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We're back to cloudy nights again so I decided to measure the trail of 1989 JA using Photoshop to compare the result to the SkyTools 4 Information. Here are the results, noting that using PS to measure the 2 sides of the triangle will introduce uncertainty in the Pixel Measurements, affecting the accuracy of the calculations.



SKYTOOLS 4 IMAGING



(7335) 1989 JA



Minor Planet

Apollo class (NEO)

R.A.  11h26m47.8s Dec. -44°41'24" (2000) in Centaurus

Magnitude: 12.00


Orbit Data:



Orbit Period:    2.4 years

Perihelion Distance:  0.9 AU

Aphelion Distance:  2.6 AU

Diameter: 1 - 2 km



Orbital Elements Epoch 2022 May 1.



Current Status:

Earth Distance:  0.03 AU

Sun Distance:  1.0 AU

Total motion: 40.3 "/min PA 237.0°

  RA:  -47.66 "/min

  Dec: -21.97 "/min


PHOTOSHOP MEASUREMENTS

Cropped the image to 1024x1024 Pixels (full resolution).

Selected one of the 30 second trails and measured the 2 sides of the triangle.

Horizontal = 28 Pixels

Vertical = 48 Pixels

Hypotenuse = 56 Pixels.

Therefore, movement along trail = 56 Pixels in 30 seconds.

This gives a rate of 1.87 Pixels/Second.

Image Scale = 0.364 Arcsec/Pixel.

Therefore rate = 0.68 Arcsec/Second, or,

40.8 Arcsec/Minute.


CONCLUSION

So, pretty close to the SkyTools data I think.

Cheers


Dennis


[attachment=2393]

So, the error is (40.8-40.3)/40.8=0.012 or 1.2%. Not bad when you measured 28 & 48 pixels.

Well done!

Phil S.

Hi Phil

More cloudy nights, so I had a play with grabbing a screen capture in ST4 and overlaying it on a 1600x1600 crop of the image and discovered that I had also grabbed a Galaxy in the field.

Cheers

Dennis

ST4 Screen Capture
[attachment=2394]

1600x1600 Crop of image
[attachment=2395]

Nice! Too bad you don't get more clear nights  .

Phil S.

Thanks Phil, the Bureau of Meteorology just released some figures indicating that this has been our wettest Autumn in the last decade.

However, at least I managed to get some much needed beauty sleep.

Cheers

Dennis

Yes, it's best to always look on the bright side  . You don't get so frustrated that way. Especially about the weather.

If it clears up, you might have a go at 2022 KD2 in Scorpius.

Phil S.