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

From: Marco Langbroek via Seesat-l <seesat-l_at_satobs.org>
Date: Mon, 11 Dec 2017 23:34:42 +0100
Hi Phil,

4 seconds is a much too long duration for a satellite transit over the moon. It probably was a balloon, a bird or a high-flying aircraft.

- Marco


Verstuurd vanaf mijn iPad

> Op 11 dec. 2017 om 22:37 heeft pstewart--- via Seesat-l <seesat-l_at_satobs.org> het volgende geschreven:
> 
> 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! 
> 
> IT WAS 
> 
> - 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. 
> 
> IT CROSSED THE MOON 
> 
> - 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
> ESE). 
> 
> - 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 
> 
> ANGULAR RATE OF TRAVEL ESTIMATE: 
> 
> Chord Described by the Object's Transit of Moon: 
> 
> Chord's Length as Proportion of Moon Diameter: 0.42 x moon diameter
> (measured) 
> 
> Chord's Angular Length (from estimated moon distance from Earth): 0.206
> degrees 
> 
> 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) 
> 
> APPARENT (ANGULAR) SIZE ESTIMATE: 
> 
> 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. 
> 
> ALBEDO / FLASHING / PERIODICITY / ETC.: 
> 
> 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
> noise. 
> 
> EQUIPMENT: 
> 
> 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
> camera) 
> 
> Sensor: 1/5.8" MOS, 2.20 megapixels (in video mode &16:9 aspect ratio as
> here) 
> 
> 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
> focus. 
> 
> 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
> 2: 
> 
> Brightness (Mag):     -                                   - 
> 
> Start:                           
> 
>            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 
> 
> End 
> 
>            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.
> 
> 
> http://www.heavens-above.com/PassSummary.aspx?satid=25544&lat=38.9081&lng=-77.0361&loc=Downtown%2c+Washington%2c+DC%2c+USA&alt=23&tz=EST
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Received on Mon Dec 11 2017 - 16:35:12 UTC

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