Psi1 Aquarii North Pole Fly By

[Paz]

I wasn't planning on going out tonight but found myself out with the ST120/Porta 2 for a quick look at the moon. I was going to have a look at the terminator right on the limb but a bright star close to the moon caught my eye.  I checked it out on Sky Safari - it was Psi1 Aquarii and it was going to do a flyby of the north pole (or should I say moon's north pole was going to do a flyby of the star). My set up was ST120>semi apo filter>mirror diagonal>2.5x Powermate>ND0.9 filter>Mk 4 Zoom eyepiece. Best seemed to be at 16mm (so x2.5 equates to 6.5mm which equates to 92x).

There was still some blue fringing on the northern limb despite my filtering efforts that cast out to Psi1 but the star remained well visible. I could see the moon gliding past it in real time and the movement was noticeable even during a single pass through the eyepiece before having to repoint the scope.  This was exciting stuff!

I swapped in my 12.5mm reticule eyepiece (with 2.5x powermate still in place) and measured the star to be 1.5 small units (which equates to about 21") from the limb at 22:08. I took out the Powermate and measured the full width of the moon to be about 52.4 units wide (about 30'). If it is 3475km across then that makes it 397901km away which is within 3000km of what Sky Safari makes it. I swapped back in the powermate and Psi 1 skimmed past the north pole about 0.5 units (about 7") from the edge at 22:14 or so. I noted a nearby crater at closest approach that I discovered to be called Gioja - not a crater I ever recall noting before I guess as it is in a bit of a no mans land area very near the north pole. It was good fun to be trying to actually measure these things directly and noting new craters.

Before packing up I swapped diagonals to try a Baader T2 prism diagonal I have just acquired (all of the above was with an altair astro dielectric diagonal) , although I understand prism diagonals aren't particularly supposed to go with f5 achromats. I didn't have time to do much comparing but I thought the stars near the moon I was using to focus came to tighter points - but I put this down to most likely being good luck with hitting a slightly better focus in the minute or so I had a look - I had to pack up then but am looking forward to giving that diagonal more of a go with the MC127 and C8 which are what it is intended for.

As it happens I also tried out for the first time some vibration suppression pads on the Porta 2 tripod having recently realised from a  recent SGL post that they can be bought very cheaply if you know where to look, and was pleased to see that they do make a difference.

All in this was a short but action packed observing session.

[John]

Great report !

I saw the latter part of the psi1 Aquari "fly by" and shortly after an occulation by the lunar limb of Psi02 Aquari. Nice stuff

[goodricke1]

Yes I managed to observe the occultation too. Hope you weren't distracted from the main event Paz, by those interesting events off the north pole

[Paz]

8 hours ago, John said:

Great report !

I saw the latter part of the psi1 Aquari "fly by" and shortly after an occulation by the lunar limb of Psi02 Aquari. Nice stuff

 

7 hours ago, goodricke1 said:

Yes I managed to observe the occultation too. Hope you weren't distracted from the main event Paz, by those interesting events off the north pole

I completely overlooked Psi2, a bad case of target fixation!