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Re: {MPML} LSST and follow-up

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  • David Tholen
    ... In virtually every situation that you would normally encounter in practice, unfiltered is likely to be better than a V filter. Those tend to run about
    Message 1 of 13 , Feb 7, 2003
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      > In this regard, is it worth amateurs experimenting with filtered observations,
      > or are amateur apertures typically so small that this is a lost cause?
      >
      > If it isn't a lost cause, what is the best filter to experiment with? V?

      In virtually every situation that you would normally encounter in practice,
      unfiltered is likely to be better than a V filter. Those tend to run about
      1000 Angstroms wide, whereas the optimum filter is likely to be at least
      3000 Angstroms wide and possibly as wide as 5000 Angstroms. It's hard to
      be too exact because of the wide range of moonlight conditions that can
      occur.
    • David Tholen
      ... I had the opportunity to use a relatively recent vintage Lincoln Labs CCD with the better substrate you referred to. The claim was that it wouldn t
      Message 2 of 13 , Feb 7, 2003
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        > As far as fringing is concerned, this seems to be a problem of the past,
        > there are now CCDs with better substrates or other techniques which
        > remove this effect. I don't see the LSST camera being built with a CCD
        > technology from the 90s...

        I had the opportunity to use a relatively recent vintage Lincoln Labs
        CCD with the better substrate you referred to. The claim was that it
        wouldn't fringe, or at least wouldn't fringe as bad as our existing
        Tektronix CCD, which is thinner. However, when working unfiltered, I
        saw much stronger fringing than with the Tektronix chip. Why? Well,
        the amount of fringing was less in one sense, but the quantum efficiency
        in the infrared portion of the spectrum where the fringing occurs was so
        much higher that it more than compensated for the reduced fringing!
      • James McGaha
        The question of whether NEO surveys could be done with the LSST is somewhat academic. The LSST has not been funded and at 300 to 350 million dollars it may
        Message 3 of 13 , Feb 7, 2003
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          The question of whether NEO surveys could be done with the LSST is somewhat
          academic. The LSST has not been funded and at 300 to 350 million dollars
          it may never be funded.


          James McGaha


          At 01:01 PM 2/8/2003 +1100, Greg Crawford wrote:
          >In this regard, is it worth amateurs experimenting with filtered observations,
          >or are amateur apertures typically so small that this is a lost cause?
          >
          >If it isn't a lost cause, what is the best filter to experiment with? V?
          >
          >- Greg

          Any system (LSST, etc.) would use a filter of some sort, even if only a
          very broad-band one that optimizes S/N, cuts out extreme dispersion from
          atmospheric refraction, etc. The issue for LSST and its relatives is
          trying to do multi-filter colorimetry and use the resulting frames for NEO
          surveys. When you get to extremes of the color range where atmospheric
          absorption is extreme and signal is weak (infrared or blue to UV), it
          becomes silly to even bother to use the frames to hunt for new
          objects. There are some of the "tough gang of astrophysicists" who are
          audacious enough to try telling the asteroid astronomers that we "need"
          this as a part of a survey. Rest assured that we will stand firm on what
          we "need", and reply by telling them what of their needs can be tolerated
          for NEO surveys. If allowed to run amuck, it could indeed reduce the
          effectiveness of an 8-m telescope to that of a dedicated 4-m NEO hunting
          telescope. But then if it does half a dozen other projects at the same
          time, maybe it's a cost-effective way to go. I'm open to the suggestion
          but not convinced yet.

          Cheers,

          Alan

          *******************************************************************
          Alan W. Harris
          Senior Research Scientist
          Space Science Institute
          4603 Orange Knoll Ave. Phone: 818-790-8291
          La Canada, CA 91011-3364 email: harrisaw@...
          *******************************************************************
        • Alain Maury
          So, _this_ is the idea: remove the filter set, and get a telescope with a more attractive price, like 299.95 or 349.95 million dollars :-) It is maybe the only
          Message 4 of 13 , Feb 8, 2003
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            So, _this_ is the idea: remove the filter set, and get a telescope with
            a more attractive price, like 299.95 or 349.95 million dollars :-)
            It is maybe the only way to get the project funded : More than double
            the NEO detection efficiency, and get a telescope for less than 300
            million dollars.
            Alan, you must fight for this one.... :-)
            Alain

            James McGaha wrote:

            >The question of whether NEO surveys could be done with the LSST is somewhat
            >academic. The LSST has not been funded and at 300 to 350 million dollars
            >it may never be funded.
            >
            >
            >James McGaha
            >
            >
            >
          • Alan W Harris
            ... My main objective is to be sure it isn t gouged out of other ground-based astronomy programs like the present survey is. Cheers, Alan
            Message 5 of 13 , Feb 8, 2003
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              At 05:36 AM 2/8/2003 -0300, Alain Maury wrote:
              >So, _this_ is the idea: remove the filter set, and get a telescope with
              >a more attractive price, like 299.95 or 349.95 million dollars :-)
              >It is maybe the only way to get the project funded : More than double
              >the NEO detection efficiency, and get a telescope for less than 300
              >million dollars.
              >Alan, you must fight for this one.... :-)
              >Alain

              My main objective is to be sure it isn't gouged out of other ground-based
              astronomy programs like the present survey is.

              Cheers,

              Alan

              *******************************************************************
              Alan W. Harris
              Senior Research Scientist
              Space Science Institute
              4603 Orange Knoll Ave. Phone: 818-790-8291
              La Canada, CA 91011-3364 email: harrisaw@...
              *******************************************************************
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