From: <stingay_at_email.protected>
Date: Tue, 17 Apr 2007 00:23:14 +1000

Dear All,

Thanks very much for all your comments on the "VLBI and MIRANdA"
document. I've done my best to edit in as many comments as possible
in the time left to work on this.

Revised version is at:

http://pentane.ssi.swin.edu.au/~stingay/MIRANdA-VLBI-science-case.pdf

Probably not everyone will be entirely happy with this version. But,
to be frank, it would have been easier to converge if everyone had
sent their contributions, suggestions, ideas and views when I
initially asked for them, given that the deadline was always going to
be tight. At any rate, I think that the document, as it stands, is
ok. It is about twice as long as what Simon J. requested, but it is
probably good that we have a lot to say.

I do not push the 2.4 GHz option for MIRANdA as hard as some of you
would like. I think that this needs a lot of discussion and we need
to consider the options of upgrading Ceduna and the use of the AuScope
antennas (and New Norcia) seriously compared to MIRANdA at 2.4 GHz.
In my view, there is not a great deal of science that can be done at
2.4 GHz that cannot be done at 1.4 GHz. In the new draft I do put
more emphasis on 2.4 GHz but try to recognise that this discussion
needs to take place. Perhaps at our meeting at Swinburne next week,
some of this discussion can start.

Related to the 2.4 GHz issue, I also avoid discussing the AuScope
antennas too much. The use of these antennas in conjunction with the
LBA is currently a matter for informal discussion. And some of this
discussion is a little delicate. So, I've not really gone there.

Ultimately, I don't think that the decision for MIRANdA to go to 2.4
GHz will be made solely on the basis of these documents. I've given
us a foot in the door at 2.4 GHz and if a strong case can be made, I
think that we will have opportunities to make it later. I think there
is some serious work for someone to do, though, characterising the
benefits of MIRANdA at 2.4 GHz against a couple of other options which
acheive about the same benefits. It is not clear to me what the
optimal solution is.

Simon J. will edit all contributions to the MIRANdA science case into
a single document, so I'm not even sure that everything written down
will survive.

Please have a look over the revised draft. I hesitate to ask for
comments since this will be submitted tomorrow and I can't say that
I'll have time to incorporate further changes. However, if there are
any burning issues, let me know ASAP. No major changes will be made
but if you have clear sections of text that you want to add, or
specific references (please cite the reference), send them. Highly
specific modifications will have a better chance of being included.

I've listed everyone who has contributed text or comments as authors.
Please let me know if you are happy with this.

Cheers, Steven

On 4/13/07, Chris.Phillips_at_csiro.<!--nospam-->au <Chris.Phillips_at_csiro.<!--nospam-->au> wrote:
>Hi Richard,
>
>>> I don't see any mention of bandwidth. Will Gbps and better be possible with > the current design? That is important, and may not be included (as who'd put > 512 MHz bandwidth at 300 MHz?).
>
>300 MHz instantaneous bandwidth, dual pol (maximum for VLBI. As there is no plan for the (a) VLBI backend the actual bandwidth may be less than this).
>
>
>>> OH masers -> masers (in this case I am not sure -- what other L-band
>>> masers as observed in VLBI? There are molecular lines, but these
>>> usually resolve.)
>
>OH masers really are the only L-band masers. There are some 800 MHz methanol transitions but I cannot think much would be done with them. Non-masing molecules will not have the brightness temperature for VLBI.
>
>
>>> Rather than extending the frequency up to 2.4GHz to cover Ceduna,
>>> extend up to cover all the (global) geodetic antennae -- including the
>>> new AUSGeo ones.
>
>This is not going to happen. There is talk about going up to 10 GHz. But this would be a different instrument - probably a major upgrade in a few years.
>
>
>Cheers
>Chris
>
>

-- 
* * * * * * * * * * * * * * * * * * * * * * * * * *
Assoc. Prof. Steven Tingay
Swinburne SKA Project Leader
Centre for Astrophysics and Supercomputing
Faculty of Information and Communication Technologies
Swinburne University of Technology
Mail H39
P.O. Box 218
Hawthorn, Vic 3122
Australia
Ph     +61 (0)3 9214 8758
Fax    +61 (0)3 9214 8797
Email  stingay_at_astro.<!--nospam-->swin.edu.au
          s.tingay_at_optusnet.<!--nospam-->com.au
          Steven.Tingay_at_gmail.<!--nospam-->com

Received on 2007-04-17 00:23:44