Overheads

Direct links to instruments on UT1, UT2, UT3, UT4, ICCF, VLTI.

Telescope/

Combined focus

Instrument Action Time (seconds)
UT1   Preset + GS acquisition + active optics
360
UT1   Preset  + GS acquisition + active optics (2nd OB and following in a concatenation)
(40+target separation in deg)+60
  FORS2 Acquisition IMG/IPOL/LSS (1 loop)
90
  FORS2 Acquisition MOS/MXU/PMOS (1 loop) 120
  FORS2 Through Slit Image (2 loops w/o exp. times)[1] 240
  FORS2 Instrument Setup 30
  FORS2
Collimator exchange
270
  FORS2 Retarder Plate Setup per PMOS/IPOL OB 60
  FORS2 E2V Read-out 100kHz binned (2x2, spectroscopy) 34
  FORS2 E2V Read-out 100kHz unbinned (1x1, spectroscopy) 102
  FORS2
E2V Read-out 200kHz binned (2x2, imaging)
23
  FORS2
E2V Read-out 200kHz unbinned (1x1, imaging)
59
  FORS2 MIT Read-out 100kHz binned (2x2, spectroscopy) 34
  FORS2 MIT Read-out 100kHz unbinned (1x1, spectroscopy) 102
  FORS2 MIT Read-out 200kHz binned (2x2, imaging) 23
  FORS2 MIT Read-out 200kHz unbinned (1x1, imaging) 59
  KMOS Acquisition, MOSAIC setup 0
  KMOS Acquisition, non-MOSAIC setup, without exposure time, per cycle (2 cycles usually necessary): 300
  KMOS - : interaction + image reconstruction 35
  KMOS Acquisition (2nd OB in a concatenation, MOSAIC and non-MOSAIC setups): arms parking and deployment 240
  KMOS Read-out + writing image to disk 6
  KMOS Image reconstruction 20
  KMOS Offset (dither, i.e. within individual IFUs) 9
  KMOS Offset to sky 45
UT2   Preset + GS acquisition + active optics
360
UT2   Preset  + GS acquisition + active optics (2nd OB and following in a concatenation)
(40+target separation in deg)+60
  FLAMES Acquisition[2] 420
  FLAMES Instr. Setup GIRAFFE 60
  FLAMES Instr. Setup UVES 60
  FLAMES CCD read-out GIRAFFE 60
  FLAMES CCD read-out UVES 60
  FLAMES Screen Flatfields 420
  FLAMES Plate Configuration[3] 0-1200
  VISIR Target acquisition: normal and burst-mode imaging, blind 120
  VISIR Target acquisition: normal and burst-mode imaging, and coronagraphy, 1 loop, incl. exposure 420
  VISIR Target acquisition: SAM and coronagraphy, 1 loop, incl. exposure 900
  VISIR Target acquisition: spectroscopy (>1 Jy source) 900
  VISIR Target acquisition: spectroscopy (0.2 to 1 Jy source), incl. exposure 1200
  VISIR Chopping and nodding duty cycle losses 50% of exposure time
  UVES Instrument Setup 60
  UVES Acquisition. Bright Point Source 120
  UVES Acquisition. Faint, Extended or Crowded Field 300
  UVES Duty cycle Red arm[5], 1x1, Fast 47
  UVES Duty cycle Red arm[5], 1x2, Fast (VM only) 28
  UVES Duty cycle Red arm[5], 2x2, Slow 52
  UVES Duty cycle Red arm[5], 2x3, Slow (VM only) 39
  UVES Duty cycle Red arm[5], 1x1, Ultra-fast (VM only)
19
  UVES Duty cycle Blue arm[5], 1x1, Fast 46
  UVES Duty cycle Blue arm[5], 1x2, Fast (VM only) 32
  UVES Duty cycle Blue arm[5], 2x2, Slow 48
  UVES Duty cycle Blue arm[5], 2x3, Slow (VM only) 37
  UVES Duty cycle Blue arm[5], 1x1, Ultra-fast (VM only)
22
  UVES Attached ThAr, Night time; set-up dependent, see User Manual Table 4.2
41 to 89
  UVES Attached Flat, Night time; set-up dependent, see User Manual Table 4.2
44 to 190
UT3   Preset + GS acquisition + active optics
360
UT3   Preset  + GS acquisition + active optics (2nd OB and following in a concatenation)
(40+target separation in deg)+60
  SPHERE Acquisition with GoTo template (2nd OB and following in a concatenation)
180
  SPHERE Acquisition with Hopback template (2nd OB and following in a concatenation)
60
  SPHERE Acquisition without coronagraph centering
600
  SPHERE Acquisition with coronagraph centering
900
  SPHERE Flux measurement (incl. exposure)
210
  SPHERE Centering measurement (incl. exposure)
210
  SPHERE IFS observations, per exposure
NDIT*1.7+10
  SPHERE IFS observations, per dithering position
4
  SPHERE IRDIS observations, per exposure
NDIT*0.85+10
