Posted by: Szabolcs Nagy Comments:0
ISS – IR Pass filter (685Nm) test (very poor conditions)
This is not one of my extremely successful sessions, but I wrote this post because I would like to put out my experience about using an IR Pass filter for International Space Station imaging.
Weather forecast prediction was awful in the past 10 days and it looks like this evening flyby period will end like this. Last night it was clear, but (seemingly) there is always one factor that ruins everything. This time around the prize goes to….. (drums)…. jet stream! Yes the jet stream which was raging at a pace I have never seen before. I think the maximum value I have ever seen was below 70 m/s, well yesterdays according to Clear Outside website it was 75 m/s. So I did not expect anything ground braking.
International Space Station flyby had a maximum elevation of 56° which is always a threshold to me, anything below 50-55° is not worth imaging because ISS is too far away from my location. Seemed a perfect opportunity for testing my Baader IR Pass 685 Nm filter. I’m very glad that settings which I only guessed turn out to be good. So I only need a higher elevation pass with more calm atmospheric conditions. Using the clearest/sharpest frames this is my best animation I could put together.
I only had one very good imaging session with similar elevation (50°) back in June 2018 when I could spot Soyuz MS-08 on the zeinth (far side) of the station (the summary of that imaging session on this link). This is the animation in which MS-08 is clearly visible and below it the animation from the frames taken yesterday. If you can spot Soyuz MS-08 on the top animation, you are only one step away from identifying Soyuz MS-13 on the animation from yesterday. Currently MS-13 is docked to the far (zenith) side of the station to Poisk module, exactly where MS-08 was docked over a year ago.
By the way this is the infamous Soyuz MS-13 which I managed to photograph only 75 meters away from the International Space Station.
I do not want to draw to far-fetched conclusion just yet, but I can see using a filter like my IR-Pass can be extremely beneficial in these projects. Camera settings are crucial, therefore I will keep on experimenting with it. But I am very glad, that my initial guesstimate was better than expected and despite frames were a bit dark, I could pull out some details in Photoshop.
I also made a video about this event and a cool observation too. Faint though, but Soyuz MS-13 spacecraft can be spotted on my new animation docked to the far (zenith) side of the International Space Station. More explanation in the video below.
Skywatcher 250/1200 Flextube dobson telescope
Zwo ASI224MC camera
TeleVue 2.5x powermate
Baader IR-Pass filter (685 Nm)
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