[daip] Radio telescope imading

[Eric Greisen]

zyouhouya3 at yahoo.co.jp wrote:
> Dear Madams/Sirs,
> 
> Hello.
> My name is Fumito Saito,a high school student in Japan.
> I have the pleasure of writing to you for the first time.
> The reason why I am writing this email to you is I'd like to ask some
> questions about "The way to imaging(mapping) from some data provided by
> radio telescope".
> I belong to Kogakuin High School and I have tried to make radio telescope
> in this summer vacation with my friends,teachers,and students of Kogakuin
> Univercity.
> Now,I catched radio waves from space,and I used "analog-digital convertion"
> at first,and used "Correlation operation",and used"Fast Fourier
> transform"to got Sine wave per energy spectrum.
> But I can't image(map) it now. because there's only a few infomation about
> it in japan.
> I know the problem made by my insufficiency.
> I know you are so busy,and it's my selfishness,,,
> But could you inform me about the imaging?
> Because I want solve this problem somehow.
> 
> Your positive consideration of our situation would be greatly appreciated.
> Respectfully,

Your telescope sounds interesting and quite advanced.  I am assuming it 
is a single-dish telescope rather than an interferometer of the sort we 
work with most of the time.  A single dish sums up all the radio signals 
from the direction in which it is pointed.  To make an image, one then 
has to point the telescope at many nearby directions, recording those 
signals separately.  Then one can compute a digital "picture" by placing 
the signal level (versus observed frequency) at the appropriate position
in the picture.

daip is the generic address for a software project called AIPS.  Mostly 
this is a package to reduce data from interferometers.  But the NRAO 
does run single dish telescopes too - our old 12-meter in Tucson was 
supported by aips code.  Our "cookbook" may be found at
       http://www.aips.nrao.edu/cook.html
and chapter 10 specifically talks about using aips with single dish
telescopes.  This may be more advanced than what you are ready for at 
this time, so I will forward your message to a person who may have 
general materials for such queries.

You do sell your country short - there are numerous radio astronomers in 
Japan including scientists involved with VLBI (I forget the name - 
perhaps VERA) and with a telescope that we are building jointly in Chile 
called ALMA.

Good luck,

Eric Greisen
Scientist, NRAO