A trillion is a big number
A trillion is a big number
Most of the time a camera is mounted on Wishing Star Observatory’s 14” scope. Celestial viewing is about light and not magnification. The 14” collects 350,000 times more light than the human dilated pupil. Since you have 2 eyes, say only 175,000 times. The eye works at 30 frames/second – like a movie camera. But a film camera can capture photons with long exposures. A one minute exposure captures 1800 times more light than the same aperture at 30 fps. And my SBIG ST-8XME camera is far more sensitive than film and can expose for a quarter of an hour easy. So it's 1000 times better than film. Putting all these numbers together the scope/camera setup is 3,160,000,000 (over 3 trillion) times more sensitive than naked eye viewing.
Thoughts do wander on a cloudy nite.....
Pete
Thoughts do wander on a cloudy nite.....
Pete
Pete P.
Re: A trillion is a big number
Stop it Pete! My head is swimming
Frank N
Stellarvue 80mm APO, Skyguider Pro, Celestron AVX
"I'm a seeker too. But my dreams aren't like yours. I can't help thinking that somewhere in the universe there has to be something better than man. Has to be"
Taylor in "Planet of the Apes" 1968
Stellarvue 80mm APO, Skyguider Pro, Celestron AVX
"I'm a seeker too. But my dreams aren't like yours. I can't help thinking that somewhere in the universe there has to be something better than man. Has to be"
Taylor in "Planet of the Apes" 1968
Re: A trillion is a big number
Your thoughts do wander wondrously, Pete, and I am a grateful beneficiary of your enlightening ruminations.
Tom
Tom
Tom H
"Science knows no country, because knowledge belongs to humanity, and is the torch which illuminates the world. Science is the highest personification of the nation because that nation will remain the first which carries the furthest the works of thought and intelligence." - Louis Pasteur
"Science knows no country, because knowledge belongs to humanity, and is the torch which illuminates the world. Science is the highest personification of the nation because that nation will remain the first which carries the furthest the works of thought and intelligence." - Louis Pasteur
Re: A trillion is a big number
I remember Commander Cosmos stacked almost 500 hours of images taken through a 66 mm refractor and got down to better than mag 19... I wonder what would happen if you did the same with your scope Pete- !
Bruce D
Re: A trillion is a big number
Hi Bruce,
Near Earth asteroids have an apparent motion and as you know I'm limited to short exposures (can't accurately measure the position of a streak as a dot). But sometimes on a clear winter night when the motion is slow and the object is 19th magnitude I will expose as long as 5 minutes and stack multiple frames. Since the camera keeps running as I work the asteroid by the time I'm done I've got more frames to stack and if Guide 9 shows that there's a slightly dimmer asteroid in the FOV I'll go after that using the additional frames that have collected while working asteroid #1. Sometimes there are several dimmer asteroids within the FOV and I repeat the process as photons collect through even more images. One night there were 6 or 7 really dim asteroids and over the course of an hour I worked down to 20.7 magnitude. Since 3 positions are required by the Minor Planet Center these may have been 30 minute stacks - can't find the data now.
One thing to note. The 14" is configured for utmost sensitivity. Adaptive optics to keep the Full-Width-Half-Max minimized. No filters as even a neutral density filter cuts light throughput by 50%. Camera with a CCD sensitivity exceeding 80%. And the chip's a blooming configuration so that there's minimal spacing between pixels.
For a while I was chasing really dim quasars to see how far back in time the scope could go. Seem to recall working 20th magnitude there too.
Pete
Near Earth asteroids have an apparent motion and as you know I'm limited to short exposures (can't accurately measure the position of a streak as a dot). But sometimes on a clear winter night when the motion is slow and the object is 19th magnitude I will expose as long as 5 minutes and stack multiple frames. Since the camera keeps running as I work the asteroid by the time I'm done I've got more frames to stack and if Guide 9 shows that there's a slightly dimmer asteroid in the FOV I'll go after that using the additional frames that have collected while working asteroid #1. Sometimes there are several dimmer asteroids within the FOV and I repeat the process as photons collect through even more images. One night there were 6 or 7 really dim asteroids and over the course of an hour I worked down to 20.7 magnitude. Since 3 positions are required by the Minor Planet Center these may have been 30 minute stacks - can't find the data now.
One thing to note. The 14" is configured for utmost sensitivity. Adaptive optics to keep the Full-Width-Half-Max minimized. No filters as even a neutral density filter cuts light throughput by 50%. Camera with a CCD sensitivity exceeding 80%. And the chip's a blooming configuration so that there's minimal spacing between pixels.
