[vsnet-chat 3564] Re: [vsnet 2052] Magnitude data collaboration between projects

[Seiichi Yoshida <comet@aerith.net>]

Dear Brian,

>      A combined database of RA/Dec, date, and magnitudes from all the
> amateur-based surveys would be very useful in many areas of astronomy.
> In order to work well, the photometry in particular would have to be
> calibrated in some better way than is done at present.  For many surveys,
> use of the high-precision photometry from Tycho-2 might be enough to get
> either standard V or R magnitudes from the data.

I see that. In the case of MISAO Project, the GSC 1.1 or USNO-A1.0/2.0 
are used for automatic astrometry and photometry. So the magnitude
must be shifted from the standard system. I know the magnitude based
on those catalogs are inaccurate. But it is required in order to
process everything automatically using the PIXY System

Now I am developing the PIXY System 2, which is available at the MISAO 
Home Page:
  http://vsnet.aerith.net/misao/
I have a plan to add a function to refer the Tycho-1/2, the Landolt,
or other standard catalogs and shift the magnitude to the standard
system automatically. But right now, the function is not yet
implemented.

Even if the function is added, I wonder which is better, to keep the
current style only using the USNO-A1.0/2.0 catalog and report the
inaccurate magnitude, or, to use the new function and start to report
the accureate magntiude after it is implemented, or, to re-measure all 
images using the new function and report again the past 50 thousands
magnitude data.

>      Has the MISAO group considered starting to make digital scans of 
> existing emulsion-based surveys?  I would think having the films/plates
> of Takamizawa, Dahlmark, Collins, et al. scanned and analyzed in the same way
> as you have been doing CCD images would also be of great value.  The
> additional time baseline would provide "instant" lightcurves for huge numbers
> of variables now merely detected as a change on two or three dates.
>      Similarly, would you be prepared to collect CCD data provided by others?
> This would mean having huge amounts of disc-storage available.

Well, I have worked on some scanned photos. The PIXY System can
measure automatically the scanned photos as same as the CCD images.
But now no people are sending me their scanned photos. I think
Takamizawa-san has so many photos but he is checking his images by
himself. In addition, I have no scanner, so even if someone start to
send me (not scanned) photos, I cannot process them.

On the other hand, some Japanese amateurs are sending me their
unfiltered CCD images. Some have a plan to start taking filtered CCD
images. We are inviting those CCD image offerers, as described in the
MISAO's web page.

I have a CD-R writer. Now I have 27 CD-R disks containing CCD images
taken by Japanese amateurs. I also have 60-GB HDD.

>      Scanners for 35mm format film running at 1200dpi (i.e. about 2 microns
> per pixel) are quite common, and would seem to me to be entirely adequate
> for the purpose.  Someone simply needs to try this on some typical 
> astrophotos for a field with some photometric reference stars to see how
> good the photometry is (and astrometry for that matter).  

If someone send me some scanned photos and the data such as R.A.,
Decl., and field of view, I can process them by the PIXY System and
report the results.

Best regards,

--
Seiichi Yoshida
comet@aerith.net
http://vsnet.aerith.net/

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