The "Dome" portion of the Main Window diplays three related message panels indicating the status of the dome with respect to the telescope. The illustration above shows four possible combinations of the three message panels (other combinations are possible).
When DomeAuto is enabled (under the Main Window's Start/Stop panel), POCO moves the dome to follow the telescope. When the telescope reaches its target position the dome is aligned accordingly, and will follow incrementally as the telescope tracks. Note, however, that due to the geometry of the Nickel dome, when the telescope is pointed within 6-degrees of zenith, it is unavoidably occulted up to a maximum of about 40% at zenith.
The first message panel displays either the "Dome Clear" or "Dome in Way" message. "Dome in Way" indicates that the dome is still aligning itself with the telescope. "Dome Clear" indicates that the dome is aligned. However, because of the vignetting near zenith as described in the preceding paragraph, there may still be some occultation even when the "Dome Clear" message is displayed. This can be seen from the second and third message panels.
The second message panel displays the percent of dome occultation. This will be non-zero when the dome is moving to align itself to a new telescope position or when the telescope is within 6-degrees of zenith.
The third message panel indicates whether the telescope is clear of, nearing, or within the 6-degree zone of occultation. In the first case the gray "Zenith Clear" message is displayed; in the second case, the green "Near Zenith" message appears as the telescope nears the zone of occultation; in the third case, when the telescope enters the zone, the yellow "Zenith Warning" is displayed.
N.B.The displayed dome occultation percentages are approximate and should not be used to adjust photometry. Photometry targets that pass within 6-degrees of zenith should be observed to the east or west, before or after they pass into the occulted zone.
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