Monday, 18 April 2016

ISS transiting the Moon - experiment on reducer

Hunting for ISS is a tiring task, needs lots of passion and enthusiasm for sure.
I still did not forget the disappointment of two missed transit on Jupiter within the last week or two but I don't give up that easy. I realized that the app that predicts transits (called ISS Transit Prediction for android only) can be set to alarm you about the coming up event.

Well yesterday 25 mins before the pass my alarm went on. Sky was clear so did a very very quick setup and 5 mins before the pass I was all ready to capture the moment. 


Skywatcher 127/1500 maksutov scope on an eq5 mount. Teamed up with a Zwo ASI 120 MC colour camera, but if I only insert the camera, it will give me a very small 
field of view (FOV) - no surprise, that's what planetary cameras are 
designed for.
I used exactly this setup yesterday
So lately I spent a little amount of money on a no name 0.5x focal reducer to roughly half the focal length of my scope. 

It gave me a pretty good FOV and I don't need to sacrifice the
resolution or the clarity of the photo. This proved to be an excellent
setup for this purpose, planning to use it fot the Mercury transit as well.


I use ISS Transit prediction app (only for android), but if I really want good accurate info, I visit CalSky website. They showed me the following information:

Proper description of the transit

Transit path on the map - zoomable on the website

This photo shows where ISS will appear relative to Moon's surface


My ASI camera definitely does not like daylight, every time I had to deal with imaging in daytime it is just a bit of a pain. But in Fire Capture you can change the amount blue colour (Wblue) - otherwise the whole Moon will be just blue. But that little option helped to find a right(ish ) colour balance.

Main parameters:Gain                        18
Shutter                     0.747ms

Histogram               29%
ROI                         1280x960
FPS (average) =       26

Only strange thing I've noticed is that most likely my laptop memory couldn't keep up with the data flow, so it kept missing frames. It happened to me before, but not on a scale like this. You can see the photo below, I could even squeeze my name in the gap, at least a good 3-4 frames were dropped. Also it occurred one more time, when ISS was at the Mare Nectaris/Mare Fecunditatis area. But it is what it is, I personally can't do anything with it, only a laptop/camera update will help. Not a major issue at the moment :)



The photo above without the enlargement, but zoomable

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