HOW IT's DONE.

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Saturn and Jupiter grand conjunction (one day before)


Camera is a Nikon P1000 on a Fornax tracking stage so the planet stays in frame. Get the zoom setting right at 6000 mm equivalent. Take 1 min videos at different ISO settings for the moons and planets. Wait for the perfect align to get a single align shot. Wait for planets to move away. Go back and get a video of the right bit of foreground. Use software to separate into frames and then stack 100+ frames to a single low noise image at each ISO. Then assemble the images in Photoshop. Using the align image as background image in the layers, cut around the foreground, planets and moons layers to form a spatially correct, very high dynamic range, composite. You have to size the cuts to cover up the overexposed planets in the background layer. Merge the layers and adjust to taste !! Its the better part of a day post processing to get it to work. The key really is the frame stacking it reduces the low light ISO noise and the atmospheric noise. QED!

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Andromeda (M31) Mag.  3.4, Size 3 degrees.

Above M110 Mag. 8.9, Size 21'.

 

Photographed using a Canon 7as

400mm f6.1 exposed at 1.5M ISOsecs, Fornax tracking stage.

Bortle 2 sky - background at Mag. 11. 

 

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Flame Nebula in Orion Mag. 7.2, Size 30', illuminated by the neighboring star Alnitak Mag. 1.74.

Photographed using astro mod Canon 7as 400mm f6.1, exposed at 0.6M ISOsecs. Fornax tracking stage 

Bortle 4 sky - background at Mag. 9

HDR created with the stars imaged by 4 smaller exposures, converted to B&W and stacked, then stacked with the nebula image. 

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Stitched fish eye view panorama June, Sept and Dec, March in southern hemisphere. 

20 mm lens with a  84x61 degree field. In landscape orientation starting  20 degrees angled up. In 4 vertical rows 25 degree increments; on the horizon 25 x 15 degree rotations, 12 x 30 degree, 4 x 90 degree, 1 vertical view. Assemble using PTgui software using circular fisheye mode, discard any excess images.

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To scale, temporal shifted, composite of deep sky objects

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I have a new appreciation for the nerds at Nikon. Here is a picture of Saturn that I think provides a direct measure of the optical performance of the P1000. It was taken at 12,000 mm zoom – 3000 mm optical and 4 x digital (i.e. cropped and resampled). The image was taken as a video on a tripod with a Fornax tracking stage. The focus was set manually using the remote control. A selection of the 250 best frames in a 2 minute video were averaged using Austostakkert. The results is the image with my best focus, least atmospherics, and minimized digitization.  Atmospherics dominate so frame count and pixel count is more important than low compression.  The NikonP1000 supports higher video resolution and better pixel resolution at 12kmm zoom, than the Sony 7as.   If seeing creates 20 pixel noise in 1 frame, 100 frames  = 13 pixel noise, 2000 frames = 10 pixel noise, 4000 frames 25% = 5 pixel noise. 

The dark band (Cassini’s Division) between the 2 major rings is hinted but not resolved. The average Saturn diameter is 14.5″ to 20.1″ excluding rings, 35" for outer ring. Using a high resolution Hubble photo of Saturn, also shown, Cassini’s Division is about 0.5 arc secs wide, and the dark band between the planet and the first ring is about 5 arc secs wide.

The aperture of the P1000 is 70 mm, which translates into a Rayleigh diffraction limited resolution of 1.97 arc secs. (https://astronomy.tools/calculators/telescope_capabilities). Rayliegh limit (1.22 lambda/d) = 1.8 arc secs, edge resolution 0.9 arc secs, recorded at 2160i video so pixel = 0.25 arc secs, with 4x video compression.

At 3000 mm, the pixel resolution of the P1000 is 0.7 arc secs, equal to the edge resolution – as it should be !

It looks to me like the limiting resolution of the P1000 must be close to the diffraction limit of 2 arc secs based on almost resolving Cassini’s Division at 0.5 arc secs, and clearly resolving the first dark band at 5 arc secs.

BRAVO – to Nikon nerds !

BTW In 1675, Cassini in the Paris Observatory used telescopes with focal lengths up to 136 feet long to observe Saturn and his division. (http://www.cosmicelk.net/telrev.htm)

TELESCOPE SET UP 

Jupiter diameter 40".

                        Aperture/focal    opt X     Edge res       Digitization  Medium      Jupiter Dia    Edge Res                           

Reflector       150/1200 mm        3x         0.4"                 0.11"      RAW ASI            400p drizzle    0.5"

Nikon P1000   70/3000 mm                     0.9"                 0.24"     2061i video       240p drizzle   1.25"                    Refractor         80/480   mm       10x        0.8 "                1.0"       1080i  video        40p

                                                                                              0.5"        RAW  Sony         80p

                                                                                              0.3"        RAW  ASI          200p  drizzle

SEEING 

A 1.0″ disk of  seeing for a single star  is a good one for average astronomical sites. The seeing of an urban environment is usually much worse. Good seeing nights tend to be clear, cold nights without wind gusts. Warm air rises (convection), degrading the seeing, as do wind and clouds. At the best high-altitude mountaintop observatories, the wind brings in stable air which has not previously been in contact with the ground, sometimes providing seeing as good as 0.4". Seeing disk 0.4 arcsecs in a hundredth of a sec. is regarded as "good" available at Mauna Kea. 

"In my garden, using a Skywatchtcher 150PL 1200mm Newtonian reflector, x3 Barlow and ZWO ASI120MC camera, stacking and drizzling the best of 1800 frames, then applying wavelet sharpening. Previously published: https://stargazerslounge.com/topic/74272-sharpcap-free-astro-webcam-capture-software/?page=60#comment-3213238  This lucky image of Jupiter shows details close to the theoretical maximum resolution of 0.1 arc-seconds of the 150mm aperture telescope it was taken with, although individual frames were of much lower resolution due to the limitations of astronomical seeing."

Seeing for best Jupiter in Nikon P1000  is 1.6" (edge resolution 0.8") requires 4000f@25% to get decent image, and matches lens performance, should see some improvement with better seeing. 

Most recent test using Sony 7as has seeing  of  6", 1700f@80% not good enough.