Starship Asterisk*

The Cerro Pachon (CP) CONCAM3 has been delivered and awaits deployment in Chile. My understanding is that a perch, new outer shell, and dome are being specially constructed, despite my assurances that it should work fine without them.

- RJN

First light for the Cerro Pachon CONCAM!


The above image is not as spectacular as the recent first light from the Haleakala CONCAM and so we are trying to figure out why. My first guess is that the fisheye lens iris is not very open. Now this is not as simple to fix as it sounds. First, power off the box. Next, get a flashlight and look into the lens to see if you can see the iris. Next, open up the box and fiddle with the lens dial that opens up the iris. Now the lens bottom is surrounded by scaffolding and your fingers make a tight fit. Which dial is the iris? Which way to turn the diial? Trial and error is the easiest way to find out. Please be sure to return the focus to its original position. The iris should be all the way open. Confirm this by shining the flashlight into the top of the lens and look for the iris.

The good news is that the FITS image
http://nightskylive.net/cp/cp040917/cp0 ... 4330p.fits
that corresponds to the above JPG is much better than the JPG and shows reasonable focus. The bad news is that the tower on the right is really annoying and has power lines hanging going off in both directions! Is there a better place to put this CONCAM?

Also, please turn the CONCAM box so that north is at the top. Also, please use a level to make sure that the CCD is level with the ground, making the zenith with 10 arcminutes of the frame center, if possible.

- RJN

I agree. This must be the iris. The low counts that we get implies that this is the problem. We had the same problem in Mauna Kea and they opened the iris to get a whole different picture.
I don't think it should be so difficult to do, even though you need a screw driver to get to the iris ring. I don't think it is possible to reach it with the finger.

Well apparently Felipe opened the iris and re-oriented the camera. The first good moonless image is pretty good!

Note the Large and Small Magellanic Clouds toward the South of the image. The plane of the galaxy sweeps across the East. The dome of Gemini South is on the South West horizon.

The big power-tower to the North East is apparently there to stay. I hope it does not compromise any of the automatic atmospheric opacity computations. I wonder if it can be used for anything? Eclipses? Reflections?

- RJN

The photmetry files are now enabled enabled at Cerror Pachon.

The Cerro Pachon (CP) CONCAM is recording some really great images lately and the automated software appears to be generating some really stable photometric measurements of all the bright stars in the fields. It looks like CP should teach all the other CONCAMs how to CONCAM. I was just browsing some of the files over the last new moon and the annoying weather tower on the upper left appears to have little effect on most photometric measurements. Many of the opacity maps look great too. - RJN

The CP Concam has not returned images for the last 5 days.
Hopefully the Concam just needs to be restarted, we await more information from the CP site managers.

I'm getting a nice image from the CP concam today with the exception of the bright spot (pesky moon!). I agree the communication tower or whatever it is doesn't really seem to interfere with what you can see. I also agree that the CP concam should teach those other concams how it's done!

Hi, I was going through CP archive randomly and cannot access any of the opacity maps. The Photometry files are working, but show a zero in the C5c-Bc column in each archive I accessed. My Concam at RH doesn't have opacity maps, I guess because it's a Concam-2 and CP is a Concam-3? Anyway, is this problem with the opacity files related to the RH photometry problem?

I'm trying to get FITSview installed on my computer at home and am having a little difficulty, but I'll get it worked out.

It looks like the CP Concam may be experiencing some troubles. The last image displayed is from 2Mar2005 @ 09:39:34UT.

CP Concam is back online returning nice images, photometry, and opacity maps.

CP Concam returning nice images some with spiders...


Photometry available (not for the spider) and no opacity.

Hi, here at CP we build an enclosure for the camera in order to improve
its weatherproofing because the winter in Pachon is very hard, plenty of
snowstorms, rain and fog.
We use an acrylic transparent dome got from Edmund Optics, as a window,
which has prove to have excelent optical quality. Also, the UV radiation
seems to not affect it and, after almost a year, it looks like the first day.
We also add some vents to keep it with a temperature similar than the
outside.

Here are some pictures:

Great pictures Felipe, it is nice for people to see what the operational setup of a Concam is.

Hi, glad to hear that you liked what we did.

This case help us to protect the CONCAM, for about a year, from the
bad weather. It works very nice because it avoid the water and fog
to go inside and also it provides vents to keep the internal air temperature
close to the external temperature to avoid the moisture to condensate
on the inside.
We made two vents in the east side and two in the west side. These vents let the air flow through the case. Also we made another vent below the
CONCAM's fan to let the warm air to go outside. All the vents has a mesh
from the inside and are covered on the outside. Se pictures for details.

Felipe,

Good work -- your case appears to be the best at avoiding condensation both inside the CONCAM lens and on the dome.

From your description, though, I must say that I do not understand why! I thought the best way to avoid condensation was to keep everything as warm as possible. A surface warmer than its surroundings will not condense.

A surface that cools by radiative cooling, like an outside lens or a dome, will become colder than the outside air and so, when the dew point is right, water will condense on this lens or dome.

From your description, it appears that your enclosure is designed to expell warm air. And I would have thought that expelling warm air would promote condensation, not inhibit it.

Any thoughts on this?

- RJN

Felipe,

Thanks for posting those pictures of your Concam setup. From what I have seen your configuration does seem to take care of the moisture problems and may be worth duplicating at other sites (CI comes to mind).

The only explanation I can come up with as to why it works so well is that the free flowing air prevents moisture form condensing on the surfaces in the first place.

The same thing happens with frost, if you have a slight breeze blowing you usually don't have frost formation on cold surfaces like grass, car windows, mirrors etc.

There could also be a slight temperature differential in the case due to heating by the stations components.

Whatever the reason, it seems to be working. Experimentation is how we learn and improve! Thank you for your dedication to the project and keep up the great work.

Glad to hear that you liked my work, thanks!

We made all the vents and we are expelling the warm air in order to
have the same temperature and humidity inside and outside the case.
Why? I thought, if the warm air is kept inside, the camera will be always
warmer than the outside. Then, when the temperature drops outside, the
acrylic dome will get cold and also will make the temperature drop in the
first layer of air inside the case with the posibility to reach Dew Point
and get condensation, depending on the internal humidity, so having the
same temperature inside and outside will let me avoid that.
I'm not quiet sure if I'm right, but it works.

The CP Concam stopped working on the 8th, I am waiting for a response from Felipe to find out what the trouble is.

The network cable was found loose at the network switch, causing
a communication problem. The camera was okay.
The cable was connected properly and now the system is back
on business.

Felipe,

Not to rain on your parade but I just peeked in on the CP Concam and it is still showing the image from the 8th. I sure hope the problem wasn't more serious then previously thought, I've been doing lots of bragging about your Concam

fdaruich wrote:The network cable was found loose at the network switch, causing
a communication problem. The camera was okay.
The cable was connected properly and now the system is back
on business.

Thanks for bragging about the Pachon CONCAM. We are doing our best effort to keep it working and giving nice pictures of our sky to all the world.
Regarding the problem, it seems that the problem is in the computer. From now on all the CONCAM3 will be offline for three weeks so I'll have time to test the computer in the lab.