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Moon-Venus Conjunction 1°14'

Posted: 13 May 2021

Wednesday morning, 12 May 2021, I was at Oracle State Park, our local IDA "International Dark Sky Park", investigating a new potential dark sky observing site. Here are two panoramic photos showing the expansive view of the sky from the new site.


Open: Wednesday, 12 May 2021, 1816 MST
Temperature: 88°F
Session: 1636
Conditions: Clear

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


1824 MST: relaxed on the observatory patio bench. A large flock of cowbirds landed in the tall tree near the observatory and then took flight a few minutes later.


1900 MST: LX600 ON, StarLock OFF, High Precision OFF.

1910 MST: viewed Venus, 102X. The thin, about 31.5 hours old, crescent Moon was not yet visible in the bright sky.

1917 MST: sunset.

I moved to the house front patio at a higher elevation to have an unobstructed view of the western horizon. Set up the D850 DSLR + 150-600mm lens.


1920 MST: observed the Moon and Venus, 1°14' apart, 12x50 binoculars.

1925 MST: took this D850 DSLR photo of the Moon (center), Venus (lower right), and a jet airliner and its contrail (f/8, 1/1000sec, ISO 1600, FL 600mm).


1928 MST: observed the Moon, naked eye.

1929 MST: observed Mercury, 12x50 binoculars.

1934 MST: observed the Moon, 12" telescope, 102X, through tree branches.

I then took some photos of the Moon-Venus conjunction. Earthshine on the Moon is faintly visible.

1947 MST (f/8, 1/30sec, ISO 1600, FL 160mm)

1956 MST (f/8, 1/4sec, ISO 1600, FL 300mm)

1958 MST (f/8, 1/4sec, ISO 1600, FL 600mm)

2003 MST: returned to the observatory and set up the D850 DSLR + 14mm UWA lens on the observatory patio.


I prepared to photograph a pass of the recently launched Chinese space Station Tianhe-1.

I did some sky photography test exposures and then began watching for Tianhe-1 at the time predicted by I did not see the space station even though the prediction said it should be bright enough to have seen it. I did a 2 minute exposure during the predicted pass but the photo did not show the space station. I turned off the camera and made some notes in my logbook. When I turned back towards the camera I briefly saw Tianhe-1 in the constellation of Corvus at the end of its visible pass. It was two minutes later than the prediction. I could not get the camera turned back on in time.

2032 MST: dome OFF.

Slewed to M86 (galaxy) to do some StarLock autoguider tests. Viewed M86 and M84 galaxies, 102X.

I had previously set the StarLock autoguide rates to RA +60% and Dec +21%. For some reason the StarLock had been having autoguiding problems when imaging this region of the sky (with many fuzzy galaxies) with these guide rates.

2037 MST: StarLock ON.

I started the StarLock Automatic Rate Calibration (ARC) process. I relaxed on the observatory patio bench enjoying the view of the night sky while the StarLock did its thing.

2049 MST: accidently saw three SpaceX Starlink satellites near Arcturus.

2103 MST: aborted the StarLock ARC process, which was still in progress. The process normally takes 10 minutes when using a moderately bright star. With no bright stars and many fuzzy galaxies in the StarLock field-of-view, it just could not get a good calibration.

I set the guide rates back to RA +60, Dec +21. Slewed to M104 (Sombrero Galaxy) and viewed it, 102X. StarLock autoguiding was good.

2106 MST: StarLock OFF.

2108 MST: LX600 OFF.

2114 MST: took a Sky Quality reading and reported the result to Globe at Night.

2118 MST: dome ON.

Close: Wednesday, 12 May 2021, 2124 MST
Temperature: 70°F
Session Length: 3h 08m
Conditions: Clear, SQM 21.13

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