A short observing session, as its a Sunday night

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A short observing session, as its a Sunday night

Unread post by Pete »

Observing log of 13 Mar 05

There’s a good chance that the sky will clear tonight around 19:00 hrs., so I shoveled out the observing area earlier in the day and then put the 12” out at 17:00 under a gray sky. By golly, it did clear just as I was beginning to have my doubts, and I was out doing a polar setup at 19:00. Used Capella and Regulus for my initial alignment stars, and then synchronized the scope on Pollux, Proycon, Rigel, Sirius and Betelgeuse to insure accurate go-to performance. By now the muddy ground underfoot is just starting to freeze, and the breeze has died.

13 Mar 05; 19:18 hrs. Asteroid 1021 Flammario is a 13.4 magnitude minor planet approximately 103 km in size. Flammario orbits 2.5 AU from the sun and is currently 1.9 AU from Earth. There were 3 bright stars in the fov, and the target asteroid was located within a few seconds to the E of an 11th magnitude star. Centering on this star and continually increasing magnification, I finally viewed Flammario thru the 12” at 242X.

13 Mar 05; 19:30 hrs. 472 Roma is a 12.7 mag asteroid 2.5 AU from the sun and currently 1.6 AU from Earth. Star hopping in from 2 bright stars in the southern edge of the fov, I’m in the area but can’t see it at 97X. Increasing magnification to 179X, I’ve got it in the 12”. Roma is approximately 48 km in size.

13 Mar 05; 19:35 hrs. Asteroid 250 Bettina shines at a relatively bright 12.0 mag. The sky isn’t really dark, and neither is the yard, but in the 12” at 97X I not only see Bettina closely bracketed by two 10th mag stars. Bettina is approximately 85 km in size. It orbits 2.9 AU from the sun and is presently 2.0 AU from Earth. Interestingly, one “non star” on the Guide 8 chart actually was a star, and one star plotted didn’t exist.

13 Mar 05; 19:46 hrs. 196 Philomela is a relatively bright 11.3 magnitude minor planet. So bright that with the 12” at 97X that I originally mistook it for a bright finder star. Philomela is 146 km in diameter. It’s orbiting 3.1 AU from the sun, and is presently 2.2 AU from Earth.

13 Mar 05; 20:04 hrs. Asteroid 584 Simiramis is only 13.0 magnitude, but it’s in a clear dark area of the sky and just a few minutes S of a bright star. So I could see it in the 12” using only 97X. This 56 km sized asteroid orbits 2.8 AU from the sun, and is now 1.9 AU from Earth.

25 Phocaea is a bright 11.9 magnitude, but with a -16° declination it’s very low, and happens to be in a large tree. Give it a month and it will be in the clear.

13 Mar 05; 20:11 hrs. Asteroid 198 Ampella is a 12.9 mag minor planet 59 km in size. By star hopping in from the E and the N, and increasing the 12” magnification to 179X (Nagler 17mm eyepiece), I’ve got it. Ampella orbits 3.0 AU from the sun and is now situated 2.1 AU from Earth.

13 Mar 05; 20:15 hrs. Asteroid 69 Hesperia shines brightly at 10.8 mag. And there’s a very bright confirmation star in the fov as well. I’ve got Hesperia sighted in the 12” with a Nagler 31 (97X) even before I’ve focused. This 143 km sized minor planet orbits the sun at 2.6 AU, and is presently 1.7 AU from Earth.

13 Mar 05; 20:26 hrs. Asteroid 500 Selinur is a dim 13.6 magnitude. Fortunately it’s in a sparse field with a bright star only 2’ to the NW. Centering this star and continually increasing magnification, I can finally see Selinur thru the 12” at 314X – but only when using averted vision. Selinur is 45 km in size. It orbits the sun at 3.0 AU, and is now 2.0 AU from Earth.

Asteroid 797 Montana is a dim 13.8 mag, and it’s in an area of the sky where I’m having trouble seeing an 11.9 mag locater star. I give up on the search at 21:03.

13 Mar 05; 21:10 hrs. Asteroid 219 Thusnelda is another dim one – 13.4 magnitude. It’s bracketed by two very bright stars, and is only 2’ S of a 11th mag star. Centering on the 11th mag star and increasing magnification, I briefly catch a glimpse of it in the 12” at 203X. Only 43 km in size, Thusnelda orbits 2.9 AU from the sun and is now 1.9 AU from Earth.

Asteroid 342 Endymion is a dim 13.4 mag, but it’s in a sparse field and I can’t increase magnification without loosing my orientation. So I can’t find it and give up at 21:17.

13 Mar 05; 21:20 hrs. Asteroid 185 Eunike shines relatively brightly at 12.0 mag. Its 4th in a chain of very bright “stars” working up from a super-bright star to the S. I’ve got it immediately in the 12” at 97X. Eunike is 165 km in size. It orbits the sun at 3.0 AU an is now located 2.1 AU from Earth.

13 Mar 05; 21:24 hrs. 218 Bianca is a bright 11.6 magnitude asteroid in a distinctive pattern of bright stars. I’ve got it quickly with the 12” at 97X. Bianca is 62 km in size. It orbits the sun at 2.5 AU and is now 1.5 AU from Earth.

Asteroid 2000 GD147 is a bright 12.3 magnitude asteroid. And although I can see bright 10th mag stars nearby I can’t see this minor planet in the 12” - even by increasing magnification to 254X. This is the last asteroid on my list. I’d intended to end things at 21:00. Looking up I see that the area of interest is now laced with high thin clouds. That may explain my present viewing problem.

So at 21:30, with the temperature now at 27°F and falling, I pack it in.

Conclusions and lessons learned.

Doing all that synchronizing works. The scope was dead on.

Got 11 out of 15 asteroids targeted this evening. That’s a bit below par. But it was a good night to be under the stars.