Re: Purpose of the fits header CLRBAND keyword in MaximDL


Jul 13, 2011

 


----------------------------

#46080 Jul 13, 2011

Hello Doug G. ,



I had a question about the behavior of MaximDL and how it uses the

CLRBAND keyword in the fits header. I have an image that I performed

PinPoint astrometry on (I have the full version of PinPoint installed)

and noticed that it creates the CLRBAND keyword in my fits header. The

image was acquired using a V-band photometric filter, and that is what

the FILTER keyword is set to ('V-band') in MaximDL. Now, when I open the

information window in MaximDL and go to the astrometric mode, it shows

me the coordinates of the stars in my image (I am using the UCAC3

database), and also the catalog coordinates. It also displays a

magnitude value for both the image star and catalog star. The only thing

is that it shows an (R) symbol next to each of the magnitudes. Now I

suspected that it got the (R) symbol from the CLRBAND keyword, and when

I changed the fits header CLRBAND keyword value to 'V', sure enough it

showed a (V) as the symbol next to the magnitudes.



I talked with Bob Denney initially about how PinPoint creates the

CLRBAND keyword and sets the value, and he told me that that keyword was

created for a customer and was not applicable for general use, and that

he was not in the habit of removing features that were not applicable.

The issue I have is that MaximDL seems to be using the CLRBAND value and

Bob told me that that was news to him, he wasn't aware that it was being

used that way. I guess what I would like to know is how is Maxim DL

calculating the magnitude value in the information window when in

astrometric mode, and how does MaximDL use the CLRBAND value ?



Thanks Doug, I appreciate any information you can provide.



Jerry Hubbell



Lake of the Woods Observatory (MPC I24)



Locust Grove, VA USA



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#46081 Jul 14, 2011

--- In MaxImDL@yahoogroups.com, "hubbell_jerry" hubbell_jerry@...> wrote: > [Astrometric mode] shows an (R) symbol next to each of the

> magnitudes.



This indicator derives from PinPoint's IPlate.ColorBand property. Your experiment suggests that PinPoint records it in/gets it from the CLRBAND FITS key, though I don't know where it comes from originally: a freshly acquired image's header contains no CLRBAND until it has been solved.



MaxIm DL doesn't use CLRBAND explicitly anywhere.



Hilderic Browne

Diffraction Limited



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#46091 Jul 14, 2011

Hello Hilderic, When I spoke with Bob Denny, he said that PinPoint generates the CLRBAND keyword when doing the astrometry as you said. Bob told me that CLRBAND property was put in for a specific customer back in 2002, and he never removed that functionality. It would be cool if you could get with Bob, and sorta hash this out between you two, and let me know. It's not really an issue, it's just that I am trying to get an accurate V-band magnitude reference from the UCAC3 catalog based on the calculation that PinPoint does using John Farrell's algorithm. Bob sent me the equation (this is from Bob's message to me):



FYI for UCAC3, the R and V mags are calculated thus (Farrell algorithm). IN the following 'm2' is the so-called aperture magnitude from the catalog:



rmag = (0.940F * m2) + (0.306F * (jmag - kmag)) + 0.480F;

vmag = (0.939F * m2) + (0.623F * (jmag - kmag)) + 0.512F;



Thanks



Jerry Hubbell

Lake of the Woods Observatory (MPC I24)

Locust Grove, VA USA



--- In MaxImDL@yahoogroups.com, "Hilderic Browne" hbrowne@...> wrote:

>

> --- In MaxImDL@yahoogroups.com, "hubbell_jerry" hubbell_jerry@> wrote:

> > [Astrometric mode] shows an (R) symbol next to each of the

> > magnitudes.

>

> This indicator derives from PinPoint's IPlate.ColorBand property. Your experiment suggests that PinPoint records it in/gets it from the CLRBAND FITS key, though I don't know where it comes from originally: a freshly acquired image's header contains no CLRBAND until it has been solved.

>

> MaxIm DL doesn't use CLRBAND explicitly anywhere.

>

> Hilderic Browne

> Diffraction Limited

>



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#46094 Jul 14, 2011

On 7/14/2011 8:13 PM, hubbell_jerry wrote: > It would be cool if you could get with Bob,

> and sorta hash this out between you two, and let me know.



There's nothing to hash out. As Hilderic said, we don't use CLRBAND, period,

nor do we perform the magnitude calculations displayed on the Information window

when in Astrometric mode. What is displayed comes *entirely* from PinPoint. We

just display what it gives us.



You'll have to "hash this out" with Bob.



Doug



--



Doug George

dgeorge@...



Diffraction Limited

Makers of Cyanogen Imaging Products

www.cyanogen.com/



100 Craig Henry Dr., Suite 202

Ottawa, Ontario,

Canada, K2G 5W3



Phone: (613) 225-2732

Fax: (613) 225-9688



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#46095 Jul 14, 2011

Thanks Doug, I appreciate what you are saying. My goal was only to understand where a value that is displayed in MaximDL is derived from. I need to know the pedigree of the data I am using when reporting my observations.



Jerry Hubbell

Lake of the Woods Observatory (MPC I24)

Locust Grove, VA USA

--- In MaxImDL@yahoogroups.com, "Douglas B. George" dg@...> wrote:

>

> On 7/14/2011 8:13 PM, hubbell_jerry wrote:

> > It would be cool if you could get with Bob,

> > and sorta hash this out between you two, and let me know.

>

> There's nothing to hash out. As Hilderic said, we don't use CLRBAND, period,

> nor do we perform the magnitude calculations displayed on the Information window

> when in Astrometric mode. What is displayed comes *entirely* from PinPoint. We

> just display what it gives us.

>

> You'll have to "hash this out" with Bob.

>

> Doug

>

> --

>

> Doug George

> dgeorge@...

>

> Diffraction Limited

> Makers of Cyanogen Imaging Products

> www.cyanogen.com/

>

> 100 Craig Henry Dr., Suite 202

> Ottawa, Ontario,

> Canada, K2G 5W3

>

> Phone: (613) 225-2732

> Fax: (613) 225-9688

>







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