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Mercury-Venus Conjunction,
Centaurus A Galaxy

Posted: 29 May 2021

Open: Friday, 28 May 2021, 1804 MST
Temperature: 87°F
Session: 1641
Conditions: High thin clouds, breezy

12" f/8 LX600 w/StarLock
2" 24mm UWA eyepiece
2" UHC filter


1808 MST: LX600 ON, StarLock OFF, High Precision OFF.

1810 MST: viewed Venus, 102X. Mercury about 24' away was not yet visible in the bright sky.

Prepared D850 DSLR for prime focus imaging.

1820 MST: Mercury not visible so relaxed on the observatory patio bench.

1842 MST: Mercury and Venus now both visible in the same field-of-view, 102X. The planets were separated by only 24'28" (about the same as the width of a Full Moon). Thin clouds were hampering the view.

1921 MST: mounted the D850 DSLR at prime focus of the 12" telescope.

1925 MST: both planets visible in the camera viewfinder.

1927 MST: sunset. Calm now.

1929 MST: began imaging the planets with the D850 DSLR. Used various exposure settings.

1937 MST: viewed Mercury and Venus, 12x50 binoculars.

1940 MST: took this full-frame image (1/320sec, ISO 800) of the planets. Mercury is at the left and Venus at the right.

Mercury-Venus conjunction (24'08")

This cropped view of the same image shows the crescent phase of Mercury. Click or tap on the image for a larger view.

Click or tap on image for larger version

1944 MST: last view of the planets as they approached tree branches, 102X. Separation was now 24'07".

1947 MST: slewed the telescope to Centaurus A (galaxy). It was not yet visible in the bright twilight sky. The thin clouds have left.

Relaxed on the bench to watch the stars come out.

1957 MST: I was visited by a Kissing Bug.

2010 MST: Mercury was now visible to the naked eye.

2045 MST: back inside the observatory. Viewed Centaurus A (galaxy), 102X.

Mounted the D850 DSLR at prime focus + UHC filter, focused on the star Spica, and locked the 12" primary mirror. Slewed back to Centaurus A.

2059 MST: StarLock ON.

Did some framing test images. Then took six StarLock autoguided, 5 minutes each, ISO 12800, White Balance 5560K, images of Centaurus A. This is a stack of the six images (effective exposure 30 minutes) using Affinity Photo.


2140 MST: StarLock OFF.

Viewed Centaurus A (galaxy), 102X. It was only 14° above the southern horizon.

2151 MST: LX600 OFF.

2201 MST: took a Sky Quality reading.

Close: Friday, 28 May 2021, 2203 MST
Temperature: 72°F
Session Length: 3h 59m
Conditions: Clear, SQM 21.09

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