Scythia Sweet

One of the enjoyable aspects of recording asteroids passing in front of stars (we call them asteroid occultations) is the interesting names of some of the asteroids. This month, Bob Dunford, Steve Messner, and I had two double-chord events across the asteroid 1306 Scythia, discovered in this month of 1930 by Soviet astronomer Grigory Neujmin (1886-1946).

The name 1306 Scythia immediately brought to mind a favorite piece of music, the Scythian Suite—surely one of the most unusual and otherworldly compositions by Sergei Prokofiev, or anyone else for that matter.

A quick look at the entry for 1306 Scythia in the 5th edition of Dictionary of Minor Planet Names by Lutz D. Schmadel (1942-2016) quickly confirmed my suspicion that the subject matter of both asteroid and musical composition is the same.

Named for the country of the ancient Scythians comprising parts of Europe and Asia now in the U.S.S.R. in regions north of the Black sea and east of the Aral sea.

In the wee hours of Friday, July 12, Bob Dunford in Illinois and I in Wisconsin observed only the second asteroid occultation of 1306 Scythia (and the first since 2014). The predicted path is shown below.

Predicted shadow path of the asteroid 1306 Scythia from the star Tycho 5189-597-1 (UCAC4 414-136241) on 12 July 2019 UT.

Bob, who was observing at Naperville, observed a 4.3-second dip in brightness as the asteroid covered the star between 8:23:46.203 and 8:23:50.531 UT, and I, observing at Dodgeville, observed a 1.3-second event between 8:24:01.783 and 8:24:03.054. Our light curves are shown below.

Bob Dunford’s light curve of the 1306 Scythia / Tycho 5189-597-1 event of 12 July 2019 UT, using a 14-inch telescope.
David Oesper’s light curve of the 1306 Scythia / Tycho 5189-597-1 event of 12 July 2019 UT, using a 12-inch telescope.

Here’s a map showing our observing locations relative to the predicted path.

1306 Scythia / Tycho 5189-597-1 event of 12 July 2019 UT – Predicted Path and Observer Locations

Here’s the profile showing the chords across the asteroid.

1306 Scythia / Tycho 5189-597-1 event of 12 July 2019 UT – Asteroid Profile and Chords

Just four days later, both Bob Dunford and I had a high probability event of the same asteroid passing in front of a different star, and this time we were joined by Steve Messner. Bob and Steve both got positives! Unfortunately, I was clouded out.

Predicted shadow path of the asteroid 1306 Scythia from the star TYC 5188-573-1 on 16 July 2019 UT.
1306 Scythia / Tycho 5188-573-1 event of 16 July 2019 UT – Predicted Path and Observer Locations
1306 Scythia / Tycho 5188-573-1 event of 16 July 2019 UT – Asteroid Profile and Chords

Sergei Prokofiev (1891-1953) wrote the Scythian Suite in 1915 when he was 24 years of age. Even at that young age, Prokofiev already showed great talent and originality.

Sergei Prokofiev, circa 1918

Here are some excerpts of the Scythian Suite performed by the Minnesota Orchestra conducted by Stanisław Skrowaczewski. This is a 1983 recording (Vox Box CD3X 3016). The movement descriptions are based on those given in Wikipedia.

1st movement: Invocation to Veles and Ala – barbaric and colorful music describing the Scythians’ invocation of the sun.

Some of the music you’ve heard in the original “Star Trek” certainly was inspired by this.
Alien landscape music
Alien landscape music #2

2nd movement: The Alien God and the Dance of the Evil Spirits – as the Scythians make a sacrifice to Ala, daughter of Veles, the Alien God performs a violent dance surrounded by seven monsters.

Best to observe this nasty dance from a distance…
This certainly reminds me of Dmitri Shostakovich, but he was only 9 years old at the time and just beginning to compose!

3rd movement: Night – the Alien God harms Ala; the Moon Maidens descend to console her.

This beautiful movement of many moods begins peacefully, then moves to a section of descending lines that might remind you of “The Planets” by Gustav Holst, but this was being written at the exact same time as the Scythian Suite! Next the music takes an ominous turn, and then returns to a little night music, but more a travel through interstellar or intergalactic space rather than a terrestrial night.

4th movement: The Glorious Departure of Lolli and the Cortège of the Sun – Lolli, the hero, comes to save Ala; the Sun God assists him in defeating the Alien God. They are victorious, and the suite ends with a musical picture of the sunrise.

Here, now, the conclusion of this remarkable work.

Prokofiev’s Scythian Suite. There is nothing else like it in the orchestral repertoire!

