This image of NGC 1499 – also known as The California Nebula – was taken using a Hydrogen-alpha filter from my back yard in light-polluted Vista, California on an unusually clear and calm night.
NGC 1499 is an excellent example of an emission nebula. Emission nebula are areas of interstellar gas which are ionised by the intense radiation of nearby O and B type stars. The ionised gas then releases photons at wavelengths specific to the type of gas present, for example, hydrogen, oxygen and sulfur gas are commonly found in emission nebula and thus can be detected by the presence of photons at particular known wavelengths.. In this case, NGC 1499 emits very strongly at the H-alpha wavelength of 656.3 nanometers which indicates the presence of a large ionised hydrogen gas component in the nebula. This image was taken with a H-alpha filter which has a very narrow light bandpass at the H-alpha emission line wavelength of 656.3 nm. The filter isolates and passes the H-alpha emission photons which are detected by the camera and also excludes most other wavelengths of light, including most forms of light pollution, which makes photography of emission nebula possible in areas of strong light pollution. In the case of NGC 1499 the most likely source of ionising radiation is the bright B type star Menkib, which can be seen directly below the nebula in this image.
NGC 1499 is located in the constellation of Perseus and is believed to be about 1,000 light years distant.
Acquisition Date: November 9, 2018
Location: Vista, San Diego County, California
- Imaging Scope – Takahashi FSQ-106 EDX IV with the Takahashi 0.6x reducer
- Imaging Camera – ZWO ASI1600MM-C with EFW2
- Filters – Baader 36mm unmounted H-alpha filter with a 7nm bandpass
- Guiding – Borg 77ED with ZWO ASI120MM-S
- Mount – Astro-Physics 900GTO
Camera Control – Sequence Generator Pro
Guider control – PHD2
- Imaging Camera – gain 76, offset 15 – cooled to -15
- Exposures – 54 x 120 seconds each for the R, G, and B channels
- PixInsight and Photoshop CC were used to process the images.
- Image calibration, alignment and integration – PixInsight. The LocalNormalization feature was used during image stacking.
- Post-Integration Processing in PixInsight – MultiscaleLinear Transform for noise attenuation and HistogramTransformation for histogram stretching.
- Photoshop – Levels, Curves, Smart Sharpen and reduce Noise tools were used.
Click on the image below for a slightly larger view. Click on this link for access to a high resolution view.