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
. 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
- 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.