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Barry W

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About Barry W

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  1. My 8" dob is the "star canon". It just seemed to carry on naturally from calling a sextant a "sky wrench"! Tools can have names too! Cheers, Barry
  2. Well done northcanadian and welcome to the "Wow" club. I only found it about two months ago and seem to head back to Saturn for a look every time I have my scope out. It's always an amazing view. Picking out the moons in different positions around the planet is a great experience as well. Cheers, Barry
  3. I've lived around and worked on the sea my whole life. Generally if you take care of the scope as mentioned, it should be fine. From personal experience (had to send in my old Olympus OM-2 for some significant repairs after using it at sea), I'd recommend being very careful about using electronics outside. The fine salt can get through seals and deposit itself inside equipment pretty easily. Cheers, Barry
  4. Hi James, I think the more experienced of the folks here might tell you to go for quality vice quantity. If you haven't got one yet, a good Barlow might be a wise investment (it will effectively double your lenses). from my memory of different posts, you should be able to get a Barlow and one other quality EP within your price range. Cheers, Barry
  5. thanks - three weeks to go and I've already downloaded all of the manuals. I really do love the photos that everyone submits. It will definitely be baby steps for me at first, but I can't wait to do some imaging Cheers, Barry
  6. Well done and thanks for being such a friendly and informative bunch for all us newbies. Cheers, Barry
  7. I finally took the plunge! Took advantage of a no interest credit plan through work to order a Canon 50D! I'll have about 4 weeks to wait for it to arrive, but I'll have time to read up and pick some brians while I'm waiting! Cheers, Barry:blob3:
  8. I know what you mean. The original constellations were defined by the ancients and have evolved into what what are the 88 officially recognized ones. In the process of defining the boundaries some stars have moved from one constellation to another. As far as the pictures are concerned, I don't think that anything is "officially" recognized. The pictures in the reference books you read, depend wholly on the author's/artist's preference. It's makes no difference to the constellations' make up. Hope this helps. Cheers, Barry
  9. Good Stuff! Pete's absolutely right. Time was only one piece of the puzzle, but it was the final piece to fit! By that time there was already a significant amount of information gathered on the positions of the stars and movements of solar system objects. The addition of accurate timekeeping made the navigation that much more precise. I remember the ship's chronometer (we held two in case one broke) and our "deck watches" were our own watches checked for error every day against the ships clock in GMT . We had to account for every know error and difference in the calculations. Unfortunately nowadays, everything is GPS based with UTC being the standard. It's still the same thing though - your position is plotted by knowing the precise time and distance from multiple satellites. (maybe I'm even more a a nerd about this, but it's sad that astro nav is becoming more of a lost art!) Cheers, Barry
  10. I was wondering if others of you out there have read the book (by Dava Sobel) or seen the docu-drama "Longitude". It's the story of John Harrison's trials and ultimate solution to the problem of time keeping at sea. After the 1707 shipwrecks of the Royal Navy's fleet, he spent the remainder of his life perfecting a time piece for use at sea. I ask because we're having a good discussion in the help and advice section on RA. I'm still trying to decide RA's importance to the amateur backyard astronomer (in terms of precision measurements). It's relationship to longitude, however, is extremely important and so is the accurate calculation in relation to time. In history, this is what led a carpenter to challenge the highly educated Royal Astronomers to gain recognition for his work and acceptance for safe navigation practices. Pretty much everything we can do now with EQ mounts and computerized tracking from the safety of our generally fixed positions stem from Harrison's work. I think it's an amazing story of the practical applications of understanding astronomy. Cheers, Barry
  11. You're welcome Chris, I actually just went back and re-read chapter 15 of Bowditch. Honestly - that's the first time in over 20 years that I've looked through those pages (it was the biggest and scariest book in our reference library at the time!) I'd recommend this for all you other beginners out there trying to get some reference material and gather a good basic understanding for astronomy. It's as good or better that half of the beginners' guides I've gone through in the past 6 weeks with outstanding explanations and some very nice sky diagrams for basic star hopping (i didn't even remember them being there). Like other books out there now - it's also written for a novice astronomer (or young sailor with no understanding of the skies!) Again, I strongly suggest you check it out and hope it helps (It's free in PDF format broken down by chapters!) Cheers, Barry
