HAWK-I was commissioned during Periods 79 and 80 and then began operations at the start of P81. Since then it has sufferred to varying degrees from several problems which afect the quality of the data. This page summarises the different problems that have affected the data quality with an indication of which periods of time the different problems have affected the data. Details for each page are provided in spearate web pages for each problem, and are linked to from this page.

All data to date...

• Cosmetic quality: The HAWK-I chips have a number of cosmetic features, which are described in section B.2 of the User's manual.
• Radioactive Events: Chip No. 2 ( #78 ) is subject of charge collection induced by radioactive events (13 events per minute).
• Spider Web Patterns in DARKS: A "spider web" like pattern is clearly seen in CHIP1 DARK frames for DITs less than about 40sec, except when the minimum DIT is used.

Some of the data...

• Crosstalk between amplifiers: [All data prior to 2009-05-07, i.e. all periods prior to, plus part of P83] Crosstalk between the amplifiers of the chips produces a series of 'crater-like' artifacts arrayed horizontally with respect to each 'bright' star in the field.
  By adjusting certain voltages of the detector electronics this effect has been virtually eliminated. In addition this change reduced the Readout Noise of the detectors, but increased the minimum-DIT from 1.2572sec to 1.6762sec. This change was applied at approximately 2009-05-07T21:30.
• Central Flare-like feature: Intermittently, for periods of months, a flare-like feature appears at the centre of the four chip array, i.e. where the four chips meet each other, see here.

Some of the data...

• Pupil Ghosts: [2008-04-01 and 2008-08-20, i.e. most of P81]
• Wrong CD matrix WCS transformation coefficients: [P81]

Features...

• Cosmetic quality: The HAWK-I chips have a number of cosmetic features, which are described in section B.2 of the User's manual.
• Radioactive Events: Chip No. 2 ( #78 ) is subject of charge collection induced by radioactive events (13 events per minute).
• Spider Web Patterns in DARKS: A "spider web" like pattern is clearly seen in CHIP1 DARK frames for DITs less than about 40sec, except when the minimum DIT is used.
• Central Flare-like feature: Intermittently, for periods of months, a flare-like feature appears at the centre of the four chip array, i.e. where the four chips meet each other, see here.

Features...

• Cosmetic quality: The HAWK-I chips have a number of cosmetic features, which are described in section B.2 of the User's manual.
• Radioactive Events: Chip No. 2 ( #78 ) is subject of charge collection induced by radioactive events (13 events per minute).
• Spider Web Patterns in DARKS: A "spider web" like pattern is clearly seen in CHIP1 DARK frames for DITs less than about 40sec, except when the minimum DIT is used.

Features...

• Cosmetic quality: The HAWK-I chips have a number of cosmetic features, which are described in section B.2 of the User's manual.
• Radioactive Events: Chip No. 2 ( #78 ) is subject of charge collection induced by radioactive events (13 events per minute).
• Spider Web Patterns in DARKS: A "spider web" like pattern is clearly seen in CHIP1 DARK frames for DITs less than about 40sec, except when the minimum DIT is used.

Features...

• Cosmetic quality: The HAWK-I chips have a number of cosmetic features, which are described in section B.2 of the User's manual.
• Radioactive Events: Chip No. 2 ( #78 ) is subject of charge collection induced by radioactive events (13 events per minute).
• Spider Web Patterns in DARKS: A "spider web" like pattern is clearly seen in CHIP1 DARK frames for DITs less than about 40sec, except when the minimum DIT is used.
• Crosstalk between amplifiers: [All data prior to 2009-05-07, i.e. all periods prior to, plus part of P83] Crosstalk between the amplifiers of the chips produces a series of 'crater-like' artifacts arrayed horizontally with respect to each 'bright' star in the field.
  By adjusting certain voltages of the detector electronics this effect has been virtually eliminated. In addition this change reduced the Readout Noise of the detectors, but increased the minimum-DIT from 1.2572sec to 1.6762sec. This change was applied at approximately 2009-05-07T21:30.
• Change of the detector read speed 2009-05-07 : The HAWKI detector read speed has been changed for reasons to reduce the electronic ghosts.

  Before 2009-05-07T21:30 it was:

  HIERARCH ESO DET VOLT1 DC6   = 2.4000 / Set value DC-Voltage
  HIERARCH ESO DET VOLT1 DC7   = 3.4000 / Set value DC-Voltage
  HIERARCH ESO DET RSPEED      = 6 / Read-Speed Factor
  HIERARCH ESO DET MINDIT      = 1.2572000 / Minimum DIT                
  

  From 2009-05-07T021:30 on it is:

  HIERARCH ESO DET VOLT1 DC6   = 2.1000 / Set value DC-Voltage
  HIERARCH ESO DET VOLT1 DC7   = 3.6000 / Set value DC-Voltage
  HIERARCH ESO DET RSPEED      = 8 / Read-Speed Factor
  HIERARCH ESO DET MINDIT      = 1.6762000 / Minimum DIT     
  

  Consider 2009-05-07T21:30 as a breakpoint to associate calibrations. Do not use twlight flats or darks acquired before 2009-05-08 to calibrate science data acquired after 2009-05-08 and vice-versa.
• No added counts on NDIT : In 2009-06 some dark setups have been acquired with a wide range of NDIT. The following setups have been taken:

  DET.DIT=1.6762 (= DET.MINDIT)

  3 frames with NDIT=1
  3 frames with NDIT=5
  3 frames with NDIT=20
  3 frames with NDIT=100
  

  The dark level was found to be (very) independent on NDIT

Features...

