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 (and Old Updates)

UPDATE: A typo in the table of DeVeny gratings has been fixed. DV2 is 300g/mm, blazed at 5000A, not 4000A. (2019Aug26)

DCT has been back on-sky since initial repairs were completed Wednesday 2019 August 14.

DCT was struck twice last week by lightning resulting in damage to several of the transient voltage surge suppression units (TVSS), including the one connecting the site to the main power lines. DCT has been out of normal operations while work has progressed to diagnose and fix the resultant issues. Today (Tuesday) the mains have been disconnected to allow for replacement of the TVSS units. Some of the parts needed are expected late today, and we are cautiously hopeful of being able to operate tomorrow night (Wednesday).

UPDATE: Please be aware that fire season has begun (for both natural and controlled burns). Check with your TOs regarding fire status. (2019Jun10)

UPDATE: The 2019B DCT Schedule has been released, and posted under the Science Schedule page. (2019Jun01)

An updated version of the NIHTS User Manual (v1.4 - 2019013) has been released and is available on the DCT confluence pages. Per the authors, NIHTS User Manual v1.4 adds a description of blind target acquisition using LMI.

We have looked into quantifying the delay between when a user requests an image with LMI, and when the shutter actually opens. Details can be found in the write up under the LMI link about the shutter delay. The bottom line is that:

The exposure times are as recorded to within a few hundredths of a second, based on the star streaks.
The shutter throw time in each direction is between roughly 0.1 and 0.2 seconds, meaning that there is also a temporal gradient across all the images.
Formal uncertainty on the measured time offsets are an underestimate of the true variation. The shutter throw time alone means the mid-time varies across the frame systematically by at least 0.1second (added as the systematic uncertainty below).
The shutter opens 2.05 +/- 0.06 (ran) +/- 0.1 (sys) seconds later than the UTCSTART in the image header.
The shutter closes 0.19 +/- 0.06 (ran) +/- 0.1 (sys) seconds earlier than the UTCEND in the image header.

Exposure times should be computed as:

Start time = UTCSTART + 2.05sec
End time = UTCEND - 0.19sec
Mid-time = UTCSTART + 2.05 + EXPTIME/2 or
Mid-time = [(UTCSTART + 2.05) + (UTCEND-0.19)] / 2

The DeVeny Spectrograph Reference and Operations Guide has been updated for the new release of the slitviewing camera GUI application. Version v1.5 (10 July 2018) of the manual is now available on the Observing at DCT confluence page.