Video Meteors 2020 – I

During the first half of 2020, I serendipitously captured a whopping nine meteors on my telescope’s 17 x 11 arcminute video field of view while observing potential asteroid occultation events. I used the method described in There’s a Meteor in My Image to determine the radiant for each meteor. Here they are.

Antihelion meteor 22 March 2020 UT; Field location UCAC4 575-024067 in Gemini
Each frame is an exposure of 0.53s

The International Meteor Organization (IMO) identifies the antihelion source as “a large, roughly oval area of about 30˚ in right ascension and 15˚ in declination, centered about 12˚ east of the solar opposition point on the ecliptic, hence its name. It is not a true shower at all, but is rather a region of sky in which a number of variably, if weakly, active minor showers have their radiants.”

Sporadic meteor 10 Apr 2020 UT, Field location HD 119307 in Centaurus
Each frame is an exposure of 0.13s

A sporadic meteor is any meteor that does not come from a known radiant.

Sporadic meteor 14 Apr 2020 UT, Field location UCAC4 387-065649 in Libra
Each frame is an exposure of 0.27s (faint meteor in the upper right corner)
Possible Eta Aquariid meteor 28 April 2020 UT; Field location UCAC4 326-064938 in Corvus
Each frame is an exposure of 0.13s
Sporadic meteor or satellite? 8 May 2020 UT; Field location UCAC4 345-084929 in Ophiuchus
Each frame is an exposure of 0.03s

Meteors enter the Earth’s atmosphere at a speed between 10 and 70 km/s, and burn up at an altitude of about 80 km. For a sight line perpendicular to the meteor’s path, the angular velocity should range between 7˚ and 41˚ per second. This means a meteor should cross the 17′ x 11′ field of my video camera in 0.03 seconds or less. Field traversal will take longer than this the closer the meteor is to its radiant or anti-radiant point.

The lowest stable altitude a satellite can orbit is about 200 km, where it will have an orbital velocity on the order of 8 km/s. This is slower than the slowest meteors. For a sight line perpendicular to the satellite’s path, the maximum angular velocity a satellite should have is about 2˚ per second.

Given these admittedly BOTEC calculations, one could reasonably conclude that if the object traverses the field in a single frame, it is probably a meteor. If not (and it is not an airplane), it is a satellite.

The object in the 8 May 2020 video does appear to be moving slow enough to be a satellite, but because it is traveling much faster than satellites usually do it must be orbiting quite low, close to re-entry. I was not able to identify the satellite, which is often the case for the fastest-moving satellites. My camera is sensitive enough to pick up tiny pieces of space debris orbiting at low altitude, and though these objects are no doubt catalogued by military organizations, they do not generally show up in the publicly-available orbital element datasets for satellites.

Antihelion meteor or satellite? 12 May 2020 UT; Field location UCAC4 585-130160 in Pegasus
Each frame is an exposure of 0.27s

This one’s unusual in that there are two distinct “flare-ups” along the path. It is reasonably good match to the antihelion radiant for 12 May 2020, and though I have seen meteors experiencing outbursts along their paths, a more likely explanation for this event is that it is low altitude satellite with two “sun glint” events. What do you think?

Sporadic meteor 13 May 2020 UT; Field location UCAC4 348-150732 in Sagittarius
Each frame is an exposure of 0.53s
Antihelion meteor 17 June 2020 UT; Field location UCAC4 294-088825 in Lupus
Each frame is an exposure of 1.07s
Sporadic meteor 18 June 2020 UT; Field location UCAC4 330-150629 in Sagittarius
Each frame is an exposure of 0.53s

I was surprised to record so many meteors during the first half of 2020, as there is generally much less meteor activity between January and June than there is between July and December.

References

International Meteor Organization, 2o2o Meteor Shower Calendar, Jürgen Rendtel, ed. https://www.imo.net/files/meteor-shower/cal2020.pdf.

Satellite and Meteor Crossings 2019 #2

Edmund Weiss (1837-1917) and many astronomers since have called asteroids “vermin of the sky”, but on October 4, 1957 another “species” of sky vermin made its debut: artificial satellites.  In the process of video recording stars for possible asteroid occultations, I frequently see satellites passing through my 17 × 11 arcminute field of view.

I’ve put together a video montage of satellites I serendipitously recorded between August 9, 2019 and December 22, 2019.  Many of the satellite crossings are moving across the fields as “dashes” because of the longer integration times I need to use for some of my asteroid occultation work. A table of these events is shown below the video. The range is the distance between observer and satellite at the time of observation. North is up and east is to the left.

