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Fwd: a problem about the phot

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valdes
IRAF Guru

Joined: 11 Nov 2005
Posts: 676

Posted: Mon Nov 28, 2005 3:32 pm Post subject: Fwd: a problem about the phot

From: "93249003-Hu Ruei-Hua" <d939003@mail.astro.ncu.edu.tw (d939003@mail.astro.ncu.edu.tw)>
Date: November 23, 2005 9:09:18 PM MST
To: Frank Valdes <valdes@noao.edu (valdes@noao.edu)>
Subject: Re: a problem about the phot

Dear Sir,

Thank you for your reply. I've found the parameter that make the magnitudes�
strange. It is the exposure time. I made a embarrassing mistake. ^^
Thank you again and have a nice day!!!

Bests,

Hu Juei-Hwa

--
Open WebMail Project (http://openwebmail.org)

---------- Original Message -----------
From: Frank Valdes <valdes@noao.edu (valdes@noao.edu)>
To: Hu Juei-Hwa <d939003@astro.ncu.edu.tw (d939003@astro.ncu.edu.tw)>
Sent: Wed, 23 Nov 2005 16:05:19 -0700
Subject: Re: a problem about the phot

Quote:

Hello,

There are a number of factors that can affect the magnitudes.� These�
�should all be identifiable from the help description.� The�
magnitude� depends on the zero point (obviously), the exposure time,�
the area of� the aperture, and the sky.� The area depends on the�
scale units� specified.� If you want me to look at your parameters�
send me the� result of

cl> lpar phot datapars photpars centerpars fitskypars

Yours,
Frank Valdes

On Nov 12, 2005, at 8:04 AM, Hu Juei-Hwa wrote:

Quote:

Dear Sir,

I have a problem about the output mag. values of the digiphotx �
package.

Recently, I always get the mag. values larger than before in both �
apphot and daophot packages. The zero point is the same before and �
now.
I set the parameters follow the cookbook, A Reference Guide to the �
IRAF/DAOPHOT Package, by Lindsey E. Davis,1994.
In the same image, I get ~2.5 mag. larger than before. I've checked �
most of the stars in the image.

About one month ago, it happened once. I checked the parameters and �
reset them. The problem was gone and I can get the "normal" mag. �
values.
In these days, it happens again. After I check and reset all �
parameters (I did what I did last time), the problem is still there.

I have no idea how I can get back the normal mag. values.
My OS system is Fedora Core 3. The vision of IRAF is 2.12.2.
Do you know what causes the problem? any parameters I missed to �
check?? Does anyone has the problem??

Thank for your help.

Regards,

Hu Juei-Hwa

--
Hu Juei-Hwa
Institute of Astronomy,
National Central University, Taiwan
TEL +886-3-4227151 ext 65969
FAX +886-3-4262304

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