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Lowell Discovery Telescope

(formerly the Discovery Channel Telescope)

Observer Information Pages

(The information in the LDTOI space supersedes 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.

Current Semester 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 2021B.The .  See 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, Coming 2021)

Instrumentation Main Page

List of LDT Scientific and Technical Publications

The facility was constructed as the Discovery Channel Telescope, and was renamed in 2019 in cooperation with Discovery Communications.

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Updates (and Old Updates)

UPDATE: Lowell Observatory is shifting to a new VPN platform.  All remote observers should update their VPN settings: Watchguard SSLVPN Installation  (2021Jul01) DeVeny is back on-line as of Jan 14. (2025Jan14)

UPDATE: LMI will be off-line Jan 9-15 for an upgrade. (2025Jan08UPDATE: NIHTS is offline until further notice.  (2021Jun10)

UPDATE: The 2021B 2025A LDT schedule Schedule has been released.  (2021Jun072024Dec06)

UPDATE:  The dome mounted flat lamp bulbs (typically used for LMI dome flats) were replaced today. One of the previous three was burned out. (2021Jun01)
UPDATE: The DeVeny spectrograph GG495 filter has been removed from the instrument; replacement plan TBD.  Order-blocking filters GG420 and OG570 are still in service. (2021Apr29)Check your VPN settings before your next remote observations (2024May14)

UPDATE:Check with staff about the upcoming PypeIt Workshop on June 11. (2024Apr24)


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

The LMI User Manual has been updated.

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titleUPDATE: The DeVeny Spectrograph User Manual has been updated.   (2023Nov16)

The 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. (2021Apr26)

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 7 includes a couple of revised figures revised figures from the NIHTS Commissioning paperpaper. 

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titleUPDATE: The DeVeny Spectrograph User Manual updated. (2021Mar22)

The new version (v1.6 – 22 March 2021) includes updated operating instructions, a reorganized structure, and more ancillary data and information on the instrument.  It is available on the LDT Observer Information Confluence page.

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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:  The LMI User Manual updated.  (2020Dec20)

The LMI User Manual has been updated.

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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

Facility Information:

Planning Your Observing Run:

At the Telescope: