[Aavso-photometry] Automated star finding

[Michael Newberry]

----- Original Message ----- 
From: "Jim Roe" <jroe at jamesroe.com>
Cc: <aavso-photometry at mira.aavso.org>
Sent: Wednesday, August 08, 2007 2:00 PM
Subject: Re: [Aavso-photometry] Automated star finding


>
>
> Michael Newberry wrote:
>> I'm really sorry if my description of th MExtract module for Mira Pro 
>> ended
>> up sounding too much like an advertisement, since I was describing a 
>> product
>> more than a technique. The trouble is that the technique is embodied in 
>> the
>> way the software works and the product is unique, thus I ended up 
>> describing
>> a specific product from a user's standpoint. In the future, I'll try 
>> harder
>> to be more generic rather than just just shooting from the hip like that. 
>> I
>> apologize in advance if it offended anyone.
>
    Sorry, I was writing that as a stream of consciousness and I really 
should have gone though and distilled it a lot better.

> I'm certainly not offended, but it will take me a while to digest your
> reply.  I also went to mirametrics.com to peruse the pages there.  I've
> seen (so far) very little mention of astrometry - one reference to WCS.
>  Do any of these products plate solve?  What engine do they use?
>
    You asked about Mira, so I hope no one minds me answering for it 
specifically. If you want to plate solve an image, all Mira plaforms (AL, 
AP, Pro) use our own astrometric solver that we wrote a number of years ago. 
Current versions of Mira require manual entry of the RA,Dec for each 
calibration star. They create an accurate solution for a FITS standard WCS 
that is saved with the image. Mira also recognizes a FITS standard WCS 
produced by other programs meeting the FITS standard, as well as the 
peculiar coordinate calibrations produced by IRAF, SAOImage, the HST Guide 
Star catalog, and others. All measurements, including photometry, centroid 
positions, distances, angles, and plots, show their results in (X,Y) and, if 
a WCS is available, also in (RA,Dec). Finally, Mira Pro can do image 
registration without marking alignment points by using the WCS (plate 
solution) stored in the image header.

> You mention variable star discovery which is one of my interests but it
> seems to be in processing "stacks" of images?  I don't want to save and
> process images that may comprise months or years worth of dates.  I was
> looking to measure the magnitudes in each image, store the results in a
> database for later searching, hence the need for RA and DEC values.
> Isn't that what TASS did?  Have they released any software? (Sorry for
> my ignorance, but tempus fugit in my life.)
>
    It sounds like your problem is a matter of database software. You get 
the photometry from your favorite astronomical IP software and then you save 
it to your master database for subsequent mining. Is your problem is that 
you match by (RA,Dec) and the database program doesn't know how to handle 
the format? If someone could write a macro to process the RA and Dec, and 
maybe do some precession if needed, then couldn't you use something as 
generic as Microsoft Access?

Michael Newberry

> Jim Roe
>
>
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