muzzin
Ensign
Posts: 95
Joined: Fri Jul 30, 2004 8:30 pm

RE Moon

Post by Vic Muzzin » Tue Aug 03, 2004 2:26 am

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!

tilvi
Ensign
Posts: 83
Joined: Wed Jul 28, 2004 2:20 am
Location: Michigan Tech
Contact:

Re: Moon

Post by tilvi » Wed Aug 04, 2004 3:51 am

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

Vic Muzzin
Ensign
Posts: 95
Joined: Fri Jul 30, 2004 8:30 pm

RE Moon

Post by Vic Muzzin » Thu Aug 05, 2004 8:45 pm

The moon (as it is on the homepage today) looks REALLY good!

AstronomyBoy

temporary fix

Post by AstronomyBoy » Tue Sep 14, 2004 2:42 am

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.

Post Reply