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Lowell Discovery Telescope

(formerly the Discovery Channel Telescope)

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COVID-19 Note:

For the duration of the COVID-19 outbreak, all observing at the LDT will be done remotely.  See LDT Remote Observing Notes.

Monthly Observer and Telescope Operator Calendar

Image: T. Ellsworth-Bowers (Lowell)

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 2020B.

The current call for observing proposals is available for Lowell Observatory and Partner Institution members:  2021A LDT Call for Proposals

Instrumentation Quick Links:

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, Coming 2021)







Updates (and Old Updates)

UPDATE: The 2021A LDT schedule has been released.  (2020Dec01)

UPDATE: The DeVeny spectrograph is back in operation. (2020Nov06)

UPDATE: NIHTS is again available for use.  (2020Oct08)

UPDATE: The GG495 blocking filter has been replaced in the DeVeny spectrograph.  (2020Oct02)


The LMI User Manual has been updated to reflect modified focusing instructions and information about fringing when using the z' filter.  (2020Sep30)

The telescope control system (TCS) has been updated, and several issues fixed. One item of particular note to observers is that ephemeris based pointing and tracking is now functioning again. If you plan to use an ephemeris, please be in touch with staff ahead of your run to ensure that things work as expected. The ephemeris file format has changed slightly. For ephemerides extracted through the TCS, there shouldn't be an issue; if you generate your own ephemeris file, then you will need to make sure it conforms to the revised format. (2020Feb19)

An updated version of the NIHTS User Manual (v1.4 - 2019013) has been released and is available on the LDT Observer Information confluence page. 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:

  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

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 LDT Observer Information confluence page.



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