[Aavso-photometry] Re: Aavso-photometry Digest, Vol 16, Issue 5
Russ Durkee
russdurkee at earthlink.net
Wed Jan 5 15:46:59 EST 2005
Hi Richard,
This time of year it is not uncommon for me to cool my ST10XE (and in the past a ST237) to -45C when the outside temperature is below zero F. It is unusual to have temperatures below -20 around here in southern Minnesota (not far from Micheal..) However I have had problems with bot cameras due to the cold.
The ST10XE power supply popped the first time it was used below 10 degrees F and damaged some electronics in the CCD. SBIG fixed it no charge. On my ST237 it would only download blank frames when the camera head cooled to 10 degrees F or so. I sent that back to SBIG as well and they were only able to replicate the error by putting into a deep freeze for a few hours before testing. In the end I think Bill at SBIG soldered a bunch of wire wrap points in the head and re-soldered all of the other contacts in the head and the camera has been solid ever since.
My only other complaint is the power cords that SBIG uses are terrible in cold weather...they freeze solid and eventually crack. Not like my AP mount...it has nice soft cable coverings even in the cold. The AP mount by the way starts to be a little noisy during slewing when temps dip below 10 F or so. I just turn down the slew speed and it seems ok. Even though slewing seems stiff it always points and tracks accurately.
Imaging in the winter is great...minimal cool-down time, no foggy CCD chips. I have never seen any fogging happening below -30 C and I cool below that on a regular basis this time of year.
Regards,
Russ Durkee
-----------------------------------------
Minneapolis, Minnesota
home.earthlink.net/~shedofscience
-----Original Message-----
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Sent: Jan 5, 2005 11:03 AM
To: aavso-photometry at mira.aavso.org
Subject: Aavso-photometry Digest, Vol 16, Issue 5
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Today's Topics:
1. Re: How cold is too cold? (Richard Huziak)
2. Re: Re: How cold is too cold? (Michael Koppelman)
3. Re: How cold is too cold? (Arto.Oksanen at tietoenator.com)
----------------------------------------------------------------------
Message: 1
Date: Wed, 05 Jan 2005 10:03:49 -0600
From: Richard Huziak <huziak at sedsystems.ca>
Subject: [Aavso-photometry] Re: How cold is too cold?
To: aavso-photometry at mira.aavso.org
Message-ID: <41DC0FE5.7000206 at sedsystems.ca>
Content-Type: text/plain; charset=us-ascii; format=flowed
A local department store is offering a discount for next week based on
the daily temperature. Today, I can get a discount of 34%, since it is
-34 deg C right now. For us Canadian humans (with small, but very
intelligent, brains tucked deeply inside thick crania for
cold-protection), this temperature is no really big deal, except that it
limits our *visual* observing sessions to only a few hours before we
have to think about warming up a bit.
However, my question is related to the other half of the equation -
equipment. Vance Petriew reminded me of a conversation with Arto
Oksanan at the Berkeley Conference regarding winter temperatures in
Finland, where Arto stated that "it's so cold that when he turns the CCD
cooler on, the camera 'warms up' instead". Yep - same here.
Since I use borrowed equipment, I don't want to over-stress what is not
mine, and our informal rule is not to use the telescopes if the ambient
temperature is <-20 deg C (mostly because the underpowered motors on the
smaller scopes have trouble keeping up & make strange noises), and not
to cool the CCD below -45 deg C. I recently emailed SBIG and asked what
minimum operating temperatures for their cameras were and what the
minimum cooling temperature was. They replied that they did not
recommend 'cooling' the camera to below -30 deg C but said nothing about
survivability of the camera itself, i.e. - what the cold operating
temperature of the electronics is. They were concerned what below -30C,
moisture would leech out of the desiccant and fog the CCD. I regularly
cool the camera to -45C and don't see this, maybe due to the usual 10%
winter humidity, but am concerned a bit about thermal stress. I run on
either Meade LX-200 12" or 14" scopes on their fork mounts and use any
one of the ST-9XE, ST-10XE or TC-237 cameras.
In my experience, commercial equipment may not work well below -20C (if
cold started), and equipment built to military standards (which the
cameras are not), should cold-start at -40C with no problems.