  SPHERE IRDIS observations, per dithering position
4
  SPHERE IRDIS_LSS observations, attached wavelength calibration
210
  SPHERE ZIMPOL observations, per exposure, StandardImaging readout mode
NDIT*0.1+3
  SPHERE ZIMPO observations, per exposure, FastPolarimetry readout mode
NDIT*0.1+3
  SPHERE ZIMPOL observations, per exposure, SlowPolarimetry readout mode NDIT*0.1+13
  SPHERE ZIMPOL observations, per polarimetric cycle 2*5
  SPHERE ZIMPOL observations, per dithering position 5
  SPHERE ZIMPOL observations, per number of field angle values 5
  XSHOOTER Target acquisition (3 loops, incl. telescope offset and AG readout time; excl. AG integration time): direct/blind 49/65
  XSHOOTER Telescope offsetting 15
  XSHOOTER Instrument setup Slit 30
  XSHOOTER Delay before start of each exposure: UVB 10
  XSHOOTER Delay before start of each exposure: VIS 10
  XSHOOTER Delay before start of each exposure: NIR 10
  XSHOOTER UVB Read-out[4], 1x1, Slow/Fast 68/16
  XSHOOTER UVB Read-out[4], 1x2, Slow/Fast 34/8
  XSHOOTER UVB Read-out[4], 2x2, Slow/Fast 17/4
  XSHOOTER VIS Read-out[4], 1x1, Slow/Fast 89/21
  XSHOOTER VIS Read-out[4], 1x2, Slow/Fast 45/11
  XSHOOTER VIS Read-out[4], 2x2, Slow/Fast 22/5
  XSHOOTER NIR Read-out (per DIT) 1.46
  XSHOOTER AG camera detector Read-out 1
  CRIRES Acquisition with AO
240
  CRIRES Acquisition without AO
150
  CRIRES Read-out
2.4 + 1.43 x (NDIT-1)
  CRIRES Nodding cycle (AB or BA)
28
  CRIRES Change of wavelength setting
80
  CRIRES Metrology in Y, J, H, L and M[8]
110
  CRIRES Metrology in K[8]
160
  CRIRES Attached wavelength calibration
180
  CRIRES Attached lamp flat
90
  CRIRES Change of derotator position angle[9]
2 + 76 x abs(PA1-PA2) / 360
  CRIRES Polarimetry - one Stokes V cycle 46
  CRIRES Polarimetry - one Stokes Q or U cycle
56
  CRIRES  Telescope offset (Generic Offsets) 14
UT4   Preset + GS acquisition + active optics
360
UT4   Preset  + GS acquisition + active optics (2nd OB and following in a concatenation)
(40+target separation in deg)+60
  HAWK-I Blind acquisition in No AO mode and Instrument Setup 60
  HAWK-I Acquisition (Move to Pixel) in No AO mode and Instrument Setup 180
  HAWK-I Blind acquisition with GRAAL and Instrument Setup 180
  HAWK-I Acquisition (Move to Pixel) with GRAAL and Instrument Setup 300
  HAWK-I Telescope offset (large) 45
  HAWK-I Telescope offset (small) 9
  HAWK-I Read Out (per DIT), normal observation
1.8
  HAWK-I Read Out (per DIT), FastPhot/Burst NXxNYx1.e-06
  HAWK-I Filter Change 21
  HAWK-I Header merging 5
  HAWK-I After exposure overhead w/o AO 8
  HAWK-I After exposure overhead with AO 16
  ERIS Acquisition (NGS)
300
  ERIS Acquisition (LGS) 360
  ERIS Acquisition (LGS-SE, no TT) 240
  ERIS Acquisition (noAO) 60
  ERIS Telescope offset (<=0.5") 5
  ERIS Telescope offset (>0.5") 15
  ERIS IFS - Acquisition (no interactive centering)
45
  ERIS IFS - Acquisition (interactive centering) 90
  ERIS IFS - Readout/transfer per NEXP 2.14*NDIT+1.14
  ERIS IFS - Persistence recording per NOFF
12
  ERIS IFS - Change of grating between hi-res gratings 5
  ERIS IFS - Change of grating (all others) 160
  ERIS NIX Imaging/APP/SAM - Acquisition (no interactive centering)
45
  ERIS NIX Imaging/APP/SAM - Acquisition (interactive centering) 90
  ERIS NIX FPC - Acquisition 180
  ERIS NIX LSS - Acquisition 180
  ERIS NIX Imaging/APP/SAM - Readout/transfer per NEXP (slow, windowF) 2.37*NDIT+2.74
  ERIS NIX Imaging/APP/SAM - Readout/transfer per NEXP (slow, window1) 1.89*NDIT+1.79
  ERIS NIX Imaging/APP/SAM - Readout/transfer per NEXP (slow, window2) 1.69*NDIT+1.59
  ERIS NIX Imaging/APP/SAM - Readout/transfer per NEXP (slow, window3/4) 1.29*NDIT+1.19
  ERIS NIX Imaging/APP/SAM - NDIT skip/readout/transfer per NEXP (fast, windowF/1/2/3/4) 10*DIT+0.5
  ERIS NIX Imaging/APP/SAM - NDIT skip/readout/transfer per NEXP (fast, windowF, cube mode, DIT>0.154s) 10*DIT+0.5
  ERIS NIX Imaging/APP/SAM - NDIT skip/readout/transfer per NEXP (fast, windowF, cube mode, DIT<=0.154s) 10*DIT+0.5+NDIT*(0.154-DIT)
  ERIS NIX Imaging/APP/SAM - NDIT skip/readout/transfer per NEXP (fast, window1, cube mode, DIT>0.116s) 10*DIT+0.5
  ERIS NIX Imaging/APP/SAM - NDIT skip/readout/transfer per NEXP (fast, window1, cube mode, DIT<=0.116s) 10*DIT+0.5+NDIT*(0.116-DIT)  
  ERIS NIX Imaging/APP/SAM - NDIT skip/readout/transfer per NEXP (fast, window2, cube mode, DIT>0.077s) 10*DIT+0.5
  ERIS NIX Imaging/APP/SAM - NDIT skip/readout/transfer per NEXP (fast, window2, cube mode, DIT<=0.077s ) 10*DIT+0.5+NDIT*(0.077-DIT)
  ERIS NIX Imaging/APP/SAM - NDIT skip/readout/transfer per NEXP (fast, window3/4, cube mode, DIT>0.039s) 10*DIT+0.5
  ERIS NIX Imaging/APP/SAM - NDIT skip/readout/transfer per NEXP (fast, window3/4, cube mode, DIT<=0.039s) 10*DIT+0.5+NDIT*(0.039-DIT)
  ERIS NIX Imaging/APP/SAM -  persistence recording per NOFF 7
  ERIS NIX Imaging/APP/SAM - change of camera 60
  ERIS NIX Imaging/APP/SAM - change of filter [10] 15
  MUSE Acquisition: Slow Guiding System loop closure 20
  MUSE Closure of AO loops (all AO modes) 180
  MUSE Detector setup 15
  MUSE Detector readout + file merging 60
  MUSE Intra-exposure detector delay (for multiple exposures) 5
  MUSE Small telescope offset < 2 arcmin 15
  MUSE Large telescope offset > 2 arcmin 45
  MUSE Slow Guiding System closure after offset 10
  MUSE Derotator offset - WFM 5 + 0.11/deg
  MUSE Derotator offset - NFM 5 + 1.1/deg
  MUSE Attached calibration - WFM 20 + 106/flatfield exposure + 112/arc lamp exposure
  MUSE Attached calibrations - NFM 20 + 162/flat field exposure + 148/arc lamp exposure (at least 1 per lamp - 3 lamps )
  MUSE Return to origin (no offset/small offset/large offset) 0/15/45
ICCF   Preset any UT + GS acquisition + active optics
360
ICCF   Preset  any UT + GS acquisition + active optics (2nd OB and following in a concatenation)
(40 + target separation in deg) + 60
ICCF
  Additional overheads in 4-UT mode 120
  ESPRESSO Target acquisition in 1-UT mode 45
  ESPRESSO Target acquisition in 4-UT mode
300
  ESPRESSO Instrument setup 30
  ESPRESSO Readout, transfer, wiping; HR11, 1x1_FAST 45
  ESPRESSO Readout, transfer, wiping; HR21, 2x1_SLOW 68
  ESPRESSO Readout, transfer, wiping; HR84, 8x4_SLOW 36
  ESPRESSO Readout, transfer, wiping; UHR11, 1x1_FAST 45
  ESPRESSO Readout, transfer, wiping; MR42, 4x2_SLOW 41
  ESPRESSO Readout, transfer, wiping; MR84, 8x4_SLOW 36
VLTI      
  GRAVITY One calibrated visibility, CAL-SCI [6], [7] 3600
  GRAVITY One calibrated visibility, CAL-SCI-CAL[6], [7] 5400 (requires waiver)
  GRAVITY Swapping template in dual-field observation 300
  GRAVITY Dual-field wide SCI-only observation[7] 1800
  MATISSE LM-band low and med resolution, no N-band phot CAL-SCI [6]   2400
  MATISSE LM-band low and med resolution, no N-band phot CAL-SCI-CAL [6] 3600
  MATISSE LM-band low and med resolution, with N-band phot CAL-SCI [6] 3600
  MATISSE LM-band low and med resolution, with N-band phot CAL-SCI-CAL  [6] 5400
  MATISSE L-band high and high+ resolution, no N-band phot CAL-SCI [6] 3000
  MATISSE L-band high and high+ resolution, no N-band phot CAL-SCI-CAL [6] 4500
  MATISSE L-band high and high+ resolution, with N-band phot CAL-SCI [6] 4200
  MATISSE L-band high and high+ resolution, with N-band phot CAL-SCI-CAL  [6] 6300
  PIONIER Hmag -1.0 to 6.0 One calibrated Visibility CAL-SCI-CAL [6] 1800
  PIONIER Hmag -1.0 to 6.0 One calibrated Visibility CAL-SCI-CAL-SCI-CAL [6] 2700
  PIONIER Hmag 6.1 to 7.5 One calibrated Visibility CAL-SCI-CAL [6] 2400
  PIONIER Hmag 6.1 to 7.5 One calibrated Visibility CAL-SCI-CAL-SCI-CAL [6] 3600
  PIONIER Hmag 7.6 to 9.0 One calibrated Visibility CAL-SCI-CAL [6] 2700
  PIONIER Hmag 7.6 to 9.0 One calibrated Visibility CAL-SCI-CAL-SCI-CAL [6] 4500

