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The Cygnus Loop: A Cosmic Shock Wave
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Six-panel (3 x 2) mosaic of the Cygnus Loop
- Telescope: Askar FRA 500 (90-mm aperture)
- Mount: ZWO AM5 (strain-wave gear drive)
- Autoguiding: Off-axis guider with ZWO ASI120-MM Mini camera
- Controller: ZWO ASIair
- Optical Configuration: Flat-field quintuplet Petzval refractor (f/5.6 w/o reducer)
- Filterwheel: RGB (Astronomik 1.25-in.); H-alpha (Baader 7-nm); O-III (Baader 4-nm)
- Imaging Camera: ZWO ASI1600-MM Pro
- Camera Gain: 70 (RGB); 0 (H-alpha & O-III)
- Sensor Temperature: -10° C
- Light Frames per Panel: ~120 (H-alpha & O-III); 40 (RGB)
- Calibration Frames: 60 darks, 60 biases, 30 flats per filter
- Total Exposure Time per Filter per Panel: 8 h (H-alpha & O-III); 0.66 h (RGB)
- Pre-Processing & Processing: PixInsight
- Post-processing: Photoshop CC
- Imaging Locations: Sierra Nevada Mountains (8,600 ft.); Los Angeles, Calif.
The Cygnus Loop, a favorite deep-sky object (DSO) among professional and amateur astronomers alike, is created from the shock wave and remnants of an ancient supernova explosion hurtling through the interstellar medium (ISM) at hypersonic speeds. The energy released into the ISM causes it to glow at wavelengths across the spectrum from x-rays to radio waves. This image, taken in the visible spectrum, captures the continuum emissions of dust/molecules (white) as well as the line emissions from hydrogen atoms (red) and oxygen atoms (teal).
The most recent and reliable distance estimates using Gaia astrometry data (https://academic.oup.com/mnras/article/481/2/1786/5088377) place the Cygnus Loop at about 2,400 light years (735 parsecs) from Earth, where it takes up 3 degrees of our sky (six Moons wide). This means that its actual diameter is about 120 light years.
To photograph such an extensive DSO with my new rig meant shooting a six-panel mosaic. RGB subframes for each panel of the mosaic were shot first at a dark-sky location far away from the city. Back in the city, I shot 8 hours of narrowband subframes for each panel in H-alpha and O-III. All imaging sessions were fully automated with the ASIair. Shooting all of the ~2,100 subframes for this mosaic took about a month and a half.
To ensure the highest color fidelity of the star field and nebulae, RGB color calibration was achieved during processing using Gaia’s latest photometric data (DR3) through PixInsight’s Spectrophotometric Color Calibration tool. Blending the narrowband data into a final HaOiiiRGB image was accomplished using the PixelMath tool. The latest AI image-processing tools were also employed for noise reduction, star-field optimization, and deconvolution.
The full-resolution mosaic image is 10,800 x 10,800 pixels, covers about four square degrees of sky, and reveals the entire Cygnus Loop and its surrounding star field with superlative color and clarity.
Spotlight on Elephant’s Trunk
The Elephant’s Trunk Nebula (IC 1396A)
- Telescope: Stellarvue SVA130T-IS
- Mount: Losmandy G-11 with Gemini 2 controller
- Autoguiding: 80-mm guide scope with ZWO ASI120-MM Mini guide camera
- Optical Configuration: 0.72x field flattener & reducer (f/5)
- Filter(s): S-II (Baader 8.0-nm); H-alpha (Baader 7-nm); O-III (Baader 8.5-nm)
- Imaging Camera: ZWO ASI1600-MM Cool
- Camera Gain: 75
- Sensor Temperature: -10° C
- Light Frames: 115 S-II subs, 113 H-alpha subs, 124 O-III subs
- Calibration Frames: 50 darks, 100 biases, 30 flats per filter
- Total Exposure Time: 1,408 min. [(115 + 113 + 124) x 4 min.] = 23 h 28 min.
- Pre-Processing: PixInsight, DeepSkyStacker
- Color Mapping: Red Channel = 100% S-II; Green Channel = 100% H-alpha; Blue Channel = 100% O-III
- Processing: Photoshop CC
- Imaging Location: Los Angeles, Calif.
This image highlights the Elephant’s Trunk Nebula (IC1396A), which is part of a much larger expanse of dust and gas (IC 1396) in the constellation Cepheus. The Nebula lies about 2,400 lightyears from Earth and features a majestic columnar cloud of compressed gases backlit by several newly formed stars, offering a spectacular look into the inner workings of a stellar nursery.
