On this page, we list the main changes that affected the instrument status during its lifetime. Note that these are in general changes that also influence the calibration database to be used.

• 2019 1st Oct: NACO is being decommissioned after P103.
• 2018 Nov 03: NACO is up and running. Concerning detector behaviour: the lower left quadrant is still bad (repeating a pattern of 2 bad, 3 good, 1 bad, 2 good) but the upper right one has not shown any stripes so far. 
• 2018 Oct 24: NACO is being warmed up for a regular maintenance intervention on the closed cycle cooler.
• 2018 Sep 06: Due to unrecoverable problems, the visible wavefront sensor was decommissioned at the end of July 2018 and will not be offered in Period 103.
  
• 2018 July 12: The intervention on the visible wavefront sensor was unsuccessful. NACO is back in operation but only with the IR WFS. It is not yet decided if and when a new attempt will be made to repair the Vis WFS.
• 2018 June 11: We noticed that the density filter of the visible wavefront sensor is not working properly anymore, This can damage the electronics of the senso. The Vis WFS has thus been put into simulation for the moment. The tentative date for repair is the  week of 3-9 July.
• 2018 April 25th: The intervention to fix the retarder plate has been scheduled for 20-25th May 2018. Success!
  
• 2018 April 17th: NACO polarimitry has not been available since 12th April 2018 due to an issue with the retarder. An intervention to fix the problem is currently being planned. Other modes of NACO are unaffected by this problem. NACO is currently in operation.
  
• 2018 March 26th: CONICA detector warmed up accidently. We are currently colling down and will report on the quality of the detector once it is operational again.
• 2018 March: The stripes on the upper right hand quadrant of NACO are increasing in frequency and almost permanent now. In addition, the pattern on the lower left quadrant remains unchanged.
  
• 2018 March: NACO is back with all modes. The electronics of the vis WFS are a bit unstable but working. The IR 9-s modes are not yet properly calibrated. The stripes in the lower left quadrant remain unchanged from the June 2017 reports (below).
• 2018-02-08: It was not possible to echange the electronics for the visible WFS. Until a solution is found the visible WFS remains out of operation.
• 2018 January: NACO is up and working again. However, the electronics of the Visible WFS have problems which will be fixed by the end of January, Until then, only the IR WFS can be used.
• 2017 December 12th: After a blackout NACO has suffered some electrical damage which affects the backplane of the instrument. An intervention is currently being planned to repair the damage. Until then NACO is NOT operational. 
  
• After an unplanned warm-up due to a power cut, the upper right quadrant of the detector occasionally shows stripes again.
  
• 2017 July 28th: The gain on FNS-HighSens mode has been adjusted, so that the saturation limit is back to the old value of 4500ADU. Recent monitoring of the detector has shown that it is much more stable than before the warmup. The lower left quadrant is still bad (repeating a pattern of 2 bad, 3 good, 1 bad, 2 good) but the upper right one has not shown any stripes so far. Linearity is stable in all modes.
• 2017 July 17th: Fowler sampling detector linearity changed
• 2017 June 27th: The emergency intervention went well, the detector temperature is back to normal and can be controlled. Intensive tests showed no damage to the detector due to the warm-up. The pattern of bad columns on the lower left quadrant has changed, the frequency of bad columns increased. NACO will be back in operation tonight.
  
• 2017 June: We have no control of the detector temperature anymore; an emergency maintenance of the Closed Cycle Cooler  for CONICA must be carried out. NACO will be out of operation from 18th June to 27th June.
  
• 2017 April 20th: The Conica detector has been very unstable over the last months. We occasionally notice stripes on the upper right quadrant (similar to the known ones on the lower left one). Since they often appear only in some DITs, they might go unnoticed in a normal exposure. If you are interested in precise photometry, either use cube mode or stick to UL or LR quadrants only. For DCR and FNS readout modes, the linearity range is changing randomly. We increased the monitoring frequency for these modes. To se the status for a certain night, check out this QC page: http://www.eso.org/observing/dfo/quality/NACO/reports/HEALTH/trend_report_DETMON_LIN_HC.html
  
• 2016 December 5th: Field stop was re-aligned and AO modes significantly reduced. The remaining ones are well charecterised to allow good AO corrections for various atmospheric conditions.
• 2016 September 30th: Change of FPN after new sequencer board had to be installed in CONICA.
• 2016 September 29th: Problems with CONICA detector readout.
• 2015 December 24th. Wollaston prism, slits and 7 Hole SAM mask have been aligned.
  
• 2015 December 14th. All modes offered in SM are operational. Some modes in VM need some further checks: grism spectroscopy, Wollaston
  polarimetry, SAM/SAMPol. Quadrant 4 (upper right) has been recovered during the intervention, HOWEVER, quadrant 2 (lower left) has not been recovered: 1 in 8 columns has no signal.  The other columns are responding normally. We still suffer from a high background. An image of full frame dark is visible here with the raw fits image being available here.  Although the image appears not to be full frame this is infact a display effect.
  