  12. I think the GOTO systems take all of this into account for us. Manual Equatorial mounts need this RA information more as you move around the celestial coordinate system. Conversion doesn't help much with an alt azimuth mount (ie a dob, like I use). I find visually identifying the celestial equator can give a good understanding of how the stars are moving around my location and can assist with "roughly" adding or subtracting for RA to point in the general direction needed. Moving to any any astro expertise I may have, I've copied a couple of astro-navigation terms below. They're generally the same as or show the relationship to astronomy terminology. Everything is based on Aries and calculations go from there. It's likely not relevant to the discussion questions, but the definitions may aid in understanding. For Chris - You said you were trying to understand the calculations and how they apply. This link (http://www.irbs.com/bowditch/) will take you to an on line book called "The American Practical Navigator", commonly called "Bowditch". He has some very good chapters on astro navigation and how to apply the various calculations. It might help you gain a better understanding. Some definitions: Declination : This marks the height above or below the equatorial plane for celestial objects. Equivalent to the latitude on earth. it is followed by North or South same as latitude. GHA : GHA (Greenwich Hour Angle) indicates the position past the plane of the Greenwich meridian measured in degrees. Equivalent to longitude on earth. It can be followed by East or West. LHA : LHA (Local Hour Angle) is the angle between the meridian of the celestial object and the meridian of the observer, LHA = GHA(of celestial object) - Longitude (of observer). SHA : Sidereal Hour Angle. Because the fixed stars (they are not really fixed, but they are so far away that they don't seem to move much), don't move relative to each other, rather than give the GHA of each star for each hour of the day, for each day of the year, the Nautical Almanac publishes only the list of GHA for a fictitious point called "first point of Aries" (also denoted by the Zodiac sign of the Ram). The SHA of the stars is simply a coordinate relative to this point. So to calculate the GHA of a star all you have to do is: GHA(star) = SHA(star) + GHA(aries). Ideally the GHA of aries should not vary relative to the stars, unfortunately, as Hipparchus noted a long time ago, the earth wobbles, its axis doing a full circle in about 26000 years (if my memory is correct) which means that the first point of Aries slowly drifts across the background of stars, making a full circle in 26000 years. It is called the first point of aries because it is the point where the sun crosses the equatorial plane on its way from the southern hemisphere to the northern one (around the 21st of March) and it happens to fall in the Zodiac sign of Aries the Ram. Will the point change name when it has drifted into another sign? Well the answer to this one is already known as the drift has already occured and the 1st point of Aries is actually in Pisces at the moment but we still call it 1st point of Aries. Old habits die hard. Note that astronomers and land surveyors use RA (Right Ascension) instead of SHA, usually measured in time (hours and minutes) and increasing in an Easterly direction, to convert just remember that 1hour=15 degrees, 1 minute of time = 15 minutes of arc and don't forget to change the sign. Instead of GHA Aries they use GST (Greenwich Sidereal Time). Hope you find this has some relevance. Cheers, Barry
  13. I've been reading the introductory chapters of Burnham's Celestial Handbook. He introduced astronomy in a very easy to read format and he put everything in an understandable scale. On to my revelation - I always thought I understood the hierarchy (earth-solar system-galaxy-universe) but the the relations of galaxies is just becoming clear. As I now see things, a vast majority of all the stars, nebulae, clusters are within our own galaxy (pretty much everything that is visible to the naked eye and at low power). The more advanced systems of the most serious amateurs and observatories are isolating individual stars and clusters within distant galaxies obviously, but am I right in assuming this beyond the scope of the average backyard astronomer? You more experienced folks have produced amazing photographic work of the observable galaxies - is it fair to say that a good proportion of the individual stars within and surrounding those still remain within our own Milky Way? I feel so much smaller now (stargazing has shrunk from the universe to the galaxy for the most part)!! Cheers, Barry
  14. I had to go downtown today for an appointment. As luck would have it, I ended up close by two used book stores. I managed to find a complete 3 volume set of "Burnham's Celestial Handbook" for $30, Patrick Moore's "The Modern Amature Astronomer" for $6, and "The Astronomy Cafe" by Sten Odenwald for $8. They're a little dated but seem to have a lot of information to keep me busy reading on cloudy nights. The library is growing. Cheers, Barry
  15. Thanks for the continued updates and advice. I'll keep looking around here for a good deal. I think it will be a Canon, but I'll have to hide away a bit more cash I think. Barry
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