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John last won the day on March 20

John had the most liked content!

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About John

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    North Somerset, United Kingdom
  1. As someone who used to work in government for many years (central rather than local in my case) I can say that one of the first things we looked at in a communication is who else it has been copied to
  2. I tend to think that a larger obstruction is OK as long as the scope is kept in accurate collimation. When the collimation is off I feel that image quality reduces more noticably in scopes with larger CO's.
  3. I had a similar situation with a light from a local school. I e.mailed them (with photos attached as evidence) and copied my e.mail to my local councillor. My councillor took an interest as did the school eventually and the light has now been effectively shielded. You need to keep the pressure up and copy your local councillor in on communications so that the council can see that it is not just you who they are accountable to.
  4. I'm sure we all know the rules here folks - no buying and selling outside of the "classifieds section". Many thanks
  5. A 900mm focal length scope (of whatever aperture) will be too much for the AZ5 to hold stablily at anything more than medium magnifications. Even an AZ4 is struggling with such a scope and that is a somewhat more robust mount than the AZ5.
  6. Stony meteorites are divided into chondrites and achondrites. The former have not been altered due to melting or differentiation of their parent body, the latter (which includes the HED group and the Lunar and Martian meteorites) have been affected by melting and recrystalisation. It has been assumed that an originating body needs to be of a certain size and mass for differentiation to occur - I think a few hundreds of km is considered to be the minium diameter but this is still under discussion / investigation and I guess proximity (even temporary) to bodies such as Jupiter could cause changes in structure. What will be interesting is when sample returns are achieved from small asteriods (eg: Bennu). If the samples include achondritic material then ideas may well change again.
  7. I don't think we disagree but these missions were planned in the 50 years ago and I suspect priorities were different then. Besides what good can being annoyed about it now actually do ?. Unless it prompts someone to mount a mission to tidy up what was left there ? We learn from past mistakes and try not to repeat them. Thats all we can do.
  8. Give your self a challenge Chris. See what you can do with this
  9. It's a traditional cassegrain, not an SCT. Different optical design. No corrector at the front to figure and coat. Parabolic primary rather than the SCT's spherical one. I'm not saying that it's better or worse than and SCT (I've never used a traditional cassegrain) but it's not the same as an SCT.
  10. But they had to land the buggy as well - from the same fuel reserves.
  11. The main issue with the AstroMasters is their poor finder. Once that is replaced / improved, the rest of the scope seems to work pretty well for the budget. Newcomers also find equatorial mounts non-intuative to use so need some guidance in setting them up and moving the scope around but thats EQ mounts generally, not just the AstroMaster. One subject that could do with a bit more "air time" is how to make the best of a less than optimum initial purchase, eg: bird-jones designs, 76mm newtonians and that sort of thing.
  12. I suspect the list of what was left there was driven by fuel availability in the LEM. They also took on a fair weight of lunar samples (22 kg for Apollo 11) so something had to be left behind to compensate. I believe the fuel margins were very tight.
  13. Judging by the scopes that turn up at the "scope surgeries" that my astro society holds, the Celestron AstroMaster 130 EQ's seem to catch many beginners eyes and are a popular 1st "proper" scope purchase.
  14. For information, in 2017 FPL-53 glass cost around 18 times as much as BK7 (crown) glass and FPL-51 cost around 11x as much as BK7. I believe those relative pricing differences have remained constant for some time.
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