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Lowell Discovery Telescope

(formerly the Discovery Channel Telescope)

Observer Information Pages

(The information on these pages supersedes the DCTIC: Observing at DCT)


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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 Continuing, limited in-person observing will be supported at LDT.  For those observing remotely, see LDT Remote Observing Notes.

Monthly Observer and Telescope Operator Calendar

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Image: TJ. Ellsworth-Bowers (Lowell)

Brief Overview:

Fernandez (Lowell)

Lowell Observatory operates the LDT in partnership with Boston University, University of Maryland, Northern Arizona University, University of Toledo, and Yale University.


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 classically scheduled by semester, with the current being 2021A.The .  See 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)

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The facility was constructed as the Discovery Channel Telescope (DCT), and was renamed in 2019 in cooperation with Discovery Communications.RIMAS (Near-infrared Spectrograph / Imager – Under Development, Coming 2021)

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Updates (and Old Updates)

The LMI User Manual UPDATE: The 2025B LDT scheduled has been updatedreleased.   (2020Dec202025Jun24)

UPDATE:The 2021A LDT schedule has been released.  (2020Dec01Call for Proposals for 2025B released. (2025Apr09)

UPDATE: LMI is back on-line as of Jan 30. (2025Jan31)

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)

on-line as of Jan 14. (2025Jan14)

UPDATE: Check your VPN settings before your next remote observations (2024May14)


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titleUPDATE: The LMI User Manual updated.  (2023Sep27)

The LMI User Manual has been updated.

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titleUPDATE: TCS The DeVeny Spectrograph User Manual has been updated, ephemeris tracking is again working.   (2020Feb192023Nov16)

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)new version (v1.8 – 16 November 2023) updates to the PypeIt instructions and introduces the LDT Observer Tools python package.  It is available on the LDT Observer Information Confluence page.

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titleUPDATE: NIHTS User Manual updated. (2019Jan302021Apr26)

An updated version of the NIHTS User Manual (v1.4 - 20190137) has been released and is available on the LDT Observer Information confluence pagepages.  Per the authors, NIHTS User Manual v1.4 adds 7 includes a description of blind target acquisition using LMIcouple of revised figures from the NIHTS Commissioning paper. 

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titleUPDATE: LDT Observer Information Pages released. (2021Mar22)

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

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titleUPDATE: LMI shutter delay. (2018Dec052021Sep09)

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 (last done 2021Sep). 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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titleUPDATE: DeVeny User Manual updated v1.5 (2018Jul11)

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.

Facility Information:

Planning Your Observing Run:

At the Telescope: