Hello one and all.
I placed my William Optics 158mm f/7 apochromatic refractor in my back garden to have a go at observing these 3 difficult doubles all in Cassiopeia. They are relatively near STF 16 which was delicately split at 40x again. Sunset occurred at 16.19UT. There was no wind so I knew dew was due to happen. Therefore I observed from just 17 to 18.45UT which was long enough as I did complete what I had set out to achieve. Figures can be checked on
www.stelledoppie.it
if anyone so wishes.
1. I start off with an apology. I thought I had separated the Robert Aitken (1864-1951) double that has the designation A 1253 on the 9th October last at a lowly magnification of 112x, but later I discovered this was a rubbish observation. I never saw B at all. Here are the figures. Magnitudes: A = 7.7. B = 11.3. Sep = 4”. PA = 83˚. So it was with great urgency I selected this double again as it is listed in Robert Burnham’s Celestial Handbook and I had ticked it off already. Tut Tut! Stelle Doppie gives no indication of a C star. But my Guide 9.1 DVD proved vital. It shows 3 stars okay and I had gotten confused with the extra field star which is nearly at the same PA (position angle). Therefore now was the time to set things right and see if I could see the correct secondary. And gosh – was it tough? At 167x there was no sign of it. Then at 225x I got a brief glimpse of it. But I’m always dissatisfied on seeing an extremely faint secondary just the once and then to have it disappear again. I tried 280x. But whatever was going on with the seeing conditions the star just would not appear at that power. I even tried 320x, but to no avail. I went back to my 5mm Nagler which gives 225x and I could see B once again 2 more times using averted vision. I am so relieved to have seen it successfully during this particular Monday night. By the way, that C star’s magnitude is 11.1. But of course it’s not a C star!
2. Next up is a true double: HLD 1. Magnitudes: A = 8.3. B = 11.2. Sep = 2.2”. PA = 13˚. I had fun once again seeing the secondary. Sometimes life’s not fair! I seemed to catch very brief sightings at 167x and 225x. But I was much satisfied seeing it with my William Optics 4mm eyepiece which gives 280x. It was visible all the time then. Phew! You would want to see how many eyepieces I had out on my tripod tray. HLD stands for Edward Singleton Holden (1846-1914).
3. Finally I observed an uncertain double: STI 1319 was discovered by the Roman Catholic priest Johan Stein (1871-1951). Magnitudes: A = 10.7. B = 11.6. Sep = 8.3”. PA = 105˚. Once again I had some difficulties seeing the secondary. However my Nagler 5mm saved the night yet again. The secondary was pointing downwards at 225x.
So my night was over. The air temperature had descended to 2˚ Celsius. And it was time for din-dins in a lovely warm house!
Bye for now, Aubrey.