• Cosmetic quality: The HAWK-I chips have a number of cosmetic features, which are described in section B.2 of the User's manual.
• Radioactive Events: Chip No. 2 ( #78 ) is subject of charge collection induced by radioactive events (13 events per minute).
• Spider Web Patterns in DARKS: A "spider web" like pattern is clearly seen in CHIP1 DARK frames for DITs less than about 40sec, except when the minimum DIT is used.
• Crosstalk between amplifiers: [All data prior to 2009-05-07, i.e. all periods prior to, plus part of P83] Crosstalk between the amplifiers of the chips produces a series of 'crater-like' artifacts arrayed horizontally with respect to each 'bright' star in the field.
  By adjusting certain voltages of the detector electronics this effect has been virtually eliminated. In addition this change reduced the Readout Noise of the detectors, but increased the minimum-DIT from 1.2572sec to 1.6762sec. This change was applied at approximately 2009-05-07T21:30.
• Central Flare-like feature: Intermittently, for periods of months, a flare-like feature appears at the centre of the four chip array, i.e. where the four chips meet each other, see here.

Features...

• Cosmetic quality: The HAWK-I chips have a number of cosmetic features, which are described in section B.2 of the User's manual.
• Radioactive Events: Chip No. 2 ( #78 ) is subject of charge collection induced by radioactive events (13 events per minute).
• Spider Web Patterns in DARKS: A "spider web" like pattern is clearly seen in CHIP1 DARK frames for DITs less than about 40sec, except when the minimum DIT is used.
• Crosstalk between amplifiers: [All data prior to 2009-05-07, i.e. all periods prior to, plus part of P83] Crosstalk between the amplifiers of the chips produces a series of 'crater-like' artifacts arrayed horizontally with respect to each 'bright' star in the field.
  By adjusting certain voltages of the detector electronics this effect has been virtually eliminated. In addition this change reduced the Readout Noise of the detectors, but increased the minimum-DIT from 1.2572sec to 1.6762sec. This change was applied at approximately 2009-05-07T21:30.
• Central Flare-like feature: Intermittently, for periods of months, a flare-like feature appears at the centre of the four chip array, i.e. where the four chips meet each other, see here.

Problems...

• Pupil Ghosts: Between the last Commissioning/Science Verification run (which ended January 30th) and the start of operations in P81, the entrance window to the instrument cryostat suffered a significant degradation and operations began in less than optimum conditions. The problem was resolved during an intervention conducted 2008-08-20 -- 2008-08-24.
• Wrong CD matrix WCS transformation coefficients : (2009-05-08)

  The keywords affected are CD1_1, CD1_2, CD2_1, and CD2_2.
  In what follows the keywords ESO.ADA.POSANG = A.
  Previous to 2008-11-03 the incorrect formula used to write the above keywords
  were:
  
  WRONG: before 2008-11-03T00:05:00.000
  
  CDELTA1 = -2.956388483633E-05
  CDELTA2 = +2.956388483633E-05
  CD1_1 = +CDELTA1*cosA
  CD1_2 = -CDELTA2*sinA
  CD2_1 = +CDELTA1*sinA
  CD2_2 = +CDELTA2*cosA
  
  The correct formulas are:
  
  CORRECT: after 2008-11-03T00:05:00.000
  
  CDELTA1 = -2.956388483633E-05
  CDELTA2 = +2.956388483633E-05
  CD1_1 = +CDELTA1*cosA
  CD1_2 = -CDELTA1*sinA
  CD2_1 = +CDELTA2*sinA
  CD2_2 = +CDELTA2*cosA
  
  Notice that 2.956388483633E-05 = 0.1064300/3600,
  is the value stored in the keyword ESO.INS.PIXSCALE.
  

  The CD keys have been repaired for the data in the archive but frames with HIERARCH ESO ADA POSANG not 0 and not 180, -180 being delivered before the fix might be affected.

  How to correct ? Change the sign of CD1_2 and CD2_1 in all four fits extensions of the HAWKI frame.

HAWK-I was commissioned during Periods 79 [Apr 2007 -- Sep 2007] and 80 [Oct 2007 -- Mar 2008] and then began operations at the start of P81 [Apr 2008 -- Sep 2008].

Features...

• Cosmetic quality: The HAWK-I chips have a number of cosmetic features, which are described in section B.2 of the User's manual.
• Radioactive Events: Chip No. 2 ( #78 ) is subject of charge collection induced by radioactive events (13 events per minute).
• Spider Web Patterns in DARKS: A "spider web" like pattern is clearly seen in CHIP1 DARK frames for DITs less than about 40sec, except when the minimum DIT is used.
• Crosstalk between amplifiers: [All data prior to 2009-05-07, i.e. all periods prior to, plus part of P83] Crosstalk between the amplifiers of the chips produces a series of 'crater-like' artifacts arrayed horizontally with respect to each 'bright' star in the field.
  By adjusting certain voltages of the detector electronics this effect has been virtually eliminated. In addition this change reduced the Readout Noise of the detectors, but increased the minimum-DIT from 1.2572sec to 1.6762sec. This change was applied at approximately 2009-05-07T21:30.