Signal to noise ratio

Here we have an example of signal to noise.  Notice the greater the exposure time the less noise in the image increasing the dynamic range of the image. 

Closer view

Flat field correction

Here we have an example of taking flat field frames. The first image is of a flat field frame, the second image is an example of B33 taken using light frames and dark frames only and image number three is with flat field correction. 

The Seagull nebula

IC2177, The Seagull Nebula. This large patch of nebulosity lies on the border of Monoceros and Canis Major at a distance of about 3,600 light years. It was discovered by the welsh astronomer Isaac Roberts. The equipment  I was using was my 4 inch f/6.3 refractor,  a Vixen Atlux mount, PHD auto guiding, an Atik 383L mono CCD camera  with a set of astronomik narrowband filters, HA , S11 and O111. I also used a blue filter to try to reveal the colour of the stars. The sky conditions were good with stars visable down to magnitude 5.5. This four section mosaic was taken on three separate evenings. The camera was set on X2 bin mode increasing the camera's sensitivity by four times. I captured two minute subframes with matching dark frames and combined them with flat field frames to reduce the effect of noise and vignetting in the final image. The total exposure time was 30 minutes for each filter. 

Hubble palette

Bicolour

RGB

NGC2359, Thor's helmet.

NGC2359, Thor's helmet. I took this image under very clear sky conditions with stars visable down to magnitude 5.5. This patch of nebulosity lies in the constellation of Canis major. I was using my 4 inch f 6/3 refractor, a Vixen Atux Mount, PHD auto guiding, a set of Astronomic narrowband filters with an  Atik 383L mono CCD camera. I captured two minute subframes with the camera set on X2 bin mode and matching dark frames and flats to reduce the effect of nose and vignetting in the final image. The total exposure time was 45 minutes in H alpha filter  50 minute in OIII and 40 minutes using a SII filter.

 RGB

Bi-colour

Hubble Palette

Some images of the Sky environment after the local streelights have been turned off

NGC7293. the Helix nebula

NGC7293. the Helix nebula . This image of the Helix nebula contains extra data, a total of 122 minutes using a H Alpha filter, 30 minutes using an O111 filter and ten minutes using a blue filter. The camera was set on X2 bin mode using sixty second sub frames with matching dark frames and flat field frames reducing the effect of noise and vignetting in the final image. 

The telescope was my 4 inch F/6.3 refractor mounted on a Vixen Atlux mount with an Atik 383L mono CCD camera ..

Notice the reduction of noise  in the image due to the extra exposure time. 

The Helix nebula

The Helix nebula and M33

The Helix nebula. Here we have additional data added from three separate evenings, 44 minutes using a H Alpha filter and 17 minutes using an O111 filter. The camera was set on X 2 bin mode capturing 60 second sub frames with matching dark frame and flat field frames. I was using my 4 inch f/6.3 refractor mounted on a Vixen Atlux mount and an Atik 383L mono CCD camera.

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M33. This face on Galaxy lies in the constellation of Triangulum. I set the camera on X2 bin mode capturing 60 second sub frames with matching dark and flat field frames. I used my 4 inch f/6.3 refractor, a Vixen Atlux mount and an Atik 383L mono CCD camera. I also used a set of Astronomik narrowband filters HA, O111 and blue. I then combined these data with some old luminance data, the camera was set on X 1 bin mode revealing the final result. The total exposure time was 33 minutes using an O111 filter, 40 minutes using a HA filter and 20 minutes using a blue filter. The old luminance data however I captured had five minute sub frames using an IDAS filter with a total exposure time of 120 minutes. 

Helix nebula

 NGC7293, The Helix Nebula.  On this particular evening I had bright moonlight, light pollution, cloudy weather and a 25-minute time slot to contend with as it drifted between the rooftops.  I could only capture 60 second sub frames so I set the camera on X2 bin mode. The total exposure time was 8 minutes using a H Alpha filter, 6 minutes using O111 filter, 2 minutes using a S11 filter and 60 seconds using a blue filter. I captured 60 second sub frames with matching dark frames and combined them with flat field frames to reduce the effect of noise and vignetting in the final image. The telescope was a 4-inch f/6.3 refractor on a Vixen Atlux mount and an Atik 383L mono CCD camera.

The time-slot

The Helix nebula appearing over the rooftop

The Helix nebula

M31

M 31, The Andromeda galaxy. This galaxy lies at a distance of about 2.3 million light years, the light possibly left this galaxy before the first human beings walked on this planet. This image is a five-section mosaic stitched together using Paint Shop Pro software. I was using my 4 inch f/6.3 refractor, a Vixen Atlux mount, PHD auto guiding, Astronomik filters, H Alpha, O111, and Blue. The camera was an Atik 383L mono CCD camera. I also combined 60 minutes of some old H Alpha data taken using an 80mm f/6.3 refractor to reveal some of the nebulosity in the spiral arms. I captured five-minute sub frames with matching dark frames and combined them with flat field frames and bias frames to reduce the effect of vignetting and noise in the final image. The total exposure time for each mosaic section using the 4 inch refractor was 10 minutes using a H A filter, 10 minutes using an O111 filter and 40 minutes using a blue filter.

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NGC 7331 and Stephan's Quintet.

NGC 7331. This galaxy lies in the constellation of Pegasus. Looking about one degree to the south west we have a group of galaxies NGC7320, NGC7319, NGC7318 and NGC 7317, commonly named Stephan's Quintet, which was discovered back in 1877.  I captured this image on three separate evenings under very hazy sky conditions with stars only visible down to magnitude 3.5. The telescope I was using was a 4 inch F/6.3 refractor, a Vixen Atlux mount, PHD auto guiding, a set of Astronomik filters and an Atik 383L mono CCD camera. I captured five minute and 60 second sub frames and combined them with matching dark frames, flat field frames and bias frames to reduce the effect of noise and vignetting in the final image. The exposure time was 110 minutes using a H Alpha filter, 50 minutes using an O111 filter and 145 minutes using a blue filter. A total exposure time of 5 hours and 5 minutes. 

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IC1396 Hubble palette

Here we have the final composition of IC1396 with colour correction and noise reduction.

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