17 October 2007

I saw an add in the Nov07 Sky & Telescope for the AstroTrac TT 320 which attaches to any photographic tripod and turns it into a short term equatorial mount. The AstroTrac web page doesn’t give a lot of detail about what it does and how it does (I found more information at the Kendrick Astro Instruments site), but once it is polar aligned it is supposed to track stars (it won’t work for planets, the Moon, the Sun, comets, asteroids or satellites as they all have different motions and rates than the stars and would require dual axis drives) for up to two hours allowing you to take photographs without getting star trails. You can also use it with a small telescope. The unit is supposed to operate with up to 20 pounds of instruments attached.

It is an arm that hangs down from the tripod head and then has another arm that extends out at right angles. During the two-hour running time a third arm scissors out from the first along a worm geat in the second (right angle) arm and turns the tripod head to which the camera is mounted. At the end of the running time you pres reset and the second arm screws back to the starting point. This all happens about 17” from the tripod head and it looks like it would be in the way of seeing through a camera viewfinder but would probably be fine for SAR. They like the Bogen 410 tripod head, which I use, for precise polar alignment.

You need to supply your own tripod, tripod heads (2), polar alignment scope, and battery pack (12v), which will drive up the cost which is already steep at £399 (roughly $813 + tax and import duties at the current conversion rate – Kendrick lists it for CAN $699 which is roughly $718 and since they ship from NY there might not be any duty involved).

You could get off cheaper buying a comparable conventional equatorial mount and single axis motor from Orion, but it would not be as compact and lightweight as the Astro Trac TT 320.

This unit was supposed to have been on display at the April 2007 NEAF but I missed it if it was there. It was supposed to have shipped from Kendrick in June 2007 but there is no button on their web site to add it to your shopping cart so I am not sure that it isn't vaporware at this point.

AstroTrac Ltd. graphic

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Observing Location	BPO
Observational Period	1930-1945 EDT
Atmospheric Conditions	Cloud Cover Scattered Clouds Temperature 66°F Wind Calm Humidity High Feels Like Moderate When I first went outside I could smell the moisture in the air. It was clear overhead but there were clouds and haze on the western horizon up to ~10° altitude. Transparency Poor Seeing
Instruments	Naked-eye Observing
Observing Party	Charlie Ridgway

The conditions tonight were not supposed to be good for observing so I was planning to go home and join my ham radio net from there. But late in the afternoon I checked into Space Weather and was alerted to comet C/2007 F1 (LONEOS) which was supposed to be best seen tonight so I changed plans.

Target Moon Constellation Sgr Category Lunar Time yyyymmdd.hhmm 20071017.1930 EDT Comments Lunation 1049 Phase Waxing crescent Age 6d18h37m Distance Light Time (from earth) 395,559 km 1.32s Elongation 74.3° % Illuminated 35.6% Morning Terminator Colongitude (λ E) 349.4° Evening Terminator Colongitude (λ W) 169.4° Libration in Latitude 6°31’ Libration in Longitude -6°8’ Magnitude -9.4 Angular Size 30.21' Altitude 21°30’ Virtual Moon Atlas graphic The Moon was hanging to the upper left of Jupiter. It is getting close to First Quarter but still has a concave terminator. Without optics I can’t make out much but Mare Crisium. The Moon is in the Teapot of Sagittarius but I can’t see any of that. Starry Night Starter graphic After finishing observing I went up onto the Staten Island Ferry for a ride over to Staten Island and back and about half way over the Moon disappeared, apparently having set into the clouds/haze on the horizon.

Target Jupiter Constellation Oph Category Planet Time yyyymmdd.hhmm 20071017.1930 EDT Comments Object Class Classical Planet Elongation 52.8° Distance Light Time (from Earth) 5.82 AU 48m23s Distance (from Sun) 5.28 AU Angular Size 33.8"x34.6" Magnitude -1.9 Central Meridian I/II 129°/346° Altitude 12.2° Jupiter was there for a while then faded into the schmutz.

Target C/2007 F1 (LONEOS) Constellation Boo Category Comet Time yyyymmdd.hhmm 20071017.1930 EDT Comments Not Seen The comet is supposed to be right next to Murfid. I could find Arcturus and thought I might have seen a glow in the clouds a couple of times where I thought Murfid should be but suspect that that was a wishful imagination. Starry Night Starter graphic Oct07 End Naut. Twi. EDT Con. Alt. Az. Mag. 17 1912 Boo 9.6° 285.0° 6.4 18 1911 9.7° 283.8° 6.2 19 1909 9.8° 281.2° 6.0 20 1908 9.7° 278.5° 5.8 21 1906 9.7° 275.5° 5.7 22 1905 9.4° 2732.3° 5.5 23 1904 Vir 8.9° 229.0° 5.5 24 1902 8.4° 265.4° 5.4 25 1901 Lib 7.7° 261.2° 5.3 26 1900 6.8° 258.2° 5.3 27 1859 5.7° 254.6° 5.3 28 1857 4.7° 251.0° 5.4 29 1856 3.5° 247.3° 5.4 30 1855 2.2° 244.6° 5.5 31 1854 Sco 0.9° 241.7° 5.7 The comet reaches its maximum altitude on Friday, 19Oct07. It reaches its maximum brightness 25-27Oct07, but by then is lower on the horizon than it was tonight and it will require a spectacular sky to see it. We will need a heavy rain followed by some wind to clear out the smog out over New Jersey. I graphed the comet's position and brightness. I decided to use the end of Nautical Twilight.beginning of Astronomical Twilight to take the position since I figure this is when the contrast will be great enough to find the comet. Then I added in the position of some of the stars to give an indication of where the comet would be. This didn't work out so well because I had to choose one date to represent the star positions during the remainder of the month. I choose 24Oct07, which is in the middle of the time period. This resulted in the comet being depicted too far to the north and east at the beginning of the period and too far to the south and west at the end. N.B.: The dates on the above chart read right to left while the ones on the chart below read left to right.