Lowell Discovery Telescope

(formerly the Discovery Channel Telescope)

Observer Information Pages

COVID-19 Note:

Continuing in 2022B, limited in-person observing will begin at LDT.  For those observing remotely, see LDT Remote Observing Notes.

Current Semester Observer and Telescope Operator Calendar

Brief Overview:

The 4.3-m Lowell Discovery Telescope (LDT) is Lowell Observatory's flagship facility at a dark-sky site approximately 40 miles southeast of Flagstaff on the Coconino National Forest.

Lowell Observatory operates the LDT in partnership with Boston University, University of Maryland, Northern Arizona University, University of Toledo, and Yale University.  The telescope is scheduled by semester, with the current being 2022B.

The current call for observing proposals is linked in the sidebar at left for Lowell Observatory and Partner Institution members.

Facility Instruments:

LMI (Optical Imager)

DeVeny (Optical Spectrograph)

NIHTS (Near-infrared Spectrograph)

Visitor / PI Instruments:

EXPRES (Optical Spectrograph)

QWSSI (Optical Speckle Imager)

RIMAS (Near-infrared Spectrograph / Imager – Under Development)

Instrumentation Main Page

List of LDT Scientific and Technical Publications

Updates (and Old Updates)

UPDATE: The 2023A LDT Call for Proposals has been released.  (2022Oct11)

UPDATE: A minor update to the DeVeny User Manual has been released.  The new version (v1.7.1 – 10 May 2022) includes corrected confluence links and updates to the PypeIt instructions.  It is available on the LDT Observer Information Confluence page. (2022May10)

UPDATE: The change over to the new confluence server https://confluence.lowell.edu has happened.  Please let us know if you run across problems with these pages. (2022Mar07)

UPDATE: DeVeny Image Quality Issue: See the DeVeny Instrument Page for more information.  (2021Nov15)

UPDATE: The new VPN platform is now required for connection to the Lowell network.  All remote observers MUST update their VPN settings: Watchguard SSLVPN Installation.  (2021Sep06)


The new version (v1.7.1 – 10 May 2022) includes corrected confluence links and updates to the PypeIt instructions.  It is available on the LDT Observer Information Confluence page.

An updated version of the NIHTS User Manual (v1.7) has been released and is available on the LDT confluence pages.  Per the authors, NIHTS User Manual v1.7 includes a couple of revised figures from the NIHTS Commissioning paper. 

The new LDT Observer Information Pages were released, replacing the prior DCT Observer Information Pages.

The LMI User Manual has been updated.

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:

  1. The exposure times are as recorded to within a few hundredths of a second, based on the star streaks.

  2. 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.

  3. 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).

  4. The shutter opens 2.05 +/- 0.06 (ran) +/- 0.1 (sys) seconds later than the UTCSTART in the image header.

  5. 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:

  1. Start time = UTCSTART + 2.05sec

  2. End time = UTCEND - 0.19sec

  3. Mid-time = UTCSTART + 2.05 + EXPTIME/2 or

  4. Mid-time = [(UTCSTART + 2.05) + (UTCEND-0.19)] / 2


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