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Can significant temperature changes alter the model? #APCC #Mach2GTO


Marcelo Figueroa
 


It's summer here in the Southern Hemisphere and I'm learning how the modeling works in my Mach2. Two nights ago the temperature at night was high, around 20ºC and in almost all the frames of that night my stars were elongated, when the night before they were perfect. Then yesterday the temperature was 16ºC and the stars were perfectly round again.
 
My installation is semi-permanent, without any recent changes. I am using 4 minute unguided narrowband exposures and use a Pegasus Pocket Powerbox Advance to get the temperature.
 
Thanks


Roland Christen
 

Yes, temperature has a large effect on the modeling. Ray can comment on that, but I have seen this many times myself.

Rolando



-----Original Message-----
From: Marcelo Figueroa via groups.io <marfig1970@...>
To: main@ap-gto.groups.io
Sent: Sun, Dec 27, 2020 2:12 pm
Subject: [ap-gto] Can significant temperature changes alter the model? #APCC #Mach2GTO


It's summer here in the Southern Hemisphere and I'm learning how the modeling works in my Mach2. Two nights ago the temperature at night was high, around 20ºC and in almost all the frames of that night my stars were elongated, when the night before they were perfect. Then yesterday the temperature was 16ºC and the stars were perfectly round again.
 
My installation is semi-permanent, without any recent changes. I am using 4 minute unguided narrowband exposures and use a Pegasus Pocket Powerbox Advance to get the temperature.
 
Thanks

--
Roland Christen
Astro-Physics


Ray Gralak
 

Hi Marcelo,

It's summer here in the Southern Hemisphere and I'm learning how the modeling works in my Mach2. Two nights ago
the temperature at night was high, around 20ºC and in almost all the frames of that night my stars were elongated,
when the night before they were perfect. Then yesterday the temperature was 16ºC and the stars were perfectly round
again.
Yes, the temperature can affect both the refraction calculation and the Young modulus (flexure) of an instrument. APCC does account for refraction, but since flexure can also change with temperature, the model can change slightly.

A future version of APCC will be able to use APPM data collected over an arbitrary number of nights with a goal to predict flexure changes in a setup based on temperature.

So, as the temperature changes, you might consider doing new mapping runs to collect data points for that future version of APCC.

BTW, what type of telescope are you using?

-Ray Gralak
Author of PEMPro
Author of APCC (Astro-Physics Command Center): https://www.astro-physics.com/apcc-pro
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver


-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Marcelo Figueroa via groups.io
Sent: Sunday, December 27, 2020 12:13 PM
To: main@ap-gto.groups.io
Subject: [ap-gto] Can significant temperature changes alter the model? #APCC #Mach2GTO


It's summer here in the Southern Hemisphere and I'm learning how the modeling works in my Mach2. Two nights ago
the temperature at night was high, around 20ºC and in almost all the frames of that night my stars were elongated,
when the night before they were perfect. Then yesterday the temperature was 16ºC and the stars were perfectly round
again.

My installation is semi-permanent, without any recent changes. I am using 4 minute unguided narrowband exposures
and use a Pegasus Pocket Powerbox Advance to get the temperature.

Thanks


Marcelo Figueroa
 

Thank you for the quick response.
 
Ray, I am using an SW Esprit 100.