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Warnings About COSMIC

The following are items about which all COSMIC observers should be fully aware.

Stowing the Guider:

It is good practice to stow the guider with the "STOW" button on the GUI at the end of the night, and before any telescope slewing. It is also good practice to click off the frame grabber "enable" button on the Sheperd autoguider display at the end of the night and before slewing the telescope.

The Shutter is SLOW:

The COSMIC shutter is not reliable or repeatable for exposures of less than 2 seconds. When using the focus script it is recommended to expose for at least 5 seconds to eliminate seeing effects.

Turning Off Lamps During Readout:

There is significant light leakage even with the shroud in place, so gradients will occur if lamps are left on during readout. This leakage also makes most twilight flats nearly impossible to obtain.

Restarting COSMIC window:

Quit the current window. Then type ``cosmic'' in any XTERM or CMDTOOL window. The data taken will be written to this directory.

Aborting Exposures:

After aborting an exposure, it is necessary to take a short (2 second) SNAP exposure in order to clean the charge off the array.

Twilight imaging flats:

The light leaks in COSMIC are bad enough that it is impossible to take proper flat-field images of the twilight sky. The problem is that the light leaks in during the long readout, causing the response to vary due to the readout, not the desired illumination pattern.

Snap mode:

A SNAP image is automatically binned 4 X 4, so the resulting image is 512 X 512. Binning values should return to the observer set values after the SNAP is read-out.

FTP and telnet:

The COSMIC workstation named "delta" is an old 486 PC. Being only a 4th or 5th iteration of Moore's law, this PC is short on memory. You will want to FTP your files to another location after each night's observing. You will also want to delete those files from "delta" before beginning each new night's observing. You must use FTP and telnet for file manipulation because ssh and sftp will not work on this old computer. Ask your friendly Instrumentation Support Engineer (Rick or Jeff) if you have questions about saving your data.

Before you FTP! :

There is a small black network interface box on the cart that carries the COSMIC computers. There are two silver switches that point up to "local" or down to "net". When using the camera (reading out) these switches must be pointing up to "local". WHEN FTP'ING YOUR DATA THESE SWITHES MUST BE DOWN TOWARD "net".

Some things on the COSMIC GUI don't do anything:

The "average" and "subraster" controls on the GUI do not work. They were included for future software upgrades that were never implemented.

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