Society for Popular Astronomy

Nigel, the intriguing flattening at the Jovian limb might be a "white drop" effect - irradiation from bright Europa spilling onto the darker image of the jovian limb, causing the apparent distortion. Keep warm, Bob

Very interesting sketches in the w58 and 47 filters Nigel, indicating persistent shading in the south of the disc. Respect for braving the cold, Bob

Thanks Jeff, re: antipodean skies, I hope there might be something in the magazine soon. Bob

I wish you luck with the weather Jeff. Yes, please do pick up pick up the threads on the solar front! I shall be away again over the northern winter and I shan't be able to observe the Sun until well into the New Year. Hopefully some more interesting solar activity will soon break out. Best wishes, ...

Thanks Nigel, The Sun is going coy on us just now and it won't show its spottiest face; numbers have dropped but no doubt as you say it should pick up shortly as it heads for maximum. 2023 Nov 18 at 1145 UT, seeing poor, transparency poor. New Farnley, Leeds UK. Equipment: as above. 1 spot group nor...

2023 Nov 17 at 1010 UT, seeing poor, transparency good. New Farnley, Leeds UK. Equipment: as above. 1 spot group north consisting of 4 spots near the p limb, and 1 spot group south consisting of 2 spots on the f limb. 6 spots in total. Best wishes, Bob

Fantastic views Nigel, the Europa transit is fascinating because it's rarer to notice the transiting moon against the disc of Jupiter as well as the shadow. You've been favoured with clearer spells recently; I have not been so fortunate. Regards, Bob

Nigel, I estimate the phase at the eyepiece by comparing the image with a set of 40 laminated Venus terminator line profiles prepared by the Sezione Planeti, Unione Astrofili Italiani. Between phase values of 0.40 and 0.59 there are 20 profiles in increments of 0.01. The traditional way of estimatin...

The phase lag is the interesting Schroter effect, due undoubtedly as you imply, to wavelength dependant light fall-off in the Venus atmosphere at the terminator against an otherwise bright disc. I observed again this morning at 1105 UT and, although the seeing was not good at x165, a few steady inte...

2023 Nov 11 at 1130 UT, seeing poor, transparency good. New Farnley, Leeds UK. Equipment: as above. 1 spot group north consisting of 14 spots, the largest of which has an interesting light bridge spanning its umbra, and 3 spot groups south consisting of 6, 6, and 5 spots. 31 spots in total counted f...

Nigel, what a great observing session. It shows just how good modern reflectors are. Even the Herschels with their 18 inch reflectors of yore did not resolve the structures that you see with a 14 inch. Regards, Bob

I agree Nigel, It's important to recognise the effects of seeing which can produce the impression of an irregular terminator (and sometimes a narrow banded appearance at the cusps). You are obviously alert to that. I might just add that I have never claimed to be able to see uv features on Venus (de...

Just an afterthought about the phase Nigel, your observations show the Venus phase diminishing according to the bluer the filter. This is often noticed. I observed Venus this afternoon at 1300 UT at x165 in my 90mm refractor with a yellow W15 filter, and I estimated the phase at 0.56, slightly gibbo...

Chilly conditions to be observing Nigel, but you are consistently recording amorphous disc shading and streaks. There is a myth that only people with uv sensitive vision (!) can see contrast features on Venus, but it's never been proved to be so. Personally, I think its more a case of using filters ...

2023 Nov 10 at 1045 UT, seeing good, transparency poor with hazy, thin cloud. New Farnley, Leeds UK. Equipment: as above. 2 spot groups north consisting of 1, and 9 spots and 3 spot groups south consisting of 6, 7, and 6 spots. 29 spots in total all counted from following to preceding. Best wishes, ...