NaCo News


On this page, we list the main changes that affected the instrument and this web site.

  • 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 May 24th: The intervention to fix the retarder plate has been successfull. NACO is up and running fine in all offered modes. Note that the detector issues remain the same as before.
  • 2018 April 25th: The intervention to fix the retarder plate has been scheduled for 20-25th May 2018.
  • 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.
  • 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.
  • NACO is up and working again.
  • December 12th, 2017: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. Stay tuned.
  • After an unplanned warm-up due to a power cut, the upper right quadrant of the detector occasionally shows stripes again.
  • 28th July: The gain on FNS-HighSens mode has been adjusted, so that the saturation limitis 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.
  • 27th June 2017: 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.
  • June 2017: 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.
  • April 20th 2017: 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:
  • December 5th 2016: 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.
  • For P99: All NACO modes are now offered in Service and Visitor mode. 
  • December 24th. Wollaston prism, slits and 7 Hole SAM mask have been aligned.
  • 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. Offsets must therefore take this fact into account. 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.
  • December 7th. Recomissioning is ongoing. User manual will be updated in due course.
  • December 3rd. NACO is cold and day-time tests ongoing. On-sky comissioning is due to occur on December 6th and 7th.
  • November 24th, 2015. Intervention onging. More news on 30th November.
  • November 4th, 2015. NACO currently warm, intervention ongoing.
  • October 23rd 2015. Intervention ongoing.
  • October 4th 2015. NACO has been removed from UT1 for a major intervention due to last several weeks. More news in mid-November.
  • August 25th 2015: For P97 spectroscopy will no longer be available and only long wave coronography will be offered (AGPM). See the manual and overview page for more information.
  • August 25th 2015: NACO intervention to start 1st October 2015 and last for around two months.
  • July 29th 2015: The precise date of the NACO intervention is under discussion but will start sometime between the window of 20th September to 5th October. More news when the exact date is known. At this point any affected visitor or designated visitor mode PIs will be informed.
  • July 3rd 2015: There will be a major intervention on NACO starting 1st October 2015 and due to last approximately two months.
  • June 29th 2015: 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 take 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:
  • June 28th 2015: 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.
  • June 22nd 2015: 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. More news in a few days.
  • June 14th 2015: There was a power cut on Paranal and NACO warmed up along with other instruments. More news when NACO is cold again. 
  • June 8th 2015: NACO is now cold and fixed in the S13 objective (1.0 to 2.5 microns). Initial on-sky observations look promising. More news soon.
  • May 24th 2015: To fix problem that affects the camera wheel requires a carefully planned, major intervention lasting for approximately 2 months likely to start in September 2015. Until then all attempts will be made to operate NACO with the S13 objective to enable the Galactic Centre astrometry. More news when NACO is back with the S13 objective. NACO currently out of operations.
  • May 21st 2015: The camera filter wheel has again stuck and is in an intermediate position so NACO is out of service and another intervention will be required. More information will be given on this webpage as soon as a concrete plan has been made. Visitors should get in touch with with cc to before coming to Paranal. 
  • May 5th 2015: NACO is cooling down after the intervention. More news soon. 
  • May 1st, 2015: Intervention has taken longer than hoped for and NACO likely not back in use until mid- to end-May.  More news will be given when it is clearer when we will be on-sky again.
  • April 29th, 2015: Intervention still ongoing with work on camera filter wheel and radiation shield. Instrument should be availabe on sky between 7th and 11th May. Hence visitor runs until 12th May will have to be rescheduled.
  • April 24th, 2015: NACO has had to be warmed up again due to a problem with the camera filter wheel. All visitor mode runs up until 5th May 2015 have been cancelled. More information on the situation will be given on this webpage on 29th April.
  • March 24th, 2015: Since March 20th, NACO has been 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.


  • February 27th, 2015: The P96 Call for Proposals is out. The P96 User Manual is online for Phase 1. The P93 Calibration Plan remains valid for P96. A new ETC for spectoscopy offers the possibility to use the new Paranal Advanced Sky Model. The ETC for imaging now includes the curremt extra  background contribution from CONICA and new readout noise values (Aladdin 2). The situation might improve for P96. 
  • January 17th, 2015: 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.
  • November 11th, 2014: We are sorry to say that there are still unresolved issues with NACO (for now believed to be confined to CONICA).  These issues are under investigation, but owing to their complex nature it is not possible at this time to make further statements about time scales for the return of NACO into operations. Please check this page again for updates.
  • September 16th, 2014: 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. We are very sorry about this unfortunate situation and all SM/VM runs planned for the end of P93 had to be canceled. While we hope to repair the detector and resume the commissioning as soon as possible, there is a significant risk for some P94 programs to be affected. More news will come shortly.
  • August 27th, 2014: The P95 Call for Proposals is out. The P93 Calibration Plan and P94 User Manual remain valid for P95. NACO is offered in P94 pending a successful recommissioning on UT1 in September 2014.
  • February 28th, 2014: The P94 Call for Proposals is out and the P94 User Manual is available for downloads (including the templates/keywords table). The P93 Calibration Plan remains valid for P94. We again warn users that the move from UT4/NasB to UT1/NasA that will take place early September has a non-negligible risk of failure.
  • January 16th, 2014: NACO will be mounted on UT1/NasA in place of CRIRES towards the end of P93. Only a few programs have been scheduled in September 2014. The P93 Phase 2 User Manual is online. 
  • September 12th, 2013: The P93 Phase 1 User Manual and Calibration Plan (issue 1) are online. Please, beware of the changes of the offered observing modes (P93 is the right most column).
  • August 30th, 2013: NACO will be 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.
  • June 28th, 2013: 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.
  • April 3rd, 2013: The first light paper of the AGPM coronagraph has just been accepted for publication in A&ALccepted for publication in A&AL (Mawet et al. 2013). For P91 the AGPM is offered in VM only via a setup change request.
  • March 1st, 2013: The PHASE-I version of the P92 User Manual is online (including the templates/keywords table). The P89 Calibration Plan (issue 4) is the latest to follow for P91-P92. The AGPM coronagraph section has been updated. For P91 it is offered to VM users who were awarded time for deep L'-band imaging with pupil tracking. They can request it via a setup change request prior to the start of their run. In P92 it will be offered in SM as well as we think all staff will be trained for it by then.
  • December 22th, 2012: The PHASE-II version of the P91 User Manual is online (now including the templates/keywords table). The P89 Calibration Plan (issue 4) is the latest to follow for P91. The AGPM coronagraph is now desscribed and will be (optionally) offered to users who were awarded time for deep L'-band imaging with pupil tracking. Please check for a new issue of the Manual around mid-February, it will contain more details about the AGPM.
  • December 12th, 2012: After a week of hard work, the IR-WFS is back!
  • December 5th, 2012: The IR-WFS is currently unavailable. News will be given shortly.
  • November 30th, 2012: 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.
  • November 20th, 2012: 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 on November 16th 2012. More news and information to come.
  • September 6th, 2012: The P91 Call for Proposals is out and the PHASE-2 version of the P91 User Manual is available for downloads (including the templates/keywords table). The P89 Calibration Plan remains valid for P91.
  • September 5th, 2012: we are very much pleased to announce that NACO is fully back to operations, including with the IR-WFS and the LGS. We shall resume P89 normally.
  • Aug 25th, 2012: Due to a serious, partially recovered, issue with NACO's field selector electronics, the IR-WFS modes are currently unavailable. If you have service mode OBs originally using the IR-WFS but that can be done with the VIS-WFS, please notice our USD colleagues as soon as possible. Please check regurlarly this web page for updates as we are working hard to recover all NAOS modes at the earliest convenience.
  • August 8th, 2012: We recall the P90 users that NACO will not be available from October 1st to ~mid-November (6 weeks of intervention as stated in the P90 call for proposals). We will do our best to resume operations as quickly as possible but please take this information into account while preparing and submitting your PHASE-II material. You might also want to check the Late Breaking News in November.
  • May 25th, 2012: The PHASE 2 version of the P90 User Manual is online (including the templates/keywords table).
  • May 25th, 2012: The PHASE 2 version (issue 4) of the P89 Calibration Plan (valid for P89 and onwards) is online.
  • May 5th, 2012: The PHASE 2 version (issue 3) of the P89 Calibration Plan (valid for P89 and onwards) is online.
  • May 2nd, 2012: 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.
  • March 26th, 2012: 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. Please check this page or contact USD for your SM material. In the case your programme absolutely requires the use of all quadrants, it may be wise to prepare two distinct strategies in caseone of two quadrant are to become noisy again for your run or for part of P89.
  • March 21th - May 3rd, 2012: Because of preparatory work for the installation of the Adaptive Optics Facility, Yepun is not available for operations.
    Observations with HAWK-I/NACO/SINFONI are therefore not possible.
  • February 29th, 2012: The PHASE 2 version of the P89 Calibration Plan (valid for P89 and onwards) is online.
  • February 24th, 2012: The PHASE 1 version of the P90 User Manual is online (including the templates/keywords table). Note that the CONICA detector issue described below could unfortunately extend through P89 and possibly P90 (we do not know when we will be able to fix it). Please be prepared with a backup strategy if it affects your program(s).
  • February 15th, 2012: the NACO Instrument Operations Team regrets to inform you that 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). The Paranal and Garching engineers and detector specialists have been working around the clock to solve this problem, but it appears that the repair will require a replacement of internal parts, which could take several weeks/months and therefore will affect the remaining P88 visitor mode runs as well as possibly some of the P89 runs .
    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).
    If you judge that your program will suffer too much from this pattern, we advise you to reconsider your strategy to use the two bottom quadrants only (i.e. PA, offset pattern, use of mask(s), etc...).
    Do not hesitate to contact the instrument scientists ( about your adapting your program. For current P88 service mode OBs, please contact the USD department (
  • December 20th, 2011: The PHASE-II version of the P89 User Manual is online (now including the template/keyword table). The P88 Calibration Plan is the latest to follow for P89.
  • October 15th, 2011 (beginning of P88): the NACO IOT is pleased to announce that 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 (still VM only for P88-P89). The residual drift of about 1 pix/hour (very much acceptable) can be attributed to an imperfect flexure compensation model.
  • September 1st, 2011: as stated in the P89 call for proposals, UT4 (HAWK-I, NACO and SINFONI) will not be available in April 2012 as preparatory work required for the installation of the Adaptive Optics Facility (AOF) will take place in addition to the planned recoating of the M1. In addition, NACO is currently planned to be decommissioned at the end of P89 or early P90 (october 2012). Proposers for Large Programmes using NACO and/or ISAAC should take their limited availability into account.
  • August 31th, 2011: The PHASE-I version of the P89 User Manual is online (+ template/keywords table). The P88 Calibration Plan is the latest to follow for P89.
  • June 17th, 2011: The PHASE-II version of the P88 User Manual is online (+ template/keywordstable). The P88 Calibration Plan features minor fixes from P87's.
  • April 26th, 2011: all visible WFS (NGS/LGS 7x7, NGS 14x14,LGS 14x14) are back in service! The performance level reached duringrecommissioning is the same as prior to the intervention (on month ago).
  • March 8th, 2011: The PHASE-1 version of the P88 User Manual is online (+ template/keywordstable). The P87 Calibration Plan is the latest to follow for P88.
  • March 7th, 2011: new versions of the P87 User Manual (+ template/keywordstable) and P87 Calibration Plan are online.
  • March 6th, 2011: the 7x7 VIS-WFS (NGS and LGS) is currently not available and for probably a few weeks (please ask the instrument scientists for updates). Other WFS (14x14 VIS, 14x14 IR, 7x7 IR and 14x14 LGS) are available.
  • December 20th, 2010: A version of the P87 User Manual was online but not linked to this page, apologies.
  • March 15th, 2010: new modes are offered in P86 (see call for proposals). The web pages have been updated and the P86 user manual is now available (please check again in May for updated version).
  • Sept 12th, 2009: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.
  • Feb. 27th, 2009:SAMPol and Seeing enhancer are pending commissioning; as soon as this is over the relative information willbe updated on these web pages and on the manual. In the meantime,the last version of the P83 manual should be considered valid for P84 as well.
  • Nov. 15th, 2008: 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. Users have to be aware that there has not yet been time to update the P2PP time calculator. The reported execution times are not correct, especially in the case of cube mode, which is actually much more efficient than normal observations. Visiting astronomers are encouraged to contact the night astronomer to discuss their observing strategies.
  • Oct. 5th, 2008:p82 starts. The new version of the p82 manual has been posted on the web. It is the same as the one offered for Phase1 of P83. The web pages have also been updated with more information on SAM, cube mode and pupil tracking. Interested users are encouraged tocheck the relative web pages on this site (under Instrument Description).
  • June 24th, 2008: p82 phase II officially starts. The new version of the p82 manual has been posted on the web. Among the news:
    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.

      SAM is offered in VM only. Users with approved proposals are encouraged to contact the IS at in advance of theirrun to discuss the details.

    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. There are stringent limitations to theuse of this mode, in particular it will only be offered in combination with basic imaging (no LGS).

      This mode is only offered for VM proposals. Users who requested it are encouraged to contact the IS at inadvance of their run to discuss the details.

    3. Pupil tracking mode for imaging applications (includes 4QPM coronagraphy and SDI+) - Tentatively offered, pending commissioning. We are working on the implementation and preparing final on-sky tests.

      Pupil tracking mode is being implemented to support SAM, but given thedemand from the community, it will be tentatively offered for use withimaging and 4QPM coronagraphic observations. In this mode, thetelescope, 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.

      Given its complexity and novelty, pupil tracking is onlyoffered in VM. Users with approved proposals are encouraged to contactthe IS at in advance of their run to discuss the details.

    4. Chopping in Lp and Mp (imaging) will be offered again inP82'.There are more stringent limitations on the brightness of the AO starand on the size of the chop throw. Check the user's manual for details.
  • March 19th, 2008: 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.
  • February, 2008: 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.
  • December 22, 2007: new version of User's Manual and Web Pages for Phase 2 of P81 publicly released.
  • September 23-24, 2007: commissioned the SDI+4 mode: SDI+ with Coronagraphic 4QPM_H
  • August 24, 2007: News in the Call for Proposals P81
  • August 1, 2007; New IOT settles in.


  • April 03, 2007: Laser guide star facility: observing policies
  • March 15, 2007: Novelties in the Call for Proposal P80
  • February 28, 2006: Novelties in the Call for Proposal P78
  • February 23, 2006: Latest important news about chopping
  • February 16, 2006: Latest news about the SDI


  • June 1, 2005: Important last minute news for service and visitor, concerning the SDI observations.
  • January 6, 2005: Updated user manual for period 75 serviceand visitor mode observation runs.
  • October 21, 2004: Important news for service and visitor, concerning chopping & SDI observations.
  • August 8, 2004: Updated user manual for period 74 serviceand visitor mode observation runs.
  • June 1, 2004: A new Aladdin3 array recently installed in CONICA, becomes operational.





Old News


  • April 03, 2007: Laser guide star facility: observing policies
  • March 15, 2007: Novelties in the Call for Proposal P80
  • February 28, 2006: Novelties in the Call for Proposal P78
  • February 23, 2006: Latest important news about chopping
  • February 16, 2006: Latest news about the SDI
  • June 1, 2005: Important last minute news for service and visitor, concerning the SDI observations.
  • January 6, 2005: Updated user manual for period 75 service and visitor mode observation runs.
  • October 21, 2004: Important news for service and visitor, concerning chopping & SDI observations.
  • August 8, 2004: Updated user manual for period 74 service and visitor mode observation runs.
  • June 1, 2004: A new Aladdin3 array recently installed in CONICA, becomes operational.