post

2013_07_1617

Weather

Very warm; 85 degrees dropping to about 80 by late tonight – humidity around 70%.  Winds calm, seeing around 1.9 arcsec.  From the second WR135 image on there were short periods of clouds that passed overhead.  From about 00:45 EDST on.

Rig #1:  Spectra of WR134, 135, and 137

Same program as last night (and has been for the past six weeks!)  Get one 30-min spectrum of each star, cycle back and get another of each – total of three cycles if possible – then a spectrum of Beta Aqr at the end of the night.  Last night clouds rolled in just as I was about to acquire Beta Aqr, the rest seemed okay.

LHiRes Focus Issues

Still fighting focus issues – though not really sure it’s focus.  Basically I’m still getting asymmetrical spectral traces through images.  Here’s an example from last night – basically a cut in Y across the spectrum:

A vertical slice through a spectrum of WR135.  Note the asymmetrical shape with extended "skirt" towards lower 'y' values

A vertical slice through a spectrum of WR135. Note the asymmetrical shape with extended “skirt” towards lower ‘y’ values

I’ve not been able to figure out what is causing this – but it seems to be getting worse over the past few sessions.  I re-focused the doublet on Ne lines before sunset tonight to see if that was the problem.  I’m also moving where each object’s trace is recorded on the imaging chip tonight to see if position along the slit is the problem.  Each object will be imaged at it’s own location; in the guide camera those locations (in X) are:  WR134: x=120, WR135: x=160, wr137:x=200.  There are two things I suspect – 1) perhaps the main mirror needs adjustment, or 2) perhaps it is poor collimation?  I also notice that traces through the Ne comparison lines also show some bit of asymmetry as well – though the extended “skirt” it towards higher x values.  Even at best focus (maximum peak value for line):

Slice through a Neon calibration line (5400 angstroms, if it matters).  Note here the asymmetry is toward increasing wavelength.

Slice through a Neon calibration line (5400 angstroms, if it matters). Note here the asymmetry is toward increasing wavelength.

It does look suspiciously similar but I really have no idea if the two phenomenon are related!  Because moving the main mirror will require new flat fields I’m not likely to try that until this spell of clear nights is past.  Also note that I was able to solve this same issue late last winter during the Mintaka campaign – if I recall at the time I though it was due to something in the optical path (some black tape that had come loose from the side of the support for the main mirror).  Need to check the light path – but again that will require taking new flats so not until later this week when the clouds return.  Is it possible something loose in the Ne lamp assembly?  The power cable?  More tape?

New issue with AP1200 mount

Tonight something really scary occurred with the mount.  I was going to attempt some short-exposure spectra of Deneb, placing it at various locations along the slit to see if it made any difference in the asymmetrical spectral traces.  Since Deneb is bright I set the guide rate to a very high rate – basically 0.1-second exposures.  I’m not sure that’s what caused things to go haywire – but immediately the mount tracked very quickly north.  I stopped the guider, then tried to slew the telescope back but the mount “jumped” then froze with the yellow LED showing an overload.  Basically I was unable to slew in declination – every time I would press one of the N or S buttons the mount would run for less than a second then violently stop with the yellow light coming on.  I could slew at 64x but not 600x.  Frustrated and worried I went in to have some dinner.  When I came back out all seemed to be fine!  Tomorrow I’ll remove the declination motor assembly and see if there is anything obvious.  I only recently re-greased both the motor spur and worm gears (white lithium and Extreme Pressure Lube #3, respectively).  I’ve noticed a bit of backlash in Dec – so it might be worth a look in any event.

For the first time I’m beginning to think this mount is a lemon and maybe I should sell it.  I sure hope I’m wrong as it has worked flawlessly for the past two months!

 

Rig #2: J191502+071947

Same as last night – tonight using 100-second integrations.  Here’s the plot from last night:

Still exhibiting "super humps"!

Still exhibiting “super humps”!

 Meridian Flip issues

The CGE mount in dome #2 is having difficulty near the meridian.  It seems to loose it’s sense of position.  As per usual I let it run a few minutes past the meridian, then issue a slew to go to the target.  It should try to go to the target from the other side of the mount but either it just continues to try to goto with the ‘scope on the west side of the pier (no flip) or it goes completely off, pointing south and I must turn the power off to prevent it from running into the floor.  The only recovery seems to be to turn the mount off and re-boot – move to switch, use previous alignment, the goto the target.  I suspect perhaps the switches are going bad or there is still another loose connection somewhere.  More fun for tomorrow.