June 10, 2017 (UTC) moon crossing by possible satellite, viewed from Washington, DC

From: pstewart--- via Seesat-l <seesat-l_at_satobs.org>
Date: Mon, 11 Dec 2017 16:37:16 -0500
Hi all, 

This is my first post here. I'm writing to report a video sighting I
made of something crossing the moon that was not a plane and which may
have been a satellite. (I am assuming it was extra-atmospheric, not a
balloon floating by a mile away or whatnot, for the purpose of this
post) I appreciate any help identifying it! 


- compact (such as a circle, a sphere, or a cube is - with small
perimeter-to-area ratio -- at least as viewed at my camera's resolution)

- apparently symmetric (as seen from a distance), or nearly symmetric
(as seen magnified in an image editor) 

- tiny in relative terms (about 16 x 12 arcseconds - estimated, see
below) but: 

- large in apparent (or angular) size for a satellite . . . 

- e.g. it seemed comparable in size to the ISS, _BUT_ 

_- _I believe the ISS did not cross that part of the local sky that
evening, and that when it appeared, it crossed in a different direction.
I paste an extract from Heavens Above's satellite pass calculator for my
location on that date at the end of the present email, with URL to
specify what I've fed into it. 


- on June 9, 2017 local time (which is daylight savings, EDT) here in
Washington, DC at UTC minus 4:00 hours (it occurs early June 10th UTC) 

- Time:            June 10th,      01:01 UTC 

                        June 9th,        21:01 EDT (local time in
Washington, DC) 

- therefore crossing the moon at / around 

            -           3.7 degrees altitude 

            -           118.6 degrees azimuth 

            -           (both positions per Photographer's Ephemeris
(app.photoephemeris.com) given camera's time stamp) 

- as viewed from Washington, DC: Lat 38.92 N, Lon - 77.07 (W) 

- apparently from southwest to northeast at a shallow incline and quite
slow-moving, in angular terms (i.e., from my right to my left as I faced

- following a slope of -0.273 (precision unknown: my tripod may have had
a tilt on the order of a degree or so), i.e. 

- at an angle of incline of 15 degrees clockwise from "9 o'clock"; i.e.
195 degrees clockwise from straight up i.e. from normal to the Earth
surface (I'm not sure of the last digit down to the degree, since my
tripod may have some tilt I haven't accounted for) 

- giving the appearance of rolling in the video, though that seems
likely to me to be a video processing or aliasing artefact of some kind 

- giving NO appearance of rolling upon inspection of still screen caps
of the image, its slightly asymmetric (4 W x 3 H) profile keeping a
roughly constant attitude while it is visible 


Chord Described by the Object's Transit of Moon: 

Chord's Length as Proportion of Moon Diameter: 0.42 x moon diameter

Chord's Angular Length (from estimated moon distance from Earth): 0.206

Estimated Moon Distance used for the above calculation: 250,000 miles
(topocentric or geocentric -- similar at this angle of viewing) 

Duration of sighting: 4.0833… seconds (not sure of the precision of this
number: limited by spatial & temporal resolution of video camera) 

Angular Rate of Travel: 0.05 degrees / second (I assume that is the
correct precision for this number) 

Direction of Crossing: Southwest-to-Northeast, apparently (observer's
right to left when facing roughly ESE) 


On a 440 (Width) x 425 (Height) image of the moon (cropped w/in at most,
I estimate, +/- 2 pixels of exact size of moon's edges on the image, for
accuracy of apparent diameter measure within +/- 4 pixels I estimate),
the object measures about 4 x 3 pixels, or 0.009 diameter D (so c. 1/100
D) in Width dimension & 0.007 D in Height dimension. 

This gives 15.9 arcseconds (Width) & 12.4 arcseconds (Height). 

Again I base this measure on the estimate of the moon's distance at
250,000 miles. 


I saw NO evidence of this object's reflectivity at all either in the
video or by eye. I don't know what that signifies, but Washington's sky
is extremely light-polluted and there was about average haze for this
year's sky--which I don't know how to quantify, but which is pretty bad,
and exacerbated by the low altitude angle. Enhancing video by turning up
the brightness etc. didn't reveal any flashing or continuous
illumination coming from the object, at least visible to the eye in


Panasonic HC-W580k camcorder with 50x optical zoom, & up to 90x
"intelligent" zoom. I was using it somewhere low in the intelligent zoom
range, maybe 60x. 

Resolution: 1920 x 1080 

Aperture: f4.2 (telephoto) 

Focal length: 103 mm (telephoto) (equivalent to 1740 mm in a 35 mm

Sensor: 1/5.8" MOS, 2.20 megapixels (in video mode &16:9 aspect ratio as

Format: Progressive scan (?) in this recording 

Frame Rate: 59.93 frames per second (from file metadata) 

Encoding: h.264 

Recording mode: Intelligent Auto Plus (IA+), with contrast turned up and
white point biased towards red): camera controls aperture, exposure, and

Thank you for any help with this! I'm very curious what appeared in my
video, assuming it can be individuated or characterized beyond what I
report here. Please let me know where I may have made errors or not
stated something clearly. 

The video is available separately on request. 

Best regards, 

Phil Stewart 

Appendix: ISS in the Washington DC Sky on June 9th, 2017 (local) / June
10th, 2017 (UTC): 

Date:                           June 9, 2017 (local time) / June 10,
2017 (UTC) 

                                    Pass 1:                       Pass

Brightness (Mag):     -                                   - 


            Time               20:33:03                    22:09:08 

            Alt.                  10 degrees                10 degrees 

            Az.                  NNW                          SW 

Highest Point             

            Time               20:35:31                    22:12:30 

            Alt                   18 degrees                76 degrees 

            Az.                  NNE                           SW 


            Time               20:37:58                    22:15:51 

            Alt.                  10 degrees                10 degrees 

            Az.                  ENE                            SE 

Pass Type:                daylight                       visible 

Three prior passes are reported on Heaven's Above for this day, for the
ISS; for clarity I skip them here. 

Heaven's Above posts the present date & UTC-5:00 at the upper right, & I
don't know if that pertains to this table they generate or not. If so,
it's in error & any correction for UTC should be UTC-4:00 for June 9th
evening (local time) / June 10th, 2017 (UTC). 

To make clear what Heavens Above's table is being fed to generate these
results, here is the URL, embedding my approximate lat/lon location etc.

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Received on Mon Dec 11 2017 - 15:38:01 UTC

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