Satellites in higher orbits take longer to cross the field. In the next video, the originally geosynchronous satellite OPS 1570 (IMEWS-3, “Integrated Missile Early Warning System”) is barely visible until it exhibits an amazing sunglint around 3:41:22 UT.

I caught one meteor on October 6, 2019 at 9:57:43 UT. Field location was UCAC4 515-043597. The meteor was a Daytime Sextantid, as determined using the method I described previously in There’s a Meteor in My Image. The meteor even left a brief afterglow—a meteor train!

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

Satellite, Meteor, and Aircraft Crossings 2019

Edmund Weiss (1837-1917) and many astronomers since have called asteroids “vermin of the sky”, but on October 4, 1957 another “species” of sky vermin made its 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 serendipitously recorded between March 31, 2019 and July 12, 2019.  Many of the satellite crossings are moving across the fields as “dashes” because of the longer integration times I need to use for some of my asteroid occultation work. A table of these events is shown below the video. The range is the distance between observer and satellite at the time of observation.

Satellites in higher orbits take longer to cross the field. When possible, I’ve included graphs of brightness as a function of time for these slower-moving satellites after each individual video and corresponding table. When you watch the videos of geostationary satellites, you are actually seeing the rotation of the Earth as the line between you and the satellite sweeps across the stars as the Earth rotates!

Uncertain of identification
A tumbler with sun glints!
A high-amplitude tumbler! Satellite is no longer operational.

I caught one meteor on 4 Jan 2019 between 5:32:57 and 5:32:59 UT. Field location was UCAC4 419-017279. I’m pretty sure the meteor was a Quadrantid!

And two aircraft crossed my field: on 7 Dec 2018 1:40:05 – 1:40:13 UT (UCAC4 563-026131) and 26 Jun 2019 5:02:07 – 5:02:10 UT (UCAC4 291-144196).

And high energy particles (natural radioactivity or cosmic rays) “zing” my CCD/CMOS detector every once in a while. Here are a few examples: 5 Jan 2019 3:46:00 – 3:46:02 UT (UCAC4 473-001074); 20 Apr 2019 3:41:46 – 3:41:47 UT (UCAC4 501-062663); 30 Jun 2019 7:37:31 – 7:37:33 (UCAC4 354-179484) and 7:47:41 – 7:46:44 (TYC 6243-00130-1).

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

A Shroud of Satellites

The first five Iridium satellites were launched on May 5, 1997, and by 2002 there were 66 operational satellites, providing consistent global satellite phone coverage. These satellites have the interesting property that their antenna panels sometimes reflect sunlight down to the Earth’s surface, causing what came to be known as “Iridium flares”, delighting terrestrial observers—myself included. During an Iridium flare event, the satellite suddenly appears and gradually brightens and then dims to invisibility as it moves slowly across a section of sky over several seconds. Many of these events reach negative magnitude, with some getting as bright as magnitude -9.5.

The next generation of Iridium satellites began launching in 2017, but these satellites are constructed in such a way that they do not produce flares. Gradually, the original Iridium satellites are de-orbiting (or being de-orbited), so eventually there will be no more Iridium flares.

The Iridium flares haven’t been much of a nuisance to astronomers because the number of events per night for a given observer have been in the single digits.

But now we’re facing too much of a good thing. The first volley of 60 Starlink satellites was launched on May 24, with 12,000 expected to be in orbit by 2028. These satellites will provide broadband internet service to the entire planet. Though the Starlink satellites aren’t expected to produce spectacular flares like the first generation of the Iridium satellites, they do reflect sunlight as any satellite does, and the sheer number of them in relatively low Earth orbit is sure to cause a lot of headaches for astronomers and stargazers throughout the world.

I estimate that about 468 of the 12,000 satellites will be above your horizon at any given moment, but how many of them will be visible will depend on their altitude (both in terms of distance above the Earth’s surface and degrees above the horizon), and where they are relative to the Earth’s shadow cone (they have to be illuminated by sunlight to be seen).

And Starlink will not be the only swarm of global broadband internet satellites, as other companies and countries plan to fly their own satellite constellations.

This situation illustrates yet another reason why we need a binding set of international laws that apply to all nations and are enforced by a global authority. The sooner we have this the better, as our survival may depend upon it. How else can we effectively confront anthropogenic climate change and the precipitous decline in biodiversity?

As for these swarms of satellites, two requirements are needed now to minimize their impact on astronomy:

  1. Build the satellites with minimally reflective materials and finishes
  2. Fly one internationally-managed robust constellation of global broadband internet satellites, and require competing companies and nations to utilize them, similar to the co-location often required for terrestrial communication towers

I’d like to close this piece with a few questions. Will future “stargazers” go out to watch all the satellites and generally ignore the real stars and constellations because they are too “boring”? Will professional astronomers increasingly have to move their operations off the Earth’s surface to the far side of the Moon and beyond? Will we continue to devalue the natural world and immerse ourselves ever more deeply into our human-invented virtual environments?