29769 (1999 CE28)

Early in the morning of Tuesday, May 29, 2018, I was fortunate enough to record a 3.2 second occultation of the 12.6 magnitude star UCAC4 359-140328 in Sagittarius by the unnamed asteroid 29769, originally given the provisional designation 1999 CE28.

Not only is this the first time this asteroid has been observed to pass in front of a star, it is the smallest asteroid I have ever observed passing in front of a star.  At an estimated diameter of 14.7 miles, had I been located just 7.4 miles either side of the centerline of the shadow path, I would have missed this event altogether!  This is also the first positive event I’ve recorded for an (as yet) unnamed asteroid, and the first positive event I’ve recorded for an asteroid having more than a four-digit number (29769).

As you can see in the map above, the predicted shadow path was quite a ways northwest of my location.  Even though I used the Gaia DR2 position for UCAC4 359-140328 for the path prediction, the existing orbital elements for asteroid 29769 did not yield a correspondingly accurate position for the asteroid.

Though a single chord across an asteroid does not give us any definitive information about its overall size and shape, it does give us a very accurate astrometric position that will be used to improve the orbital elements for this asteroid.

The central moment of this occultation event was 6:00:02.414 UT on May 29, 2018, which was about 20 seconds later than predicted.  The astrometric equatorial coordinates for the star UCAC4 359-140328 referenced to the J2000 equinox (using Gaia DR2 with proper motion applied) are

UCAC4 359-140328

α = 18h 21m 01.6467

δ = -18° 20′ 46.282″

Using JPL Horizons (with the extra precision option selected), the astrometric equatorial coordinates for the asteroid 29769 (1999 CE28), again referenced to the J2000 equinox, are

29769 (1999 CE28)

α = 18h 21m 01.6388

δ = -18° 20′ 46.320″

As we can see above, the actual position of the asteroid at the time of the event was 0.0079 seconds of time east and 0.038 seconds of arc north of its predicted position.  This observation will provide a high quality astrometric data point for the asteroid that will be used to improve its orbit.  Gratifying!

As of this writing, there are 523,584 minor planets that have sufficiently well enough determined orbits to have received a number.  Of these, only 21,348 have received names (4.1%).  So, I guess you could say there is quite a backlog of numbered asteroids awaiting to receive names.  The IAU should consider naming some minor planets after the most productive asteroid occultation observers around the world.  There aren’t very many of us, and this would certainly be an encouragement to new and existing observers.

Satellite Crossings 2016-2017

Edmund Weiss (1837-1917) and many astronomers since have called asteroids “vermin of the sky”, but since October 4, 1957 another “species” of sky vermin made their debut: artificial satellites.  In the process of video recording stars for possible asteroid occultations, I frequently see satellites passing through my ~¼° field of view.

I’ve put together a video montage of satellites I’ve recorded between December 14, 2016 and August 5, 2017.  The component events are presented chronologically as follows:

UT Date
7-25-2017 (2 satellites)

Target Star
UCAC4 538-7253
Tycho 586-1051-1
Tycho 1422-911-1
Tycho 4997-136-1
Tycho 6799-309-1
Tycho 666-190-1
UCAC4 548-7392

2485 Scheffler
19807 (2000 SE16)
71612 (2000 EH12)
11133 Kumotori
68112 (2000 YC143)
491 Carina
151 Abundantia

In all cases, the asteroids were too faint to be recorded.  And, in all cases, the target star was not occulted by the asteroid (a miss).  In the final event, the satellite passed right over the target star (9:40:11.679 UT) during the period of time the event would be most likely to occur (9:40:10 ± 3 s)!  Fortunately, the seeing disc of the target star was never completely obliterated by the passing satellite, so I was able to determine unequivocally that the asteroid missed passing in front of the star from my location on Spaceship Earth.

Here’s a graph of the brightness of UCAC4 548-7392 during the last video clip.  You can definitely see the close appulse of the satellite with the star!

In general, the slower the satellite is moving across the field, the higher is its orbit around the Earth.  One must also consider how much of the satellite’s orbital motion is along your line of sight to the satellite.  In the following montage of two video clips, the first satellite is very slow moving and thus most likely in a very high orbit.  The second video clip shows a satellite that is quite faint.  Again, the asteroids are too faint to be recorded and no asteroid occultation event occurred.

UT Date

Target Star
Tycho 5011-133-1
Tycho 5719-308-1

190471 (2000 DG27)
321656 (2010 BM90)

Hughes, D. W. & Marsden, B. G. 2007, J. Astron. Hist. Heritage, 10, 21