Satellite (and Meteor ) Crossings 2017-2018

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 June 21, 2017 and October 20, 2017.  The component events are presented chronologically as follows:

UT Date
6-21-2017
8-15-2017
9-4-2017
9-5-2017
9-12-2017
10-20-2017 (2 satellites)

Target Star
Tycho 5723-663-1
Tycho 1668-1258-1
Tycho 1281-225-1
UCAC4 553-20591
Tycho 5731-996-1
Tycho 6289-1504-1

Asteroid
798 Ruth
30981(1995 SJ4)
34532 (2000 SO213)
1294 Antwerpia
85985 (1999 JW)
25036 Elizabethof

You’ll notice that sometimes the satellite crosses the field as a moving “dash”.  That’s because sometimes I used longer exposure times to record a fainter target 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 video clip, you’ll see a slow-moving “tumbler” satellite moving from right to left across the top of the field.

UT Date
8-25-2017

Target Star
Tycho 676-828-1

Asteroid
179462 (2002 AJ202)

 

On January 10th of this year, I figured out how to identify satellites crossing the telescope field of view using the amazing program Guide 9.1, which I use for all my observatory research work.  On March 4th, I was hoping to be the first to record the asteroid 3706 Sinnott passing in front of a star.  This asteroid is named after Sky & Telescope Senior Editor Roger Sinnott, whom I had the good fortune to work with in writing the article “A Roll-Down-Roof Observatory” in the May 1993 issue of Sky & Telescope, p. 90.  Roger is amazing.  He took an article that I had written and edited it in a way that only lightly touched my original text yet ended up saying what I wanted to say even better than I was able to say it myself.  The mark of a great editor!  Anyway, I’m sure Roger remembers me and I was looking forward to giving him the news that I had observed the first stellar occultation by “his” asteroid.  Alas, it was not to be, because, as so often happens, the too-faint-to-be-seen asteroid passed either above or below the target star.  The consolation prize, however, was recording a third stage Long March Chinese rocket booster (CZ-3B R/B; NORAD 43004U; International # 17069D) passing through the field.  This rocket launched on November 5, 2017, and added two satellites to China’s Beidou positioning network.  As you can see in the light curve below, the rotation period of the rocket booster is a bit longer than the 19 seconds of usable video I had.

UT Date
3-4-2018

Target Star
UCAC4 556-42881

Asteroid
3706 Sinnott

 

Once in a great while, I record a telescopic meteor.  Here are two.

UT Date
7-15-2017
3-4-2018

Target Star
Tycho 6269-2747-1
UCAC4 561-14746

Asteroid
17136(1999 JE82)
6890 Savinykh

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

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
12-14-2016
1-15-2017
5-5-2017
6-7-2017
6-19-2017
7-25-2017 (2 satellites)
8-5-2017

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

Asteroid
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
5-14-2017
6-8-2017

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

Asteroid
190471 (2000 DG27)
321656 (2010 BM90)

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