August 17/18 – First Night for AP1200 in the North Dome

The photometric rig in the North Dome on its new ride.

The photometric rig in the North Dome on its new ride.

No entries here for two nights past.  The first was the night of August 17/18.  On that night I was able to get a full set of spectra for the UMontreal BRITE campaign on Deneb & P-Cyg.  More significantly, however, it was the first night of observing using the new AP1200 mount in the north dome.  A couple of things were obvious.  First of all the pointing is dead-on.  After a 12-star MaxPoint solution using stars both east and west of the meridian, but with the telescope always west of the counterweights (using the AP “meridian delay” feature) the mount puts most targets within the central half of the chip, usually closer.  The other thing is that it does not track well in declination.   Looking at the guide logs it appears to me that there might be a bit of stiction due to the dec worm being too tight against the wheel.  I will likely loosen that just a bit to see if it solves the problem.  The symptom is that as the star begins to drift away from center the mount is being sent commands to make corrections – which don’t seem to show up.  But then it jumps, in the direction it needed to move, but typically by half again as much as necessary.  Pretty typical of stiction problems.  The other thing I may do, which I did with the other 1200, is to clean and re-grease everything.  The 1200 in the south dome, despite its early troubles, guides very smoothly.  Note that it does have a small amount of backlash in declination and that the worm on the declination could be tighter against the wheel.  Here’s the night’s data.  At magnitude 16.5 this object is near the limit of what I can expect to do here in the soup.

Note the sudden half-magnitude jump and return to “normal over the course of around 30 minutes.  If it stays clear tonight I may revisit this one.  I’ve got data on GD522 from 2010 and 2011 as well and have seen jumps like that before.  It was a night of really amazing seeing, likely near 1 arcsecond.  It is interesting that, while having lots of cloudy weather this summer when it has been clear the seeing has been better than normal.

August 24/25 – Dodging the Clouds

Last night was an exercise in dodging periods of cloudiness.  So on the photometric side I only got a few hour stretch on AO Psc, and on the spectroscopic side I just barely squeaked in a full set of spectra.

Software Headaches

I really don’t know why I do this to myself.  I’m totally inept in a unix-like environment.  But last weekend I got this irrational desire to try to update the virtual machine I use which came to me via Dr. John Beaver at U Wisconsin-Fox Valley.  Called VARMiNT, it is a complete set of astronomy software pre-loaded on a hard disk which can be run using the VMWare Virtual Machine Player.  It is loaded with Ubuntu 12.04, IRAF 2.14, PyRAF, SciPy, NumPy, Python 2.7, lots and lots of other stuff.  But hey, there was a newer version of IRAF, the Space Telexcope Institute had this thing called STScI-Python which included up-do-date versions of IRAF, PyRAF, Python and all the rest, and a new version of Ubuntu – 14.04LTS.  I had already tried to simply run all the Ubuntu updates for VARMiNT, but it screwed up the display.  I tried it several times, each time re-installing the VMWare Tools, to no avail.  So I decided to start clean to try to create a “VARMiNT 2.0”.  Did I say I’m unix illiterate?  Well, amazingly I managed to get a working virtual machine with Ubuntu 14.04, IRAF 2.16.1, and have downloaded and supposedly installed STScI-Python.  But being the Unidiot I am I can’t even figure out how to get a PyRAF prompt!   I do seem to have Python 3.4 installed and running (as well as 2.7, which I think came with Ubuntu).  It looks like I’ll be learning another programming language.  Just bought a Python programming book.  Oh joy!


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