Observing at DCT

This page gives a general overview for visitors and staff

(Please send us any comments or suggestions for ways to improve these pages.)

Updates

Road Status as of Oct 2017

Lake Mary Road construction is mostly completed. The speed limit between the south side Mormon Lake turnoff and Stoneman Lake Road is still posted as 25 mph. Occasionally people are still seen working on the side of the road.

2017 Sept 21: Because of the differences in the re-installation of the secondary mirror, there are two key items that impact observing:

The nominal focus offsets for each instrument have changed, some of them significantly. Please, please, check with your TOs for current nominal focus offsets before setting them yourself, at least until you are comfortable with the current range of settings.
The actual performance of the optics has changed. The predictive model that keeps the optics tuned is in the process of being re-built, but will take some time. In general,
1. If you have had the optics tuned up recently, near where you are observing, things should be ok.
2. If you have not tuned recently, or have slewed a significant distance, or the temperature has changed drastically (by more than 5 degrees C or so), then you should ask the TO to re-tune.
3. If you think your focus needs to be checked, then you should consider asking the TO to re-tune the optics.
4. In particular, we are recommending that on split nights, the optics be tuned at minimum at the night start, and at turn over in the middle of the night.

2017 Oct 10: Change to all focus offsets:

In addition to the changes, as of 10 October 2017, we are moving the primary down, which will change the M2 focus offsets by a roughly constant value. This is necessary because of the limitations in M2 piston in extension. Without the shift to M1, we will not be able to focus DeVeny and NIHTS as it gets colder. The M1 offset will reduce the M2 offsets by roughly 1000microns. Again, check with your TOs for the latest values.

As part of an effort to address safe access to the DCT, we have added an alarm keypad by the backdoor of the telescope building. This means that you can enter through either the normal front door, or if the steps are icy, you can enter through the backdoor. We are also in the process of installing an overhead shield above the backdoor to protect against snow and ice falling off of the dome.

The same alarm code that works for the front door will work for the back one.

2017 Sep 21 - The DeVeny Spectrograph Manual has been updated. The new version is v. 170921.

One item in the new manual that has changed from what was in earlier versions of the manual is in the step where you log into vishnu to start up the slit viewing camera (manual version 170420, page 22). The ssh command should be changed slightly to:

    ssh -Y lois@vishnu

The -Y replaces the -X that is listed.

For LMI, DeVeny, and NIHTS, the primary User Interface machine has shifted to dct-obs1.lowell.edu. This is instead of baggins.lowell.edu. The user name and password for dct-obs1 are different from those on baggins. See your TO when you are on-site for this information. If you will be observing remotely, please contact either your TO or Stephen Levine (sel .at. lowell) to get the updated credentials. Observing should otherwise look pretty much the same as before. If you notice a problem, please let us know.

The LMI VR filter has been moved from the upper filter wheel to the lower wheel.

In late August 2017, I took a quick look at the VR filter dome flats in the upper and lower wheels. The letter-boxing effect is less pronounced when it is mounted in the lower wheel (images and normalized row plots attached - the plots have been shifted to separate them on the plot). In the row plots, the upper wheel shows about 2.5 to 3% peak to valley variation, and the lower show about 1 to 1.5% on the rows through chip center. They are worse towards the corners. I have moved it to the lower wheel.

VR should be added to the list of filters used in the lower wheel only.

The VR filter was used mostly in the upper wheel prior to Summer 2017, though it was not mounted there exclusively.