David's Astronomy - Notes 2020-09-19 (S812)

Temperature effects on Foc1 Focusing were examined from two sessions (S811 and S812)

S811 (2020-09-18)

Best Focus Chart for Foc1 System (LX200 + TCF-S focuser) and Focus Temperature Chart are shown below. Although outside Ambient Temperature drops 5°C across the course of the nights observing session and Telescope's OTA Temperature drops 6°C over the same interval, the position of Measured Best Focus Position doesn't change by much, but remains around 2000+/- 200 across the night. The main change in focus position occurs between 02:00 and 03:00 where there is a distinct (+1 to +2°C) shift in temperature trend that corresponds with a a possible weak warm front. There was no change in seeing conditions, as has been seen before with passage of weather fronts.

Charts from Session S811

S812 (2020-09-19)

Best Focus Chart for Foc1 System (LX200 + TCF-S focuser) and Focus Temperature Chart are shown below. Although outside Ambient Temperature dropped 4°C across the course of the nights observing session and Telescope's OTA Temperature dropped 4.5°C over the same interval, the position of Measured Best Focus Position again doesn't change by much, but remains around 1900+/- 100 across the night. Whilst best focus position would normally increase in value with falling temperature, there is, if anything, a general decrease in best focus position. Similar to previous night there is a distinct (+1 to +1.5°C) shift in temperature trend at 02:15-02:30, with a smaller shift in trend at 04:30-04:45 The larger shift is associated with a shift in focus position. There is a change in wind strength and direction at this time, but there is no change in sky clarity or seeing.

Charts from Session S812

After running well for a fortnight since replacing the batteries in WMR800X Wind Sensor, data problems again returned around 18:30 in 2020-09-25. Starting at around 18:30 the data resolution suddenly falls and instead of normal high frequency data, the data becomes a series of flat-lined segments. Between 21:45 and 22:00 the normal higher frequency character returns briefly, before there was a complete data dropout at 22:40.

Wind data returned for short periods of time during the night, before finally coming back at around 05:25, but data is still somewhat ragged.

[ WMR800X Wind Sensor (see New Wind Sensor (WMR800X), 2019-09-09) is associated with WMR80 Weather Station which feeds data to the observatory via wireless link to AllSky/Weather computer running Virtual Weather Station (VWS) software where data is finally charted using AstroWeather. ]

8h Wind Chart from 2020-09-25 (pm)

16h Wind Chart from 2020-09-26 (am)

8h Wind Chart from 2020-09-26 (am)


	Session Aims & Highlights
	- Observing Result - Night Summary Plot - Session Event Log

	Operational Issues
	- Critical Issues (0), Major Issues (0), Minor Issues (4), Continuous Improvement (6)

	Images from 2020-09-19 >>

	Temperature Effects on Foc1 Focusing (S811 & S812)
	Wind Data Problems (2020-09-25)

This Web Page:	Notes - Session 812 (2020-09-19)
Last Updated :	2025-12-07
Site Owner :	David Richards
Home Page :	David's Astronomy Web Site

David's Astronomy Pages
Notes - Session 812 (2020-09-19)

Session Aims & Highlights (2020-09-19)

Operational Issues (2020-09-19 S812)

Temperature Effects on Foc1 Focusing (S811 & S812)

Wind Data Problems (2020-09-25)

David's Astronomy Pages Notes - Session 812 (2020-09-19)

Session Aims & Highlights (2020-09-19)

Operational Issues (2020-09-19 S812)

Temperature Effects on Foc1 Focusing (S811 & S812)

Wind Data Problems (2020-09-25)

David's Astronomy Pages
Notes - Session 812 (2020-09-19)