Date: Mon, 24 Feb 2003 10:58:12 -0700
From: "Peregrine M. McGehee"
Subject: Re: 2.5m obslog 20030223 (MJD 52694)
Mike, Steph,
Thanks for acquiring the tracking data.
A few observations from last night's log and TPM data:
o NO dewar serial communications errors have been reported since
the doors were closed and the fans were shut down at 11:00Z. Could
this be an electrical noise issue??
o The rotator servo errors undergo large amplitude (> 0.5 arcsec)
swings every 60 seconds (i.e. on guider updates).  Conditions
were marginal - and the overall level of the rotator errors
grew in the final ~15 minutes.
The azimuth servo errors exhibited excursions every 15 seconds.
No obvious structure was seen in the altitude axis errors. The TPM
reported several rotator tracking alarms during the test.
o What are the tracking performance requirements in imaging and
spectroscopic modes?
- Peregrine
> We are using a new version of TPM (2_27_0) after Peregrine noticed some
> problems with the tracking alarms after we got on the sky (briefly) last
> night.  This version of tpm seems to be sending false dewar alarms:
>
> dewar (MAJOR: 2003-02-23 23:56:11Z)
> dewar (MAJOR: 2003-02-24 01:27:28Z)
> dewar (MAJOR: 2003-02-24 01:50:28Z)
> dewar (MAJOR: 2003-02-24 03:02:39Z)
> dewar (MAJOR: 2003-02-24 03:28:01Z)
> dewar (MAJOR: 2003-02-24 08:37:12Z)
> dewar (MAJOR: 2003-02-24 10:23:57Z)
> ---=== TELESCOPE STATUS ===---
>
> 01:00Z Enclosure doors opened, fans and blowers on, louvers opened.
> 01:30Z Enclosure off.
> 03:05Z Enclosure on (clouds).
> 11:00Z Doors closed, fans and blowers off, louvers closed.
> that we continue to guide with one minute integrations for the
> purpose of obtaining engineering data to test the TPM.  The one
> minute guider integrations began at approximately 0220Z and ended
> at 0301Z.  Peregrine also commented on the false dewar alarms,
> suggesting that the problem was with serial communication and appeared
> to be triggered by activity in the enclosure, possibly by fills or
> by jiggling the dewar (turning it off/on, bumping it, etc.).
--
Peregrine M. McGehee	peregrine@lanl.gov	(505) 667-3273
Sloan Digital Sky Survey / Spallation Neutron Source
MS H820, Los Alamos National Laboratory, Los Alamos, NM 87545