Direct links to instruments on UT1, UT2, UT3, UT4, ICCF, VLTI.


[1] Through-slit exposures are mandatory for all spectroscopic OBs. Two cycles are typically enough to center the target on the slit (exposure time of the through slit image not included). MXU,MOS,PMOS,LSS,ECH 2.0 min (per cycle), IMG and IPOL none.

[2] Includes configuration of UVES fibres, homing the rotator to zero degrees, swapping of the plates, and the acquisition of field. For ARGUS fast acquisition (VM only), the acquisition overhead is 2 minutes and is calculated assuming that plate 2 is already attached to the telescope.

[3] Plate configuration takes 20 minutes at most (Medusa fibres). This does not translate into additional overheads if the running exposure on the other plate is at least 20 minutes long. Plate configuration overheads have to be added if the exposure time is shorter than 20 minutes.

[4] Detectors are read sequentially.

[5] Duty cycle includes readout, writing image to disk, and detector wiping. In a dichroic exposure the CCDs are read out in parallel: only the longest duty cycle must be taken into account.

[6] This time includes all telescope and instrument overheads as well as the integration times on the science target and the calibrator. In p1, set the time from this table in the total "Telescope Time" field (in the blue box), and leave the details of the observations unused; cf. this example in p1demo.

[7] Setting MET.MODE = FAINT in GRAVITY OBs leads to an increased overhead of 1 second per detector integration (DIT). It is therefore recommended only for faint targets in dual-field observations where DIT > 10s. Users are recommended to check the execution times using the P2 demo account.

[8] If the metrology is enabled in the acquisition template, but not the science template(s), then no overheads associated to the metrology apply.

[9] If done in parallel with a change of the wavelength setting, the overhead listed here does not apply.

[10] Can be done in parallel with a change of camera.