We had a better night for observing last Saturday, the 17th September, when the sky cleared in the earlier part of the evening. Drifting light cloud was still a bit of an issue but not as much as on the 5th. Twilight ended just after 9pm BST when I started observing and the moon wasn't due to rise until 10:11pm BST it being at last quarter.
It was earlier enough that I could get a decent observation of AC Herculis before it began to head over to the west. At 19:52 UT I could make out star E on chart 048.04 and so my limiting magnitude was fainter than 8.2. At 20:09 UT I estimated that AC was about equal in brightness to star D which made it magnitude 7.4.
I then went on to look at CH Cygni which lies in the wingtip of Cygnus the swan and overhead at this time of the year. At 20:29 UT I estimated that CH was about equal in brightness to star A on chart 089.04 (pdf) which made it magnitude 6.5. I think my estimate may have been 0.2 to 0.3 magnitudes brighter than other BAA observers who saw this star on the same night.
I moved round to the other side of the house to have another go at TX and AH Draconis. At 21:11 UT I thought that TX was brighter than star N (mag. 7.7) on chart 106.03 but only somewhat fainter than star K (mag. 7.0). So my estimate was that it was 2 "points" from N and one from K making it magnitude 7.2.
Finally, at 21:28 I estimated that AH Dra was about midway in brightness between star 1 (mag. 7.1) on chart the same chart and star 6 (mag. 7.8) making it magnitude 7.5.
All text and images © Duncan Hale-Sutton 2022
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