Challenge results
Alan Whitman (RASC Okanagan Centre), one of the world's premier visual observers, and the outstanding observer among the Society's ranks, has logged a truly remarkable record of six(!) independant sightings of Sirius B over more than a quarter century. Alan recounts his experince as follows:
My six observations of Sirius B:
a/ October 12, 1983 in very bright morning twilight, transparency very good to excellent, seeing very good, location Kelowna, BC
at latitude 49d 52' 07"N
8-inch f/6 driven equatorial Meade Newtonian at 348x (7mm orthoscopic eyepiece with a Barlow lens) with a polarizing filter, quoted from my logbook: "I saw Sirius's white dwarf companion clearly and definitely for a couple of seconds at a time. The position angle was correct and it was at the correct distance. (Sirius's comes had the same separation as Rigel's comes so this was easy to establish.) The observation was made in fine seeing as an upper ridge passed over, with Sirius at culmination at 23 degrees altitude, at 348x, with Sirius glare reduced by the polarizing filter and bright twilight. (The 2nd magnitude stars of Orion's Belt were fading from view.) Sirius was twinkling only leisurely to the unaided eye at one point while Betelgeuse was nearly steady. Sirius's seeing disk (blob) was as small as I've ever seen it, as small as 3 arc-seconds at times. I note in Burnham's that it has been seen from Paris, latitude 49N."
As far as I could establish at the time, that 1983 success seemed to be a new world record for the northernmost split of Sirius. Since then somebody in southernmost England did it from a couple of minutes of latitude (that's a couple of miles) farther north. So if observers located north of latitude 49d 55' can split Sirius they will, I believe, be setting a new world record for the furthest north.
b/ February 18, 1984 Seeing Good, Transparency Good, location Kelowna, BC at latitude 49d 52' 07"N
8-inch f/6 driven equatorial Meade Newtonian, quoted from my logbook: "I suspected Sirius's companion at 232x and 348x (10.5 mm and 7mm orthoscopic eyepieces with a Barlow lens) with the polarizing filter, but it was never more than a suspected glimpse."
c/ Three observations over four nights during a period of exceptional seeing, which is surprisingly frequent in mid-February according to my logs of Jupiter and Saturn. Location south of Penticton, BC at latitude 49d 22' 36"N altitude 342m
Feb 17, 2008 Seeing Excellent Full Moon
16-inch f/4.5 Meade Newtonian equatorial, from my logbook: "The approach of an upper ridge promised steady seeing here so I decided to give Sirius B a try the easy way, with my occulting bar eyepiece, a 7mm Meade Research Grade orthoscopic and a 2x Televue Barlow giving 522x . Around 10pm, an hour after culmination, Sirius was twinkling far less than I have seen it do in years, and with the occulting bar the Pup (Sirius B) was trivially easy 8.1" east of Sirius at PA 98. (I didn't have a chance to try it without the occulting bar before it went behind a part of my open observatory roof.)"
Feb 18, 2008 Seeing Excellent Full Moon
16-inch f/4.5 Meade Newtonian equatorial, from my logbook: "Went out at 2050, minutes before Sirius transited, and it was twinkling away, but Capella was steady high in the sky. So I put the 16-inch on Sirius anyways, with little expectation of success. The star was too big a blob until 2119, when it suddenly settled down and there was the Pup, at 522x using the occulting bar. Looked up at Sirius with the unaided eye and it was twinkling much less than it had been. Sirius B was frequently visible for five minutes, then gone as Sirius started scintillating more actively again."
Feb 20, 2008 Seeing Superb Full Moon in Total Eclipse
8-inch f/6 Meade Newtonian in its Dobsonian version, quoted from my logbook: "During the partial phase, after totality, Sirius was twinkling only leisurely at culmination, so I viewed Sirius at 244x (5mm Radian eyepiece so no occulting bar) using the polarizing lunar filter and had a few glimpses of Sirius B. The forecast winds aloft were for exceptionally light winds this evening as well, the end of the spell of memorable seeing due to an upper high."
d/ October 17, 2010 Transparency Excellent Seeing Excellent Location south of Penticton, BC at latitude 49d 22' 36" N, altitude 342m
16-inch f/4.5 Meade Newtonian equatorial, from my logbook: "Sirius mostly not twinkling so spotted Sirius B a few times at 522x with the occulting bar. Tried Procyon, but no way." This was during bright morning twilight.
Alan Whitman
Whirlpool Observatory south of Penticton, BC
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