Professional Science from 'Amateur' Equipment: Finding A Kilometre-sized Kuiper Belt Object

[Ikonnikov]

An interesting study published in Nature Astronomy using amateur off the shelf gear for some occultation photometry (alas full article requires online purchase or journal subscription but abstract, figures and raw fits data available here https://www.nature.com/articles/s41550-018-0685-8).  

 

In essence they’ve done a lot of high-speed photometry using two identical setups situated on opposite sides of a building roof in Okinawa (both observing the same region of sky) and looked for occultations of any stars with the appropriate decrease in magnitude for the appropriate duration (up to around 1 second for ~1km diameter object) recorded simultaneously with both scopes (to rule out non-astronomical interference like birds/bats etc).

 

To record such a fast transit with enough (temporal) resolution they had to use very short exposures (~65ms) which requires a very fast optical system to gather sufficient light. To achieve this, they used a Celestron Rowe Ackerman 11” scope (already F2.2) and made it even faster with a DSLR to M43 Speed Booster (Metabones 0.71x) and acquired images with a ZWO ASI1600 CMOS camera. Crazily they can get a usable signal for stars down to magnitude 13 with these very short exposures.

 

Unfortunately for the budding amateur scientist, what is described in the paper as an ‘extremely low cost’ system still comes to $16,000 per setup, but nonetheless it’s interesting to see what can be done with gear that people do own here on SGL (albeit not usually in duplicate!).

[Gina]

Guess that shows just how good the ZWO ASI1600 CMOS camera is.  Really must get back to using mine!!

[Alien 13]

I wonder if an array of ZWO cameras and Samyang 135mm f/2 lenses would work as well if not faster in that they would cover more sky?

Alan

[Klitwo]

1 hour ago, Ikonnikov said:

An interesting study published in Nature Astronomy using amateur off the shelf gear for some occultation photometry (alas full article requires online purchase or journal subscription but abstract, figures and raw fits data available here https://www.nature.com/articles/s41550-018-0685-8).  

 

 

 

In essence they’ve done a lot of high-speed photometry using two identical setups situated on opposite sides of a building roof in Okinawa (both observing the same region of sky) and looked for occultations of any stars with the appropriate decrease in magnitude for the appropriate duration (up to around 1 second for ~1km diameter object) recorded simultaneously with both scopes (to rule out non-astronomical interference like birds/bats etc).

 

 

 

To record such a fast transit with enough (temporal) resolution they had to use very short exposures (~65ms) which requires a very fast optical system to gather sufficient light. To achieve this, they used a Celestron Rowe Ackerman 11” scope (already F2.2) and made it even faster with a DSLR to M43 Speed Booster (Metabones 0.71x) and acquired images with a ZWO ASI1600 CMOS camera. Crazily they can get a usable signal for stars down to magnitude 13 with these very short exposures.

 

 

 

Unfortunately for the budding amateur scientist, what is described in the paper as an ‘extremely low cost’ system still comes to $16,000 per setup, but nonetheless it’s interesting to see what can be done with gear that people do own here on SGL (albeit not usually in duplicate!).

 

Many people don't know this....William Bradfield (18 individual comet discoveries) found his 11th comet C/1980 Y1 (Bradfield) using just 7x35 binoculars, even though it was just a 6th-magnitude fuzz.....>

http://cs.astronomy.com/asy/b/astronomy/archive/2013/11/04/a-tribute-to-comet-hunters.aspx

Klitwo

[andrew s]

10 minutes ago, Alien 13 said:

I wonder if an array of ZWO cameras and Samyang 135mm f/2 lenses would work as well if not faster in that they would cover more sky?

Alan

Quite possibly but you would need the software to examine the images and lots of clear nights.

Regards Andrew 

[Ikonnikov]

1 minute ago, andrew s said:

Quite possibly but you would need the software to examine the images and lots of clear nights.

Regards Andrew 

I'm guessing the signal to noise for the short exposures required in this study wouldn't be high enough using a smaller aperture system (with much lower limiting magnitude). Camera lenses have been used in other professional setups I've seen e.g. http://mascara.strw.leidenuniv.nl/technical/ and   https://www.canonwatch.com/canon-ef-400mm-f2-8l-ii-lenses-used-discover-new-dark-galaxy-dragonfly-telephoto-array/  although in the latter one, each lens costs the same as 3x 11" RASA scopes! ?

[michael.h.f.wilkinson]

Interesting stuff. If you click on the link to the Nature Astronomy paper in the article on this in The Register, you get access to the full paper (at least, I got it).

https://www.theregister.co.uk/2019/01/30/japan_astronomers_kuiper_belt/

 

[andrew s]

9 hours ago, Ikonnikov said:

I'm guessing the signal to noise for the short exposures required in this study wouldn't be high enough using a smaller aperture system (with much lower limiting magnitude). Camera lenses have been used in other professional setups I've seen e.g. http://mascara.strw.leidenuniv.nl/technical/ and   https://www.canonwatch.com/canon-ef-400mm-f2-8l-ii-lenses-used-discover-new-dark-galaxy-dragonfly-telephoto-array/  although in the latter one, each lens costs the same as 3x 11" RASA scopes! ?

I suspect you are right but have not done any calculations on this. On the up side S/N is proportional to diameter not its square.

Regards Andrew