[time-nuts] Re: VLBI

Tom Clark w3iwi at toad.net
Thu Jul 7 01:53:07 EDT 2005

   David Forbes wrote:
> At 12:06 AM -0400 7/7/05, Tom Clark wrote:
>>      [As an aside, for many years until I retired, I headed NASA's VLBI
>>      program --  [3]see more about the Goddard VLBI group here. You
>>      might enjoy some of my tutorials on how the VLBI stations get their
>>      UTC reference time so that their measurements of UT1-UTC can be
>>      derived at the catch-all repository  [4][1]http://gpstime.com ]
>>    Tom Clark
> Tom,
> With those credentials, you must know what a Mark IV Tape Drive is. We
> had one at the Submillimeter Telescope on Mt. Graham for a few years,
> till they replaced it with the Mark 5 box of hard disks.
> It's amazing how those things could write a hundred megabytes per
> second. I never saw it in operation, but I can imagine what it was
> like when the tape got loose - a mile of tape on the floor in a few
> seconds.
> [2]ftp://web.haystack.edu/pub/mark4/memos/230.2.pdf

Sure -- I know Mk3/4 well -- I was re$ponsible for its development. (If
you look in any of the Mk3/4 modules, you will see a card called the MAT
that enables the RS232 control of the modules. I wrote the 8085 code
running in the MAT back in 1978 as one of my personal contributions.)
I also got the Mk5 started "under my watch" & kept Haystack alive for 30+
years. I'm now on the Haystack's Board of Trustees and get up there several
times a year (including this year's Technical Operations Workshop=TOW).

At this year's TOW, I gave all the station people my myoptic view of the
history of VLBI -- a version can be fetched from Haystack at
This presentation was an expanded version of a talk I gave originally in Feb'05

to the St.  Petersburg (Russia) VLBI folks when they awarded me a Gold Medal
from the Russian Academy of Sciences. [4]My local weekly newspaper even gave th
medal award a nice writeup.



   1. http://gpstime.com/
   2. ftp://web.haystack.edu/pub/mark4/memos/230.2.pdf
   3. ftp://web.haystack.edu/pub/heidi/Notebook/ClarkLecture.pdf
   4. http://news.mywebpal.com/news_tool_v2.cfm?show=archivedetails&pnpid=573&om=1&ArchiveID=1101667&requesttimeout=100

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