Satellite, Meteor, and Aircraft Crossings 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 and some individual videos of satellites I’ve recorded between March 10, 2018 and November 24, 2018.  All of the events are shown below, with the boldface events being presented chronologically in the first video.  Both the NORAD and International designations are given for each satellite.  The range is the distance between observer and satellite at the time of observation.

UT Date
3-10-2018
3-25-2018
4-1-2018
4-2-2018
5-5-2018
7-6-2018
7-26-2018
7-31-2018
8-3-2018
8-23-2018
9-16-2018
10-21-2018 (2 satellites)
10-24-2018

Target Star
UCAC4 459-002239
TYC 621-45742-1
UCAC4 497-035454
UCAC4 416-092784
UCAC4 385-061427
N Sct 2018
UCAC4 429-110724
UCAC4 384-149264
UCAC4 362-194694
UCAC4 526-007192
UCAC4 316-210974
UCAC4 418-144100
UCAC4 302-215969

Satellite
SL-8 RB (Kosmos 726)
unknown space debris
unknown satellite
unknown satellite
unknown satellite
Ariane 5 RB (Payload A)
SL-8 RB (Kosmos 726)
Ariane 5 RB (VA209)
YURI 2A (BS-2A)
Kosmos 1092
SL-8 RB (Kosmos 80)
Galaxy 17 & NIMIQ 6
Sentinel 1B

Satellite
SL-8 RB (Kosmos 726)
unknown space debris
unknown satellite
unknown satellite
unknown satellite
Ariane 5 RB (Payload A)
SL-8 RB (Kosmos 726)
Ariane 5 RB (VA209)
YURI 2A (BS-2A)
Kosmos 1092
SL-8 RB (Kosmos 80)
Galaxy 17
NIMIQ 6
Sentinel 1B

Designation
7737; 1975-028-B
unknown
unknown
unknown
unknown
27946; 2003-043-B
7737; 1975-028-B
38780; 2012-051-C
14659; 1984-005-A
11326; 1979-030-A
1575; 1965-070-F
31307; 2007-016-B
38342; 2012-026-A
41456; 2016-025-A

Range & Direction
2,199.9 km SE
unknown SE
unknown SE
unknown NE
unknown NE
34,141.7 km NE
1,483.2 km SE
18,153.7 km NE
39,042.5 km NE
1,870.9 km NE
3,137.8 km NE
37,737.7 km E
37,736.3 km E
2,028.6 km NW

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.  A wind gust hit the telescope during the second event (3-25-2018).  The field is oriented North up and East to the left.  In this first video, you’ll notice that Sentinel 1B (the last event) has a unusual retrograde orbit (sun-synchronous) and is moving towards the NW.

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 an unidentified piece of space debris, a very faint “dash” (due to integration) moving NE across the field from lower right to upper left, recorded on May 5, 2018 UT.

Next, we see a Ariane rocket body used to hoist SMART-1 towards the Moon and the Insat 3E and eBird 1 towards their geostationary orbits.  This recording was made on July 6, 2018 UT.  The rocket body is traveling NE (mostly east).  The light curve below the video suggests the possibility of some tumbling motion, but the satellite is faint and the photometry noisy.

And here is a rapidly tumbling (but low amplitude) Ariane rocket body, observed on July 31, 2018 UT and traveling NE.

Here is a no-longer-operational Japanese communications satellite named Yuri 2A, launched in 1984 and captured here on August 3, 2018 UT.  It is traveling NE (mostly east) and shows a beautiful long-period large-amplitude light curve.

Finally, we see not one but two geostationary communication satellites, Galaxy 17 (first and fainter) and NIMIQ 6 moving east across the field (as my telescope tracks westward to follow the Earth’s rotation), captured here on October 21, 2018 UT.  Galaxy 17 exhibits no discernible rotation, but NIMIQ 6 shows a low-amplitude long-period change in brightness.

Next we turn to three telescopic meteors I recorded on June 4, July 7, and September 11, 2018 UT.

UT Date
6-4-2018
7-7-2018
9-11-2018

Target Star
UCAC4 408-094611
UCAC4 275-188730
UCAC4 399-093188

Constellation & Direction
Scutum, SSE
Sagittarius, SW
Scutum, NNE

Here these meteors are presented in a video montage.

I even captured an airplane crossing the field on August 22, 2018 UT:

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