Thursday, 27 September 2018

More images of Kounotori (HTV) 7

click image to enlarge

The image above is a stack (combination) of six images, taken at 10-second intervals with a 5-second exposure (Canon EOS 60D + EF 2.0/35 mm, 800 ISO). It shows Kounotori HTV 7 (2018-073A), a Japanese cargoship on its way to the ISS launched on September 22. This image was taken some 17 hours before it berthed to the ISS.

The cargoship was about 1m 38s behind the ISS at the time of observation. As no recent orbital elements were available, I did not know where to expect it relative to the ISS, so I started watching well before the ISS pass, and next noted it ascending over the roof just after the ISS had disappeared in Earth shadow.

The HTV 7 spacecraft was very bright during this pass: near magnitude +1, and a very easy naked eye object. Just like the day before (see an earlier post), it flared brightly, to at least mag -1/-2 at 19:50:18 UT (26 Sep 2018). The flare can be seen on the composite image above, and on the single image from this series below:

click image to enlarge

Also note the distinct orange colour of the trail, which is due to the fact that HTV 7 is wrapped in gold-coloured insulation foil.

The flare happened while HTV 7 was passing through the field of view of my video setup:

The image below is a composite of the images taken while the ISS passed, and the images of HTV 7 passing 1m 38s later (i.e., they didn't move this close in the sky in reality!). The orange colour of HTV 7 stands out. Also well visible is that HTV 7 was somewhat faster than the ISS, due to a difference in orbital altitude (and hence orbital period):

click image to enlarge

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