So - Cold Boys! Those of you that run equipment and cameras under
extremes of temperature, can you please comment on the surviveability of
your equipment and problems you have in the cold. I'd like to be able
to extend my -20C run temperature if possible, because I am currently
missing a whole lot of nights where I might be running. :-)
-10C = 14F
-15C = 5F
-20C = -4F
-25C = -13F
-30C = -22F
-35C = -31F
-40C = -40F
-45C = -49F
--
* * * * * * * * * * * * *
Richard Huziak
Manufacturing Engineering
SED Systems, Saskatoon
tel. (306) 933-1676
<huziak at SEDSystems.ca>
* * * * * * * * * * * * *
------------------------------
Message: 2
Date: Wed, 5 Jan 2005 10:15:37 -0600
From: Michael Koppelman <lolife at bitstream.net>
Subject: Re: [Aavso-photometry] Re: How cold is too cold?
To: Richard Huziak <huziak at sedsystems.ca>
Cc: aavso-photometry at mira.aavso.org
Message-ID: <08E974AB-5F35-11D9-A3AF-000A95C4DF7E at bitstream.net>
Content-Type: text/plain; charset=US-ASCII; format=flowed
At about -10F my mount starts acting funny. Stuff usually works pretty
well until then. I cool my chip down to -45C and colder if I can. I
have not seen fogging or the like. It sure is nice to drive the thermal
noise down to nothing. I personally would not worry about the camera.
The mount, if it starts struggling, is another story.
On the human side, I am a study of layers when it gets that cold. I
probably have 10 layers or so on -- thermal underwear, thermal shirt,
t-shirt, cotton shirt, fleece, fleece, quilted shirt, fleece, parka or
something like that. I'm all about hoods, too. I have hoods on 2 or 3
of my layers and they make a big difference. When you are sitting still
it becomes virtually impossible to stay warm but with even slight
movement and a lot of layers I am perfectly comfortable below 0F.
Cheers,
Michael Koppelman
http://www.lolife.com/astronomy/
On Jan 5, 2005, at 10:03 AM, Richard Huziak wrote:
> A local department store is offering a discount for next week based on
> the daily temperature. Today, I can get a discount of 34%, since it
> is -34 deg C right now. For us Canadian humans (with small, but very
> intelligent, brains tucked deeply inside thick crania for
> cold-protection), this temperature is no really big deal, except that
> it limits our *visual* observing sessions to only a few hours before
> we have to think about warming up a bit.
>
> However, my question is related to the other half of the equation -
> equipment. Vance Petriew reminded me of a conversation with Arto
> Oksanan at the Berkeley Conference regarding winter temperatures in
> Finland, where Arto stated that "it's so cold that when he turns the
> CCD cooler on, the camera 'warms up' instead". Yep - same here.
> Since I use borrowed equipment, I don't want to over-stress what is
> not mine, and our informal rule is not to use the telescopes if the
> ambient temperature is <-20 deg C (mostly because the underpowered
> motors on the smaller scopes have trouble keeping up & make strange
> noises), and not to cool the CCD below -45 deg C. I recently emailed
> SBIG and asked what minimum operating temperatures for their cameras
> were and what the minimum cooling temperature was. They replied that
> they did not recommend 'cooling' the camera to below -30 deg C but
> said nothing about survivability of the camera itself, i.e. - what the
> cold operating temperature of the electronics is. They were concerned
> what below -30C, moisture would leech out of the desiccant and fog the
> CCD. I regularly cool the camera to -45C and don't see this, maybe
> due to the usual 10% winter humidity, but am concerned a bit about
> thermal stress. I run on either Meade LX-200 12" or 14" scopes on
> their fork mounts and use any one of the ST-9XE, ST-10XE or TC-237
> cameras.
>
> In my experience, commercial equipment may not work well below -20C
> (if cold started), and equipment built to military standards (which
> the cameras are not), should cold-start at -40C with no problems.
> So - Cold Boys! Those of you that run equipment and cameras under
> extremes of temperature, can you please comment on the surviveability
> of your equipment and problems you have in the cold. I'd like to be
> able to extend my -20C run temperature if possible, because I am
> currently missing a whole lot of nights where I might be running. :-)
>
> -10C = 14F
> -15C = 5F
> -20C = -4F
> -25C = -13F
> -30C = -22F
> -35C = -31F
> -40C = -40F
> -45C = -49F
>
> --
>
> * * * * * * * * * * * * *
> Richard Huziak
> Manufacturing Engineering
> SED Systems, Saskatoon
> tel. (306) 933-1676
> <huziak at SEDSystems.ca>
> * * * * * * * * * * * * *
>
>
> _______________________________________________
> Aavso-photometry mailing list
> Aavso-photometry at mira.aavso.org
> http://www.aavso.org/mailman/listinfo/aavso-photometry
------------------------------
Message: 3
Date: Wed, 5 Jan 2005 18:59:43 +0200
From: <Arto.Oksanen at tietoenator.com>
Subject: [Aavso-photometry] Re: How cold is too cold?
