Sep 26

ISS – HTV-7 flying solo closely following the station

What a wonderful few days behind us ISS fans! (click on photos to fit screen)

In these moments when I am writing these lines, HTV-7 is only a few metres of a distance from ISS and its robotic arm called Canadarm. It will grab HTV and move to Harmony module.

We have all been desperately waiting for the launch of HTV-7 cargo vehicle, which was due originally on 10th September but delayed a couple of days for various reasons. My evening ISS flybys just started in London and the delay turned out to be very beneficial for me. It coincided with the beginning of the flybys, so this way I had the opportunity to see and photograph both objects. And I just did that!!

The predictions for HTV proved to be wrong somehow. All the forecasts predicted the flyby twenty odd minutes before ISS. But a good friend of mine, Monika Landy-Gyebnar in Hungary saw the flyby about and hour earlier and she told me a different story. According to her experience HTV-7 was following ISS with an approximate 2 minutes delay. It was kind of a surprise, but proved to be a very important information.

I have downloaded though the star chart which I wanted to paste here, but since all the predictions were wrong I will not.

So first ISS came, such a beauty as always. I managed to identify Canadarm ready for today’s arrival. I think that is Canadarm, the position is absolutely correct and I saw on the live HD feed as well. Let me show you what I mean.


I had to use different camera settings for HTV-7 because this object is much smaller and fainter compared to ISS. But I had some pervious experience with Cygnus and Progress cargo crafts. What turned out to be the case is that HTV-7 flared. Twice! We have been observing HTV for the third night in a row and it just kept flaring. I only recon it is spinning at a very slow rate… Here are my best shots of HTV-7. Most of the frames were overexposed partially due flare effect, luckily I managed to capture a handful of good shots too. The predicted brightness was mag. +2.5, but it was brighter than that! Now we know so I am ready for the next Kounotori mission whenever it is due (lol).

Distance of HTV-7 – well good question. It means to flyby on a much lower path with a max. elevation of 40 degrees. But it caught up with ISS quite a lot during the past day and it followed the station almost exactly on the same fly path. ISS was at 440km of distance from my location at its closest point, so HTV-7 should have been at a similar distance. But I think HTV-7 was not at the same altitude as ISS for safety reasons, most likely 100km lower at around 300km above Earth and maybe 340km away from my location.

Video summary – timelapse




Skywatcher 250/1200 Flextube dobson telescope
Zwo ASI224MC camera
TeleVue 2.5x powermate



  1. Jay Cooper-groves

    Still amazed at how you can follow the ISS with that scope?? Full credit to you for your efforts to crack the imaging of such a close fast object. Keep it up. Is there the slightess chance that you could post this whole thing on my FB site for the armchair astronomers to enjoy. The JG astronomy forum of Bricket Wood. Jay G

  2. Szabolcs Nagy

    Hey Jay!
    Thanks again for your kind words. It is all about enthusiasm and commitment I guess, this whole website is purely dedicated to make the International Space Station or ISS even more known amongst people. When I’m out and about doing imaging I always have to come to the realisation that so many people never even heard of the ISS. And when they see it they love it! 🙂
    Anyway I’ll be doing imaging for sure as long as I like it and ISS is up there.
    Feel free to share the link for this post or the website, just copy/paste it and should appear in your group.
    Many thanks for sharing it!

  3. Rick Mills

    I was the guy in the white t-shirt out running on the Common when you were filming the ISS. Thanks for introducing me to the delights of the night sky, educating me about the space station and letting me see Saturn like never before. Best of luck, Rick

  4. Szabolcs Nagy

    Hi Rick!
    I am really happy we’ve meet in the park and also glad to hear that thoroughly enjoyed the experience! Partially the reason why I go to that spot is to meet people and to offer them a heavenly look through my telescope. I might see you again there!
    Clear skies!

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