Re: [guide-user] UCAC4 permanently in Guide

Denis Oct 9 8:58 PM

Bill,

an update to my email below. I extracted the info from A20.idx, figured
out the process and wrote codes to rebuilt it when I want to filter a
new version of A2 then use it into Guide 9. Works just fine.

Here my process:

Filter the full A2 from 16 to 18 mag or any mag one wishes, rebuild the
index from the results and copy it to the Guide folder, modified
Guide.dat to show at 16 mag or else and added path to new modified A2
folder.

Result:

Guide only shows 16 to 18 mag A2 when Guide magnitude reaches 16 mag or
above.

Works well,

Denis


On 09/10/2012 3:27 PM, Denis wrote:
> Thanks Bill,
>
> I have these codes. I translated the ucac3 to Delphi and its works very
> well.
>
> One thing I have done is written a little program which take the present
> A2 files and filters them by mag, ie. 16 to 20 mag data only.
>
> I used to have an A20.index in text mode not bin but somehow can't find
> it anymore. I notice that when you delete the A20.idx in Guide 9 it
> re-creates itself. What I would like to do is use my A2 set of files in
> Guide 9 but need to replace the A20.idx to match my new files.
>
> I vaguely remember how to produce one but it would easier and quicker if
> I had the codes. Thinking clearly, I could simply extract the data in a
> text file which is quite easy to do.
>
>
> Denis
>
>
>
> On 09/10/2012 9:46 AM, Bill J Gray wrote:
>> Hi Denis,
>>
>>> Are you planning to take the UCAC4 permanently into Guide 9? With all
>>> the improvements, it would be worth to create the a new Guide 9 set of
>>> files as you did for UCAC3. The best way would be to create codes to
>>> convert UCAC4 to Guide 9 format and use the resulting files to replace
>>> the UCAC3 360 files.
>>
>> I expect to do that at some point. First step has been to get Guide
>> to show UCAC4 from the original disks. This serves several purposes,
>> one of which is that anybody (including Guide 8 users) can get UCAC4
>> displaying as soon as they have the UCAC4 disks.
>>
>> Another advantage: in order to get UCAC3 to fit on the Guide 9 DVD,
>> I had to compress it, and the compression was not lossless. I reduced
>> the precision (usually to a point well within the error levels of the data)
>> and threw out some internal flags and similar "less important" data.
>> I'll have to do the same sort of things with UCAC4. If you run from the
>> raw data, you get absolutely everything. (If you look at "more info"
>> for UCAC4, you'll see that there is quite a lot of data: three infrared
>> magnitudes from 2MASS, two magnitudes from UCAC4 itself, and -- for a
>> lot of brighter stars -- five APASS magnitudes. Be warned that these last
>> are not to be trusted to the degree their errors indicate, though.)
>>
>>> If I had the codes I would give it a try. Are the codes to access the
>>> reformatted ucac3 in guide 9 available?
>>
>> I haven't gotten those posted yet (I have a _lot_ of code that needs
>> to be posted... it also needs to be commented and cleaned up to the point
>> where it won't drive anyone too crazy). I _do_ have C code posted for
>> accessing the raw UCAC4, 3, and 2 data, at
>>
>> http://www.projectpluto.com/ucac4.htm
>> http://www.projectpluto.com/ucac3.htm
>> http://www.projectpluto.com/ucac2.htm
>>
>> This code should be quite readable and, I hope, useful to any C or
>> C++ programmers out there.
>>
>> -- Bill
>>
>>
>>
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