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EGB 4 (Ellis-Grayson-Bond 4)


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About this observation
Peter Goodhew FRAS
Time of observation
30/12/2019 - 16:32
Observing location
Fregenal de la Sierra, Spain
APM TMB 152 LZOS Refractors
10Micron GM2000 HPS mount
QSI6120wsg8 cameras
Astrodon Blue: 15x300" Astrodon Green: 15x300" Astrodon Lum: 20x600" Astrodon Red: 15x300" Astrodon OIII: 25x1800s bin 2x2 As

EGB 4 (a nebula discovered by Ellis, Grayson, & Bond in 1984) is NOT a comet, despite it's comet-like appearance. It is an emission nebula surrounding a catacylismic binary star system called BZ Cam in the constellation of Camelopardis.

It has an unusual bow-shock structure as BZ Cam (with it's associated wind) moves through the interstellar medium, similar to the bow wave in front of a ship that is moving through water.

BZ Cam is believed to be a white dwarf star that is accreting  mass from an accompanying main-sequence star of 0.3-0.4 solar masses.
It is around 2,500 light years away, and has a space velocity of 125 km/second.

I can only find one previous image of EGB 4 online, a NASA APOD from 2000, so I believe this could be the first amateur image and thef irst colour image.

Yes it's incredibly faint!


THE ASTRONOMICAL JOURNAL, 115:286-295, 1998 January © 1998. The American Astronomical Society.

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