Re: Rochester Mark IV news

[Tom Droege <tdroege2@earthlink.net>]

Michael,

That is just great news!  Soon you will have tons of data too!

OK, the way the air system was planned was a one pass system.  Your idea of 
a circulating system is a great idea and will much reduce the desiccant 
required.  But that is not the way fish pumps work.  Possibly you can seal 
one up well enough that it will suck air in from the output.

Note that I put a trap and a bubbler on the output.  Not sure that I gave 
you one, but that is the way I am doing systems now.

OK, folks, what we need is something like a fish tank air pump that has 
both an input and an output.  That way we can have a more efficient closed 
loop system.  I will not go off to the Cole-Parmer catalog and see what I 
can find.

If you want it, I can provide a stiffer motor for the Dec drive.  It has a 
higher gear ratio so that it moves one degree for 125 (roughly) steps.  I 
think this is 10x or so the present ratio.  You give up speed of motion for 
no movement when you turn of the motor.  Let me know.

Tom Droege



At 01:42 PM 8/3/02 -0400, you wrote:

>   Last night, I ran the Rochester Mark IV for about three hours,
>following a field as it moved across the sky.  I acquired about
>38 pairs of images, each 60 seconds long.  This is still the
>"commissioning" phase, but it's a good step forward.  I'm learning
>quite a lot.
>
>   Air flow: I noticed that images taken earlier this summer
>showed "measles", which I believe are caused by water condensing
>on the silicon.  It's a big problem during the hot, humid summer
>months, as Tom has noted.  Anyway, I wondered why the dry air
>system wasn't doing its job.  I took apart the pump and discovered
>that the two connections to the air tubing were _not_ "intake"
>and "output", but instead 2 separate outputs!  That is, the pump
>was pushing air into both ends of the loop which ran though the
>camera heads!  Yow.  No wonder the moisture wasn't getting sucked
>up by the dessicant: there must have been very little flow.
>
>   So, during the afternoon yesterday, I hacked up a method
>to send the air back into one of the two pump units, so that it does
>make a closed loop.  I don't think I sealed it very well, but
>at least the air should flow.  Last night, the images show a much
>more mild case of the measles than before.  Rah!  I am leaving
>the air pump on overnight and through the day today, and hope
>to remove all the moisture by tonight.
>
>   FITS header: As I try to reduce the data today, I have found
>four or five different errors in information written to the FITS
>header.  I need to fix the "tait" program so that it writes the
>data in a format that the pipeline can read.
>
>   Time: The clock on the computer controlling the telescope was fast
>by 19 minutes.  Oops.  Must fix that.
>
>   Pointing: I know the Dec of the camera home position, but not yet
>the relationship between degrees and steps of the Dec motor.  I know
>roughly the Hour Angle of the home position, but not yet the relationship
>between (time leaving the RA drive running at high speed) and motion
>in RA.  I need to write code which allows the user to point the
>telescope to a given (RA, Dec) position.
>
>   Control: The "taitcl" clien program does let me control the
>camera remotely.  Good.  However, as currently written, the client
>sends a command to the camera (good) and then immediately terminates,
>without waiting for a reply that the command has finished executing
>(bad).  As a result, I can't easily send a string of commands.
>Need to fix the interprocess communication so that one can opt
>to wait for one command to finish before sending another.
>
>   Despite the many errors and mishaps, it's exciting!
>
>                                                      Michael Richmond