To: <aavso-photometry at aavso.org>
Message-ID:
<084F7D0358A6AF4784D1D4EE04A795C703DB658B at zonda.eu.tieto.com>
Content-Type: text/plain; charset="iso-8859-1"
Hi Richard!
We havent got really cold weather yet for this winter, currently we have some degrees bellow freezing.
The 16-inch Meade LX200 has worked well even on the coldest nights when I have been observing (about -30C or so), but the 10-inch one did break once (the plastic gears were too fragile and lubricants too stiff). Of course the LCD display freezes, but otherways the keypad works if needed.
On very cold night we try to make long time-series of very few objects to minimize the mechanical stress of the telescope.
Our CCD (ST8XE) does not like very cold temperatures. We used to keep the CCD as cold as possible, but around -40C or so the transfer efficiency of KAF-chips drops. The hot and warm pixels are starting to have 'ghosts' on following pixels making calibration impossible. Since finding this we have imaged at -25C (unless ambient is bellow that). The dark current is nearly zero at that temperature too so there is no point going colder. Keeping the same temperature also allows re-using the darks from previous nights.
I think the camera electronics work well even lower temperatures. We keep the camera in the warm room when it is not in use so the start-up temperature is always warmer than ambient temperature outside.
Some cables, especially the power cable of the CCD is very stiff at low temperatures.
To keep the observers warm we do our CCD work from a warm room next to the telescope building. :)
arto
ps. It is the cars that are more difficult to start after a cold winter observing night if they are not being heated.
--
Arto Oksanen arto.oksanen at jklsirius.fi
Jyvaskylan Sirius ry, Kyllikinkatu 1, FI-40100 Jyv�skyl�, Finland
Tel: +358-40-5659438 Fax: +358-14-4157803
Nyrola Observatory http://www.ursa.fi/sirius/nytt/nytt_info.html
-----Original Message-----
From: aavso-photometry-bounces at mira.aavso.org [mailto:aavso-photometry-bounces at mira.aavso.org] On Behalf Of Richard Huziak
Sent: 5. tammikuuta 2005 18:04
To: aavso-photometry at mira.aavso.org
Subject: [Aavso-photometry] Re: How cold is too cold?
A local department store is offering a discount for next week based on
the daily temperature. Today, I can get a discount of 34%, since it is
-34 deg C right now. For us Canadian humans (with small, but very
intelligent, brains tucked deeply inside thick crania for
cold-protection), this temperature is no really big deal, except that it
limits our *visual* observing sessions to only a few hours before we
have to think about warming up a bit.
However, my question is related to the other half of the equation -
equipment. Vance Petriew reminded me of a conversation with Arto
Oksanan at the Berkeley Conference regarding winter temperatures in
Finland, where Arto stated that "it's so cold that when he turns the CCD
cooler on, the camera 'warms up' instead". Yep - same here.
Since I use borrowed equipment, I don't want to over-stress what is not
mine, and our informal rule is not to use the telescopes if the ambient
temperature is <-20 deg C (mostly because the underpowered motors on the
smaller scopes have trouble keeping up & make strange noises), and not
to cool the CCD below -45 deg C. I recently emailed SBIG and asked what
minimum operating temperatures for their cameras were and what the
minimum cooling temperature was. They replied that they did not
recommend 'cooling' the camera to below -30 deg C but said nothing about
survivability of the camera itself, i.e. - what the cold operating
temperature of the electronics is. They were concerned what below -30C,
moisture would leech out of the desiccant and fog the CCD. I regularly
cool the camera to -45C and don't see this, maybe due to the usual 10%
winter humidity, but am concerned a bit about thermal stress. I run on
either Meade LX-200 12" or 14" scopes on their fork mounts and use any
one of the ST-9XE, ST-10XE or TC-237 cameras.
In my experience, commercial equipment may not work well below -20C (if
cold started), and equipment built to military standards (which the
cameras are not), should cold-start at -40C with no problems.
So - Cold Boys! Those of you that run equipment and cameras under
extremes of temperature, can you please comment on the surviveability of
your equipment and problems you have in the cold. I'd like to be able
to extend my -20C run temperature if possible, because I am currently
missing a whole lot of nights where I might be running. :-)
-10C = 14F
-15C = 5F
-20C = -4F
-25C = -13F
-30C = -22F
-35C = -31F
-40C = -40F
-45C = -49F
--
* * * * * * * * * * * * *
Richard Huziak
Manufacturing Engineering
SED Systems, Saskatoon
tel. (306) 933-1676
<huziak at SEDSystems.ca>
* * * * * * * * * * * * *
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