• 2015 December 3rd. NACO is cold and day-time tests ongoing. On-sky comissioning is due to occur on December 6th and 7th.
• 2015 October 4th. NACO has been removed from UT1 for a major intervention due to last several weeks.
• 2015 August 25th: For P97 spectroscopy will no longer be available and only long wave coronography will be offered (AGPM).
• 2015 June 29th: Eight attempts to warm up and cool down the NACO detector have been made, but the upper right hand quadrant still is not suitable for most science. No further action will be taken to fix this until a likely major intervention starting in September/October. The objective is fixed in S13. The extra background level caused by insufficient shielding in the instrument varies from around 30 to 60 electrons per second depending on the region of the detector. See the following image of a 300s dark: http://www.sc.eso.org/~jsmoker/NACO/NACO_Dark_300s.NACO.2015-06-25T12:01:49.031.fits.png
• 2015 June 28th: NACO exposure time calculator appears to be overestimating the counts in imaging by between ~25 and ~50 percent. To be fixed at the next release.
• 2015 June 22nd: NACO is cool but the upper hand quadrant shows problems. To be decided if a thermal cycling of the detector will be able to fix the issue. 
• 2015 June 14th: There was a power cut on Paranal and NACO warmed up along with other instruments. 
• 2015 June 8th: NACO is now cold and fixed in the S13 objective (1.0 to 2.5 microns). Initial on-sky observations look promising.
  
• 2015 May 21st: The camera filter wheel has again stuck and is in an intermediate position so NACO is out of service and another intervention is required.
  
• 2015 May 5th: NACO is cooling down after the intervention.
• 2015 April 24th: NACO has had to be warmed up again due to a problem with the camera filter wheel. 
• 2015 March 20th: NACO is unavailable. The mechanism that allows to switch objectives suffered a severe failure and CONICA had to be warmed up to be serviced. In addition, a special intervention has been planned to reduce the cryostat background noise (through improved thermal shielding) at the beginning of April. All together it is very unlikely that regular science operations with NACO resume before mid to end of April.
• 2015 March 4th: The detector SW was rebuilt, new FPN.
• 2015 January 17th: NACO is resuming operations! The AO performances are nominal and all offered modes have been recommissioned. The new Aladdin2 (former ISAAC LW) detector installed in CONICA features slightly different noise properties than the Aladdin3. In addition, there is a significant additional thermal background that will slightly reduce the dynamic range and detection limits when long exposure times are used, associated with short wavelength broadband filters. The L' band is little affected. We are working towards finding a solution to bring down the level of this spurious background (about 70 electrons/pixel/second) in the coming months. A web page dedicated to the characterisation of the replacement detector and the thermal background is in preparation. In the mean time, we will proceed with the observations that are not affected and may contact corresponding PIs if we have a doubt. The User Manual and ETC for Period 95 remain unchanged until the detector characterisation is better defined.
• 2014-12-31: New detector (Aladdin2) installed
• 2014 September 16th: The recomissioning of NACO on UT1 scheduled earlier this month could not take place due to a failure of CONICA's detector.  Recovering the detector requires a deeper intervention. 
• 2014 September: NACO is being moved to UT1.
• 2013 August 30th: NACO is temporarily offered on the UT4 Nasmyth A focus during Period 93 - until the focus is necessary for AOF-related activities - with a limited list of offered modes. Please check the P93 Call for Proposals to be published on Monday September 2nd 2013.
• 2013 June 28th: Offical Announcement; On account of the activities related to the installation of MUSE, NACO will be dismounted from the Nasmyth platform of UT4 and unavailable from 2 September 2013. NACO will therefore be unavailable for the whole duration of Period 92. The instrument will be stored for future re-use.
• 2012 December 12th: After a week of hard work, the IR-WFS is back!
• 2012 December 5th: The IR-WFS is currently unavailable. 
• 2012 November 30th: An annular groove phase mask (AGPM)- commonly known as "vortex coronagraph" - was insterted inside CONICA . It is optimized for 4 microns (NB_3.74, NB_4.05 and L_prime filters only) and is currently beeing tested. We will try to make it available for P91 Phase II upon test results. The User Manual will then also be updated. The observing mode remains the same as LW Lyot coronagraphy, only we hope to improve the inner-working angle to ~1 lambda/D rather than 700 mas (C_0.7 mask) corresponding to ~7 lambda/D at 4 microns.
• 2012 November 16th: The 6-week intervention carried out on CONICA was successful. A new cooling system has been installed (less vibrations and more reliability), all 4 detector quadrants are working, the non-common path aberrations have been calibrated and we resumed normal operations.
• 2012 October 1sr: NACO is not be available from October 1st to ~mid-November (6 weeks of intervention as stated in the P90 call for proposals). 
• 2012 September 5th: NACO is fully back to operations, including with the IR-WFS and the LGS.
• 2012 Aug 25th: Due to a serious, partially recovered, issue with NACO's field selector electronics, the IR-WFS modes are currently unavailable.
• 2012 May 2nd: UT4 and NACO have been recommissioned after the 6-week ceasure (AOF work on UT4). The operations resumed normally (CONICA detector included) and the performances are ok.
• 2012 March 26th: The CONICA detector issue (reported here on Feb 15th 2012) has disappeared or at least has diminished to an acceptable level of ~5 ADU RMS. Visually, one can see worst frames than others (every 20 or so). It is currently impossible to know in which state the detector will be when operations resume on May 3rd 2012).
• 2012 February 15th: The detector of CONICA is suffering from a strong electronic pattern affecting the two 512x512 upper quadrants (northern quadrants at a position angle of 0 deg). There are vertical stripes (image1,image2) every 8 columns featuring a RMS readout noise about a factor 3 higher than normal (~30 ADU peak to peak for these column using the Double_RdRstRd mode). Please note that the affected quadrants are not blind, but the data quality will of course be compromised (see attached image and cut for a 2-second dark frame).
  
• 2011 October 15th (beginning of P88): The drift associated to pupil tracking is now fixed! NACO is therefore more suited for high contrast imaging and can be used with coronagraphic masks in the image plane (Lyot, 4QPM) without much issue. The residual drift of about 1 pix/hour (very much acceptable) can be attributed to an imperfect flexure compensation model.
• 2011 April 26th: all visible WFS (NGS/LGS 7x7, NGS 14x14,LGS 14x14) are back in service! The performance level reached during recommissioning is the same as prior to the intervention (on month ago).
  
• 2011 March 6th: the 7x7 VIS-WFS (NGS and LGS) is not available and for probably a few weeks. Other WFS (14x14 VIS, 14x14 IR, 7x7 IR and 14x14 LGS) are available.
  
• 2010 March 15th: new modes are offered in P86 (see call for proposals). The web pages have been updated and the P86 user manual is now available.
  
• 2009 Sept 12th:SAMPol and Seeing enhancer have been succesfully commissioned and are offered for P85. Cube imaging, alsoknown as lucky imaging is offered in SM for P85.
  Chopping is decommissioned from P85 onward.
• 2008 Nov. 15th: all the new modes of NaCo are offered in VM and have been succesfully proven on sky: SAM, pupil tracking, cube mode and SDI+4. The modes work well and some last minute improvements have been documented in the web pages.
• 2008 June 24th: 

1. SAM: the Mode has been successfully commissioned. We are working on the templates. Sparse aperture mask interferometry uses special aperture masks in the pupil wheel to obtain the very highest angular resolution at the diffraction limit. When used correctly, these masks transform the single 8-m telescope pupil into a sparse interferometer array, and it is therefore necessary to understand the principles of optical interferometry and in particular the recovery of complex Fourier data(amplitudes and phases) from the Fizeau interference patterns that result.
2. Cube mode - The mode is in advance stage of characterization. This mode is a variant of the of the burst mode already offered with VISIR and ISAAC. In this mode, a data-cube with each single DIT frame is saved. This mode is particularly interesting for lucky-imaging typeof observations, where one wants to select the best frames out of a set before co-adding them. The mode is not suited for time resolved applications, since we have no way to time-stamp each single DIT frame and we occasionally lose frames. 
3. Pupil tracking mode for imaging applications (includes 4QPM coronagraphy and SDI+) - Tentatively offered, pending commissioning.

4. Pupil tracking mode is being implemented to support SAM, but given the demand from the community, it will be tentatively offered for use with imaging and 4QPM coronagraphic observations. In this mode, the telescope, independently from NaCo, tracks the pupil instead of the field.This new tracking mode opens the possibility to do Angular Differential Imaging (ADI), a high contrast imaging technique that reduces quasi-static speckle noise and facilitates the detection of nearby companions.

• 2008 March 19th: a bug in the ETC caused off-axis S/N values to be systematically overestimated (that is, cases where the target and AO reference bjects differed). This bug only affected the imaging ETC as called via the NAOS Preparation Software (NAOS-PS). The bug has bee fixed.
• 2008 February: News in the Call for Proposals P82. New modes tentatively offered (pending commissioning): cube mode in imaging (NGS only), Sparse Aperture Interferometric Masks, Pupil Tracking with imaging and coronagraphy.
• 2007 September 23-24: commissioned the SDI+4 mode: SDI+ with Coronagraphic 4QPM_H
  
• 2007 August 24: News in the Call for Proposals P81 
• 2007 April 03: Laser guide star facility: observing policies
• 2007 March 15: Novelties in the Call for Proposal P80
• 2006 February 28: Novelties in the Call for Proposal P78
• 2006 February 23: Latest important news about chopping
• 2006 February 16: Latest news about the SDI
• 2004 October 21, 2004: Important news for service and visitor, concerning chopping & SDI observations.
  
• 2004 June 1: The new detector recently installed in CONICA, becomes operational.
• 2004 May 14: New detector (Aladdin3 array) installed in CONICA