TX and AH Dra, CH Cyg, Z and RY UMa on the 30th October 2022

We had some more clear weather here on Sunday the 30th October. The moon was nearly at first quarter but it would set at 20:04 UT. The sky transparency wasn't great but I decided to go ahead with my observations anyway. The constellation of Draco was in the west but still high enough in the sky to make estimates of the semiregular (Srb) variables TX and AH Dra.

Beginning with TX on chart 106.03 with my 7x50 binoculars I could make out star P at visual magnitude 8.4. TX was fainter than star K (=7.0 mag.) and star N (=7.7 mag.) but brighter than P. At 21:16 UT I saw that TX was much closer to N in brightness than star P, so I estimated it at 1 point from N and 3 points from P (i.e. N(1)V(3)P). This put it at magnitude 7.9 to 1 decimal place.

I then moved on to AH Dra which is south of TX. At 21:40 AH was fainter than star 1 (=7.1 mag.) but brighter than star 8 (=8.4 mag). In fact it was probably middle way between these two stars and this was confirmed by comparison with star 6 (=7.8 mag.). So my estimate was 1(1)V(1)8 which made AH visual magnitude 7.8 to 1 d.p.

Whilst I have been writing up this observing session I have noticed that there is a new chart for TX and AH Draconis. Chart 106.03 has now been redrawn and is now 106.04. The only difference that I could spot was that the star labelled 1 is now magnitude 7.0 rather than 7.1. I will use the new chart in my next session.

Cygnus was also reasonably well placed so my next target was the ZAND+SR variable star CH Cyg. This was easy to estimate as its brightness indistinguishable from star A and was thus magnitude 6.5.

Finally, the constellation of Ursa Major is beginning to rise again about 11pm having swung round under the pole, so I could have a go at Z and RY UMa. At 22:34 UT Z UMa was brighter than star D (=7.9 mag.) but was equal to B meaning that my estimate was magnitude 7.3. At 22:43 UT RY UMa was fainter than star 1 (=6.7 mag.) but was brighter than star 4 (=7.7 mag.). In fact its brightness was indistinguishable from star 2 which made it magnitude 7.4.

All text and images © Duncan Hale-Sutton 2022