Hiya again Roger

Evidently you'd like to plot SDSS stuff in Guide, and there is an
alternative way of doing it, but it's a bit mulish.

Some data has to be processed a bit, and I do that with a little
qbasic proggie, however it can be done in Excel, and I vaguely
remember sending Mike Simonsen a minitutorial on how to do that some
ages ago.

Basically Guide TDF commands of the following nature

~r 4 6 do this that,
~b 8 10 and the other

are of a syntax such that the first number is the _start_ column
number of a field of data on a line, and the second number is the
length of the field, the total number of columns, so for instance with
data of this nature

object1 17.5 22.6994 5.6
object2 22.8 01.4255 1.0

to display the second set of figures would mean writing

~b 9 4 %s\n

ie display in Both help and more info the value (returned by the %s
symbol) shown starting at column 9 and of length 4 columns, then start
a new line (that's what the \n does).

So ~b 9 4 %s\n would return 17.5 for object1, and 22.8 for object2.

Anyway, back to da sdss.

http://cas.sdss.org/dr5/en/tools/search/x_radial.asp?ra=RDEG&dec=DDEG&radius=9&entries=all&format=csv

is the basic url for fetching SDSS data. RDEG is replaced by any
value in decimal degrees, as is DDEG, within the sdss coverage.

So

http://cas.sdss.org/dr5/en/tools/search/x_radial.asp?ra=120.4&dec=+37.8&radius=9&entries=all&format=csv

returns data centred on RA 120.4 degrees declination +37.8 degrees,
for a radius (&radius=) of 9 arcminutes in this instance.

You type that into your browser, it all goes away to sdss, and after a
while your browser tells you that you have a file called

results.csv

to download.

This is a comma delimited file, with the first line as a header line
telling what the columns are, you save that to disk and the load it
into excel.

Now, here's the TDF that this will need converting for :-

file SDSS.dat
title SDSS dr5
RA H 3 9
units0 -2 # RA 'hours' are really decimal degrees
de d 13 9
mag 37 6
text 94 13
~c 1 1 SDSS dr5
~c 1 0 0 unknown\n
~c 1 0 1 cosmic ray\n
~c 1 0 3 galaxy\n
~c 1 0 4 ghost\n
~c 1 0 6 star\n
~r 3 9 RA 2000 %R\n
~r 13 9 Dec2000 %D\n\n
~b 23 6 u' %s
~b 58 6 err %s\n
~b 30 6 g' %s
~b 65 6 err %s\n
~b 37 6 r' %s
~b 72 6 err %s\n
~b 44 6 i' %s
~b 79 6 err %s\n
~b 51 6 z' %s
~b 86 6 err %s\n
~b 94 5 V %s B-V
~b101 5 %s\n
~r 1 1
\n^DATA//xhttp://cas.sdss.org/dr5/en/tools/explore/obj.asp?ra=%[3,9]&dec=%[13,9]^\n

epoch 2000
type 6
field 0.00 2.00
mag lim 60
shown 7
end

(The line starting ~r 1 1 followed by another line starting \n^DATA
is all one line that'll have been wordwrapped, fix it so it starts

~r 1 1 \n^DATA//xhttp://cas.sdss. and carries on to the end).

So, you have to convert the comma delimited file such that this sdss
tdf file will work with it.

Load results.csv into excel and change it as per the TDF, ie the RA
has to start at column 3 and be 9 columns long. This is standard
excel column widening and shortening practice, you may need to change
the number of decimals displayed too.

You may be able to use record macro for this, not sure, but if so,
then once you've done it once it's just a matter of invoking the macro
on future occasions.

When it's all lined up properly to fit the TDF, save it as a .prn
file, ie space delimited.

It's likely that a coupla columns from the input data need to be
deleted, as you only need stuff like the mag etc.

The SDSSdr5.tdf data file is called sdss.dat and needs to live in the
guide directory, using a text editor you append the new .prn files to
the main sdss.dat file... ...yeah, I know, tedious.

But it works, and after a while you'll have quite a few SDSS fields,
I'm guessing for CVs in your case, all there ready.

Oh, I've missed a bit, the V and B-V entries are added by adding
columns in Excel using the formulae

V = r' + 0.44*(g'-r') - 0.02

good to about +/- 0.05 V

and

B-V = 1.04*(g'-r') + 0.19

good to about +/- 0.1 B-V (which is a bit ropy actually, but just
about usable).

However, as these are the last values in the tdf it does not matter if
they are not generated, if they aren't there they'll simply not be
displayed.

Someone who knew what they were doing could likely compile a bit of C
or perl or something that'd take as input RA and Dec and radius, go to
sdss, fetch the comma delimited data, expand it out to space delimited
that fits the above tdf column discipline, and even autogenerate the
arithmetically derived V and B-V, and append it to the sdss.dat file.

I kind of do that with qbasic, but that's archaic, and don't work all
that cleanly, needing a coupla stages (the data has to be converted
from unix to dos line ending protocol for a start else qbasic thinks
it's all just one very long line) and few folk know how to run dos off
their PCs nowadays, let alone have access to qbasic.

It's mulish, but it works, until SDSS became available in VizieR
that's how I did it, and still do sometimes, because the above route
uses full SDSS data release 5, whereas VizieR has only just upgraded
to SDSS data release 4.

Cheers

John

--- In guide-user@yahoogroups.com, "Roger Pickard" <rdp@...> wrote:
>
> Hi John,
> Well thanks for your kind efforts but . . . .
> I run UCAC2 from the hard drive so don't even have the toolbar for it
> at all. But . . . . .
> It still doesn't work even with the new s come gsc22 .exe so it must
> be something Bill has done.
> Oh well, interesting exorcise and at least I've learnt a tiny bit more
> about these things.
> Cheers,
> Roger