The California Nebula, NGC1499
The California Nebula (NGC 1499) is named from the vague resemblance it has to the outline of
the state. Frankly, I don’t see the resemblance. The nebula (a cloud of hydrogen atoms and
dust) is only about 1,000 to 1,500 light-years away in the constellation Perseus. It is thought to
be about 100 light years long. To give you an idea of the size of a light year, the Sun is about 8
light minutes from earth. Although the California Nebula is almost 2.5° long on the sky (5 x the
width of the full moon) it is extremely difficult to observe visually because it is so dim.
The grayscale image shown below was taken with a hydrogen-alpha filter which only allows light
emitted from excited hydrogen atoms to reach the detector of the camera. This image is a mosaic
of two images each of which is made up of 10 subframes exposed for 10 minutes each. The star
most likely providing the energetic starlight to activate the hydrogen in this nebula is the bright,
hot, bluish Xi Persei, just off the field of view near the top of the image.
If you were passing this nebula in a spaceship, you would likely see the glow of red light
characteristic of hydrogen-alpha radiation. This is shown in the color image shown below. Click
on the image for its full size.
the state. Frankly, I don’t see the resemblance. The nebula (a cloud of hydrogen atoms and
dust) is only about 1,000 to 1,500 light-years away in the constellation Perseus. It is thought to
be about 100 light years long. To give you an idea of the size of a light year, the Sun is about 8
light minutes from earth. Although the California Nebula is almost 2.5° long on the sky (5 x the
width of the full moon) it is extremely difficult to observe visually because it is so dim.
The grayscale image shown below was taken with a hydrogen-alpha filter which only allows light
emitted from excited hydrogen atoms to reach the detector of the camera. This image is a mosaic
of two images each of which is made up of 10 subframes exposed for 10 minutes each. The star
most likely providing the energetic starlight to activate the hydrogen in this nebula is the bright,
hot, bluish Xi Persei, just off the field of view near the top of the image.
If you were passing this nebula in a spaceship, you would likely see the glow of red light
characteristic of hydrogen-alpha radiation. This is shown in the color image shown below. Click
on the image for its full size.
Hydrogen-alpha image of NGC 1499; mosaic of two images each created from 10 x 10 min
subframes; TAK 106ED scope, SBIG ST10XME camera. External guiding with a Borg 77ED.
Click twice on the image for full size.
subframes; TAK 106ED scope, SBIG ST10XME camera. External guiding with a Borg 77ED.
Click twice on the image for full size.
The color image below was taken with a modified Canon XSi and shows both the reddish color
of the nebula and the star, Xi Persei, which is thought to illuminate it. This image is from 16 x 4
minute exposures at ISO1600 using a 200mm lens at f/4. Click on the image for full size.
of the nebula and the star, Xi Persei, which is thought to illuminate it. This image is from 16 x 4
minute exposures at ISO1600 using a 200mm lens at f/4. Click on the image for full size.