Cassiopeia Observatory - Report - Daytime ISS-Moon Transit (bust)

Daytime ISS-Moon Transit (bust)

Posted: 16 April 2015

I had been alerted to a transit of the Moon by the International Space Station (ISS) mid-afternoon on Thursday, 16 April 2015, by CalSky:

Open: Thursday, 16 April 2015, 1355 MST
Temperature: 82°F

Session: 809
Conditions: Clear, very breezy

Synced the observatory clock to WWV. 1407 MST: viewed the thin waning crescent Moon, 83X, with great difficulty. Focusing using the eyepiece was a challenge. Focusing with the camera would be even more difficult.

Mounted the D7200 DSLR at prime focus + diagonal using a 2" adapter. This unedited 1/1600sec, ISO 2500, photo closely matches the view I saw in the 2" 24mm UWA eyepiece (83X):

I did some exposure tests at various ISO settings. This edited (and mirrored to match the CalSky image) 1/1600sec, ISO 1250, exposure seemed to provide the best illumination and contrast:

I decided to use an exposure of 1/1600sec, ISO 1250, for the HD video recording, 1.3X crop factor, 60 fps. Did a test video at 1420 MST that seemed OK, albiet with a faint Moon.

1423 MST: all was ready for the ISS-Moon transit at 151157 MST. Several times while waiting for the transit I checked the focus and tried to improve it. I could never be certain I had a precise focus of the Moon. As it turns out I probably should have left the focus where it was. As the Moon lowered in the western sky it became more and more difficult to see, making focusing even more difficult. 1440 MST: the breezes were getting stronger, but the sky was not as dusty as on the previous day.

Began HD video recording at 151048 MST and continued it for 1m52s. During post-processing I could not find any evidence of the ISS in any frame. Here's a frame from the video at the time of the transit:

You can easily see why finding the ISS was impossible! But it was a fun attempt.

Close: Thursday, 16 April 2015, 1525 MST
Temperature: 72°F

My initial review of "Astrophotography with the Nikon D7200 DSLR" has now been posted.

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