by Gregory T. Shanos
On June 17, 2026, a lunar occultation of Venus occurred which was visible from most locations in North America. Unfortunately, the occultation occurred during the afternoon while the sun was still high in the sky making this a rather challenging event to observe and image. The International Occultation Timing Association (IOTA) published a list of major cities stating the times of disappearance and reappearance of Venus from the lunar limb. The times are listed in Universal Time which must be converted to local time for each observer location. I use the free program WinJupos to convert Universal Time to Local Time. Within WinJupos, choose the Moon and enter the date and time in Universal Time. The Local Time appears above in military 24-hour time. See Figure 2.
Note that only major cities are listed on the IOTA website, therefore each observer must choose the nearest city to their specific location. My location of Sarasota, Florida was not listed, however the times of disappearance on the lunar dark limb for nearby St. Petersburg and Tampa were 19h 56m 8s UT and 19h 56m 10s UT respectively. Note there is only a 2 second difference between these two cities! The local time for me was 3:56pm with only an 11% illumined crescent Moon. The reappearance occurred on the bright limb at 21h 16m 41s in St. Petersburg, and 21h 17m 5s for Tampa, a difference of 24 seconds. This is 5:16pm and 5:17pm local time respectively. The Moon was near the zenith at 82° at disappearance and 75° above the horizon during the reappearance. I typically start recording at least 4 to 5 minutes prior to the published theoretical occultation times.
I could not visually see the Moon due to the nearby bright Sun. My house provided a shady area where I set up my Seestar smart scope. I purchased all three models: the S50, S30, and S30 Pro. I have the S30 Pro and S50 equatorially mounted. The Seestar in equatorial mode requires three stars for alignment which in broad daylight cannot be configured. I have the S30 in alt-azimuth mode since this only requires that I spin the telescope to calibrate the compass then level the tripod and the setup is complete
I then had the S30 slew to the Moon. The Seestar S30 failed to find the Moon. Fortunately, the S30 and S30 Pro also have a wide-field camera which had the faint sliver of the crescent Moon in view. I manually slewed the telescope until the Moon and Venus were in the field of view of the primary camera, which is 1.22° by 2.17°. Success!
I began by taking single snapshot photographs as Venus slowly approached the Moon. See Figures 3 & 4. Just prior to occultation, I took an AVI and MP4 video of the event. The Seestar can take both these video formats simultaneously. Unfortunately, the Seestar does not have a time stamp during the video recording. I will contact ZWO support to possibly include this feature in a future software/firmware update.
The weather began with perfectly clear skies in the morning, however the clouds began to build throughout the afternoon. During the time of disappearance there were clouds moving throughout the field of view, fortunately the Moon and Venus were still visible in the Seestar. There were fewer passing clouds during the time of disappearance. The state of Florida is far from paradise during the summer months. My personal weather station, the Ambient Weather model WS8480 falcon recorded a temperature of 92.4°F with a relative humidity of 64% and a heat index (feels like temp) of 108.6°F. Rather uncomfortable to say the least. See Figure 1.
Venus on June 17, 2026 was at magnitude -4.0, at 74% phase, and 14.6” in diameter. Unlike a stellar lunar occultation where the star instantaneously blinks in or out, Venus being a disk can be seen slowly emerging or disappearing behind the disk of the Moon. Unfortunately, I was unable to obtain the exact time of disappearance and reappearance of Venus from the video, however I was able to obtain how long it took for the planet to go behind then reemerge from the lunar disk. I used the free program Video to JPG Converter from the DVD video software website to extract all the individual frames from each video. I took a five-minute (301 second) video of the disappearance, which had 9055 frames. Each frame was 0.033 seconds apart. For the reappearance I took a 4-minute video (240 sec), which had 7205 frames that were also 0.033 seconds apart. I then determined the time it took for Venus to disappear and reappear behind the lunar limb. The disappearance was more difficult to determine since there were rather thick clouds passing through at the time. My best estimate is Venus touched the Moon at frame 6992 and was not visible at frame 7000. This makes 8 frames at 0.033 sec per frame a total of 0.264 seconds. The reappearance was more accurate since there were much lighter clouds passing through at this time. Venus was not visible on frame 4125 and clearly visible on frame 4155. This is 30 frames at 0.033 sec per frame for a total of 0.99 sec. I trust the disappearance time to be more accurate due to lighter clouds in the field.
In conclusion, this was my first lunar occultation during the daytime, with the Sun high in the sky under partly cloudy skies and scorching temperatures. Given all these adverse conditions, the daytime lunar occultation of Venus was a memorable experience and a complete success!