For a while I was chasing really dim quasars to see how far back in time the scope could go. Seem to recall working 20th magnitude there too.
Pete
Pete P.
Re: A trillion is a big number
I wonder if there's a formula that would predict what magnitude you could reach if you were to take a 500 hour exposure with your setup
Bruce D
Re: A trillion is a big number
Stars are pretty.
Tim W.
Laurie J. Wood
March 22, 1967 - August 23, 2019
Forever in my memory. Forever in my heart.
Scope: 8" Celestron SCT on an AVX equatorial mount
Solar Scope: Lunt Solar System 60 mm Double-Stacked H-Alpha
Solar Imaging Camera: ZWO ASI174mm monochrome
Imaging Camera: ZWO ASI1600MC-Cool
Autoguide: PHD2
Image Capturing: SharpCap
DebayerIng: PIPP
Planetary Stacking: Autostakkert
Planetary Post Processing: Registax
Deep Sky Stacking: Deep Sky Stacker
Deep Sky Post Processing: Photoshop
Laurie J. Wood
March 22, 1967 - August 23, 2019
Forever in my memory. Forever in my heart.
Scope: 8" Celestron SCT on an AVX equatorial mount
Solar Scope: Lunt Solar System 60 mm Double-Stacked H-Alpha
Solar Imaging Camera: ZWO ASI174mm monochrome
Imaging Camera: ZWO ASI1600MC-Cool
Autoguide: PHD2
Image Capturing: SharpCap
DebayerIng: PIPP
Planetary Stacking: Autostakkert
Planetary Post Processing: Registax
Deep Sky Stacking: Deep Sky Stacker
Deep Sky Post Processing: Photoshop
Re: A trillion is a big number
Wouldn't attempt to calculate this one Bruce. It wouldn't be linear as I seem to recall that S/N deteriorates as you stack. (A single 5-minute long exposure's supposed to be better than stacking 5 one-minute exposures. And the maximum length of a single exposure depends upon many factors.)
Pete P.
Re: A trillion is a big number
well- here's my guestimate-
Obviously the Commander stacked his images to get 500 hours of data, else he put his scope in orbit and didn't tell any of us! I don't know whether he stacked 500 hours worth of 1 hour exposures or 5 minute exposures but- assuming Pete stacked the same number of images at the same exposure the Commander used:
Pete's 356mm scope has roughly 27 times the light gathering power of the Commander's 66mm scope. A difference of 1 magnitude is 250% increase in brightness so divide 27/2.5 = 10 or 11 magnitudes deeper than the Commander's 19.5 mag so I'm thinking Pete would come darn close to mag 29 or 30 by stacking 500 hours of images.
Sounds perposterous at first, but, Pete has hit almost mag 21 with a 30 minute stack so who knows what 1000 times more imaging time would do?
Or, maybe I am remembering the Commander's story wrong! (or my methodology is all off)
Obviously the Commander stacked his images to get 500 hours of data, else he put his scope in orbit and didn't tell any of us! I don't know whether he stacked 500 hours worth of 1 hour exposures or 5 minute exposures but- assuming Pete stacked the same number of images at the same exposure the Commander used:
Pete's 356mm scope has roughly 27 times the light gathering power of the Commander's 66mm scope. A difference of 1 magnitude is 250% increase in brightness so divide 27/2.5 = 10 or 11 magnitudes deeper than the Commander's 19.5 mag so I'm thinking Pete would come darn close to mag 29 or 30 by stacking 500 hours of images.
Sounds perposterous at first, but, Pete has hit almost mag 21 with a 30 minute stack so who knows what 1000 times more imaging time would do?
Or, maybe I am remembering the Commander's story wrong! (or my methodology is all off)
Bruce D
Re: A trillion is a big number
Well, area is a function of the square of the diameter, so actually my 3550mm scope has 2893X the "light gathering power" of a 66mm scope.Bruce D wrote: ↑Sun Jul 07, 2019 11:20 pm Pete's 356mm scope has roughly 27 times the light gathering power of the Commander's 66mm scope. A difference of 1 magnitude is 250% increase in brightness so divide 27/2.5 = 10 or 11 magnitudes deeper than the Commander's 19.5 mag so I'm thinking Pete would come darn close to mag 29 or 30 by stacking 500 hours of images.
And since the magnitude thing is also non-linear I need a 22" scope to delve a full magnitude deeper
Pete
Pete P.