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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

Exoplanet hunting project...

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A while ago I bought two second hand harmonic drives off eBay for a lot less than brand new ones, my intention was to build an EQ mount in the style of the CRUX170HD . I didn't go ahead with it.
My new plan is to actually build a fork mount, maybe a single arm one, using the two mentioned drives. And it is going to be quite compact...

The list of bits and bobs I'm planning to use/build.
I'll be using a camera lens I bought for wide-field astrophotography, a manual Canon 200mm f2.8 (again off eBay, mint condition at a bargain price)
For the actual camera, I'm leaning towards either a ZWO ASI 183MM or a ZWO ASI 174MM (both mono).
A simple filter drawer as there is no need for many filters, just something like this one Astrodon ExoPlanet-BB
The enclosure will be similar to my current one (in terms of build) but in a much much smaller size (ie: ultra compact).
Same electronics, Odroid powered, the new one maybe Odroid-n2 which has 4x USB3.
OnStep controller.

Now on the software side, the all lot will have to be 100% scripted INDI, ie: running from command line.
From moving the mount, taking pictures, stacking etc...
There isn't a need for auto-guiding from what I'm reading, and with the CMOS cameras short exposure is key.
You basically take hundreds of pictures over a period of time that could be 5 or 6 hours...

The Exoplanet Transit Database is available at:
var2.astro.cz/EN/index.php

I have no ETA for this project.
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4 years 11 months ago #37702

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Gonzo,

Look into AstroImageJ

www.astro.louisville.edu/software/astroimagej/

It can automatically calibrate your science images and update the light curve of an exoplanet or variable star in real-time (see screenshots at that link.) AAVSO is also a great resource.
4 years 11 months ago #37705

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thanks, yes I read about this tool, a must have. There is also a command line option for it imagej.nih.gov/ij/docs/guide/146-18.html which is excellent for what I'm planning to do.
4 years 11 months ago #37711

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Great! I don't know how far along you are with measuring exoplanets but the difference between maximum light and minimum can be quite small. I would recommend starting with a short period variable star like YZ Boo just to get your kit dialed in. It undergoes a 0.4 magnitude swing over a two to three hour period. I used a 12-bit CMOS camera but I would not recommend it. Go with 14-bit or 16-bit if your pockets are deep :-)

The attached was generated by AAVSO's tool called VPhot. It was not created in real-time.

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Last edit: 4 years 11 months ago by kamisan.
4 years 11 months ago #37715
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Thanks for the heads up on the 12bit.
Over on Cloudynight forum, they do have quite some technical posts about it, a very quick search www.cloudynights.com/topic/560533-photometry-ccd-vs-cmos/
4 years 11 months ago #37717

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I guess I'll be spending some time over on the aavso forum to gather info...
www.aavso.org/zwo-asi178mm-cooled-cmos-camera
it looks like the ASI174MM works well.
4 years 11 months ago #37718

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4 years 11 months ago #37722

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Yes, that is a great guide.

I highly recommend these courses:
www.aavso.org/choice-schedule-registration-2019-non-members

I took the class "CCD Photometry I" with Ed Wiley last year. He's a great instructor and I learned a lot. After that I enrolled in "CCD Photometry II" but my wife fell ill and I dropped out.

Too bad we didn't connect a couple weeks ago. You could have enrolled in "Exoplanet Observing" that started April 1. Registration is now closed. I think they do it just once a year.

In the meantime I would recommend not making huge investments in cameras until you can measure short-period variables with confidence using your current equipment. As you gain more experience find variables that have smaller magnitude drops. You will get a feel for how your equipment performs and whether investing in a different camera is required.
4 years 11 months ago #37725

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thanks.
I'm at the planning stage, not going to buy any expensive equipment yet before I research...
4 years 11 months ago #37727

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I think you may need autoguiding becuse the requirements for guiding seem to be much more stringent than for imaging because you need to be pixel accurate over the whole run.

I tried exoplanet imaging a few years ago and when using a separate guide scope there was enough flexure over the 5 hours of images at 30 second intervals that the noise in the processed brightness was enough to swamp the planet brightness dip. This was with a CPC1100 with a ST80 mounted with ADM mounting rail and rings.
I changed to an OAG and the results were considerably different. The stars stayed put and I could detect the exoplanet.
Come to think of it you may be able to use the science image to guide between frames but that could need different software or scripting.
4 years 11 months ago #37740

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