The image was shot from Los Angeles using narrowband filters in the Hubble Palette (S-II, H-alpha, O-III). It took almost two months to shoot all of the subframes. The final image uses 23 hours and 28 minutes of exposures, which represent about 70% of the total integration time. The result is a very low-noise, high-signal portrait of the Elephant’s Trunk Nebula in all of its glory.
The Elephant’s Trunk Nebula
The Elephant’s Trunk Nebula
- Telescope: Stellarvue SVA130T-IS
- Mount: Losmandy G-11 with Gemini 2 controller
- Autoguiding: Yes
- Optical Configuration: 0.72x field flattener & reducer (f/5)
- Filter(s): S-II (Baader 8.0-nm); H-alpha (Baader 7-nm); O-III (Baader 8.5-nm)
- Camera: ZWO ASI1600-MM Cool
- Light Frames: 115 S-II subs, 113 H-alpha subs, 124 O-III subs
- Calibration Frames: 50 darks, 100 biases, 30 flats per filter
- Total Exposure Time: 1,408 min. [(115 + 113 + 124) x 4 min.] = 23 h 28 min.
- Gain: 75
- Sensor Temperature: -10° C
- Pre-Processing: PixInsight, DeepSkyStacker
- Color Mapping: Red Channel = 100% S-II; Green Channel = 100% H-alpha; Blue Channel = 100% O-III
- Processing: Photoshop CC
- Imaging Location: Los Angeles, Calif.
The Elephant’s Trunk Nebula (IC 1396A) can be found within a much larger expanse of dust and gas (IC 1396) in the constellation Cepheus. This deep-sky object lies about 2,400 lightyears from Earth and features a majestic columnar cloud of compressed gases backlit by several newly formed stars, offering a spectacular look into the inner workings of a stellar nursery.
This image of Elephant’s Trunk was shot in the Hubble Palette, made famous by photos from the Hubble Space Telescope. It consists of three sets of 4-min. exposures (subframes) taken through narrowband optical filters designed to pass the light from singly ionized sulfur (S-II), hydrogen (H-alpha), and doubly ionized oxygen (O-III). The total exposure time through all three filters totals 23 hours and 28 minutes. It took almost two months to shoot all of the subframes for this image. The result is a very low-noise, high-signal depiction of the Elephant’s Trunk Nebula in all of its glory.
Comet NEOWISE on July 16
Comet NEOWISE on July 16
- Telescope: None
- Mount: Standard camera tripod
- Autoguiding: No
- Optical Configuration: 28-135mm f/3.5-5.6 lens @ 28mm
- Filter: None
- Camera: Canon 60Da
- Light Frames: Single frame
- Calibration: N/A
- Exposure Time: 8s
- ISO: 2000
- Pre-Processing: None
- Processing: Photoshop CC
- Imaging Location: One hour north of Los Angeles, Calif.
Comet NEOWISE has moved from the morning to the evening and now sets after the sun here in Southern California. However, it has become increasingly harder to spot from light-polluted Los Angeles, so this image was grabbed about an hour north of the city at 9:23 p.m. on July 16, 2020.
[This one’s also for Phil and for all the great moments we shared over the years. Like comets, memories may fade with time, but you, my friend, will always be remembered.]
Comet NEOWISE
Comet NEOWISE from Los Angeles on July 11, 2020
- Telescope: N/A
- Mount: Standard camera tripod
- Autoguiding: No
- Optical Configuration: 28-135mm f/3.5-5.6 lens
- Filter: None
- Camera: Canon 60Da
- Light Frames: Single frame
- Calibration: N/A
- Exposure Time: 8s
- ISO: 800
- Pre-Processing: None
- Processing: Photoshop CC
- Imaging Location: Los Angeles, Calif.
Not since Comet Hale-Bopp in 1997 has a really bright comet graced our northern skies. That has all changed with the latest interloper to our neck of the solar system. Comet C/2020 F3, as it is known to astronomers, was discovered on March 27 by the NEOWISE space telescope. By tradition, comets are named after their discoverers, so this one is known to the rest of us as Comet NEOWISE.
As Comet NEOWISE approached the Sun, its orbital period was calculated to be about 4,500 years. But its encounter with the Sun’s massive gravitational field has now boosted its speed and increased its orbital period to about 6,700 years.
This photograph was shot from my back yard about an hour before sunrise at 4:49 a.m. on the morning of July 11. The comet is fading now as it moves away from the Sun, but it will always be remembered for brightening up an otherwise difficult year.
[This one’s for Phil and for all the great moments we shared. Like comets, memories may fade with time, but you, my friend, will always be remembered.]