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OSU College of Arts and Sciences Department of Astronomy

Known Problems with TIFKAM

These are problems with known causes and (probably) known fixes. The instrument has other problems that we do not know how to fix; some of these are discussed in the main TIFKAM User's Manual. In most cases, we will fix the problems noted below as soon as possible (usually the next opportunity to open the dewar).

Please report any other problems you notice to Rick Pogge at OSU

One corner of the array in f/7 imaging mode is vignetted
This problem is probably caused by a slight vignetting of the beam by one of the mechanisms. There is no simple corrective at this time.

X-axis pupil motion fails sporadically.
Sometimes we think it is a software problem, other times a hardware problem, and sometimes we want to forget about it altogether. Which is just another way of saying that this problem has been with us most of the instrument's lifetime and we're still stumped. It is clearly temperature dependent in that the mechanism works fine at room temperature and the fails when at liquid-nitrogen temperatures. Every instrument has at least one such problem mechanism, this is ours.

The J and Kshort filters have long wavelength leaks
Both the J filter and the Kshort filter have significant long wavelength leaks. Be sure to use the PK-50 blocker in the prefilter wheel when using these filters. The HgCdTe detector we are using has more long-wavelength response than is typical, so this problem did not go away when we swapped out the old InSb detector. In the future we will probably put a piece of PK-50 in the same cell as the J and Kshort filters. For now, only the H-band filter has an integrated PK-50 filter.

The communications with the TCS occasionally "lock up"
There have been reports that the MDM TCS link can be locked up if you attempt to command an offset while the telescope is moving, or if a conflicting TCS command is issued from the xtcs tool on the sparcstation (via the GUI front-end) while the TCS is busy executing a move. Both behaviors have been reported.

If the TCS locks up, issue the command

from the Prospero keyboard. This will reset the ariel/XTCS socket connection. To verify that it has been reset correctly, type
which asks the TCS for the current pointing info.  If it responds, check
the output printed in the Prospero window with the info on the TCS PC
main screen.  The data should all match.

This has been better since implementing the Linux versions of xtcs and Prospero, but can still happen from time to time if the tcs is restarted without remembering to also restart Prospero and its related subsystems.